--- /dev/null
+/*
+** 2005 December 14
+**
+** The author disclaims copyright to this source code. In place of
+** a legal notice, here is a blessing:
+**
+** May you do good and not evil.
+** May you find forgiveness for yourself and forgive others.
+** May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** $Id: sqlite3async.c,v 1.1 2009/04/23 14:58:40 danielk1977 Exp $
+**
+** This file contains an example implementation of an asynchronous IO
+** backend for SQLite.
+**
+** WHAT IS ASYNCHRONOUS I/O?
+**
+** With asynchronous I/O, write requests are handled by a separate thread
+** running in the background. This means that the thread that initiates
+** a database write does not have to wait for (sometimes slow) disk I/O
+** to occur. The write seems to happen very quickly, though in reality
+** it is happening at its usual slow pace in the background.
+**
+** Asynchronous I/O appears to give better responsiveness, but at a price.
+** You lose the Durable property. With the default I/O backend of SQLite,
+** once a write completes, you know that the information you wrote is
+** safely on disk. With the asynchronous I/O, this is not the case. If
+** your program crashes or if a power loss occurs after the database
+** write but before the asynchronous write thread has completed, then the
+** database change might never make it to disk and the next user of the
+** database might not see your change.
+**
+** You lose Durability with asynchronous I/O, but you still retain the
+** other parts of ACID: Atomic, Consistent, and Isolated. Many
+** appliations get along fine without the Durablity.
+**
+** HOW IT WORKS
+**
+** Asynchronous I/O works by creating a special SQLite "vfs" structure
+** and registering it with sqlite3_vfs_register(). When files opened via
+** this vfs are written to (using sqlite3OsWrite()), the data is not
+** written directly to disk, but is placed in the "write-queue" to be
+** handled by the background thread.
+**
+** When files opened with the asynchronous vfs are read from
+** (using sqlite3OsRead()), the data is read from the file on
+** disk and the write-queue, so that from the point of view of
+** the vfs reader the OsWrite() appears to have already completed.
+**
+** The special vfs is registered (and unregistered) by calls to
+** function asyncEnable() (see below).
+**
+** LIMITATIONS
+**
+** This demonstration code is deliberately kept simple in order to keep
+** the main ideas clear and easy to understand. Real applications that
+** want to do asynchronous I/O might want to add additional capabilities.
+** For example, in this demonstration if writes are happening at a steady
+** stream that exceeds the I/O capability of the background writer thread,
+** the queue of pending write operations will grow without bound until we
+** run out of memory. Users of this technique may want to keep track of
+** the quantity of pending writes and stop accepting new write requests
+** when the buffer gets to be too big.
+**
+** LOCKING + CONCURRENCY
+**
+** Multiple connections from within a single process that use this
+** implementation of asynchronous IO may access a single database
+** file concurrently. From the point of view of the user, if all
+** connections are from within a single process, there is no difference
+** between the concurrency offered by "normal" SQLite and SQLite
+** using the asynchronous backend.
+**
+** If connections from within multiple processes may access the
+** database file, the ENABLE_FILE_LOCKING symbol (see below) must be
+** defined. If it is not defined, then no locks are established on
+** the database file. In this case, if multiple processes access
+** the database file, corruption will quickly result.
+**
+** If ENABLE_FILE_LOCKING is defined (the default), then connections
+** from within multiple processes may access a single database file
+** without risking corruption. However concurrency is reduced as
+** follows:
+**
+** * When a connection using asynchronous IO begins a database
+** transaction, the database is locked immediately. However the
+** lock is not released until after all relevant operations
+** in the write-queue have been flushed to disk. This means
+** (for example) that the database may remain locked for some
+** time after a "COMMIT" or "ROLLBACK" is issued.
+**
+** * If an application using asynchronous IO executes transactions
+** in quick succession, other database users may be effectively
+** locked out of the database. This is because when a BEGIN
+** is executed, a database lock is established immediately. But
+** when the corresponding COMMIT or ROLLBACK occurs, the lock
+** is not released until the relevant part of the write-queue
+** has been flushed through. As a result, if a COMMIT is followed
+** by a BEGIN before the write-queue is flushed through, the database
+** is never unlocked,preventing other processes from accessing
+** the database.
+**
+** Defining ENABLE_FILE_LOCKING when using an NFS or other remote
+** file-system may slow things down, as synchronous round-trips to the
+** server may be required to establish database file locks.
+*/
+
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_ASYNCIO)
+
+#include "sqlite3async.h"
+
+#define ENABLE_FILE_LOCKING
+
+#ifndef SQLITE_AMALGAMATION
+# include "sqliteInt.h"
+# include <assert.h>
+# include <string.h>
+#endif
+
+/* Useful macros used in several places */
+#define MIN(x,y) ((x)<(y)?(x):(y))
+#define MAX(x,y) ((x)>(y)?(x):(y))
+
+/* Forward references */
+typedef struct AsyncWrite AsyncWrite;
+typedef struct AsyncFile AsyncFile;
+typedef struct AsyncFileData AsyncFileData;
+typedef struct AsyncFileLock AsyncFileLock;
+typedef struct AsyncLock AsyncLock;
+
+/* Enable for debugging */
+static int sqlite3async_trace = 0;
+# define ASYNC_TRACE(X) if( sqlite3async_trace ) asyncTrace X
+static void asyncTrace(const char *zFormat, ...){
+ char *z;
+ va_list ap;
+ va_start(ap, zFormat);
+ z = sqlite3_vmprintf(zFormat, ap);
+ va_end(ap);
+ fprintf(stderr, "[%d] %s", 0 /* (int)pthread_self() */, z);
+ sqlite3_free(z);
+}
+
+/*
+** THREAD SAFETY NOTES
+**
+** Basic rules:
+**
+** * Both read and write access to the global write-op queue must be
+** protected by the async.queueMutex. As are the async.ioError and
+** async.nFile variables.
+**
+** * The async.pLock list and all AsyncLock and AsyncFileLock
+** structures must be protected by the async.lockMutex mutex.
+**
+** * The file handles from the underlying system are not assumed to
+** be thread safe.
+**
+** * See the last two paragraphs under "The Writer Thread" for
+** an assumption to do with file-handle synchronization by the Os.
+**
+** Deadlock prevention:
+**
+** There are three mutex used by the system: the "writer" mutex,
+** the "queue" mutex and the "lock" mutex. Rules are:
+**
+** * It is illegal to block on the writer mutex when any other mutex
+** are held, and
+**
+** * It is illegal to block on the queue mutex when the lock mutex
+** is held.
+**
+** i.e. mutex's must be grabbed in the order "writer", "queue", "lock".
+**
+** File system operations (invoked by SQLite thread):
+**
+** xOpen
+** xDelete
+** xFileExists
+**
+** File handle operations (invoked by SQLite thread):
+**
+** asyncWrite, asyncClose, asyncTruncate, asyncSync
+**
+** The operations above add an entry to the global write-op list. They
+** prepare the entry, acquire the async.queueMutex momentarily while
+** list pointers are manipulated to insert the new entry, then release
+** the mutex and signal the writer thread to wake up in case it happens
+** to be asleep.
+**
+**
+** asyncRead, asyncFileSize.
+**
+** Read operations. Both of these read from both the underlying file
+** first then adjust their result based on pending writes in the
+** write-op queue. So async.queueMutex is held for the duration
+** of these operations to prevent other threads from changing the
+** queue in mid operation.
+**
+**
+** asyncLock, asyncUnlock, asyncCheckReservedLock
+**
+** These primitives implement in-process locking using a hash table
+** on the file name. Files are locked correctly for connections coming
+** from the same process. But other processes cannot see these locks
+** and will therefore not honor them.
+**
+**
+** The writer thread:
+**
+** The async.writerMutex is used to make sure only there is only
+** a single writer thread running at a time.
+**
+** Inside the writer thread is a loop that works like this:
+**
+** WHILE (write-op list is not empty)
+** Do IO operation at head of write-op list
+** Remove entry from head of write-op list
+** END WHILE
+**
+** The async.queueMutex is always held during the <write-op list is
+** not empty> test, and when the entry is removed from the head
+** of the write-op list. Sometimes it is held for the interim
+** period (while the IO is performed), and sometimes it is
+** relinquished. It is relinquished if (a) the IO op is an
+** ASYNC_CLOSE or (b) when the file handle was opened, two of
+** the underlying systems handles were opened on the same
+** file-system entry.
+**
+** If condition (b) above is true, then one file-handle
+** (AsyncFile.pBaseRead) is used exclusively by sqlite threads to read the
+** file, the other (AsyncFile.pBaseWrite) by sqlite3_async_flush()
+** threads to perform write() operations. This means that read
+** operations are not blocked by asynchronous writes (although
+** asynchronous writes may still be blocked by reads).
+**
+** This assumes that the OS keeps two handles open on the same file
+** properly in sync. That is, any read operation that starts after a
+** write operation on the same file system entry has completed returns
+** data consistent with the write. We also assume that if one thread
+** reads a file while another is writing it all bytes other than the
+** ones actually being written contain valid data.
+**
+** If the above assumptions are not true, set the preprocessor symbol
+** SQLITE_ASYNC_TWO_FILEHANDLES to 0.
+*/
+
+
+#ifndef NDEBUG
+# define TESTONLY( X ) X
+#else
+# define TESTONLY( X )
+#endif
+
+/*
+** There are two definitions of the following functions. One for pthreads
+** compatible systems and one for Win32. These functions isolate the OS
+** specific code required by each platform.
+**
+** The system uses three mutexes and a single condition variable. To
+** block on a mutex, async_mutex_enter() is called. The parameter passed
+** to async_mutex_enter(), which must be one of ASYNC_MUTEX_LOCK,
+** ASYNC_MUTEX_QUEUE or ASYNC_MUTEX_WRITER, identifies which of the three
+** mutexes to lock. Similarly, to unlock a mutex, async_mutex_leave() is
+** called with a parameter identifying the mutex being unlocked. Mutexes
+** are not recursive - it is an error to call async_mutex_enter() to
+** lock a mutex that is already locked, or to call async_mutex_leave()
+** to unlock a mutex that is not currently locked.
+**
+** The async_cond_wait() and async_cond_signal() functions are modelled
+** on the pthreads functions with similar names. The first parameter to
+** both functions is always ASYNC_COND_QUEUE. When async_cond_wait()
+** is called the mutex identified by the second parameter must be held.
+** The mutex is unlocked, and the calling thread simultaneously begins
+** waiting for the condition variable to be signalled by another thread.
+** After another thread signals the condition variable, the calling
+** thread stops waiting, locks mutex eMutex and returns. The
+** async_cond_signal() function is used to signal the condition variable.
+** It is assumed that the mutex used by the thread calling async_cond_wait()
+** is held by the caller of async_cond_signal() (otherwise there would be
+** a race condition).
+**
+** It is guaranteed that no other thread will call async_cond_wait() when
+** there is already a thread waiting on the condition variable.
+**
+** The async_sched_yield() function is called to suggest to the operating
+** system that it would be a good time to shift the current thread off the
+** CPU. The system will still work if this function is not implemented
+** (it is not currently implemented for win32), but it might be marginally
+** more efficient if it is.
+*/
+static void async_mutex_enter(int eMutex);
+static void async_mutex_leave(int eMutex);
+static void async_cond_wait(int eCond, int eMutex);
+static void async_cond_signal(int eCond);
+static void async_sched_yield(void);
+
+/*
+** There are also two definitions of the following. async_os_initialize()
+** is called when the asynchronous VFS is first installed, and os_shutdown()
+** is called when it is uninstalled (from within sqlite3async_shutdown()).
+**
+** For pthreads builds, both of these functions are no-ops. For win32,
+** they provide an opportunity to initialize and finalize the required
+** mutex and condition variables.
+**
+** If async_os_initialize() returns other than zero, then the initialization
+** fails and SQLITE_ERROR is returned to the user.
+*/
+static int async_os_initialize(void);
+static void async_os_shutdown(void);
+
+/* Values for use as the 'eMutex' argument of the above functions. The
+** integer values assigned to these constants are important for assert()
+** statements that verify that mutexes are locked in the correct order.
+** Specifically, it is unsafe to try to lock mutex N while holding a lock
+** on mutex M if (M<=N).
+*/
+#define ASYNC_MUTEX_LOCK 0
+#define ASYNC_MUTEX_QUEUE 1
+#define ASYNC_MUTEX_WRITER 2
+
+/* Values for use as the 'eCond' argument of the above functions. */
+#define ASYNC_COND_QUEUE 0
+
+/*************************************************************************
+** Start of OS specific code.
+*/
+#if SQLITE_OS_WIN || defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || defined(__MINGW32__) || defined(__BORLANDC__)
+
+/* The following block contains the win32 specific code. */
+
+#define mutex_held(X) (GetCurrentThreadId()==primitives.aHolder[X])
+
+static struct AsyncPrimitives {
+ int isInit;
+ DWORD aHolder[3];
+ CRITICAL_SECTION aMutex[3];
+ HANDLE aCond[1];
+} primitives = { 0 };
+
+static int async_os_initialize(void){
+ if( !primitives.isInit ){
+ primitives.aCond[0] = CreateEvent(NULL, TRUE, FALSE, 0);
+ if( primitives.aCond[0]==NULL ){
+ return 1;
+ }
+ InitializeCriticalSection(&primitives.aMutex[0]);
+ InitializeCriticalSection(&primitives.aMutex[1]);
+ InitializeCriticalSection(&primitives.aMutex[2]);
+ primitives.isInit = 1;
+ }
+ return 0;
+}
+static void async_os_shutdown(void){
+ if( primitives.isInit ){
+ DeleteCriticalSection(&primitives.aMutex[0]);
+ DeleteCriticalSection(&primitives.aMutex[1]);
+ DeleteCriticalSection(&primitives.aMutex[2]);
+ CloseHandle(primitives.aCond[0]);
+ primitives.isInit = 0;
+ }
+}
+
+/* The following block contains the Win32 specific code. */
+static void async_mutex_enter(int eMutex){
+ assert( eMutex==0 || eMutex==1 || eMutex==2 );
+ assert( eMutex!=2 || (!mutex_held(0) && !mutex_held(1) && !mutex_held(2)) );
+ assert( eMutex!=1 || (!mutex_held(0) && !mutex_held(1)) );
+ assert( eMutex!=0 || (!mutex_held(0)) );
+ EnterCriticalSection(&primitives.aMutex[eMutex]);
+ TESTONLY( primitives.aHolder[eMutex] = GetCurrentThreadId(); )
+}
+static void async_mutex_leave(int eMutex){
+ assert( eMutex==0 || eMutex==1 || eMutex==2 );
+ assert( mutex_held(eMutex) );
+ TESTONLY( primitives.aHolder[eMutex] = 0; )
+ LeaveCriticalSection(&primitives.aMutex[eMutex]);
+}
+static void async_cond_wait(int eCond, int eMutex){
+ ResetEvent(primitives.aCond[eCond]);
+ async_mutex_leave(eMutex);
+ WaitForSingleObject(primitives.aCond[eCond], INFINITE);
+ async_mutex_enter(eMutex);
+}
+static void async_cond_signal(int eCond){
+ assert( mutex_held(ASYNC_MUTEX_QUEUE) );
+ SetEvent(primitives.aCond[eCond]);
+}
+static void async_sched_yield(void){
+ /* Todo: Find out if win32 offers anything like sched_yield() */
+}
+#else
+
+/* The following block contains the pthreads specific code. */
+#include <pthread.h>
+#include <sched.h>
+
+#define mutex_held(X) pthread_equal(primitives.aHolder[X], pthread_self())
+
+static int async_os_initialize(void) {return 0;}
+static void async_os_shutdown(void) {}
+
+static struct AsyncPrimitives {
+ pthread_mutex_t aMutex[3];
+ pthread_cond_t aCond[1];
+ pthread_t aHolder[3];
+} primitives = {
+ { PTHREAD_MUTEX_INITIALIZER,
+ PTHREAD_MUTEX_INITIALIZER,
+ PTHREAD_MUTEX_INITIALIZER
+ } , {
+ PTHREAD_COND_INITIALIZER
+ } , { 0, 0, 0 }
+};
+
+static void async_mutex_enter(int eMutex){
+ assert( eMutex==0 || eMutex==1 || eMutex==2 );
+ assert( eMutex!=2 || (!mutex_held(0) && !mutex_held(1) && !mutex_held(2)) );
+ assert( eMutex!=1 || (!mutex_held(0) && !mutex_held(1)) );
+ assert( eMutex!=0 || (!mutex_held(0)) );
+ pthread_mutex_lock(&primitives.aMutex[eMutex]);
+ TESTONLY( primitives.aHolder[eMutex] = pthread_self(); )
+}
+static void async_mutex_leave(int eMutex){
+ assert( eMutex==0 || eMutex==1 || eMutex==2 );
+ assert( mutex_held(eMutex) );
+ TESTONLY( primitives.aHolder[eMutex] = 0; )
+ pthread_mutex_unlock(&primitives.aMutex[eMutex]);
+}
+static void async_cond_wait(int eCond, int eMutex){
+ assert( eMutex==0 || eMutex==1 || eMutex==2 );
+ assert( mutex_held(eMutex) );
+ TESTONLY( primitives.aHolder[eMutex] = 0; )
+ pthread_cond_wait(&primitives.aCond[eCond], &primitives.aMutex[eMutex]);
+ TESTONLY( primitives.aHolder[eMutex] = pthread_self(); )
+}
+static void async_cond_signal(int eCond){
+ assert( mutex_held(ASYNC_MUTEX_QUEUE) );
+ pthread_cond_signal(&primitives.aCond[eCond]);
+}
+static void async_sched_yield(void){
+ sched_yield();
+}
+#endif
+/*
+** End of OS specific code.
+*************************************************************************/
+
+#define assert_mutex_is_held(X) assert( mutex_held(X) )
+
+
+#ifndef SQLITE_ASYNC_TWO_FILEHANDLES
+/* #define SQLITE_ASYNC_TWO_FILEHANDLES 0 */
+#define SQLITE_ASYNC_TWO_FILEHANDLES 1
+#endif
+
+/*
+** State information is held in the static variable "async" defined
+** as the following structure.
+**
+** Both async.ioError and async.nFile are protected by async.queueMutex.
