return rc;
}
+/* Each entry in the frame-cache is represented by an instance of the
+** following structure. */
+typedef struct ZonefileFrame ZonefileFrame;
+struct ZonefileFrame {
+ i64 iFileid; /* Fileid for this frame */
+ i64 iFrameOff; /* Offset of frame in file */
+ int nBuf; /* Size of aBuf[] in bytes */
+ u8 *aBuf; /* Buffer containing uncompressed frame data */
+ ZonefileFrame *pLruNext; /* Next element in LRU list */
+ ZonefileFrame *pLruPrev; /* Previous element in LRU list */
+ ZonefileFrame *pHashNext; /* Next element in same hash bucket */
+};
+
typedef struct ZonefileTab ZonefileTab;
struct ZonefileTab {
sqlite3_vtab base; /* Base class - must be first */
ZonefileGlobal *pGlobal;
char *zName; /* Name of this table */
char *zDb; /* Name of db containing this table */
- int nCacheSize;
+
+ /* The following variables are used to implement the frame-cache */
+ int nCacheSize; /* Configured cache size */
+ int nCacheEntry; /* Current number of entries in cache */
+ int nCacheBucket; /* Number of buckets in frame cache hash table */
+ ZonefileFrame **aCache; /* Array of hash buckets */
+ ZonefileFrame *pCacheFirst;/* Most recently used frame */
+ ZonefileFrame *pCacheLast; /* Least recently used frame (first to discard) */
};
typedef struct ZonefileCsr ZonefileCsr;
sqlite3_stmt *pSelect; /* SELECT on %_shadow_idx table */
};
-typedef struct ZonefileFrame ZonefileFrame;
-struct ZonefileFrame {
- i64 iFileid; /* Fileid for this frame */
- i64 iFrameOff; /* Offset of frame in file */
- int nBuf; /* Size of aBuf[] in bytes */
- u8 *aBuf; /* Buffer containing uncompressed frame data */
-};
-
/*
** Attempt to interpret the contents of string z as an integer. If
** successful, set (*piVal) to the integer value and return SQLITE_OK.
for(i=3; i<argc && rc==SQLITE_OK; i++){
zonefileParseOption(p, argv[i], pzErr);
}
+ if( rc==SQLITE_OK && p->nCacheSize<1 ) p->nCacheSize = 1;
}
if( rc!=SQLITE_OK ){
return zonefileCreateConnect(0, pAux, db, argc, argv, ppVtab, pzErr);
}
-/*
-** zonefile virtual table module xDisconnect method.
-*/
-static int zonefileDisconnect(sqlite3_vtab *pVtab){
- ZonefileTab *pTab = (ZonefileTab*)pVtab;
- sqlite3_finalize(pTab->pIdToName);
- sqlite3_free(pTab);
- return SQLITE_OK;
-}
-
/*
** Zonefile virtual table module xBestIndex method.
**
return SQLITE_OK;
}
-/*
-** zonefile virtual table module xDestroy method.
-*/
-static int zonefileDestroy(sqlite3_vtab *pVtab){
- ZonefileTab *pTab = (ZonefileTab*)pVtab;
- int rc = SQLITE_OK;
- char *zSql = sqlite3_mprintf(
- "DROP TABLE IF EXISTS %Q.'%q_shadow_idx';"
- "DROP TABLE IF EXISTS %Q.'%q_shadow_file';"
- "DROP TABLE IF EXISTS %Q.'%q_shadow_frame';"
- "DROP TABLE IF EXISTS %Q.'%q_files';",
- pTab->zDb, pTab->zName, pTab->zDb, pTab->zName, pTab->zDb, pTab->zName
- );
- if( zSql==0 ){
- rc = SQLITE_NOMEM;
- }else{
- rc = sqlite3_exec(pTab->db, zSql, 0, 0, 0);
- sqlite3_free(zSql);
- }
-
- if( rc==SQLITE_OK ){
- zonefileDisconnect(pVtab);
- }
- return rc;
