From: dan <dan@noemail.net>
Date: Mon, 1 Oct 2018 17:33:35 +0000 (+0000)
Subject: Speed up xAccess() calls made on an RBU VFS when there are lots of open
X-Git-Tag: version-3.26.0~107
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=49f84ce1cde53b03a92f3bf00c47d37a7f609c7e;p=thirdparty%2Fsqlite.git

Speed up xAccess() calls made on an RBU VFS when there are lots of open
connections.

FossilOrigin-Name: 310b4b65b8c8ee080760c7efb4c7e20244c6063a5dba37a4f40490105aafd29f
---

diff --git a/ext/rbu/sqlite3rbu.c b/ext/rbu/sqlite3rbu.c
index 065b13c7fa..cd2f96c51b 100644
--- a/ext/rbu/sqlite3rbu.c
+++ b/ext/rbu/sqlite3rbu.c
@@ -405,7 +405,8 @@ struct rbu_vfs {
   sqlite3_vfs *pRealVfs;          /* Underlying VFS */
   sqlite3_mutex *mutex;           /* Mutex to protect pMain */
   sqlite3rbu *pRbu;               /* Owner RBU object */
-  rbu_file *pMain;                /* Linked list of main db files */
+  rbu_file *pMain;                /* List of main db files */
+  rbu_file *pMainRbu;             /* List of main db files with pRbu!=0 */
 };
 
 /*
@@ -434,6 +435,7 @@ struct rbu_file {
   const char *zWal;               /* Wal filename for this main db file */
   rbu_file *pWalFd;               /* Wal file descriptor for this main db */
   rbu_file *pMainNext;            /* Next MAIN_DB file */
+  rbu_file *pMainRbuNext;         /* Next MAIN_DB file with pRbu!=0 */
 };
 
 /*
@@ -4030,6 +4032,69 @@ static int rbuUpdateTempSize(rbu_file *pFd, sqlite3_int64 nNew){
   return SQLITE_OK;
 }
 
+/*
+** Add an item to the main-db lists, if it is not already present.
+**
+** There are two main-db lists. One for all file descriptors, and one
+** for all file descriptors with rbu_file.pDb!=0. If the argument has
+** rbu_file.pDb!=0, then it is assumed to already be present on the
+** main list and is only added to the pDb!=0 list.
+*/
+static void rbuMainlistAdd(rbu_file *p){
+  rbu_vfs *pRbuVfs = p->pRbuVfs;
+  rbu_file *pIter;
+  assert( (p->openFlags & SQLITE_OPEN_MAIN_DB) );
+  sqlite3_mutex_enter(pRbuVfs->mutex);
+  if( p->pRbu==0 ){
+    for(pIter=pRbuVfs->pMain; pIter; pIter=pIter->pMainNext);
+    p->pMainNext = pRbuVfs->pMain;
+    pRbuVfs->pMain = p;
+  }else{
+    for(pIter=pRbuVfs->pMainRbu; pIter && pIter!=p; pIter=pIter->pMainRbuNext){}
+    if( pIter==0 ){
+      p->pMainRbuNext = pRbuVfs->pMainRbu;
+      pRbuVfs->pMainRbu = p;
+    }
+  }
+  sqlite3_mutex_leave(pRbuVfs->mutex);
+}
+
+/*
+** Remove an item from the main-db lists.
+*/
+static void rbuMainlistRemove(rbu_file *p){
+  rbu_file **pp;
+  sqlite3_mutex_enter(p->pRbuVfs->mutex);
+  for(pp=&p->pRbuVfs->pMain; *pp && *pp!=p; pp=&((*pp)->pMainNext)){}
+  if( *pp ) *pp = p->pMainNext;
+  p->pMainNext = 0;
+  for(pp=&p->pRbuVfs->pMainRbu; *pp && *pp!=p; pp=&((*pp)->pMainRbuNext)){}
+  if( *pp ) *pp = p->pMainRbuNext;
+  p->pMainRbuNext = 0;
+  sqlite3_mutex_leave(p->pRbuVfs->mutex);
+}
+
+/*
+** Given that zWal points to a buffer containing a wal file name passed to 
+** either the xOpen() or xAccess() VFS method, search the main-db list for
+** a file-handle opened by the same database connection on the corresponding
+** database file.
+**
+** If parameter bRbu is true, only search for file-descriptors with
+** rbu_file.pDb!=0.
+*/
+static rbu_file *rbuFindMaindb(rbu_vfs *pRbuVfs, const char *zWal, int bRbu){
+  rbu_file *pDb;
+  sqlite3_mutex_enter(pRbuVfs->mutex);
+  if( bRbu ){
+    for(pDb=pRbuVfs->pMainRbu; pDb && pDb->zWal!=zWal; pDb=pDb->pMainRbuNext){}
+  }else{
+    for(pDb=pRbuVfs->pMain; pDb && pDb->zWal!=zWal; pDb=pDb->pMainNext){}
+  }
+  sqlite3_mutex_leave(pRbuVfs->mutex);
+  return pDb;
+}
+
 /*
 ** Close an rbu file.
 */
@@ -4047,17 +4112,14 @@ static int rbuVfsClose(sqlite3_file *pFile){
   sqlite3_free(p->zDel);
 