+*/
+static struct TestAsyncStaticData {
+ AsyncWrite *pQueueFirst; /* Next write operation to be processed */
+ AsyncWrite *pQueueLast; /* Last write operation on the list */
+ AsyncLock *pLock; /* Linked list of all AsyncLock structures */
+ volatile int ioDelay; /* Extra delay between write operations */
+ volatile int eHalt; /* One of the SQLITEASYNC_HALT_XXX values */
+ int ioError; /* True if an IO error has occurred */
+ int nFile; /* Number of open files (from sqlite pov) */
+} async = { 0,0,0,0,0,0,0 };
+
+/* Possible values of AsyncWrite.op */
+#define ASYNC_NOOP 0
+#define ASYNC_WRITE 1
+#define ASYNC_SYNC 2
+#define ASYNC_TRUNCATE 3
+#define ASYNC_CLOSE 4
+#define ASYNC_DELETE 5
+#define ASYNC_OPENEXCLUSIVE 6
+#define ASYNC_UNLOCK 7
+
+/* Names of opcodes. Used for debugging only.
+** Make sure these stay in sync with the macros above!
+*/
+static const char *azOpcodeName[] = {
+ "NOOP", "WRITE", "SYNC", "TRUNCATE", "CLOSE", "DELETE", "OPENEX", "UNLOCK"
+};
+
+/*
+** Entries on the write-op queue are instances of the AsyncWrite
+** structure, defined here.
+**
+** The interpretation of the iOffset and nByte variables varies depending
+** on the value of AsyncWrite.op:
+**
+** ASYNC_NOOP:
+** No values used.
+**
+** ASYNC_WRITE:
+** iOffset -> Offset in file to write to.
+** nByte -> Number of bytes of data to write (pointed to by zBuf).
+**
+** ASYNC_SYNC:
+** nByte -> flags to pass to sqlite3OsSync().
+**
+** ASYNC_TRUNCATE:
+** iOffset -> Size to truncate file to.
+** nByte -> Unused.
+**
+** ASYNC_CLOSE:
+** iOffset -> Unused.
+** nByte -> Unused.
+**
+** ASYNC_DELETE:
+** iOffset -> Contains the "syncDir" flag.
+** nByte -> Number of bytes of zBuf points to (file name).
+**
+** ASYNC_OPENEXCLUSIVE:
+** iOffset -> Value of "delflag".
+** nByte -> Number of bytes of zBuf points to (file name).
+**
+** ASYNC_UNLOCK:
+** nByte -> Argument to sqlite3OsUnlock().
+**
+**
+** For an ASYNC_WRITE operation, zBuf points to the data to write to the file.
+** This space is sqlite3_malloc()d along with the AsyncWrite structure in a
+** single blob, so is deleted when sqlite3_free() is called on the parent
+** structure.
+*/
+struct AsyncWrite {
+ AsyncFileData *pFileData; /* File to write data to or sync */
+ int op; /* One of ASYNC_xxx etc. */
+ sqlite_int64 iOffset; /* See above */
+ int nByte; /* See above */
+ char *zBuf; /* Data to write to file (or NULL if op!=ASYNC_WRITE) */
+ AsyncWrite *pNext; /* Next write operation (to any file) */
+};
+
+/*
+** An instance of this structure is created for each distinct open file
+** (i.e. if two handles are opened on the one file, only one of these
+** structures is allocated) and stored in the async.aLock hash table. The
+** keys for async.aLock are the full pathnames of the opened files.
+**
+** AsyncLock.pList points to the head of a linked list of AsyncFileLock
+** structures, one for each handle currently open on the file.
+**
+** If the opened file is not a main-database (the SQLITE_OPEN_MAIN_DB is
+** not passed to the sqlite3OsOpen() call), or if ENABLE_FILE_LOCKING is
+** not defined at compile time, variables AsyncLock.pFile and
+** AsyncLock.eLock are never used. Otherwise, pFile is a file handle
+** opened on the file in question and used to obtain the file-system
+** locks required by database connections within this process.
+**
+** See comments above the asyncLock() function for more details on
+** the implementation of database locking used by this backend.
+*/
+struct AsyncLock {
+ char *zFile;
+ int nFile;
+ sqlite3_file *pFile;
+ int eLock;
+ AsyncFileLock *pList;
+ AsyncLock *pNext; /* Next in linked list headed by async.pLock */
+};
+
+/*
+** An instance of the following structure is allocated along with each
+** AsyncFileData structure (see AsyncFileData.lock), but is only used if the
+** file was opened with the SQLITE_OPEN_MAIN_DB.
+*/
+struct AsyncFileLock {
+ int eLock; /* Internally visible lock state (sqlite pov) */
+ int eAsyncLock; /* Lock-state with write-queue unlock */
+ AsyncFileLock *pNext;
+};
+
+/*
+** The AsyncFile structure is a subclass of sqlite3_file used for
+** asynchronous IO.
+**
+** All of the actual data for the structure is stored in the structure
+** pointed to by AsyncFile.pData, which is allocated as part of the
+** sqlite3OsOpen() using sqlite3_malloc(). The reason for this is that the
+** lifetime of the AsyncFile structure is ended by the caller after OsClose()
+** is called, but the data in AsyncFileData may be required by the
+** writer thread after that point.
+*/
+struct AsyncFile {
+ sqlite3_io_methods *pMethod;
+ AsyncFileData *pData;
+};
+struct AsyncFileData {
+ char *zName; /* Underlying OS filename - used for debugging */
+ int nName; /* Number of characters in zName */
+ sqlite3_file *pBaseRead; /* Read handle to the underlying Os file */
+ sqlite3_file *pBaseWrite; /* Write handle to the underlying Os file */
+ AsyncFileLock lock; /* Lock state for this handle */
+ AsyncLock *pLock; /* AsyncLock object for this file system entry */
+ AsyncWrite closeOp; /* Preallocated close operation */
+};
+
+/*
+** Add an entry to the end of the global write-op list. pWrite should point
+** to an AsyncWrite structure allocated using sqlite3_malloc(). The writer
+** thread will call sqlite3_free() to free the structure after the specified
+** operation has been completed.
+**
+** Once an AsyncWrite structure has been added to the list, it becomes the
+** property of the writer thread and must not be read or modified by the
+** caller.
+*/
+static void addAsyncWrite(AsyncWrite *pWrite){
+ /* We must hold the queue mutex in order to modify the queue pointers */
+ if( pWrite->op!=ASYNC_UNLOCK ){
+ async_mutex_enter(ASYNC_MUTEX_QUEUE);
+ }
+
+ /* Add the record to the end of the write-op queue */
+ assert( !pWrite->pNext );
+ if( async.pQueueLast ){
+ assert( async.pQueueFirst );
+ async.pQueueLast->pNext = pWrite;
+ }else{
+ async.pQueueFirst = pWrite;
+ }
+ async.pQueueLast = pWrite;
+ ASYNC_TRACE(("PUSH %p (%s %s %d)\n", pWrite, azOpcodeName[pWrite->op],
+ pWrite->pFileData ? pWrite->pFileData->zName : "-", pWrite->iOffset));
+
+ if( pWrite->op==ASYNC_CLOSE ){
+ async.nFile--;
+ }
+
+ /* The writer thread might have been idle because there was nothing
+ ** on the write-op queue for it to do. So wake it up. */
+ async_cond_signal(ASYNC_COND_QUEUE);
+
+ /* Drop the queue mutex */
+ if( pWrite->op!=ASYNC_UNLOCK ){
+ async_mutex_leave(ASYNC_MUTEX_QUEUE);
+ }
+}
+
+/*
+** Increment async.nFile in a thread-safe manner.
+*/
+static void incrOpenFileCount(void){
+ /* We must hold the queue mutex in order to modify async.nFile */
+ async_mutex_enter(ASYNC_MUTEX_QUEUE);
+ if( async.nFile==0 ){
+ async.ioError = SQLITE_OK;
+ }
+ async.nFile++;
+ async_mutex_leave(ASYNC_MUTEX_QUEUE);
+}
+
+/*
+** This is a utility function to allocate and populate a new AsyncWrite
+** structure and insert it (via addAsyncWrite() ) into the global list.
+*/
+static int addNewAsyncWrite(
+ AsyncFileData *pFileData,
+ int op,
+ sqlite3_int64 iOffset,
+ int nByte,
+ const char *zByte
+){
+ AsyncWrite *p;
+ if( op!=ASYNC_CLOSE && async.ioError ){
+ return async.ioError;
+ }
+ p = sqlite3_malloc(sizeof(AsyncWrite) + (zByte?nByte:0));
+ if( !p ){
+ /* The upper layer does not expect operations like OsWrite() to
+ ** return SQLITE_NOMEM. This is partly because under normal conditions
+ ** SQLite is required to do rollback without calling malloc(). So
+ ** if malloc() fails here, treat it as an I/O error. The above
+ ** layer knows how to handle that.
+ */
+ return SQLITE_IOERR;
+ }
+ p->op = op;
+ p->iOffset = iOffset;
+ p->nByte = nByte;
+ p->pFileData = pFileData;
+ p->pNext = 0;
+ if( zByte ){
+ p->zBuf = (char *)&p[1];
+ memcpy(p->zBuf, zByte, nByte);
+ }else{
+ p->zBuf = 0;
+ }
+ addAsyncWrite(p);
+ return SQLITE_OK;
+}
+
+/*
+** Close the file. This just adds an entry to the write-op list, the file is
+** not actually closed.
+*/
+static int asyncClose(sqlite3_file *pFile){
+ AsyncFileData *p = ((AsyncFile *)pFile)->pData;
+
+ /* Unlock the file, if it is locked */
+ async_mutex_enter(ASYNC_MUTEX_LOCK);
+ p->lock.eLock = 0;
+ async_mutex_leave(ASYNC_MUTEX_LOCK);
+
+ addAsyncWrite(&p->closeOp);
+ return SQLITE_OK;
+}
+
+/*
+** Implementation of sqlite3OsWrite() for asynchronous files. Instead of
+** writing to the underlying file, this function adds an entry to the end of
+** the global AsyncWrite list. Either SQLITE_OK or SQLITE_NOMEM may be
+** returned.
+*/
+static int asyncWrite(
+ sqlite3_file *pFile,
+ const void *pBuf,
+ int amt,
+ sqlite3_int64 iOff
+){
+ AsyncFileData *p = ((AsyncFile *)pFile)->pData;
+ return addNewAsyncWrite(p, ASYNC_WRITE, iOff, amt, pBuf);
+}
+
+/*
+** Read data from the file. First we read from the filesystem, then adjust
+** the contents of the buffer based on ASYNC_WRITE operations in the
+** write-op queue.
+**
+** This method holds the mutex from start to finish.
+*/
+static int asyncRead(
+ sqlite3_file *pFile,
+ void *zOut,
+ int iAmt,
+ sqlite3_int64 iOffset
+){
+ AsyncFileData *p = ((AsyncFile *)pFile)->pData;
+ int rc = SQLITE_OK;
+ sqlite3_int64 filesize;
+ int nRead;
+ sqlite3_file *pBase = p->pBaseRead;
+
+ /* Grab the write queue mutex for the duration of the call */
+ async_mutex_enter(ASYNC_MUTEX_QUEUE);
+
+ /* If an I/O error has previously occurred in this virtual file
+ ** system, then all subsequent operations fail.
+ */
+ if( async.ioError!=SQLITE_OK ){
+ rc = async.ioError;
+ goto asyncread_out;
+ }
+
+ if( pBase->pMethods ){
+ rc = pBase->pMethods->xFileSize(pBase, &filesize);
+ if( rc!=SQLITE_OK ){
+ goto asyncread_out;
+ }
+ nRead = MIN(filesize - iOffset, iAmt);
+ if( nRead>0 ){
+ rc = pBase->pMethods->xRead(pBase, zOut, nRead, iOffset);
+ ASYNC_TRACE(("READ %s %d bytes at %d\n", p->zName, nRead, iOffset));
+ }
+ }
+
+ if( rc==SQLITE_OK ){
+ AsyncWrite *pWrite;
+ char *zName = p->zName;
+
+ for(pWrite=async.pQueueFirst; pWrite; pWrite = pWrite->pNext){
+ if( pWrite->op==ASYNC_WRITE && (
+ (pWrite->pFileData==p) ||
+ (zName && pWrite->pFileData->zName==zName)
+ )){
+ int iBeginOut = (pWrite->iOffset-iOffset);
+ int iBeginIn = -iBeginOut;
+ int nCopy;
+
+ if( iBeginIn<0 ) iBeginIn = 0;
+ if( iBeginOut<0 ) iBeginOut = 0;
+ nCopy = MIN(pWrite->nByte-iBeginIn, iAmt-iBeginOut);
+
+ if( nCopy>0 ){
+ memcpy(&((char *)zOut)[iBeginOut], &pWrite->zBuf[iBeginIn], nCopy);
+ ASYNC_TRACE(("OVERREAD %d bytes at %d\n", nCopy, iBeginOut+iOffset));
+ }
+ }
+ }
+ }
+
+asyncread_out:
+ async_mutex_leave(ASYNC_MUTEX_QUEUE);
+ return rc;
+}
+
+/*
+** Truncate the file to nByte bytes in length. This just adds an entry to
+** the write-op list, no IO actually takes place.
+*/
+static int asyncTruncate(sqlite3_file *pFile, sqlite3_int64 nByte){
+ AsyncFileData *p = ((AsyncFile *)pFile)->pData;
+ return addNewAsyncWrite(p, ASYNC_TRUNCATE, nByte, 0, 0);
+}
+
+/*
+** Sync the file. This just adds an entry to the write-op list, the
+** sync() is done later by sqlite3_async_flush().
+*/
+static int asyncSync(sqlite3_file *pFile, int flags){
+ AsyncFileData *p = ((AsyncFile *)pFile)->pData;
+ return addNewAsyncWrite(p, ASYNC_SYNC, 0, flags, 0);
+}
+
+/*
+** Read the size of the file. First we read the size of the file system
+** entry, then adjust for any ASYNC_WRITE or ASYNC_TRUNCATE operations
+** currently in the write-op list.
+**
+** This method holds the mutex from start to finish.
+*/
+int asyncFileSize(sqlite3_file *pFile, sqlite3_int64 *piSize){
+ AsyncFileData *p = ((AsyncFile *)pFile)->pData;
+ int rc = SQLITE_OK;
+ sqlite3_int64 s = 0;
+ sqlite3_file *pBase;
+
+ async_mutex_enter(ASYNC_MUTEX_QUEUE);
+
+ /* Read the filesystem size from the base file. If pBaseRead is NULL, this
+ ** means the file hasn't been opened yet. In this case all relevant data
+ ** must be in the write-op queue anyway, so we can omit reading from the
+ ** file-system.
+ */
+ pBase = p->pBaseRead;
+ if( pBase->pMethods ){
+ rc = pBase->pMethods->xFileSize(pBase, &s);
+ }
+
+ if( rc==SQLITE_OK ){
+ AsyncWrite *pWrite;
+ for(pWrite=async.pQueueFirst; pWrite; pWrite = pWrite->pNext){
+ if( pWrite->op==ASYNC_DELETE
+ && p->zName
+ && strcmp(p->zName, pWrite->zBuf)==0
+ ){
+ s = 0;
+ }else if( pWrite->pFileData && (
+ (pWrite->pFileData==p)
+ || (p->zName && pWrite->pFileData->zName==p->zName)
+ )){
+ switch( pWrite->op ){
+ case ASYNC_WRITE:
+ s = MAX(pWrite->iOffset + (sqlite3_int64)(pWrite->nByte), s);
+ break;
+ case ASYNC_TRUNCATE:
+ s = MIN(s, pWrite->iOffset);
+ break;
+ }
+ }
+ }
+ *piSize = s;
+ }
+ async_mutex_leave(ASYNC_MUTEX_QUEUE);
+ return rc;
+}
+
+/*
+** Lock or unlock the actual file-system entry.
+*/
+static int getFileLock(AsyncLock *pLock){
+ int rc = SQLITE_OK;
+ AsyncFileLock *pIter;
+ int eRequired = 0;
+
+ if( pLock->pFile ){
+ for(pIter=pLock->pList; pIter; pIter=pIter->pNext){
+ assert(pIter->eAsyncLock>=pIter->eLock);
+ if( pIter->eAsyncLock>eRequired ){
+ eRequired = pIter->eAsyncLock;
+ assert(eRequired>=0 && eRequired<=SQLITE_LOCK_EXCLUSIVE);
+ }
+ }
+
+ if( eRequired>pLock->eLock ){
+ rc = pLock->pFile->pMethods->xLock(pLock->pFile, eRequired);
+ if( rc==SQLITE_OK ){
+ pLock->eLock = eRequired;
+ }
+ }
+ else if( eRequired<pLock->eLock && eRequired<=SQLITE_LOCK_SHARED ){
+ rc = pLock->pFile->pMethods->xUnlock(pLock->pFile, eRequired);
+ if( rc==SQLITE_OK ){
+ pLock->eLock = eRequired;
+ }
+ }
+ }
+
+ return rc;
+}
+
+/*
+** Return the AsyncLock structure from the global async.pLock list
+** associated with the file-system entry identified by path zName
+** (a string of nName bytes). If no such structure exists, return 0.
+*/
+static AsyncLock *findLock(const char *zName, int nName){
+ AsyncLock *p = async.pLock;
+ while( p && (p->nFile!=nName || memcmp(p->zFile, zName, nName)) ){
+ p = p->pNext;
+ }
+ return p;
+}
+
+/*
+** The following two methods - asyncLock() and asyncUnlock() - are used
+** to obtain and release locks on database files opened with the
+** asynchronous backend.