-}
-
/*
** zonefile virtual table module xOpen method.
*/
sqlite3_free(p);
}
-static int zonefileCtxUncompress(
- sqlite3_context *pCtx,
- ZonefileCompress *pMethod,
- void *pCmp,
- u8 *aBuf, int nBuf,
- int iKeyOff, int nKey
-){
- int rc;
- u8 *aUn = 0;
- int nUn = 0;
-
- rc = zonefileUncompress(pMethod, pCmp, aBuf, nBuf, &aUn, &nUn);
- if( rc==SQLITE_OK ){
- sqlite3_result_blob(pCtx, &aUn[iKeyOff], nKey, SQLITE_TRANSIENT);
- }else if( rc==SQLITE_ERROR ){
- zonefileCtxError(pCtx, "failed to uncompress frame");
- }
-
- sqlite3_free(aUn);
- return rc;
-}
-
static int zonefileGetFile(
sqlite3_context *pCtx, /* Leave error message here */
ZonefileCsr *pCsr, /* Cursor object */
return rc;
}
+#ifndef NDEBUG
+static void zonefileCacheCheck(ZonefileTab *pTab){
+ ZonefileFrame *p;
+ int n = 0;
+ for(p=pTab->pCacheFirst; p; p=p->pLruNext){
+ assert( p!=pTab->pCacheFirst || p->pLruPrev==0 );
+ assert( p!=pTab->pCacheLast || p->pLruNext==0 );
+ assert( p==pTab->pCacheFirst || p->pLruPrev->pLruNext==p );
+ assert( p==pTab->pCacheLast || p->pLruNext->pLruPrev==p );
+ n++;
+ }
+ assert( n==pTab->nCacheEntry );
+}
+#else
+# define zonefileCacheCheck(x)
+#endif
+
+/*
+** Search the frame-cache belonging to virtual table pTab for an entry
+** corresponding to the frame at byte offset iFrameOff of the file with
+** file id iFile. If such an entry is found, return a pointer to it.
+** Otherwise, if no such entry exists, return NULL.
+*/
static ZonefileFrame *zonefileCacheFind(
ZonefileTab *pTab,
i64 iFile,
i64 iFrameOff
){
+ ZonefileFrame *pFrame;
+ for(pFrame=pTab->pCacheFirst; pFrame; pFrame=pFrame->pLruNext){
+ if( pFrame->iFileid==iFile && pFrame->iFrameOff==iFrameOff ){
+ /* Found a match. Move it to the front of the LRU list and return
+ ** a pointer to it. */
+ assert( (pFrame->pLruPrev==0)==(pFrame==pTab->pCacheFirst) );
+ assert( (pFrame->pLruNext==0)==(pFrame==pTab->pCacheLast) );
+ if( pFrame->pLruPrev ){
+ assert( pFrame==pFrame->pLruPrev->pLruNext );
+ pFrame->pLruPrev->pLruNext = pFrame->pLruNext;
+
+ if( pFrame->pLruNext ){
+ assert( pFrame==pFrame->pLruNext->pLruPrev );
+ pFrame->pLruNext->pLruPrev = pFrame->pLruPrev;
+ }else{
+ assert( pFrame==pTab->pCacheLast );
+ pTab->pCacheLast = pFrame->pLruPrev;
+ pTab->pCacheLast->pLruNext = 0;
+ }
+
+ pFrame->pLruPrev = 0;
+ pFrame->pLruNext = pTab->pCacheFirst;
+ pTab->pCacheFirst->pLruPrev = pFrame;
+ pTab->pCacheFirst = pFrame;
+ }
+
+ zonefileCacheCheck(pTab);
+ return pFrame;
+ }
+ }
return 0;
}
-static void zonefileCacheStore(
- ZonefileTab *pTab,
- ZonefileFrame *pFrame
-){
+/*
+** Return the index of the hash bucket that iFileid/iFrameOff belongs to.
+*/
+int zonefileCacheHash(ZonefileTab *pTab, i64 iFileid, i64 iFrameOff){
+ u32 h;
+ h = (iFileid & 0xFFFFFFFF) ^ (iFrameOff & 0xFFFFFFFF);
+ return (h % pTab->nCacheBucket);
+}
+
+/*
+** Store the frame object passed as the second argument in the frame
+** cache belonging to table pTab.