+*/
+static int asyncLock(sqlite3_file *pFile, int eLock){
+ int rc = SQLITE_OK;
+ AsyncFileData *p = ((AsyncFile *)pFile)->pData;
+
+ if( p->zName ){
+ async_mutex_enter(ASYNC_MUTEX_LOCK);
+ if( p->lock.eLock<eLock ){
+ AsyncLock *pLock = p->pLock;
+ AsyncFileLock *pIter;
+ assert(pLock && pLock->pList);
+ for(pIter=pLock->pList; pIter; pIter=pIter->pNext){
+ if( pIter!=&p->lock && (
+ (eLock==SQLITE_LOCK_EXCLUSIVE && pIter->eLock>=SQLITE_LOCK_SHARED) ||
+ (eLock==SQLITE_LOCK_PENDING && pIter->eLock>=SQLITE_LOCK_RESERVED) ||
+ (eLock==SQLITE_LOCK_RESERVED && pIter->eLock>=SQLITE_LOCK_RESERVED) ||
+ (eLock==SQLITE_LOCK_SHARED && pIter->eLock>=SQLITE_LOCK_PENDING)
+ )){
+ rc = SQLITE_BUSY;
+ }
+ }
+ if( rc==SQLITE_OK ){
+ p->lock.eLock = eLock;
+ p->lock.eAsyncLock = MAX(p->lock.eAsyncLock, eLock);
+ }
+ assert(p->lock.eAsyncLock>=p->lock.eLock);
+ if( rc==SQLITE_OK ){
+ rc = getFileLock(pLock);
+ }
+ }
+ async_mutex_leave(ASYNC_MUTEX_LOCK);
+ }
+
+ ASYNC_TRACE(("LOCK %d (%s) rc=%d\n", eLock, p->zName, rc));
+ return rc;
+}
+static int asyncUnlock(sqlite3_file *pFile, int eLock){
+ int rc = SQLITE_OK;
+ AsyncFileData *p = ((AsyncFile *)pFile)->pData;
+ if( p->zName ){
+ AsyncFileLock *pLock = &p->lock;
+ async_mutex_enter(ASYNC_MUTEX_QUEUE);
+ async_mutex_enter(ASYNC_MUTEX_LOCK);
+ pLock->eLock = MIN(pLock->eLock, eLock);
+ rc = addNewAsyncWrite(p, ASYNC_UNLOCK, 0, eLock, 0);
+ async_mutex_leave(ASYNC_MUTEX_LOCK);
+ async_mutex_leave(ASYNC_MUTEX_QUEUE);
+ }
+ return rc;
+}
+
+/*
+** This function is called when the pager layer first opens a database file
+** and is checking for a hot-journal.
+*/
+static int asyncCheckReservedLock(sqlite3_file *pFile, int *pResOut){
+ int ret = 0;
+ AsyncFileLock *pIter;
+ AsyncFileData *p = ((AsyncFile *)pFile)->pData;
+
+ async_mutex_enter(ASYNC_MUTEX_LOCK);
+ for(pIter=p->pLock->pList; pIter; pIter=pIter->pNext){
+ if( pIter->eLock>=SQLITE_LOCK_RESERVED ){
+ ret = 1;
+ }
+ }
+ async_mutex_leave(ASYNC_MUTEX_LOCK);
+
+ ASYNC_TRACE(("CHECK-LOCK %d (%s)\n", ret, p->zName));
+ *pResOut = ret;
+ return SQLITE_OK;
+}
+
+/*
+** sqlite3_file_control() implementation.
+*/
+static int asyncFileControl(sqlite3_file *id, int op, void *pArg){
+ switch( op ){
+ case SQLITE_FCNTL_LOCKSTATE: {
+ async_mutex_enter(ASYNC_MUTEX_LOCK);
+ *(int*)pArg = ((AsyncFile*)id)->pData->lock.eLock;
+ async_mutex_leave(ASYNC_MUTEX_LOCK);
+ return SQLITE_OK;
+ }
+ }
+ return SQLITE_ERROR;
+}
+
+/*
+** Return the device characteristics and sector-size of the device. It
+** is not tricky to implement these correctly, as this backend might
+** not have an open file handle at this point.
+*/
+static int asyncSectorSize(sqlite3_file *pFile){
+ return 512;
+}
+static int asyncDeviceCharacteristics(sqlite3_file *pFile){
+ return 0;
+}
+
+static int unlinkAsyncFile(AsyncFileData *pData){
+ AsyncFileLock **ppIter;
+ int rc = SQLITE_OK;
+
+ if( pData->zName ){
+ AsyncLock *pLock = pData->pLock;
+ for(ppIter=&pLock->pList; *ppIter; ppIter=&((*ppIter)->pNext)){
+ if( (*ppIter)==&pData->lock ){
+ *ppIter = pData->lock.pNext;
+ break;
+ }
+ }
+ if( !pLock->pList ){
+ AsyncLock **pp;
+ if( pLock->pFile ){
+ pLock->pFile->pMethods->xClose(pLock->pFile);
+ }
+ for(pp=&async.pLock; *pp!=pLock; pp=&((*pp)->pNext));
+ *pp = pLock->pNext;
+ sqlite3_free(pLock);
+ }else{
+ rc = getFileLock(pLock);
+ }
+ }
+
+ return rc;
+}
+
+/*
+** The parameter passed to this function is a copy of a 'flags' parameter
+** passed to this modules xOpen() method. This function returns true
+** if the file should be opened asynchronously, or false if it should
+** be opened immediately.
+**
+** If the file is to be opened asynchronously, then asyncOpen() will add
+** an entry to the event queue and the file will not actually be opened
+** until the event is processed. Otherwise, the file is opened directly
+** by the caller.
+*/
+static int doAsynchronousOpen(int flags){
+ return (flags&SQLITE_OPEN_CREATE) && (
+ (flags&SQLITE_OPEN_MAIN_JOURNAL) ||
+ (flags&SQLITE_OPEN_TEMP_JOURNAL) ||
+ (flags&SQLITE_OPEN_DELETEONCLOSE)
+ );
+}
+
+/*
+** Open a file.
+*/
+static int asyncOpen(
+ sqlite3_vfs *pAsyncVfs,
+ const char *zName,
+ sqlite3_file *pFile,
+ int flags,
+ int *pOutFlags
+){
+ static sqlite3_io_methods async_methods = {
+ 1, /* iVersion */
+ asyncClose, /* xClose */
+ asyncRead, /* xRead */
+ asyncWrite, /* xWrite */
+ asyncTruncate, /* xTruncate */
+ asyncSync, /* xSync */
+ asyncFileSize, /* xFileSize */
+ asyncLock, /* xLock */
+ asyncUnlock, /* xUnlock */
+ asyncCheckReservedLock, /* xCheckReservedLock */
+ asyncFileControl, /* xFileControl */
+ asyncSectorSize, /* xSectorSize */
+ asyncDeviceCharacteristics /* xDeviceCharacteristics */
+ };
+
+ sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
+ AsyncFile *p = (AsyncFile *)pFile;
+ int nName = 0;
+ int rc = SQLITE_OK;
+ int nByte;
+ AsyncFileData *pData;
+ AsyncLock *pLock = 0;
+ char *z;
+ int isAsyncOpen = doAsynchronousOpen(flags);
+
+ /* If zName is NULL, then the upper layer is requesting an anonymous file */
+ if( zName ){
+ nName = strlen(zName)+1;
+ }
+
+ nByte = (
+ sizeof(AsyncFileData) + /* AsyncFileData structure */
+ 2 * pVfs->szOsFile + /* AsyncFileData.pBaseRead and pBaseWrite */
+ nName /* AsyncFileData.zName */
+ );
+ z = sqlite3_malloc(nByte);
+ if( !z ){
+ return SQLITE_NOMEM;
+ }
+ memset(z, 0, nByte);
+ pData = (AsyncFileData*)z;
+ z += sizeof(pData[0]);
+ pData->pBaseRead = (sqlite3_file*)z;
+ z += pVfs->szOsFile;
+ pData->pBaseWrite = (sqlite3_file*)z;
+ pData->closeOp.pFileData = pData;
+ pData->closeOp.op = ASYNC_CLOSE;
+
+ if( zName ){
+ z += pVfs->szOsFile;
+ pData->zName = z;
+ pData->nName = nName;
+ memcpy(pData->zName, zName, nName);
+ }
+
+ if( !isAsyncOpen ){
+ int flagsout;
+ rc = pVfs->xOpen(pVfs, pData->zName, pData->pBaseRead, flags, &flagsout);
+ if( rc==SQLITE_OK && (flagsout&SQLITE_OPEN_READWRITE) ){
+ rc = pVfs->xOpen(pVfs, pData->zName, pData->pBaseWrite, flags, 0);
+ }
+ if( pOutFlags ){
+ *pOutFlags = flagsout;
+ }
+ }
+
+ async_mutex_enter(ASYNC_MUTEX_LOCK);
+
+ if( zName && rc==SQLITE_OK ){
+ pLock = findLock(pData->zName, pData->nName);
+ if( !pLock ){
+ int nByte = pVfs->szOsFile + sizeof(AsyncLock) + pData->nName + 1;
+ pLock = (AsyncLock *)sqlite3_malloc(nByte);
+ if( pLock ){
+ memset(pLock, 0, nByte);
+#ifdef ENABLE_FILE_LOCKING
+ if( flags&SQLITE_OPEN_MAIN_DB ){
+ pLock->pFile = (sqlite3_file *)&pLock[1];
+ rc = pVfs->xOpen(pVfs, pData->zName, pLock->pFile, flags, 0);
+ if( rc!=SQLITE_OK ){
+ sqlite3_free(pLock);
+ pLock = 0;
+ }
+ }
+#endif
+ if( pLock ){
+ pLock->nFile = pData->nName;
+ pLock->zFile = &((char *)(&pLock[1]))[pVfs->szOsFile];
+ memcpy(pLock->zFile, pData->zName, pLock->nFile);
+ pLock->pNext = async.pLock;
+ async.pLock = pLock;
+ }
+ }else{
+ rc = SQLITE_NOMEM;
+ }
+ }
+ }
+
+ if( rc==SQLITE_OK ){
+ p->pMethod = &async_methods;
+ p->pData = pData;
+
+ /* Link AsyncFileData.lock into the linked list of
+ ** AsyncFileLock structures for this file.
+ */
+ if( zName ){
+ pData->lock.pNext = pLock->pList;
+ pLock->pList = &pData->lock;
+ pData->zName = pLock->zFile;
+ }
+ }else{
+ if( pData->pBaseRead->pMethods ){
+ pData->pBaseRead->pMethods->xClose(pData->pBaseRead);
+ }
+ if( pData->pBaseWrite->pMethods ){
+ pData->pBaseWrite->pMethods->xClose(pData->pBaseWrite);
+ }
+ sqlite3_free(pData);
+ }
+
+ async_mutex_leave(ASYNC_MUTEX_LOCK);
+
+ if( rc==SQLITE_OK ){
+ incrOpenFileCount();
+ pData->pLock = pLock;
+ }
+
+ if( rc==SQLITE_OK && isAsyncOpen ){
+ rc = addNewAsyncWrite(pData, ASYNC_OPENEXCLUSIVE, (sqlite3_int64)flags,0,0);
+ if( rc==SQLITE_OK ){
+ if( pOutFlags ) *pOutFlags = flags;
+ }else{
+ async_mutex_enter(ASYNC_MUTEX_LOCK);
+ unlinkAsyncFile(pData);
+ async_mutex_leave(ASYNC_MUTEX_LOCK);
+ sqlite3_free(pData);
+ }
+ }
+ if( rc!=SQLITE_OK ){
+ p->pMethod = 0;
+ }
+ return rc;
+}
+
+/*
+** Implementation of sqlite3OsDelete. Add an entry to the end of the
+** write-op queue to perform the delete.
+*/
+static int asyncDelete(sqlite3_vfs *pAsyncVfs, const char *z, int syncDir){
+ return addNewAsyncWrite(0, ASYNC_DELETE, syncDir, strlen(z)+1, z);
+}
+
+/*
+** Implementation of sqlite3OsAccess. This method holds the mutex from
+** start to finish.
+*/
+static int asyncAccess(
+ sqlite3_vfs *pAsyncVfs,
+ const char *zName,
+ int flags,
+ int *pResOut
+){
+ int rc;
+ int ret;
+ AsyncWrite *p;
+ sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
+
+ assert(flags==SQLITE_ACCESS_READWRITE
+ || flags==SQLITE_ACCESS_READ
+ || flags==SQLITE_ACCESS_EXISTS
+ );
+
+ async_mutex_enter(ASYNC_MUTEX_QUEUE);
+ rc = pVfs->xAccess(pVfs, zName, flags, &ret);
+ if( rc==SQLITE_OK && flags==SQLITE_ACCESS_EXISTS ){
+ for(p=async.pQueueFirst; p; p = p->pNext){
+ if( p->op==ASYNC_DELETE && 0==strcmp(p->zBuf, zName) ){
+ ret = 0;
+ }else if( p->op==ASYNC_OPENEXCLUSIVE
+ && p->pFileData->zName
+ && 0==strcmp(p->pFileData->zName, zName)
+ ){
+ ret = 1;
+ }
+ }
+ }
+ ASYNC_TRACE(("ACCESS(%s): %s = %d\n",
+ flags==SQLITE_ACCESS_READWRITE?"read-write":
+ flags==SQLITE_ACCESS_READ?"read":"exists"
+ , zName, ret)
+ );
+ async_mutex_leave(ASYNC_MUTEX_QUEUE);
+ *pResOut = ret;
+ return rc;
+}
+
+/*
+** Fill in zPathOut with the full path to the file identified by zPath.
+*/
+static int asyncFullPathname(
+ sqlite3_vfs *pAsyncVfs,
+ const char *zPath,
+ int nPathOut,
+ char *zPathOut
+){
+ int rc;
+ sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
+ rc = pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
+
+ /* Because of the way intra-process file locking works, this backend
+ ** needs to return a canonical path. The following block assumes the
+ ** file-system uses unix style paths.
+ */
+ if( rc==SQLITE_OK ){
+ int i, j;
+ int n = nPathOut;
+ char *z = zPathOut;
+ while( n>1 && z[n-1]=='/' ){ n--; }
+ for(i=j=0; i<n; i++){
+ if( z[i]=='/' ){
+ if( z[i+1]=='/' ) continue;
+ if( z[i+1]=='.' && i+2<n && z[i+2]=='/' ){
+ i += 1;
+ continue;
+ }
+ if( z[i+1]=='.' && i+3<n && z[i+2]=='.' && z[i+3]=='/' ){
+ while( j>0 && z[j-1]!='/' ){ j--; }
+ if( j>0 ){ j--; }
+ i += 2;
+ continue;
+ }
+ }
+ z[j++] = z[i];
+ }
+ z[j] = 0;
+ }
+
+ return rc;
+}
+static void *asyncDlOpen(sqlite3_vfs *pAsyncVfs, const char *zPath){
+ sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
+ return pVfs->xDlOpen(pVfs, zPath);
+}
+static void asyncDlError(sqlite3_vfs *pAsyncVfs, int nByte, char *zErrMsg){
+ sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
+ pVfs->xDlError(pVfs, nByte, zErrMsg);
+}
+static void (*asyncDlSym(
+ sqlite3_vfs *pAsyncVfs,
+ void *pHandle,
+ const char *zSymbol
+))(void){
+ sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
+ return pVfs->xDlSym(pVfs, pHandle, zSymbol);
+}
+static void asyncDlClose(sqlite3_vfs *pAsyncVfs, void *pHandle){
+ sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
+ pVfs->xDlClose(pVfs, pHandle);
+}
+static int asyncRandomness(sqlite3_vfs *pAsyncVfs, int nByte, char *zBufOut){
+ sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
+ return pVfs->xRandomness(pVfs, nByte, zBufOut);
+}
+static int asyncSleep(sqlite3_vfs *pAsyncVfs, int nMicro){
+ sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
+ return pVfs->xSleep(pVfs, nMicro);
+}
+static int asyncCurrentTime(sqlite3_vfs *pAsyncVfs, double *pTimeOut){
+ sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
+ return pVfs->xCurrentTime(pVfs, pTimeOut);
+}
+
+static sqlite3_vfs async_vfs = {
+ 1, /* iVersion */
+ sizeof(AsyncFile), /* szOsFile */
+ 0, /* mxPathname */
+ 0, /* pNext */
+ SQLITEASYNC_VFSNAME, /* zName */
+ 0, /* pAppData */
+ asyncOpen, /* xOpen */
+ asyncDelete, /* xDelete */
+ asyncAccess, /* xAccess */
+ asyncFullPathname, /* xFullPathname */
+ asyncDlOpen, /* xDlOpen */
+ asyncDlError, /* xDlError */
+ asyncDlSym, /* xDlSym */
+ asyncDlClose, /* xDlClose */
+ asyncRandomness, /* xDlError */
+ asyncSleep, /* xDlSym */
+ asyncCurrentTime /* xDlClose */
+};
+
+/*
+** This procedure runs in a separate thread, reading messages off of the
+** write queue and processing them one by one.
+**
+** If async.writerHaltNow is true, then this procedure exits
+** after processing a single message.
+**
+** If async.writerHaltWhenIdle is true, then this procedure exits when
+** the write queue is empty.
+**
+** If both of the above variables are false, this procedure runs
+** indefinately, waiting for operations to be added to the write queue
+** and processing them in the order in which they arrive.
+**
+** An artifical delay of async.ioDelay milliseconds is inserted before
+** each write operation in order to simulate the effect of a slow disk.
+**
+** Only one instance of this procedure may be running at a time.
+*/
+static void asyncWriterThread(void){
+ sqlite3_vfs *pVfs = (sqlite3_vfs *)(async_vfs.pAppData);
+ AsyncWrite *p = 0;
+ int rc = SQLITE_OK;
+ int holdingMutex = 0;
+
+ async_mutex_enter(ASYNC_MUTEX_WRITER);
+
+ while( async.eHalt!=SQLITEASYNC_HALT_NOW ){
+ int doNotFree = 0;
+ sqlite3_file *pBase = 0;
+
+ if( !holdingMutex ){
+ async_mutex_enter(ASYNC_MUTEX_QUEUE);
+ }
+ while( (p = async.pQueueFirst)==0 ){
+ if( async.eHalt!=SQLITEASYNC_HALT_NEVER ){
+ async_mutex_leave(ASYNC_MUTEX_QUEUE);
+ break;
+ }else{
+ ASYNC_TRACE(("IDLE\n"));
+ async_cond_wait(ASYNC_COND_QUEUE, ASYNC_MUTEX_QUEUE);
+ ASYNC_TRACE(("WAKEUP\n"));
+ }
+ }
+ if( p==0 ) break;
+ holdingMutex = 1;
+
+ /* Right now this thread is holding the mutex on the write-op queue.
+ ** Variable 'p' points to the first entry in the write-op queue. In
+ ** the general case, we hold on to the mutex for the entire body of
+ ** the loop.
+ **
+ ** However in the cases enumerated below, we relinquish the mutex,
+ ** perform the IO, and then re-request the mutex before removing 'p' from
+ ** the head of the write-op queue. The idea is to increase concurrency with
+ ** sqlite threads.
+ **
+ ** * An ASYNC_CLOSE operation.
+ ** * An ASYNC_OPENEXCLUSIVE operation. For this one, we relinquish
+ ** the mutex, call the underlying xOpenExclusive() function, then
+ ** re-aquire the mutex before seting the AsyncFile.pBaseRead
+ ** variable.
+ ** * ASYNC_SYNC and ASYNC_WRITE operations, if
+ ** SQLITE_ASYNC_TWO_FILEHANDLES was set at compile time and two
+ ** file-handles are open for the particular file being "synced".
+ */
+ if( async.ioError!=SQLITE_OK && p->op!=ASYNC_CLOSE ){
+ p->op = ASYNC_NOOP;
+ }
+ if( p->pFileData ){
+ pBase = p->pFileData->pBaseWrite;
+ if(
+ p->op==ASYNC_CLOSE ||
+ p->op==ASYNC_OPENEXCLUSIVE ||
+ (pBase->pMethods && (p->op==ASYNC_SYNC || p->op==ASYNC_WRITE) )
+ ){
+ async_mutex_leave(ASYNC_MUTEX_QUEUE);
+ holdingMutex = 0;
+ }
+ if( !pBase->pMethods ){
+ pBase = p->pFileData->pBaseRead;
+ }
+ }
+
+ switch( p->op ){
+ case ASYNC_NOOP:
+ break;
+
+ case ASYNC_WRITE:
+ assert( pBase );
+ ASYNC_TRACE(("WRITE %s %d bytes at %d\n",
+ p->pFileData->zName, p->nByte, p->iOffset));
+ rc = pBase->pMethods->xWrite(pBase, (void *)(p->zBuf), p->nByte, p->iOffset);
+ break;
+
+ case ASYNC_SYNC:
+ assert( pBase );
+ ASYNC_TRACE(("SYNC %s\n", p->pFileData->zName));
+ rc = pBase->pMethods->xSync(pBase, p->nByte);
+ break;
+
+ case ASYNC_TRUNCATE:
+ assert( pBase );
+ ASYNC_TRACE(("TRUNCATE %s to %d bytes\n",
+ p->pFileData->zName, p->iOffset));
+ rc = pBase->pMethods->xTruncate(pBase, p->iOffset);
+ break;
+
+ case ASYNC_CLOSE: {
+ AsyncFileData *pData = p->pFileData;
+ ASYNC_TRACE(("CLOSE %s\n", p->pFileData->zName));
+ if( pData->pBaseWrite->pMethods ){
+ pData->pBaseWrite->pMethods->xClose(pData->pBaseWrite);
+ }
+ if( pData->pBaseRead->pMethods ){
+ pData->pBaseRead->pMethods->xClose(pData->pBaseRead);
+ }
+
+ /* Unlink AsyncFileData.lock from the linked list of AsyncFileLock
+ ** structures for this file. Obtain the async.lockMutex mutex
+ ** before doing so.
+ */
+ async_mutex_enter(ASYNC_MUTEX_LOCK);
+ rc = unlinkAsyncFile(pData);
+ async_mutex_leave(ASYNC_MUTEX_LOCK);
+
+ if( !holdingMutex ){
+ async_mutex_enter(ASYNC_MUTEX_QUEUE);
+ holdingMutex = 1;
+ }
+ assert_mutex_is_held(ASYNC_MUTEX_QUEUE);
+ async.pQueueFirst = p->pNext;
+ sqlite3_free(pData);
+ doNotFree = 1;
+ break;
+ }
+
+ case ASYNC_UNLOCK: {
+ AsyncWrite *pIter;
+ AsyncFileData *pData = p->pFileData;
+ int eLock = p->nByte;
+
+ /* When a file is locked by SQLite using the async backend, it is
+ ** locked within the 'real' file-system synchronously. When it is
+ ** unlocked, an ASYNC_UNLOCK event is added to the write-queue to
+ ** unlock the file asynchronously. The design of the async backend
+ ** requires that the 'real' file-system file be locked from the
+ ** time that SQLite first locks it (and probably reads from it)
+ ** until all asynchronous write events that were scheduled before
+ ** SQLite unlocked the file have been processed.
+ **
+ ** This is more complex if SQLite locks and unlocks the file multiple
+ ** times in quick succession. For example, if SQLite does:
+ **
+ ** lock, write, unlock, lock, write, unlock
+ **
+ ** Each "lock" operation locks the file immediately. Each "write"
+ ** and "unlock" operation adds an event to the event queue. If the
+ ** second "lock" operation is performed before the first "unlock"
+ ** operation has been processed asynchronously, then the first
+ ** "unlock" cannot be safely processed as is, since this would mean
+ ** the file was unlocked when the second "write" operation is
+ ** processed. To work around this, when processing an ASYNC_UNLOCK
+ ** operation, SQLite:
+ **
+ ** 1) Unlocks the file to the minimum of the argument passed to
+ ** the xUnlock() call and the current lock from SQLite's point
+ ** of view, and
+ **
+ ** 2) Only unlocks the file at all if this event is the last
+ ** ASYNC_UNLOCK event on this file in the write-queue.
+ */
+ assert( holdingMutex==1 );
+ assert( async.pQueueFirst==p );
+ for(pIter=async.pQueueFirst->pNext; pIter; pIter=pIter->pNext){
+ if( pIter->pFileData==pData && pIter->op==ASYNC_UNLOCK ) break;
+ }
+ if( !pIter ){
+ async_mutex_enter(ASYNC_MUTEX_LOCK);
+ pData->lock.eAsyncLock = MIN(
+ pData->lock.eAsyncLock, MAX(pData->lock.eLock, eLock)
+ );
+ assert(pData->lock.eAsyncLock>=pData->lock.eLock);
+ rc = getFileLock(pData->pLock);
+ async_mutex_leave(ASYNC_MUTEX_LOCK);
+ }
+ break;
+ }
+
+ case ASYNC_DELETE:
+ ASYNC_TRACE(("DELETE %s\n", p->zBuf));
+ rc = pVfs->xDelete(pVfs, p->zBuf, (int)p->iOffset);
+ break;
+
+ case ASYNC_OPENEXCLUSIVE: {
+ int flags = (int)p->iOffset;
+ AsyncFileData *pData = p->pFileData;
+ ASYNC_TRACE(("OPEN %s flags=%d\n", p->zBuf, (int)p->iOffset));
+ assert(pData->pBaseRead->pMethods==0 && pData->pBaseWrite->pMethods==0);
+ rc = pVfs->xOpen(pVfs, pData->zName, pData->pBaseRead, flags, 0);
+ assert( holdingMutex==0 );
+ async_mutex_enter(ASYNC_MUTEX_QUEUE);
+ holdingMutex = 1;
+ break;
+ }
+
+ default: assert(!"Illegal value for AsyncWrite.op");
+ }
+
+ /* If we didn't hang on to the mutex during the IO op, obtain it now
+ ** so that the AsyncWrite structure can be safely removed from the
+ ** global write-op queue.
+ */
+ if( !holdingMutex ){
+ async_mutex_enter(ASYNC_MUTEX_QUEUE);
+ holdingMutex = 1;
+ }
+ /* ASYNC_TRACE(("UNLINK %p\n", p)); */
+ if( p==async.pQueueLast ){
+ async.pQueueLast = 0;
+ }
+ if( !doNotFree ){
+ assert_mutex_is_held(ASYNC_MUTEX_QUEUE);
+ async.pQueueFirst = p->pNext;
+ sqlite3_free(p);
+ }
+ assert( holdingMutex );
+
+ /* An IO error has occurred. We cannot report the error back to the
+ ** connection that requested the I/O since the error happened
+ ** asynchronously. The connection has already moved on. There
+ ** really is nobody to report the error to.
+ **
+ ** The file for which the error occurred may have been a database or
+ ** journal file. Regardless, none of the currently queued operations
+ ** associated with the same database should now be performed. Nor should
+ ** any subsequently requested IO on either a database or journal file
+ ** handle for the same database be accepted until the main database
+ ** file handle has been closed and reopened.
+ **
+ ** Furthermore, no further IO should be queued or performed on any file
+ ** handle associated with a database that may have been part of a
+ ** multi-file transaction that included the database associated with
+ ** the IO error (i.e. a database ATTACHed to the same handle at some
+ ** point in time).
+ */
+ if( rc!=SQLITE_OK ){
+ async.ioError = rc;
+ }
+
+ if( async.ioError && !async.pQueueFirst ){
+ async_mutex_enter(ASYNC_MUTEX_LOCK);
+ if( 0==async.pLock ){
+ async.ioError = SQLITE_OK;
+ }
+ async_mutex_leave(ASYNC_MUTEX_LOCK);
+ }
+
+ /* Drop the queue mutex before continuing to the next write operation
+ ** in order to give other threads a chance to work with the write queue.
+ */
+ if( !async.pQueueFirst || !async.ioError ){
+ async_mutex_leave(ASYNC_MUTEX_QUEUE);
+ holdingMutex = 0;
+ if( async.ioDelay>0 ){
+ pVfs->xSleep(pVfs, async.ioDelay);
+ }else{
+ async_sched_yield();
+ }
+ }
+ }
+
+ async_mutex_leave(ASYNC_MUTEX_WRITER);
+ return;
+}
+
+/*
+** Install the asynchronous VFS.
+*/
+int sqlite3async_initialize(const char *zParent, int isDefault){
+ int rc = SQLITE_OK;
+ if( async_vfs.pAppData==0 ){
+ sqlite3_vfs *pParent = sqlite3_vfs_find(zParent);
+ if( !pParent || async_os_initialize() ){
+ rc = SQLITE_ERROR;
+ }else if( SQLITE_OK!=(rc = sqlite3_vfs_register(&async_vfs, isDefault)) ){
+ async_os_shutdown();
+ }else{
+ async_vfs.pAppData = (void *)pParent;
+ async_vfs.mxPathname = ((sqlite3_vfs *)async_vfs.pAppData)->mxPathname;
+ }
+ }
+ return rc;
+}
+
+/*
+** Uninstall the asynchronous VFS.
+*/
+void sqlite3async_shutdown(void){
+ if( async_vfs.pAppData ){
+ async_os_shutdown();
+ sqlite3_vfs_unregister((sqlite3_vfs *)&async_vfs);
+ async_vfs.pAppData = 0;
+ }
+}
+
+/*
+** Process events on the write-queue.
+*/
+void sqlite3async_run(void){
+ asyncWriterThread();
+}
+
+/*
+** Control/configure the asynchronous IO system.
+*/
+int sqlite3async_control(int op, ...){
+ va_list ap;
+ va_start(ap, op);
+ switch( op ){
+ case SQLITEASYNC_HALT: {
+ int eWhen = va_arg(ap, int);
+ if( eWhen!=SQLITEASYNC_HALT_NEVER
+ && eWhen!=SQLITEASYNC_HALT_NOW
+ && eWhen!=SQLITEASYNC_HALT_IDLE
+ ){
+ return SQLITE_ERROR;
+ }
+ async.eHalt = eWhen;
+ async_mutex_enter(ASYNC_MUTEX_QUEUE);
+ async_cond_signal(ASYNC_COND_QUEUE);
+ async_mutex_leave(ASYNC_MUTEX_QUEUE);
+ break;
+ }
+
+ case SQLITEASYNC_DELAY: {
+ int iDelay = va_arg(ap, int);
+ async.ioDelay = iDelay;
+ break;
+ }
+
+ case SQLITEASYNC_GET_HALT: {
+ int *peWhen = va_arg(ap, int *);
+ *peWhen = async.eHalt;
+ break;
+ }
+ case SQLITEASYNC_GET_DELAY: {
+ int *piDelay = va_arg(ap, int *);
+ *piDelay = async.ioDelay;
+ break;
+ }
+
+ default:
+ return SQLITE_ERROR;
+ }
+ return SQLITE_OK;
+}
+
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_ASYNCIO) */
+
--- /dev/null
+
+#ifndef __SQLITEASYNC_H_
+#define __SQLITEASYNC_H_ 1
+
+#define SQLITEASYNC_VFSNAME "sqlite3async"
+
+/*
+** Install the asynchronous IO VFS.
+*/
+int sqlite3async_initialize(const char *zParent, int isDefault);
+
+/*
+** Uninstall the asynchronous IO VFS.
+*/
+void sqlite3async_shutdown();
+
+/*
+** Process events on the write-queue.
+*/
+void sqlite3async_run();
+
+/*
+** Control/configure the asynchronous IO system.
+*/
+int sqlite3async_control(int op, ...);
+
+/*
+** Values that can be used as the first argument to sqlite3async_control().
+*/
+#define SQLITEASYNC_HALT 1
+#define SQLITEASYNC_DELAY 2
+#define SQLITEASYNC_GET_HALT 3
+#define SQLITEASYNC_GET_DELAY 4
+
+/*
+** If the first argument to sqlite3async_control() is SQLITEASYNC_HALT,
+** the second argument should be one of the following.
+*/
+#define SQLITEASYNC_HALT_NEVER 0 /* Never halt (default value) */
+#define SQLITEASYNC_HALT_NOW 1 /* Halt as soon as possible */
+#define SQLITEASYNC_HALT_IDLE 2 /* Halt when write-queue is empty */
+
+#endif /* ifndef __SQLITEASYNC_H_ */
+
#
TCCX = $(TCC) $(OPTS) -I. -I$(TOP)/src -I$(TOP)
TCCX += -I$(TOP)/ext/rtree -I$(TOP)/ext/icu -I$(TOP)/ext/fts3
+TCCX += -I$(TOP)/ext/async
# Object files for the SQLite library.
#
$(TOP)/src/utf.c $(TOP)/src/util.c $(TOP)/src/vdbeapi.c $(TOP)/src/vdbeaux.c \
$(TOP)/src/vdbe.c $(TOP)/src/vdbemem.c $(TOP)/src/where.c parse.c \
$(TOP)/ext/fts3/fts3.c $(TOP)/ext/fts3/fts3_expr.c \
- $(TOP)/ext/fts3/fts3_tokenizer.c
+ $(TOP)/ext/fts3/fts3_tokenizer.c \
+ $(TOP)/ext/async/sqlite3async.c
# Header files used by all library source files.
#
-C Rework\sthe\scolumn-cache\smechanism\sto\sbe\smore\srobust\s(and\smore\scorrect).\nThe\scolumn-alias\scache\sis\scurrently\sdisabled,\s(CVS\s6538)
-D 2009-04-23T13:22:43
+C Move\sthe\sasynchronous\sIO\scode\sfrom\ssrc/test_async.c\sto\sext/async/.\sRefactor\sit\sto\sbe\sa\sstandalone\smodule\sand\sto\ssupport\swindows.\s(CVS\s6539)
+D 2009-04-23T14:58:40
F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
F Makefile.in 583e87706abc3026960ed759aff6371faf84c211
F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
F doc/lemon.html f0f682f50210928c07e562621c3b7e8ab912a538
F doc/report1.txt a031aaf37b185e4fa540223cb516d3bccec7eeac
F ext/README.txt 913a7bd3f4837ab14d7e063304181787658b14e1
+F ext/async/sqlite3async.c d59701cc27f8a7a2bf6ffa997af12b32f05633e6
+F ext/async/sqlite3async.h 73d37b60bc37cbd86f836a172fb57a59a7dd2697
F ext/fts1/README.txt 20ac73b006a70bcfd80069bdaf59214b6cf1db5e
F ext/fts1/ft_hash.c 3927bd880e65329bdc6f506555b228b28924921b
F ext/fts1/ft_hash.h 1a35e654a235c2c662d3ca0dfc3138ad60b8b7d5
F ext/rtree/viewrtree.tcl 09526398dae87a5a87c5aac2b3854dbaf8376869
F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895
F ltmain.sh 3ff0879076df340d2e23ae905484d8c15d5fdea8
-F main.mk bbb170882a34fe51dbd2d2e9c450c6cc0dad3325
+F main.mk 8388687358db061fa98f062f8b417b986d8ff3fe
F mkdll.sh 7d09b23c05d56532e9d44a50868eb4b12ff4f74a
F mkextu.sh 416f9b7089d80e5590a29692c9d9280a10dbad9f
F mkextw.sh 4123480947681d9b434a5e7b1ee08135abe409ac
F src/test7.c b94e68c2236de76889d82b8d7d8e00ad6a4d80b1
F src/test8.c b1061548f7ce3aeedea3cc4d649ee1487c2b4eaf
F src/test9.c 963d380922f25c1c323712d05db01b19197ee6f7
-F src/test_async.c 636451da68b7ff4a6d19b266441b2f28790967db
+F src/test_async.c 95c15d9085ea9a837a5c4332a9ae3a8df1afd2cd
F src/test_autoext.c f53b0cdf7bf5f08100009572a5d65cdb540bd0ad
F src/test_backup.c 1384a18985a5a2d275c2662e48473bf1542ebd08
F src/test_btree.c d7b8716544611c323860370ee364e897c861f1b0
F test/indexedby.test 946ca2628a521f4ced0520421a0788345abaf3dc
F test/insert.test aef273dd1cee84cc92407469e6bd1b3cdcb76908
F test/insert2.test 4f3a04d168c728ed5ec2c88842e772606c7ce435
-F test/insert3.test 7188f1da1126eb15f1b27cf34f4c2753c7d5fd27
+F test/insert3.test 1b7db95a03ad9c5013fdf7d6722b6cd66ee55e30
F test/insert4.test 6e382eaf7295a4463e6f29ea20fcd8e63d097eeb
F test/insert5.test 1f93cbe9742110119133d7e8e3ccfe6d7c249766
F test/interrupt.test 42e7cf98646fd9cb4a3b131a93ed3c50b9e149f1
F test/misc6.test 953cc693924d88e6117aeba16f46f0bf5abede91
F test/misc7.test debcd7dbfd847ae97b16ceb7fec6f567902874a6
F test/misuse.test 30b3a458e5a70c31e74c291937b6c82204c59f33
-F test/mutex1.test ebd54720401fafe854799dc86b7bf60b75631935
+F test/mutex1.test 5b71777fc127509cd257910c8db799de557a02de
F test/mutex2.test bfeaeac2e73095b2ac32285d2756e3a65e681660
F test/nan.test c627d79b3d36ea892563fd67584b3e8a18f0618a
F test/notify1.test 533cf60a81f59c1c88a99ce46b1c14f47d14c32c
F test/savepoint6.test e28f7d8ab8a389d4e5bd1dc08bf2c3312754cc67
F test/schema.test deafe5472099ab5bc65748059dc5182fc8ebad74
F test/schema2.test 906408621ea881fdb496d878b1822572a34e32c5
-F test/select1.test 7de2cabb417c142c40e5b8005855b8bd4eedc9e7
+F test/select1.test 041fe01f2a8b7d77ffe77872f7b18ef531b31dfa
F test/select2.test 9735da20ccd41e42bf2b4c19fd939141b591adae
F test/select3.test 2ce595f8fb8e2ac10071d3b4e424cadd4634a054
F test/select4.test 44aa6e7110592e18110b0b9cf5c024d37d23be17
F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
-P ecbef45011f1f98d940b2d3492941213d9f04172
-R 809b7ccefbb8e27249a22441796f79d9
-U drh
-Z 84c7a808c7a31870885d027c8c29d439
+P dd4d67a67454a3ff13c286a2a8360c5f0432c91d
+R 07be84b60f3cf1fb3263cdf9b0c910bb
+U danielk1977
+Z 9ac60e3337f4b3b00edc92808d492861
-dd4d67a67454a3ff13c286a2a8360c5f0432c91d
\ No newline at end of file
+e71fb0fb8d83b4453c3c1e84606bf58d04926809
\ No newline at end of file
**
*************************************************************************
**
-** $Id: test_async.c,v 1.58 2009/04/21 18:20:45 danielk1977 Exp $
+** $Id: test_async.c,v 1.59 2009/04/23 14:58:40 danielk1977 Exp $
**
-** This file contains an example implementation of an asynchronous IO
-** backend for SQLite.