+*/
+static int zonefileCacheStore(ZonefileTab *pTab, ZonefileFrame *pFrame){
+ int h;
+
+ /* Allocate the hash table if it has not already been allocated. */
+ if( pTab->aCache==0 ){
+ int nByte = pTab->nCacheSize * 2 * sizeof(ZonefileFrame*);
+ pTab->aCache = (ZonefileFrame**)sqlite3_malloc(nByte);
+ if( pTab->aCache==0 ){
+ sqlite3_free(pFrame);
+ return SQLITE_NOMEM;
+ }
+ memset(pTab->aCache, 0, nByte);
+ pTab->nCacheBucket = pTab->nCacheSize * 2;
+ }
+
+ /* Add the new entry to the hash table */
+ h = zonefileCacheHash(pTab, pFrame->iFileid, pFrame->iFrameOff);
+ assert( h>=0 && h<pTab->nCacheBucket );
+ pFrame->pHashNext = pTab->aCache[h];
+ pTab->aCache[h] = pFrame;
+
+ /* Add the new entry to the LRU list */
+ pFrame->pLruPrev = 0;
+ pFrame->pLruNext = pTab->pCacheFirst;
+ pTab->pCacheFirst = pFrame;
+ if( pFrame->pLruNext==0 ){
+ pTab->pCacheLast = pFrame;
+ }else{
+ pFrame->pLruNext->pLruPrev = pFrame;
+ }
+ pTab->nCacheEntry++;
+
+ if( pTab->nCacheEntry>pTab->nCacheSize ){
+ ZonefileFrame **pp;
+
+ /* Remove the oldest entry from the LRU list. */
+ ZonefileFrame *pLast = pTab->pCacheLast;
+ assert( pTab->pCacheLast );
+ assert( pTab->nCacheEntry>1 );
+ pTab->pCacheLast = pLast->pLruPrev;
+ pTab->pCacheLast->pLruNext = 0;
+ pTab->nCacheEntry--;
+
+ /* Remove the same entry from the hash table. */
+ h = zonefileCacheHash(pTab, pLast->iFileid, pLast->iFrameOff);
+ assert( h>=0 && h<pTab->nCacheBucket );
+ for(pp=&pTab->aCache[h]; *pp!=pLast; pp=&((*pp)->pHashNext));
+ *pp = pLast->pHashNext;
+ sqlite3_free(pLast);
+ }
+ zonefileCacheCheck(pTab);
+
+ return SQLITE_OK;
+}
+
+/*
+** Delete all resources associated with the frame-cache for table pTab.
+*/
+static void zonefileCacheDelete(ZonefileTab *pTab){
+ ZonefileFrame *p;
+ ZonefileFrame *pNext;
+ for(p=pTab->pCacheFirst; p; p=pNext){
+ pNext = p->pLruNext;
+ sqlite3_free(p);
+ }
+ sqlite3_free(pTab->aCache);
}
static int zonefileValueReadCache(sqlite3_context *pCtx, ZonefileCsr *pCsr){
if( p==0 ){
rc = SQLITE_NOMEM;
}else{
+ memset(p, 0, sizeof(ZonefileFrame));
p->aBuf = (u8*)&p[1];
p->nBuf = nOut;
p->iFrameOff = iFrameOff;
if( rc!=SQLITE_OK ){
sqlite3_free(pFrame);
pFrame = 0;
+ }else{
+ rc = zonefileCacheStore(pTab, pFrame);
+ if( rc!=SQLITE_OK ) pFrame = 0;
}
zonefileReleaseFile(pCsr);
zonefileFileClose(pFd);
if( pFrame ){
assert( rc==SQLITE_OK );
sqlite3_result_blob(pCtx, &pFrame->aBuf[iKeyOff], nKeySz, SQLITE_TRANSIENT);
- sqlite3_free(pFrame);
}
return rc;
return rc;
}
+/*
+** zonefile virtual table module xDisconnect method.
+*/
+static int zonefileDisconnect(sqlite3_vtab *pVtab){
+ ZonefileTab *pTab = (ZonefileTab*)pVtab;
+ zonefileCacheDelete(pTab);
+ sqlite3_finalize(pTab->pIdToName);
+ sqlite3_free(pTab);
+ return SQLITE_OK;
+}
+
+/*
+** zonefile virtual table module xDestroy method.
+*/
+static int zonefileDestroy(sqlite3_vtab *pVtab){
+ ZonefileTab *pTab = (ZonefileTab*)pVtab;
+ int rc = SQLITE_OK;
+ char *zSql = sqlite3_mprintf(
+ "DROP TABLE IF EXISTS %Q.'%q_shadow_idx';"
+ "DROP TABLE IF EXISTS %Q.'%q_shadow_file';"
+ "DROP TABLE IF EXISTS %Q.'%q_shadow_frame';"
+ "DROP TABLE IF EXISTS %Q.'%q_files';",
+ pTab->zDb, pTab->zName, pTab->zDb, pTab->zName, pTab->zDb, pTab->zName
+ );
+ if( zSql==0 ){
+ rc = SQLITE_NOMEM;
+ }else{
+ rc = sqlite3_exec(pTab->db, zSql, 0, 0, 0);
+ sqlite3_free(zSql);
+ }
+
+ if( rc==SQLITE_OK ){
+ zonefileDisconnect(pVtab);
+ }
+ return rc;
+}
+
/*
** zonefile virtual table module xRowid method.
*/
projects / thirdparty / sqlite.git / commitdiff