-**
-** WHAT IS ASYNCHRONOUS I/O?
-**
-** With asynchronous I/O, write requests are handled by a separate thread
-** running in the background. This means that the thread that initiates
-** a database write does not have to wait for (sometimes slow) disk I/O
-** to occur. The write seems to happen very quickly, though in reality
-** it is happening at its usual slow pace in the background.
-**
-** Asynchronous I/O appears to give better responsiveness, but at a price.
-** You lose the Durable property. With the default I/O backend of SQLite,
-** once a write completes, you know that the information you wrote is
-** safely on disk. With the asynchronous I/O, this is not the case. If
-** your program crashes or if a power loss occurs after the database
-** write but before the asynchronous write thread has completed, then the
-** database change might never make it to disk and the next user of the
-** database might not see your change.
-**
-** You lose Durability with asynchronous I/O, but you still retain the
-** other parts of ACID: Atomic, Consistent, and Isolated. Many
-** appliations get along fine without the Durablity.
-**
-** HOW IT WORKS
-**
-** Asynchronous I/O works by creating a special SQLite "vfs" structure
-** and registering it with sqlite3_vfs_register(). When files opened via
-** this vfs are written to (using sqlite3OsWrite()), the data is not
-** written directly to disk, but is placed in the "write-queue" to be
-** handled by the background thread.
-**
-** When files opened with the asynchronous vfs are read from
-** (using sqlite3OsRead()), the data is read from the file on
-** disk and the write-queue, so that from the point of view of
-** the vfs reader the OsWrite() appears to have already completed.
-**
-** The special vfs is registered (and unregistered) by calls to
-** function asyncEnable() (see below).
-**
-** LIMITATIONS
-**
-** This demonstration code is deliberately kept simple in order to keep
-** the main ideas clear and easy to understand. Real applications that
-** want to do asynchronous I/O might want to add additional capabilities.
-** For example, in this demonstration if writes are happening at a steady
-** stream that exceeds the I/O capability of the background writer thread,
-** the queue of pending write operations will grow without bound until we
-** run out of memory. Users of this technique may want to keep track of
-** the quantity of pending writes and stop accepting new write requests
-** when the buffer gets to be too big.
-**
-** LOCKING + CONCURRENCY
-**
-** Multiple connections from within a single process that use this
-** implementation of asynchronous IO may access a single database
-** file concurrently. From the point of view of the user, if all
-** connections are from within a single process, there is no difference
-** between the concurrency offered by "normal" SQLite and SQLite
-** using the asynchronous backend.
-**
-** If connections from within multiple processes may access the
-** database file, the ENABLE_FILE_LOCKING symbol (see below) must be
-** defined. If it is not defined, then no locks are established on
-** the database file. In this case, if multiple processes access
-** the database file, corruption will quickly result.
-**
-** If ENABLE_FILE_LOCKING is defined (the default), then connections
-** from within multiple processes may access a single database file
-** without risking corruption. However concurrency is reduced as
-** follows:
-**
-** * When a connection using asynchronous IO begins a database
-** transaction, the database is locked immediately. However the
-** lock is not released until after all relevant operations
-** in the write-queue have been flushed to disk. This means
-** (for example) that the database may remain locked for some
-** time after a "COMMIT" or "ROLLBACK" is issued.
-**
-** * If an application using asynchronous IO executes transactions
-** in quick succession, other database users may be effectively
-** locked out of the database. This is because when a BEGIN
-** is executed, a database lock is established immediately. But
-** when the corresponding COMMIT or ROLLBACK occurs, the lock
-** is not released until the relevant part of the write-queue
-** has been flushed through. As a result, if a COMMIT is followed
-** by a BEGIN before the write-queue is flushed through, the database
-** is never unlocked,preventing other processes from accessing
-** the database.
-**
-** Defining ENABLE_FILE_LOCKING when using an NFS or other remote
-** file-system may slow things down, as synchronous round-trips to the
-** server may be required to establish database file locks.
+** This file contains a binding of the asynchronous IO extension interface
+** (defined in ext/async/sqlite3async.h) to Tcl.
*/
-#define ENABLE_FILE_LOCKING
-#ifndef SQLITE_AMALGAMATION
-# include "sqliteInt.h"
-# include <assert.h>
-# include <string.h>
-#endif
+#define TCL_THREADS
#include <tcl.h>
-/*
-** This test uses pthreads and hence only works on unix and with
-** a threadsafe build of SQLite.
-*/
-#if SQLITE_OS_UNIX && SQLITE_THREADSAFE
-
-/*
-** This demo uses pthreads. If you do not have a pthreads implementation
-** for your operating system, you will need to recode the threading
-** logic.
-*/
-#include <pthread.h>
-#include <sched.h>
-
-/* Useful macros used in several places */
-#define MIN(x,y) ((x)<(y)?(x):(y))
-#define MAX(x,y) ((x)>(y)?(x):(y))
-
-/* Forward references */
-typedef struct AsyncWrite AsyncWrite;
-typedef struct AsyncFile AsyncFile;
-typedef struct AsyncFileData AsyncFileData;
-typedef struct AsyncFileLock AsyncFileLock;
-typedef struct AsyncLock AsyncLock;
-
-/* Enable for debugging */
-static int sqlite3async_trace = 0;
-# define ASYNC_TRACE(X) if( sqlite3async_trace ) asyncTrace X
-static void asyncTrace(const char *zFormat, ...){
- char *z;
- va_list ap;
- va_start(ap, zFormat);
- z = sqlite3_vmprintf(zFormat, ap);
- va_end(ap);
- fprintf(stderr, "[%d] %s", (int)pthread_self(), z);
- sqlite3_free(z);
-}
-
-/*
-** THREAD SAFETY NOTES
-**
-** Basic rules:
-**
-** * Both read and write access to the global write-op queue must be
-** protected by the async.queueMutex. As are the async.ioError and
-** async.nFile variables.
-**
-** * The async.pLock list and all AsyncLock and AsyncFileLock
-** structures must be protected by the async.lockMutex mutex.
-**
-** * The file handles from the underlying system are not assumed to
-** be thread safe.
-**
-** * See the last two paragraphs under "The Writer Thread" for
-** an assumption to do with file-handle synchronization by the Os.
-**
-** Deadlock prevention:
-**
-** There are three mutex used by the system: the "writer" mutex,
-** the "queue" mutex and the "lock" mutex. Rules are:
-**
-** * It is illegal to block on the writer mutex when any other mutex
-** are held, and
-**
-** * It is illegal to block on the queue mutex when the lock mutex
-** is held.
-**
-** i.e. mutex's must be grabbed in the order "writer", "queue", "lock".
-**
-** File system operations (invoked by SQLite thread):
-**
-** xOpen
-** xDelete
-** xFileExists
-**
-** File handle operations (invoked by SQLite thread):
-**
-** asyncWrite, asyncClose, asyncTruncate, asyncSync
-**
-** The operations above add an entry to the global write-op list. They
-** prepare the entry, acquire the async.queueMutex momentarily while
-** list pointers are manipulated to insert the new entry, then release
-** the mutex and signal the writer thread to wake up in case it happens
-** to be asleep.
-**
-**
-** asyncRead, asyncFileSize.
-**
-** Read operations. Both of these read from both the underlying file
-** first then adjust their result based on pending writes in the
-** write-op queue. So async.queueMutex is held for the duration
-** of these operations to prevent other threads from changing the
-** queue in mid operation.
-**
-**
-** asyncLock, asyncUnlock, asyncCheckReservedLock
-**
-** These primitives implement in-process locking using a hash table
-** on the file name. Files are locked correctly for connections coming
-** from the same process. But other processes cannot see these locks
-** and will therefore not honor them.
-**
-**
-** The writer thread:
-**
-** The async.writerMutex is used to make sure only there is only
-** a single writer thread running at a time.
-**
-** Inside the writer thread is a loop that works like this:
-**
-** WHILE (write-op list is not empty)
-** Do IO operation at head of write-op list
-** Remove entry from head of write-op list
-** END WHILE
-**
-** The async.queueMutex is always held during the <write-op list is
-** not empty> test, and when the entry is removed from the head
-** of the write-op list. Sometimes it is held for the interim
-** period (while the IO is performed), and sometimes it is
-** relinquished. It is relinquished if (a) the IO op is an
-** ASYNC_CLOSE or (b) when the file handle was opened, two of
-** the underlying systems handles were opened on the same
-** file-system entry.
-**
-** If condition (b) above is true, then one file-handle
-** (AsyncFile.pBaseRead) is used exclusively by sqlite threads to read the
-** file, the other (AsyncFile.pBaseWrite) by sqlite3_async_flush()
-** threads to perform write() operations. This means that read
-** operations are not blocked by asynchronous writes (although
-** asynchronous writes may still be blocked by reads).
-**
-** This assumes that the OS keeps two handles open on the same file
-** properly in sync. That is, any read operation that starts after a
-** write operation on the same file system entry has completed returns
-** data consistent with the write. We also assume that if one thread
-** reads a file while another is writing it all bytes other than the
-** ones actually being written contain valid data.
-**
-** If the above assumptions are not true, set the preprocessor symbol
-** SQLITE_ASYNC_TWO_FILEHANDLES to 0.
-*/
-
-#ifndef SQLITE_ASYNC_TWO_FILEHANDLES
-/* #define SQLITE_ASYNC_TWO_FILEHANDLES 0 */
-#define SQLITE_ASYNC_TWO_FILEHANDLES 1
-#endif
-
-/*
-** State information is held in the static variable "async" defined
-** as the following structure.
-**
-** Both async.ioError and async.nFile are protected by async.queueMutex.
-*/
-static struct TestAsyncStaticData {
- pthread_mutex_t lockMutex; /* For access to aLock hash table */
- pthread_mutex_t queueMutex; /* Mutex for access to write operation queue */
- pthread_mutex_t writerMutex; /* Prevents multiple writer threads */
- pthread_cond_t queueSignal; /* For waking up sleeping writer thread */
- pthread_cond_t emptySignal; /* Notify when the write queue is empty */
- AsyncWrite *pQueueFirst; /* Next write operation to be processed */
- AsyncWrite *pQueueLast; /* Last write operation on the list */
- AsyncLock *pLock; /* Linked list of all AsyncLock structures */
- volatile int ioDelay; /* Extra delay between write operations */
- volatile int writerHaltWhenIdle; /* Writer thread halts when queue empty */
- volatile int writerHaltNow; /* Writer thread halts after next op */
- int ioError; /* True if an IO error has occurred */
- int nFile; /* Number of open files (from sqlite pov) */
-} async = {
- PTHREAD_MUTEX_INITIALIZER,
- PTHREAD_MUTEX_INITIALIZER,
- PTHREAD_MUTEX_INITIALIZER,
- PTHREAD_COND_INITIALIZER,
- PTHREAD_COND_INITIALIZER,
-};
-
-/* Possible values of AsyncWrite.op */
-#define ASYNC_NOOP 0
-#define ASYNC_WRITE 1
-#define ASYNC_SYNC 2
-#define ASYNC_TRUNCATE 3
-#define ASYNC_CLOSE 4
-#define ASYNC_DELETE 5
-#define ASYNC_OPENEXCLUSIVE 6
-#define ASYNC_UNLOCK 7
-
-/* Names of opcodes. Used for debugging only.
-** Make sure these stay in sync with the macros above!
-*/
-static const char *azOpcodeName[] = {
- "NOOP", "WRITE", "SYNC", "TRUNCATE", "CLOSE", "DELETE", "OPENEX", "UNLOCK"
-};
-
-/*
-** Entries on the write-op queue are instances of the AsyncWrite
-** structure, defined here.
-**
-** The interpretation of the iOffset and nByte variables varies depending
-** on the value of AsyncWrite.op:
-**
-** ASYNC_NOOP:
-** No values used.
-**
-** ASYNC_WRITE:
-** iOffset -> Offset in file to write to.
-** nByte -> Number of bytes of data to write (pointed to by zBuf).
-**
-** ASYNC_SYNC:
-** nByte -> flags to pass to sqlite3OsSync().
-**
-** ASYNC_TRUNCATE:
-** iOffset -> Size to truncate file to.
-** nByte -> Unused.
-**
-** ASYNC_CLOSE:
-** iOffset -> Unused.
-** nByte -> Unused.
-**
-** ASYNC_DELETE:
-** iOffset -> Contains the "syncDir" flag.
-** nByte -> Number of bytes of zBuf points to (file name).
-**
-** ASYNC_OPENEXCLUSIVE:
-** iOffset -> Value of "delflag".
-** nByte -> Number of bytes of zBuf points to (file name).
-**
-** ASYNC_UNLOCK:
-** nByte -> Argument to sqlite3OsUnlock().
-**
-**
-** For an ASYNC_WRITE operation, zBuf points to the data to write to the file.
-** This space is sqlite3_malloc()d along with the AsyncWrite structure in a
-** single blob, so is deleted when sqlite3_free() is called on the parent
-** structure.
-*/
-struct AsyncWrite {
- AsyncFileData *pFileData; /* File to write data to or sync */
- int op; /* One of ASYNC_xxx etc. */
- sqlite_int64 iOffset; /* See above */
- int nByte; /* See above */
- char *zBuf; /* Data to write to file (or NULL if op!=ASYNC_WRITE) */
- AsyncWrite *pNext; /* Next write operation (to any file) */
-};
-
-/*
-** An instance of this structure is created for each distinct open file
-** (i.e. if two handles are opened on the one file, only one of these
-** structures is allocated) and stored in the async.aLock hash table. The
-** keys for async.aLock are the full pathnames of the opened files.
-**
-** AsyncLock.pList points to the head of a linked list of AsyncFileLock
-** structures, one for each handle currently open on the file.
-**
-** If the opened file is not a main-database (the SQLITE_OPEN_MAIN_DB is
-** not passed to the sqlite3OsOpen() call), or if ENABLE_FILE_LOCKING is
-** not defined at compile time, variables AsyncLock.pFile and
-** AsyncLock.eLock are never used. Otherwise, pFile is a file handle
-** opened on the file in question and used to obtain the file-system
-** locks required by database connections within this process.
-**
-** See comments above the asyncLock() function for more details on
-** the implementation of database locking used by this backend.
-*/
-struct AsyncLock {
- char *zFile;
- int nFile;
- sqlite3_file *pFile;
- int eLock;
- AsyncFileLock *pList;
- AsyncLock *pNext; /* Next in linked list headed by async.pLock */
-};
-
-/*
-** An instance of the following structure is allocated along with each
-** AsyncFileData structure (see AsyncFileData.lock), but is only used if the
-** file was opened with the SQLITE_OPEN_MAIN_DB.
-*/
-struct AsyncFileLock {
- int eLock; /* Internally visible lock state (sqlite pov) */
- int eAsyncLock; /* Lock-state with write-queue unlock */
- AsyncFileLock *pNext;
-};
+#ifdef SQLITE_ENABLE_ASYNCIO
-/*
-** The AsyncFile structure is a subclass of sqlite3_file used for
-** asynchronous IO.
-**
-** All of the actual data for the structure is stored in the structure
-** pointed to by AsyncFile.pData, which is allocated as part of the
-** sqlite3OsOpen() using sqlite3_malloc(). The reason for this is that the
-** lifetime of the AsyncFile structure is ended by the caller after OsClose()
-** is called, but the data in AsyncFileData may be required by the
-** writer thread after that point.
-*/
-struct AsyncFile {
- sqlite3_io_methods *pMethod;
- AsyncFileData *pData;
-};
-struct AsyncFileData {
- char *zName; /* Underlying OS filename - used for debugging */
- int nName; /* Number of characters in zName */
- sqlite3_file *pBaseRead; /* Read handle to the underlying Os file */
- sqlite3_file *pBaseWrite; /* Write handle to the underlying Os file */
- AsyncFileLock lock; /* Lock state for this handle */
- AsyncLock *pLock; /* AsyncLock object for this file system entry */
- AsyncWrite closeOp; /* Preallocated close operation */
-};
+#include "sqlite3async.h"
+#include "sqlite3.h"
+#include <assert.h>
-/*
-** The following async_XXX functions are debugging wrappers around the
-** corresponding pthread_XXX functions:
-**
-** pthread_mutex_lock();
-** pthread_mutex_unlock();
-** pthread_mutex_trylock();
-** pthread_cond_wait();
-**
-** It is illegal to pass any mutex other than those stored in the
-** following global variables of these functions.
-**
-** async.queueMutex
-** async.writerMutex
-** async.lockMutex
-**
-** If NDEBUG is defined, these wrappers do nothing except call the
-** corresponding pthreads function. If NDEBUG is not defined, then the
-** following variables are used to store the thread-id (as returned
-** by pthread_self()) currently holding the mutex, or 0 otherwise:
-**
-** asyncdebug.queueMutexHolder
-** asyncdebug.writerMutexHolder
-** asyncdebug.lockMutexHolder
-**
-** These variables are used by some assert() statements that verify
-** the statements made in the "Deadlock Prevention" notes earlier
-** in this file.
-*/
-#ifndef NDEBUG
-
-static struct TestAsyncDebugData {
- pthread_t lockMutexHolder;
- pthread_t queueMutexHolder;
- pthread_t writerMutexHolder;
-} asyncdebug = {0, 0, 0};
-/*
-** Wrapper around pthread_mutex_lock(). Checks that we have not violated
-** the anti-deadlock rules (see "Deadlock prevention" above).
-*/
-static int async_mutex_lock(pthread_mutex_t *pMutex){
- int iIdx;
- int rc;
- pthread_mutex_t *aMutex = (pthread_mutex_t *)(&async);
- pthread_t *aHolder = (pthread_t *)(&asyncdebug);
+struct TestAsyncGlobal {
+ int isInstalled; /* True when async VFS is installed */
+} testasync_g = { 0 };
- /* The code in this 'ifndef NDEBUG' block depends on a certain alignment
- * of the variables in TestAsyncStaticData and TestAsyncDebugData. The
- * following assert() statements check that this has not been changed.
- *
- * Really, these only need to be run once at startup time.
- */
- assert(&(aMutex[0])==&async.lockMutex);
- assert(&(aMutex[1])==&async.queueMutex);
- assert(&(aMutex[2])==&async.writerMutex);
- assert(&(aHolder[0])==&asyncdebug.lockMutexHolder);
- assert(&(aHolder[1])==&asyncdebug.queueMutexHolder);
- assert(&(aHolder[2])==&asyncdebug.writerMutexHolder);
-
- assert( pthread_self()!=0 );
- for(iIdx=0; iIdx<3; iIdx++){
- if( pMutex==&aMutex[iIdx] ) break;
-
- /* This is the key assert(). Here we are checking that if the caller
- * is trying to block on async.writerMutex, neither of the other two
- * mutex are held. If the caller is trying to block on async.queueMutex,
- * lockMutex is not held.
- */
- assert(!pthread_equal(aHolder[iIdx], pthread_self()));
- }
- assert(iIdx<3);
-
- rc = pthread_mutex_lock(pMutex);
- if( rc==0 ){
- assert(aHolder[iIdx]==0);
- aHolder[iIdx] = pthread_self();
- }
- return rc;
-}
-
-/*
-** Wrapper around pthread_mutex_unlock().
-*/
-static int async_mutex_unlock(pthread_mutex_t *pMutex){
- int iIdx;
- int rc;
- pthread_mutex_t *aMutex = (pthread_mutex_t *)(&async);
- pthread_t *aHolder = (pthread_t *)(&asyncdebug);
-
- for(iIdx=0; iIdx<3; iIdx++){
- if( pMutex==&aMutex[iIdx] ) break;
- }
- assert(iIdx<3);
-
- assert(pthread_equal(aHolder[iIdx], pthread_self()));
- aHolder[iIdx] = 0;
- rc = pthread_mutex_unlock(pMutex);
- assert(rc==0);
-
- return 0;
-}
-
-/*
-** Wrapper around pthread_mutex_trylock().
-*/
-static int async_mutex_trylock(pthread_mutex_t *pMutex){
- int iIdx;
- int rc;
- pthread_mutex_t *aMutex = (pthread_mutex_t *)(&async);
- pthread_t *aHolder = (pthread_t *)(&asyncdebug);
-
- for(iIdx=0; iIdx<3; iIdx++){
- if( pMutex==&aMutex[iIdx] ) break;
- }
- assert(iIdx<3);
-
- rc = pthread_mutex_trylock(pMutex);
- if( rc==0 ){
- assert(aHolder[iIdx]==0);
- aHolder[iIdx] = pthread_self();
- }
- return rc;
-}
-
-/*
-** Wrapper around pthread_cond_wait().
-*/
-static int async_cond_wait(pthread_cond_t *pCond, pthread_mutex_t *pMutex){
- int iIdx;
- int rc;
- pthread_mutex_t *aMutex = (pthread_mutex_t *)(&async);
- pthread_t *aHolder = (pthread_t *)(&asyncdebug);
-
- for(iIdx=0; iIdx<3; iIdx++){
- if( pMutex==&aMutex[iIdx] ) break;
- }
- assert(iIdx<3);
-
- assert(pthread_equal(aHolder[iIdx],pthread_self()));
- aHolder[iIdx] = 0;
- rc = pthread_cond_wait(pCond, pMutex);
- if( rc==0 ){
- aHolder[iIdx] = pthread_self();
- }
- return rc;
-}
-
-/*
-** Assert that the mutex is held by the current thread.
-*/
-static void assert_mutex_is_held(pthread_mutex_t *pMutex){
- int iIdx;
- pthread_mutex_t *aMutex = (pthread_mutex_t *)(&async);
- pthread_t *aHolder = (pthread_t *)(&asyncdebug);
-
- for(iIdx=0; iIdx<3; iIdx++){
- if( pMutex==&aMutex[iIdx] ) break;
- }
- assert(iIdx<3);
- assert( aHolder[iIdx]==pthread_self() );
-}
-
-/* Call our async_XX wrappers instead of selected pthread_XX functions */
-#define pthread_mutex_lock async_mutex_lock
-#define pthread_mutex_unlock async_mutex_unlock
-#define pthread_mutex_trylock async_mutex_trylock
-#define pthread_cond_wait async_cond_wait
-
-#else /* if defined(NDEBUG) */
-
-#define assert_mutex_is_held(X) /* A no-op when not debugging */
-
-#endif /* !defined(NDEBUG) */
-
-/*
-** Add an entry to the end of the global write-op list. pWrite should point
-** to an AsyncWrite structure allocated using sqlite3_malloc(). The writer
-** thread will call sqlite3_free() to free the structure after the specified
-** operation has been completed.
-**
-** Once an AsyncWrite structure has been added to the list, it becomes the
-** property of the writer thread and must not be read or modified by the
-** caller.
-*/
-static void addAsyncWrite(AsyncWrite *pWrite){
- /* We must hold the queue mutex in order to modify the queue pointers */
- if( pWrite->op!=ASYNC_UNLOCK ){
- pthread_mutex_lock(&async.queueMutex);
- }
-
- /* Add the record to the end of the write-op queue */
- assert( !pWrite->pNext );
- if( async.pQueueLast ){
- assert( async.pQueueFirst );
- async.pQueueLast->pNext = pWrite;
- }else{
- async.pQueueFirst = pWrite;
- }
- async.pQueueLast = pWrite;
- ASYNC_TRACE(("PUSH %p (%s %s %d)\n", pWrite, azOpcodeName[pWrite->op],
- pWrite->pFileData ? pWrite->pFileData->zName : "-", pWrite->iOffset));
-
- if( pWrite->op==ASYNC_CLOSE ){
- async.nFile--;
- }
-
- /* Drop the queue mutex */
- if( pWrite->op!=ASYNC_UNLOCK ){
- pthread_mutex_unlock(&async.queueMutex);
- }
-
- /* The writer thread might have been idle because there was nothing
- ** on the write-op queue for it to do. So wake it up. */
- pthread_cond_signal(&async.queueSignal);
-}
-
-/*
-** Increment async.nFile in a thread-safe manner.
-*/
-static void incrOpenFileCount(void){
- /* We must hold the queue mutex in order to modify async.nFile */
- pthread_mutex_lock(&async.queueMutex);
- if( async.nFile==0 ){
- async.ioError = SQLITE_OK;
- }
- async.nFile++;
- pthread_mutex_unlock(&async.queueMutex);
-}
-
-/*
-** This is a utility function to allocate and populate a new AsyncWrite
-** structure and insert it (via addAsyncWrite() ) into the global list.
-*/
-static int addNewAsyncWrite(
- AsyncFileData *pFileData,
- int op,
- sqlite3_int64 iOffset,
- int nByte,
- const char *zByte
-){
- AsyncWrite *p;
- if( op!=ASYNC_CLOSE && async.ioError ){
- return async.ioError;
- }
- p = sqlite3_malloc(sizeof(AsyncWrite) + (zByte?nByte:0));
- if( !p ){
- /* The upper layer does not expect operations like OsWrite() to
- ** return SQLITE_NOMEM. This is partly because under normal conditions
- ** SQLite is required to do rollback without calling malloc(). So
- ** if malloc() fails here, treat it as an I/O error. The above
- ** layer knows how to handle that.
- */
- return SQLITE_IOERR;
- }
- p->op = op;
- p->iOffset = iOffset;
- p->nByte = nByte;
- p->pFileData = pFileData;
- p->pNext = 0;
- if( zByte ){
- p->zBuf = (char *)&p[1];
- memcpy(p->zBuf, zByte, nByte);
- }else{
- p->zBuf = 0;
- }
- addAsyncWrite(p);
- return SQLITE_OK;
-}
-
-/*
-** Close the file. This just adds an entry to the write-op list, the file is
-** not actually closed.
-*/
-static int asyncClose(sqlite3_file *pFile){
- AsyncFileData *p = ((AsyncFile *)pFile)->pData;
-
- /* Unlock the file, if it is locked */
- pthread_mutex_lock(&async.lockMutex);
- p->lock.eLock = 0;
- pthread_mutex_unlock(&async.lockMutex);
-
- addAsyncWrite(&p->closeOp);
- return SQLITE_OK;
-}
-
-/*
-** Implementation of sqlite3OsWrite() for asynchronous files. Instead of
-** writing to the underlying file, this function adds an entry to the end of
-** the global AsyncWrite list. Either SQLITE_OK or SQLITE_NOMEM may be
-** returned.
-*/
-static int asyncWrite(
- sqlite3_file *pFile,
- const void *pBuf,
- int amt,
- sqlite3_int64 iOff
-){
- AsyncFileData *p = ((AsyncFile *)pFile)->pData;
- return addNewAsyncWrite(p, ASYNC_WRITE, iOff, amt, pBuf);
-}
-
-/*
-** Read data from the file. First we read from the filesystem, then adjust
-** the contents of the buffer based on ASYNC_WRITE operations in the
-** write-op queue.
-**
-** This method holds the mutex from start to finish.
-*/
-static int asyncRead(
- sqlite3_file *pFile,
- void *zOut,
- int iAmt,
- sqlite3_int64 iOffset
-){
- AsyncFileData *p = ((AsyncFile *)pFile)->pData;
- int rc = SQLITE_OK;
- sqlite3_int64 filesize;
- int nRead;
- sqlite3_file *pBase = p->pBaseRead;
-
- /* Grab the write queue mutex for the duration of the call */
- pthread_mutex_lock(&async.queueMutex);
-
- /* If an I/O error has previously occurred in this virtual file
- ** system, then all subsequent operations fail.
- */
- if( async.ioError!=SQLITE_OK ){
- rc = async.ioError;
- goto asyncread_out;
- }
-
- if( pBase->pMethods ){
- rc = pBase->pMethods->xFileSize(pBase, &filesize);
- if( rc!=SQLITE_OK ){
- goto asyncread_out;
- }
- nRead = MIN(filesize - iOffset, iAmt);
- if( nRead>0 ){
- rc = pBase->pMethods->xRead(pBase, zOut, nRead, iOffset);
- ASYNC_TRACE(("READ %s %d bytes at %d\n", p->zName, nRead, iOffset));
- }
- }
-
- if( rc==SQLITE_OK ){
- AsyncWrite *pWrite;
- char *zName = p->zName;
-
- for(pWrite=async.pQueueFirst; pWrite; pWrite = pWrite->pNext){
- if( pWrite->op==ASYNC_WRITE && (
- (pWrite->pFileData==p) ||
- (zName && pWrite->pFileData->zName==zName)
- )){
- int iBeginOut = (pWrite->iOffset-iOffset);
- int iBeginIn = -iBeginOut;
- int nCopy;
-
- if( iBeginIn<0 ) iBeginIn = 0;
- if( iBeginOut<0 ) iBeginOut = 0;
- nCopy = MIN(pWrite->nByte-iBeginIn, iAmt-iBeginOut);
-
- if( nCopy>0 ){
- memcpy(&((char *)zOut)[iBeginOut], &pWrite->zBuf[iBeginIn], nCopy);
- ASYNC_TRACE(("OVERREAD %d bytes at %d\n", nCopy, iBeginOut+iOffset));
- }
- }
- }
- }
-
-asyncread_out:
- pthread_mutex_unlock(&async.queueMutex);
- return rc;
-}
-
-/*
-** Truncate the file to nByte bytes in length. This just adds an entry to
-** the write-op list, no IO actually takes place.
-*/
-static int asyncTruncate(sqlite3_file *pFile, sqlite3_int64 nByte){
- AsyncFileData *p = ((AsyncFile *)pFile)->pData;
- return addNewAsyncWrite(p, ASYNC_TRUNCATE, nByte, 0, 0);
-}
-
-/*
-** Sync the file. This just adds an entry to the write-op list, the
-** sync() is done later by sqlite3_async_flush().
-*/
-static int asyncSync(sqlite3_file *pFile, int flags){
- AsyncFileData *p = ((AsyncFile *)pFile)->pData;
- return addNewAsyncWrite(p, ASYNC_SYNC, 0, flags, 0);
-}
-
-/*
-** Read the size of the file. First we read the size of the file system
-** entry, then adjust for any ASYNC_WRITE or ASYNC_TRUNCATE operations
-** currently in the write-op list.
-**
-** This method holds the mutex from start to finish.
-*/
-int asyncFileSize(sqlite3_file *pFile, sqlite3_int64 *piSize){
- AsyncFileData *p = ((AsyncFile *)pFile)->pData;
- int rc = SQLITE_OK;
- sqlite3_int64 s = 0;
- sqlite3_file *pBase;
-
- pthread_mutex_lock(&async.queueMutex);
-
- /* Read the filesystem size from the base file. If pBaseRead is NULL, this
- ** means the file hasn't been opened yet. In this case all relevant data
- ** must be in the write-op queue anyway, so we can omit reading from the
- ** file-system.
- */
- pBase = p->pBaseRead;
- if( pBase->pMethods ){
- rc = pBase->pMethods->xFileSize(pBase, &s);
- }
-
- if( rc==SQLITE_OK ){
- AsyncWrite *pWrite;
- for(pWrite=async.pQueueFirst; pWrite; pWrite = pWrite->pNext){
- if( pWrite->op==ASYNC_DELETE
- && p->zName
- && strcmp(p->zName, pWrite->zBuf)==0
- ){
- s = 0;
- }else if( pWrite->pFileData && (
- (pWrite->pFileData==p)
- || (p->zName && pWrite->pFileData->zName==p->zName)
- )){
- switch( pWrite->op ){
- case ASYNC_WRITE:
- s = MAX(pWrite->iOffset + (sqlite3_int64)(pWrite->nByte), s);
- break;
- case ASYNC_TRUNCATE:
- s = MIN(s, pWrite->iOffset);
- break;
- }
- }
- }
- *piSize = s;
- }
- pthread_mutex_unlock(&async.queueMutex);
- return rc;
-}
-
-/*
-** Lock or unlock the actual file-system entry.
-*/
-static int getFileLock(AsyncLock *pLock){
- int rc = SQLITE_OK;
- AsyncFileLock *pIter;
- int eRequired = 0;
-
- if( pLock->pFile ){
- for(pIter=pLock->pList; pIter; pIter=pIter->pNext){
- assert(pIter->eAsyncLock>=pIter->eLock);
- if( pIter->eAsyncLock>eRequired ){
- eRequired = pIter->eAsyncLock;
- assert(eRequired>=0 && eRequired<=SQLITE_LOCK_EXCLUSIVE);
- }
- }
-
- if( eRequired>pLock->eLock ){
- rc = pLock->pFile->pMethods->xLock(pLock->pFile, eRequired);
- if( rc==SQLITE_OK ){
- pLock->eLock = eRequired;
- }
- }
- else if( eRequired<pLock->eLock && eRequired<=SQLITE_LOCK_SHARED ){
- rc = pLock->pFile->pMethods->xUnlock(pLock->pFile, eRequired);
- if( rc==SQLITE_OK ){
- pLock->eLock = eRequired;
- }
- }
- }
-
- return rc;
-}
-
-/*
-** Return the AsyncLock structure from the global async.pLock list
-** associated with the file-system entry identified by path zName
-** (a string of nName bytes). If no such structure exists, return 0.
-*/
-static AsyncLock *findLock(const char *zName, int nName){
- AsyncLock *p = async.pLock;
- while( p && (p->nFile!=nName || memcmp(p->zFile, zName, nName)) ){
- p = p->pNext;
- }
- return p;
-}
-
-/*
-** The following two methods - asyncLock() and asyncUnlock() - are used
-** to obtain and release locks on database files opened with the
-** asynchronous backend.
-*/
-static int asyncLock(sqlite3_file *pFile, int eLock){
- int rc = SQLITE_OK;
- AsyncFileData *p = ((AsyncFile *)pFile)->pData;
-
- if( p->zName ){
- pthread_mutex_lock(&async.lockMutex);
- if( p->lock.eLock<eLock ){
- AsyncLock *pLock = p->pLock;
- AsyncFileLock *pIter;
- assert(pLock && pLock->pList);
- for(pIter=pLock->pList; pIter; pIter=pIter->pNext){
- if( pIter!=&p->lock && (
- (eLock==SQLITE_LOCK_EXCLUSIVE && pIter->eLock>=SQLITE_LOCK_SHARED) ||
- (eLock==SQLITE_LOCK_PENDING && pIter->eLock>=SQLITE_LOCK_RESERVED) ||
- (eLock==SQLITE_LOCK_RESERVED && pIter->eLock>=SQLITE_LOCK_RESERVED) ||
- (eLock==SQLITE_LOCK_SHARED && pIter->eLock>=SQLITE_LOCK_PENDING)
- )){
- rc = SQLITE_BUSY;
- }
- }
- if( rc==SQLITE_OK ){
- p->lock.eLock = eLock;
- p->lock.eAsyncLock = MAX(p->lock.eAsyncLock, eLock);
- }
- assert(p->lock.eAsyncLock>=p->lock.eLock);
- if( rc==SQLITE_OK ){
- rc = getFileLock(pLock);
- }
- }
- pthread_mutex_unlock(&async.lockMutex);
- }
-
- ASYNC_TRACE(("LOCK %d (%s) rc=%d\n", eLock, p->zName, rc));
- return rc;
-}
-static int asyncUnlock(sqlite3_file *pFile, int eLock){
- int rc = SQLITE_OK;
- AsyncFileData *p = ((AsyncFile *)pFile)->pData;
- if( p->zName ){
- AsyncFileLock *pLock = &p->lock;
- pthread_mutex_lock(&async.queueMutex);
- pthread_mutex_lock(&async.lockMutex);
- pLock->eLock = MIN(pLock->eLock, eLock);
- rc = addNewAsyncWrite(p, ASYNC_UNLOCK, 0, eLock, 0);
- pthread_mutex_unlock(&async.lockMutex);
- pthread_mutex_unlock(&async.queueMutex);
- }
- return rc;
-}
-
-/*
-** This function is called when the pager layer first opens a database file
-** and is checking for a hot-journal.
-*/
-static int asyncCheckReservedLock(sqlite3_file *pFile, int *pResOut){
- int ret = 0;
- AsyncFileLock *pIter;
- AsyncFileData *p = ((AsyncFile *)pFile)->pData;
-
- pthread_mutex_lock(&async.lockMutex);
- for(pIter=p->pLock->pList; pIter; pIter=pIter->pNext){
- if( pIter->eLock>=SQLITE_LOCK_RESERVED ){
- ret = 1;
- }
- }
- pthread_mutex_unlock(&async.lockMutex);
-
- ASYNC_TRACE(("CHECK-LOCK %d (%s)\n", ret, p->zName));
- *pResOut = ret;
- return SQLITE_OK;
-}
-
-/*
-** sqlite3_file_control() implementation.
-*/
-static int asyncFileControl(sqlite3_file *id, int op, void *pArg){
- switch( op ){
- case SQLITE_FCNTL_LOCKSTATE: {
- pthread_mutex_lock(&async.lockMutex);
- *(int*)pArg = ((AsyncFile*)id)->pData->lock.eLock;
- pthread_mutex_unlock(&async.lockMutex);
- return SQLITE_OK;
- }
- }
- return SQLITE_ERROR;
-}
-
-/*
-** Return the device characteristics and sector-size of the device. It
-** is not tricky to implement these correctly, as this backend might
-** not have an open file handle at this point.
-*/
-static int asyncSectorSize(sqlite3_file *pFile){
- return 512;
-}
-static int asyncDeviceCharacteristics(sqlite3_file *pFile){
- return 0;
-}
-
-static int unlinkAsyncFile(AsyncFileData *pData){
- AsyncFileLock **ppIter;
- int rc = SQLITE_OK;
-
- if( pData->zName ){
- AsyncLock *pLock = pData->pLock;
- for(ppIter=&pLock->pList; *ppIter; ppIter=&((*ppIter)->pNext)){
- if( (*ppIter)==&pData->lock ){
- *ppIter = pData->lock.pNext;
- break;
- }
- }
- if( !pLock->pList ){
- AsyncLock **pp;
- if( pLock->pFile ){
- pLock->pFile->pMethods->xClose(pLock->pFile);
- }
- for(pp=&async.pLock; *pp!=pLock; pp=&((*pp)->pNext));
- *pp = pLock->pNext;
- sqlite3_free(pLock);
- }else{
- rc = getFileLock(pLock);
- }
- }
-
- return rc;
-}
-
-/*
-** The parameter passed to this function is a copy of a 'flags' parameter
-** passed to this modules xOpen() method. This function returns true
-** if the file should be opened asynchronously, or false if it should
-** be opened immediately.
-**
-** If the file is to be opened asynchronously, then asyncOpen() will add
-** an entry to the event queue and the file will not actually be opened
-** until the event is processed. Otherwise, the file is opened directly
-** by the caller.
-*/
-static int doAsynchronousOpen(int flags){
- return (flags&SQLITE_OPEN_CREATE) && (
- (flags&SQLITE_OPEN_MAIN_JOURNAL) ||
- (flags&SQLITE_OPEN_TEMP_JOURNAL) ||
- (flags&SQLITE_OPEN_DELETEONCLOSE)
- );
-}
-
-/*
-** Open a file.
-*/
-static int asyncOpen(
- sqlite3_vfs *pAsyncVfs,
- const char *zName,
- sqlite3_file *pFile,
- int flags,
- int *pOutFlags
-){
- static sqlite3_io_methods async_methods = {
- 1, /* iVersion */
- asyncClose, /* xClose */
- asyncRead, /* xRead */
- asyncWrite, /* xWrite */
- asyncTruncate, /* xTruncate */
- asyncSync, /* xSync */
- asyncFileSize, /* xFileSize */
- asyncLock, /* xLock */
- asyncUnlock, /* xUnlock */
- asyncCheckReservedLock, /* xCheckReservedLock */
- asyncFileControl, /* xFileControl */
- asyncSectorSize, /* xSectorSize */
- asyncDeviceCharacteristics /* xDeviceCharacteristics */
- };
-
- sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
- AsyncFile *p = (AsyncFile *)pFile;
- int nName = 0;
- int rc = SQLITE_OK;
- int nByte;
- AsyncFileData *pData;
- AsyncLock *pLock = 0;
- char *z;
- int isAsyncOpen = doAsynchronousOpen(flags);
-
- /* If zName is NULL, then the upper layer is requesting an anonymous file */
- if( zName ){
- nName = strlen(zName)+1;
- }
-
- nByte = (
- sizeof(AsyncFileData) + /* AsyncFileData structure */
- 2 * pVfs->szOsFile + /* AsyncFileData.pBaseRead and pBaseWrite */
- nName /* AsyncFileData.zName */
- );
- z = sqlite3_malloc(nByte);
- if( !z ){
- return SQLITE_NOMEM;
- }
- memset(z, 0, nByte);
- pData = (AsyncFileData*)z;
- z += sizeof(pData[0]);
- pData->pBaseRead = (sqlite3_file*)z;
- z += pVfs->szOsFile;
- pData->pBaseWrite = (sqlite3_file*)z;
- pData->closeOp.pFileData = pData;
- pData->closeOp.op = ASYNC_CLOSE;
-
- if( zName ){
- z += pVfs->szOsFile;
- pData->zName = z;
- pData->nName = nName;
- memcpy(pData->zName, zName, nName);
- }
-
- if( !isAsyncOpen ){
- int flagsout;
- rc = pVfs->xOpen(pVfs, pData->zName, pData->pBaseRead, flags, &flagsout);
- if( rc==SQLITE_OK && (flagsout&SQLITE_OPEN_READWRITE) ){
- rc = pVfs->xOpen(pVfs, pData->zName, pData->pBaseWrite, flags, 0);
- }
- if( pOutFlags ){
- *pOutFlags = flagsout;
- }
- }
-
- pthread_mutex_lock(&async.lockMutex);
-
- if( zName && rc==SQLITE_OK ){
- pLock = findLock(pData->zName, pData->nName);
- if( !pLock ){
- int nByte = pVfs->szOsFile + sizeof(AsyncLock) + pData->nName + 1;
- pLock = (AsyncLock *)sqlite3_malloc(nByte);
- if( pLock ){
- memset(pLock, 0, nByte);
-#ifdef ENABLE_FILE_LOCKING
- if( flags&SQLITE_OPEN_MAIN_DB ){
- pLock->pFile = (sqlite3_file *)&pLock[1];
- rc = pVfs->xOpen(pVfs, pData->zName, pLock->pFile, flags, 0);
- if( rc!=SQLITE_OK ){
- sqlite3_free(pLock);
- pLock = 0;
- }
- }
-#endif
- if( pLock ){
- pLock->nFile = pData->nName;
- pLock->zFile = &((char *)(&pLock[1]))[pVfs->szOsFile];
- memcpy(pLock->zFile, pData->zName, pLock->nFile);
- pLock->pNext = async.pLock;
- async.pLock = pLock;
- }
- }else{
- rc = SQLITE_NOMEM;
- }
- }
- }
-
- if( rc==SQLITE_OK ){
- p->pMethod = &async_methods;
- p->pData = pData;
-
- /* Link AsyncFileData.lock into the linked list of
- ** AsyncFileLock structures for this file.
- */
- if( zName ){
- pData->lock.pNext = pLock->pList;
- pLock->pList = &pData->lock;
- pData->zName = pLock->zFile;
- }
- }else{
- if( pData->pBaseRead->pMethods ){
- pData->pBaseRead->pMethods->xClose(pData->pBaseRead);
- }
- if( pData->pBaseWrite->pMethods ){
- pData->pBaseWrite->pMethods->xClose(pData->pBaseWrite);
- }
- sqlite3_free(pData);
- }
-
- pthread_mutex_unlock(&async.lockMutex);
-
- if( rc==SQLITE_OK ){
- incrOpenFileCount();
- pData->pLock = pLock;
- }
-
- if( rc==SQLITE_OK && isAsyncOpen ){
- rc = addNewAsyncWrite(pData, ASYNC_OPENEXCLUSIVE, (sqlite3_int64)flags,0,0);
- if( rc==SQLITE_OK ){
- if( pOutFlags ) *pOutFlags = flags;
- }else{
- pthread_mutex_lock(&async.lockMutex);
- unlinkAsyncFile(pData);
- pthread_mutex_unlock(&async.lockMutex);
- sqlite3_free(pData);
- }
- }
- if( rc!=SQLITE_OK ){
- p->pMethod = 0;
- }
- return rc;
-}
-
-/*
-** Implementation of sqlite3OsDelete. Add an entry to the end of the
-** write-op queue to perform the delete.
-*/
-static int asyncDelete(sqlite3_vfs *pAsyncVfs, const char *z, int syncDir){
- return addNewAsyncWrite(0, ASYNC_DELETE, syncDir, strlen(z)+1, z);
-}
-
-/*
-** Implementation of sqlite3OsAccess. This method holds the mutex from
-** start to finish.
-*/
-static int asyncAccess(
- sqlite3_vfs *pAsyncVfs,
- const char *zName,
- int flags,
- int *pResOut
-){
- int rc;
- int ret;
- AsyncWrite *p;
- sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
-
- assert(flags==SQLITE_ACCESS_READWRITE
- || flags==SQLITE_ACCESS_READ
- || flags==SQLITE_ACCESS_EXISTS
- );
-
- pthread_mutex_lock(&async.queueMutex);
- rc = pVfs->xAccess(pVfs, zName, flags, &ret);
- if( rc==SQLITE_OK && flags==SQLITE_ACCESS_EXISTS ){
- for(p=async.pQueueFirst; p; p = p->pNext){
- if( p->op==ASYNC_DELETE && 0==strcmp(p->zBuf, zName) ){
- ret = 0;
- }else if( p->op==ASYNC_OPENEXCLUSIVE
- && p->pFileData->zName
- && 0==strcmp(p->pFileData->zName, zName)
- ){
- ret = 1;
- }
- }
- }
- ASYNC_TRACE(("ACCESS(%s): %s = %d\n",
- flags==SQLITE_ACCESS_READWRITE?"read-write":
- flags==SQLITE_ACCESS_READ?"read":"exists"
- , zName, ret)
- );
- pthread_mutex_unlock(&async.queueMutex);
- *pResOut = ret;
- return rc;
-}
-
-/*
-** Fill in zPathOut with the full path to the file identified by zPath.
-*/
-static int asyncFullPathname(
- sqlite3_vfs *pAsyncVfs,
- const char *zPath,
- int nPathOut,
- char *zPathOut
-){
- int rc;
- sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
- rc = pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
-
- /* Because of the way intra-process file locking works, this backend
- ** needs to return a canonical path. The following block assumes the
- ** file-system uses unix style paths.
- */
- if( rc==SQLITE_OK ){
- int i, j;
- int n = nPathOut;
- char *z = zPathOut;
- while( n>1 && z[n-1]=='/' ){ n--; }
- for(i=j=0; i<n; i++){
- if( z[i]=='/' ){
- if( z[i+1]=='/' ) continue;
- if( z[i+1]=='.' && i+2<n && z[i+2]=='/' ){
- i += 1;
- continue;
- }
- if( z[i+1]=='.' && i+3<n && z[i+2]=='.' && z[i+3]=='/' ){
- while( j>0 && z[j-1]!='/' ){ j--; }
- if( j>0 ){ j--; }
- i += 2;
- continue;
- }
- }
- z[j++] = z[i];
- }
- z[j] = 0;
- }
-
- return rc;
-}
-static void *asyncDlOpen(sqlite3_vfs *pAsyncVfs, const char *zPath){
- sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
- return pVfs->xDlOpen(pVfs, zPath);
-}
-static void asyncDlError(sqlite3_vfs *pAsyncVfs, int nByte, char *zErrMsg){
- sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
- pVfs->xDlError(pVfs, nByte, zErrMsg);
-}
-static void (*asyncDlSym(
- sqlite3_vfs *pAsyncVfs,
- void *pHandle,
- const char *zSymbol
-))(void){
- sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
- return pVfs->xDlSym(pVfs, pHandle, zSymbol);
-}
-static void asyncDlClose(sqlite3_vfs *pAsyncVfs, void *pHandle){
- sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
- pVfs->xDlClose(pVfs, pHandle);
-}
-static int asyncRandomness(sqlite3_vfs *pAsyncVfs, int nByte, char *zBufOut){
- sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
- return pVfs->xRandomness(pVfs, nByte, zBufOut);
-}
-static int asyncSleep(sqlite3_vfs *pAsyncVfs, int nMicro){
- sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
- return pVfs->xSleep(pVfs, nMicro);
-}
-static int asyncCurrentTime(sqlite3_vfs *pAsyncVfs, double *pTimeOut){
- sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
- return pVfs->xCurrentTime(pVfs, pTimeOut);
-}
-
-static sqlite3_vfs async_vfs = {
- 1, /* iVersion */
- sizeof(AsyncFile), /* szOsFile */
- 0, /* mxPathname */
- 0, /* pNext */
- "async", /* zName */
- 0, /* pAppData */
- asyncOpen, /* xOpen */
- asyncDelete, /* xDelete */
- asyncAccess, /* xAccess */
- asyncFullPathname, /* xFullPathname */
- asyncDlOpen, /* xDlOpen */
- asyncDlError, /* xDlError */
- asyncDlSym, /* xDlSym */
- asyncDlClose, /* xDlClose */
- asyncRandomness, /* xDlError */
- asyncSleep, /* xDlSym */
- asyncCurrentTime /* xDlClose */
-};
-
-/*
-** Call this routine to enable or disable the
-** asynchronous IO features implemented in this file.
-**
-** This routine is not even remotely threadsafe. Do not call
-** this routine while any SQLite database connections are open.
-*/
-static void asyncEnable(int enable){
- if( enable ){
- if( !async_vfs.pAppData ){
- async_vfs.pAppData = (void *)sqlite3_vfs_find(0);
- async_vfs.mxPathname = ((sqlite3_vfs *)async_vfs.pAppData)->mxPathname;
- sqlite3_vfs_register(&async_vfs, 1);
- }
- }else{
- if( async_vfs.pAppData ){
- sqlite3_vfs_unregister(&async_vfs);
- async_vfs.pAppData = 0;
- }
- }
-}
-
-/*
-** This procedure runs in a separate thread, reading messages off of the
-** write queue and processing them one by one.
-**
-** If async.writerHaltNow is true, then this procedure exits
-** after processing a single message.
-**
-** If async.writerHaltWhenIdle is true, then this procedure exits when
-** the write queue is empty.
-**
-** If both of the above variables are false, this procedure runs
-** indefinately, waiting for operations to be added to the write queue
-** and processing them in the order in which they arrive.
-**
-** An artifical delay of async.ioDelay milliseconds is inserted before
-** each write operation in order to simulate the effect of a slow disk.
-**
-** Only one instance of this procedure may be running at a time.
-*/
-static void *asyncWriterThread(void *pIsStarted){
- sqlite3_vfs *pVfs = (sqlite3_vfs *)(async_vfs.pAppData);
- AsyncWrite *p = 0;
- int rc = SQLITE_OK;
- int holdingMutex = 0;
-
- if( pthread_mutex_trylock(&async.writerMutex) ){
- return 0;
- }
- (*(int *)pIsStarted) = 1;
- while( async.writerHaltNow==0 ){
- int doNotFree = 0;
- sqlite3_file *pBase = 0;
-
- if( !holdingMutex ){
- pthread_mutex_lock(&async.queueMutex);
- }
- while( (p = async.pQueueFirst)==0 ){
- pthread_cond_broadcast(&async.emptySignal);
- if( async.writerHaltWhenIdle ){
- pthread_mutex_unlock(&async.queueMutex);
- break;
- }else{
- ASYNC_TRACE(("IDLE\n"));
- pthread_cond_wait(&async.queueSignal, &async.queueMutex);
- ASYNC_TRACE(("WAKEUP\n"));
- }
- }
- if( p==0 ) break;
- holdingMutex = 1;
-
- /* Right now this thread is holding the mutex on the write-op queue.
- ** Variable 'p' points to the first entry in the write-op queue. In
- ** the general case, we hold on to the mutex for the entire body of
- ** the loop.
- **
- ** However in the cases enumerated below, we relinquish the mutex,
- ** perform the IO, and then re-request the mutex before removing 'p' from
- ** the head of the write-op queue. The idea is to increase concurrency with
- ** sqlite threads.
- **
- ** * An ASYNC_CLOSE operation.
- ** * An ASYNC_OPENEXCLUSIVE operation. For this one, we relinquish
- ** the mutex, call the underlying xOpenExclusive() function, then
- ** re-aquire the mutex before seting the AsyncFile.pBaseRead
- ** variable.
- ** * ASYNC_SYNC and ASYNC_WRITE operations, if
- ** SQLITE_ASYNC_TWO_FILEHANDLES was set at compile time and two
- ** file-handles are open for the particular file being "synced".
- */
- if( async.ioError!=SQLITE_OK && p->op!=ASYNC_CLOSE ){
- p->op = ASYNC_NOOP;
- }
- if( p->pFileData ){
- pBase = p->pFileData->pBaseWrite;
- if(
- p->op==ASYNC_CLOSE ||
- p->op==ASYNC_OPENEXCLUSIVE ||
- (pBase->pMethods && (p->op==ASYNC_SYNC || p->op==ASYNC_WRITE) )
- ){
- pthread_mutex_unlock(&async.queueMutex);
- holdingMutex = 0;
- }
- if( !pBase->pMethods ){
- pBase = p->pFileData->pBaseRead;
- }
- }
-
- switch( p->op ){
- case ASYNC_NOOP:
- break;
-
- case ASYNC_WRITE:
- assert( pBase );
- ASYNC_TRACE(("WRITE %s %d bytes at %d\n",
- p->pFileData->zName, p->nByte, p->iOffset));
- rc = pBase->pMethods->xWrite(pBase, (void *)(p->zBuf), p->nByte, p->iOffset);
- break;
-
- case ASYNC_SYNC:
- assert( pBase );
- ASYNC_TRACE(("SYNC %s\n", p->pFileData->zName));
- rc = pBase->pMethods->xSync(pBase, p->nByte);
- break;
-
- case ASYNC_TRUNCATE:
- assert( pBase );
- ASYNC_TRACE(("TRUNCATE %s to %d bytes\n",
- p->pFileData->zName, p->iOffset));
- rc = pBase->pMethods->xTruncate(pBase, p->iOffset);
- break;
-
- case ASYNC_CLOSE: {
- AsyncFileData *pData = p->pFileData;
- ASYNC_TRACE(("CLOSE %s\n", p->pFileData->zName));
- if( pData->pBaseWrite->pMethods ){
- pData->pBaseWrite->pMethods->xClose(pData->pBaseWrite);
- }
- if( pData->pBaseRead->pMethods ){
- pData->pBaseRead->pMethods->xClose(pData->pBaseRead);
- }
-
- /* Unlink AsyncFileData.lock from the linked list of AsyncFileLock
- ** structures for this file. Obtain the async.lockMutex mutex
- ** before doing so.
- */
- pthread_mutex_lock(&async.lockMutex);
- rc = unlinkAsyncFile(pData);
- pthread_mutex_unlock(&async.lockMutex);
-
- if( !holdingMutex ){
- pthread_mutex_lock(&async.queueMutex);
- holdingMutex = 1;
- }
- assert_mutex_is_held(&async.queueMutex);
- async.pQueueFirst = p->pNext;
- sqlite3_free(pData);
- doNotFree = 1;
- break;
- }
-
- case ASYNC_UNLOCK: {
- AsyncWrite *pIter;
- AsyncFileData *pData = p->pFileData;
- int eLock = p->nByte;
-
- /* When a file is locked by SQLite using the async backend, it is
- ** locked within the 'real' file-system synchronously. When it is
- ** unlocked, an ASYNC_UNLOCK event is added to the write-queue to
- ** unlock the file asynchronously. The design of the async backend
- ** requires that the 'real' file-system file be locked from the
- ** time that SQLite first locks it (and probably reads from it)
- ** until all asynchronous write events that were scheduled before
- ** SQLite unlocked the file have been processed.
- **
- ** This is more complex if SQLite locks and unlocks the file multiple
- ** times in quick succession. For example, if SQLite does:
- **
- ** lock, write, unlock, lock, write, unlock
- **
- ** Each "lock" operation locks the file immediately. Each "write"
- ** and "unlock" operation adds an event to the event queue. If the
- ** second "lock" operation is performed before the first "unlock"
- ** operation has been processed asynchronously, then the first
- ** "unlock" cannot be safely processed as is, since this would mean
- ** the file was unlocked when the second "write" operation is
- ** processed. To work around this, when processing an ASYNC_UNLOCK
- ** operation, SQLite:
- **
- ** 1) Unlocks the file to the minimum of the argument passed to
- ** the xUnlock() call and the current lock from SQLite's point
- ** of view, and
- **
- ** 2) Only unlocks the file at all if this event is the last
- ** ASYNC_UNLOCK event on this file in the write-queue.
- */
- assert( holdingMutex==1 );
- assert( async.pQueueFirst==p );
- for(pIter=async.pQueueFirst->pNext; pIter; pIter=pIter->pNext){
- if( pIter->pFileData==pData && pIter->op==ASYNC_UNLOCK ) break;
- }
- if( !pIter ){
- pthread_mutex_lock(&async.lockMutex);
- pData->lock.eAsyncLock = MIN(
- pData->lock.eAsyncLock, MAX(pData->lock.eLock, eLock)
- );
- assert(pData->lock.eAsyncLock>=pData->lock.eLock);
- rc = getFileLock(pData->pLock);
- pthread_mutex_unlock(&async.lockMutex);
- }
- break;
- }
-
- case ASYNC_DELETE:
- ASYNC_TRACE(("DELETE %s\n", p->zBuf));
- rc = pVfs->xDelete(pVfs, p->zBuf, (int)p->iOffset);
- break;
-
- case ASYNC_OPENEXCLUSIVE: {
- int flags = (int)p->iOffset;
- AsyncFileData *pData = p->pFileData;
- ASYNC_TRACE(("OPEN %s flags=%d\n", p->zBuf, (int)p->iOffset));
- assert(pData->pBaseRead->pMethods==0 && pData->pBaseWrite->pMethods==0);
- rc = pVfs->xOpen(pVfs, pData->zName, pData->pBaseRead, flags, 0);
- assert( holdingMutex==0 );
- pthread_mutex_lock(&async.queueMutex);
- holdingMutex = 1;
- break;
- }
-
- default: assert(!"Illegal value for AsyncWrite.op");
- }
-
- /* If we didn't hang on to the mutex during the IO op, obtain it now
- ** so that the AsyncWrite structure can be safely removed from the
- ** global write-op queue.
- */
- if( !holdingMutex ){
- pthread_mutex_lock(&async.queueMutex);
- holdingMutex = 1;
- }
- /* ASYNC_TRACE(("UNLINK %p\n", p)); */
- if( p==async.pQueueLast ){
- async.pQueueLast = 0;
- }
- if( !doNotFree ){
- assert_mutex_is_held(&async.queueMutex);
- async.pQueueFirst = p->pNext;
- sqlite3_free(p);
- }
- assert( holdingMutex );
-
- /* An IO error has occurred. We cannot report the error back to the
- ** connection that requested the I/O since the error happened
- ** asynchronously. The connection has already moved on. There
- ** really is nobody to report the error to.
- **
- ** The file for which the error occurred may have been a database or
- ** journal file. Regardless, none of the currently queued operations
- ** associated with the same database should now be performed. Nor should
- ** any subsequently requested IO on either a database or journal file
- ** handle for the same database be accepted until the main database
- ** file handle has been closed and reopened.
- **
- ** Furthermore, no further IO should be queued or performed on any file
- ** handle associated with a database that may have been part of a
- ** multi-file transaction that included the database associated with
- ** the IO error (i.e. a database ATTACHed to the same handle at some
- ** point in time).
- */
- if( rc!=SQLITE_OK ){
- async.ioError = rc;
- }
-
- if( async.ioError && !async.pQueueFirst ){
- pthread_mutex_lock(&async.lockMutex);
- if( 0==async.pLock ){
- async.ioError = SQLITE_OK;
- }
- pthread_mutex_unlock(&async.lockMutex);
- }
-
- /* Drop the queue mutex before continuing to the next write operation
- ** in order to give other threads a chance to work with the write queue.
- */
- if( !async.pQueueFirst || !async.ioError ){
- pthread_mutex_unlock(&async.queueMutex);
- holdingMutex = 0;
- if( async.ioDelay>0 ){
- pVfs->xSleep(pVfs, async.ioDelay);
- }else{
- sched_yield();
- }
- }
- }
-
- pthread_mutex_unlock(&async.writerMutex);
- return 0;
-}
-
-/**************************************************************************
-** The remaining code defines a Tcl interface for testing the asynchronous
-** IO implementation in this file.
-**
-** To adapt the code to a non-TCL environment, delete or comment out
-** the code that follows.
-*/
+TCL_DECLARE_MUTEX(testasync_g_writerMutex);
/*
** sqlite3async_enable ?YES/NO?
return TCL_ERROR;
}
if( objc==1 ){
- Tcl_SetObjResult(interp, Tcl_NewBooleanObj(async_vfs.pAppData!=0));
+ Tcl_SetObjResult(interp, Tcl_NewIntObj(testasync_g.isInstalled));
}else{
- int en;
- if( Tcl_GetBooleanFromObj(interp, objv[1], &en) ) return TCL_ERROR;
- asyncEnable(en);
+ int enable;
+ if( Tcl_GetBooleanFromObj(interp, objv[1], &enable) ) return TCL_ERROR;
+ if( enable ){
+ sqlite3async_initialize(0, 1);
+ }else{
+ sqlite3async_shutdown();
+ }
+ testasync_g.isInstalled = enable;
}
return TCL_OK;
}
/*
-** sqlite3async_halt "now"|"idle"|"never"
+** sqlite3async_halt ?"now"|"idle"|"never"?
**
** Set the conditions at which the writer thread will halt.
*/
int objc,
Tcl_Obj *CONST objv[]
){
- const char *zCond;
- if( objc!=2 ){
- Tcl_WrongNumArgs(interp, 1, objv, "\"now\"|\"idle\"|\"never\"");
+ int eWhen;
+ const char *azConstant[] = { "never", "now", "idle", 0 };
+
+ assert( SQLITEASYNC_HALT_NEVER==0 );
+ assert( SQLITEASYNC_HALT_NOW==1 );
+ assert( SQLITEASYNC_HALT_IDLE==2 );
+
+ if( objc!=1 && objc!=2 ){
+ Tcl_WrongNumArgs(interp, 1, objv, "?OPTION?");
return TCL_ERROR;
}
- zCond = Tcl_GetString(objv[1]);
- if( strcmp(zCond, "now")==0 ){
- async.writerHaltNow = 1;
- pthread_cond_broadcast(&async.queueSignal);
- }else if( strcmp(zCond, "idle")==0 ){
- async.writerHaltWhenIdle = 1;
- async.writerHaltNow = 0;
- pthread_cond_broadcast(&async.queueSignal);
- }else if( strcmp(zCond, "never")==0 ){
- async.writerHaltWhenIdle = 0;
- async.writerHaltNow = 0;
- }else{
- Tcl_AppendResult(interp,
- "should be one of: \"now\", \"idle\", or \"never\"", (char*)0);
- return TCL_ERROR;
+ if( objc==2 ){
+ if( Tcl_GetIndexFromObj(interp, objv[1], azConstant, "option", 0, &eWhen) ){
+ return TCL_ERROR;
+ }
+ sqlite3async_control(SQLITEASYNC_HALT, eWhen);
}
+
+ /* Always return the current value of the 'halt' option. */
+ sqlite3async_control(SQLITEASYNC_GET_HALT, &eWhen);
+ Tcl_SetObjResult(interp, Tcl_NewStringObj(azConstant[eWhen], -1));
+
return TCL_OK;
}
int objc,
Tcl_Obj *CONST objv[]
){
+ int iMs;
if( objc!=1 && objc!=2 ){
Tcl_WrongNumArgs(interp, 1, objv, "?MS?");
return TCL_ERROR;
}
- if( objc==1 ){
- Tcl_SetObjResult(interp, Tcl_NewIntObj(async.ioDelay));
- }else{
- int ioDelay;
- if( Tcl_GetIntFromObj(interp, objv[1], &ioDelay) ) return TCL_ERROR;
- async.ioDelay = ioDelay;
+ if( objc==2 ){
+ if( Tcl_GetIntFromObj(interp, objv[1], &iMs) ){
+ return TCL_ERROR;
+ }
+ sqlite3async_control(SQLITEASYNC_DELAY, iMs);
}
+
+ /* Always return the current value of the 'delay' option. */
+ sqlite3async_control(SQLITEASYNC_GET_DELAY, &iMs);
+ Tcl_SetObjResult(interp, Tcl_NewIntObj(iMs));
return TCL_OK;
}
+static Tcl_ThreadCreateType tclWriterThread(ClientData pIsStarted){
+ Tcl_MutexLock(&testasync_g_writerMutex);
+ *((int *)pIsStarted) = 1;
+ sqlite3async_run();
+ Tcl_MutexUnlock(&testasync_g_writerMutex);
+ TCL_THREAD_CREATE_RETURN;
+}
+
/*
** sqlite3async_start
**
int objc,
Tcl_Obj *CONST objv[]
){
- pthread_t x;
- int rc;
volatile int isStarted = 0;
- rc = pthread_create(&x, 0, asyncWriterThread, (void *)&isStarted);
- if( rc ){
- Tcl_AppendResult(interp, "failed to create the thread", 0);
+ ClientData threadData = (ClientData)&isStarted;
+
+ Tcl_ThreadId x;
+ const int nStack = TCL_THREAD_STACK_DEFAULT;
+ const int flags = TCL_THREAD_NOFLAGS;
+ int rc;
+
+ rc = Tcl_CreateThread(&x, tclWriterThread, threadData, nStack, flags);
+ if( rc!=TCL_OK ){
return TCL_ERROR;
}
- pthread_detach(x);
while( isStarted==0 ){
+#if 0
sched_yield();
+#endif
}
return TCL_OK;
}
int objc,
Tcl_Obj *CONST objv[]
){
- int cnt = 10;
- if( async.writerHaltNow==0 && async.writerHaltWhenIdle==0 ){
- Tcl_AppendResult(interp, "would block forever", (char*)0);
+ int eCond;
+ if( objc!=1 ){
+ Tcl_WrongNumArgs(interp, 1, objv, "");
return TCL_ERROR;
}
- while( cnt-- && !pthread_mutex_trylock(&async.writerMutex) ){
- pthread_mutex_unlock(&async.writerMutex);
- sched_yield();
- }
- if( cnt>=0 ){
- ASYNC_TRACE(("WAIT\n"));
- pthread_mutex_lock(&async.queueMutex);
- pthread_cond_broadcast(&async.queueSignal);
- pthread_mutex_unlock(&async.queueMutex);
- pthread_mutex_lock(&async.writerMutex);
- pthread_mutex_unlock(&async.writerMutex);
- }else{
- ASYNC_TRACE(("NO-WAIT\n"));
+ sqlite3async_control(SQLITEASYNC_GET_HALT, &eCond);
+ if( eCond==SQLITEASYNC_HALT_NEVER ){
+ Tcl_AppendResult(interp, "would block forever", (char*)0);
+ return TCL_ERROR;
}
+
+ Tcl_MutexLock(&testasync_g_writerMutex);
+ Tcl_MutexUnlock(&testasync_g_writerMutex);
return TCL_OK;
}
-
-#endif /* SQLITE_OS_UNIX and SQLITE_THREADSAFE */
+#endif /* SQLITE_ENABLE_ASYNCIO */
/*
** This routine registers the custom TCL commands defined in this
** of this module.
*/
int Sqlitetestasync_Init(Tcl_Interp *interp){
-#if SQLITE_OS_UNIX && SQLITE_THREADSAFE
+#if SQLITE_ENABLE_ASYNCIO
Tcl_CreateObjCommand(interp,"sqlite3async_enable",testAsyncEnable,0,0);
Tcl_CreateObjCommand(interp,"sqlite3async_halt",testAsyncHalt,0,0);
Tcl_CreateObjCommand(interp,"sqlite3async_delay",testAsyncDelay,0,0);
Tcl_CreateObjCommand(interp,"sqlite3async_start",testAsyncStart,0,0);
Tcl_CreateObjCommand(interp,"sqlite3async_wait",testAsyncWait,0,0);
- Tcl_LinkVar(interp, "sqlite3async_trace",
- (char*)&sqlite3async_trace, TCL_LINK_INT);
-#endif /* SQLITE_OS_UNIX and SQLITE_THREADSAFE */
+#endif /* SQLITE_ENABLE_ASYNCIO */
return TCL_OK;
}
+
# This file implements regression tests for SQLite library. The
# focus of this file is testing corner cases of the INSERT statement.
#
-# $Id: insert3.test,v 1.8 2008/12/23 10:37:47 danielk1977 Exp $
+# $Id: insert3.test,v 1.9 2009/04/23 14:58:40 danielk1977 Exp $
set testdir [file dirname $argv0]
source $testdir/tester.tcl
}
} {{} 4.3 hi}
}
-db close
-file delete -force test.db
+foreach tab [db eval {SELECT name FROM sqlite_master WHERE type = 'table'}] {
+ db eval "DROP TABLE $tab"
+}
+db close
sqlite3 db test.db
#-------------------------------------------------------------------------
#
#***********************************************************************
#
-# $Id: mutex1.test,v 1.19 2009/03/24 15:08:10 drh Exp $
+# $Id: mutex1.test,v 1.20 2009/04/23 14:58:40 danielk1977 Exp $
set testdir [file dirname $argv0]
source $testdir/tester.tcl
# * Multi-threaded mode,
# * Single-threaded mode.
#
-set enable_shared_cache [sqlite3_enable_shared_cache 1]
-ifcapable threadsafe {
+ifcapable threadsafe&&shared_cache {
+ set enable_shared_cache [sqlite3_enable_shared_cache 1]
foreach {mode mutexes} {
singlethread {}
multithread {fast static_lru static_master static_mem static_open static_prng }
lsort $res
} [lsort $mutexes]
}
-}
-sqlite3_enable_shared_cache $enable_shared_cache
+ sqlite3_enable_shared_cache $enable_shared_cache
-# Open and use a connection in "nomutex" mode. Test that no recursive
-# mutexes are obtained.
-ifcapable threadsafe {
+ # Open and use a connection in "nomutex" mode. Test that no recursive
+ # mutexes are obtained.
do_test mutex1.3.1 {
catch {db close}
clear_mutex_counters
# This file implements regression tests for SQLite library. The
# focus of this file is testing the SELECT statement.
#
-# $Id: select1.test,v 1.67 2009/04/10 15:38:43 drh Exp $
+# $Id: select1.test,v 1.68 2009/04/23 14:58:40 danielk1977 Exp $
set testdir [file dirname $argv0]
source $testdir/tester.tcl
} {0}
}
+foreach tab [db eval {SELECT name FROM sqlite_master WHERE type = 'table'}] {
+ db eval "DROP TABLE $tab"
+}
db close
-file delete -force test.db
sqlite3 db test.db
+
do_test select1-14.1 {
execsql {
SELECT * FROM sqlite_master WHERE rowid>10;
projects / thirdparty / sqlite.git / commitdiff