   if( p->openFlags & SQLITE_OPEN_MAIN_DB ){
-    rbu_file **pp;
-    sqlite3_mutex_enter(p->pRbuVfs->mutex);
-    for(pp=&p->pRbuVfs->pMain; *pp!=p; pp=&((*pp)->pMainNext));
-    *pp = p->pMainNext;
-    sqlite3_mutex_leave(p->pRbuVfs->mutex);
+    rbuMainlistRemove(p);
     rbuUnlockShm(p);
     p->pReal->pMethods->xShmUnmap(p->pReal, 0);
   }
   else if( (p->openFlags & SQLITE_OPEN_DELETEONCLOSE) && p->pRbu ){
     rbuUpdateTempSize(p, 0);
   }
+  assert( p->pMainNext==0 && p->pRbuVfs->pMain!=p );
 
   /* Close the underlying file handle */
   rc = p->pReal->pMethods->xClose(p->pReal);
@@ -4316,6 +4378,9 @@ static int rbuVfsFileControl(sqlite3_file *pFile, int op, void *pArg){
       }else if( rc==SQLITE_NOTFOUND ){
         pRbu->pTargetFd = p;
         p->pRbu = pRbu;
+        if( p->openFlags & SQLITE_OPEN_MAIN_DB ){
+          rbuMainlistAdd(p);
+        }
         if( p->pWalFd ) p->pWalFd->pRbu = pRbu;
         rc = SQLITE_OK;
       }
@@ -4477,20 +4542,6 @@ static int rbuVfsShmUnmap(sqlite3_file *pFile, int delFlag){
   return rc;
 }
 
-/*
-** Given that zWal points to a buffer containing a wal file name passed to 
-** either the xOpen() or xAccess() VFS method, return a pointer to the
-** file-handle opened by the same database connection on the corresponding
-** database file.
-*/
-static rbu_file *rbuFindMaindb(rbu_vfs *pRbuVfs, const char *zWal){
-  rbu_file *pDb;
-  sqlite3_mutex_enter(pRbuVfs->mutex);
-  for(pDb=pRbuVfs->pMain; pDb && pDb->zWal!=zWal; pDb=pDb->pMainNext){}
-  sqlite3_mutex_leave(pRbuVfs->mutex);
-  return pDb;
-}
-
 /* 
 ** A main database named zName has just been opened. The following 
 ** function returns a pointer to a buffer owned by SQLite that contains
@@ -4569,7 +4620,7 @@ static int rbuVfsOpen(
       pFd->zWal = rbuMainToWal(zName, flags);
     }
     else if( flags & SQLITE_OPEN_WAL ){
-      rbu_file *pDb = rbuFindMaindb(pRbuVfs, zName);
+      rbu_file *pDb = rbuFindMaindb(pRbuVfs, zName, 0);
       if( pDb ){
         if( pDb->pRbu && pDb->pRbu->eStage==RBU_STAGE_OAL ){
           /* This call is to open a *-wal file. Intead, open the *-oal. This
@@ -4621,10 +4672,7 @@ static int rbuVfsOpen(
     ** mutex protected linked list of all such files.  */
     pFile->pMethods = &rbuvfs_io_methods;
     if( flags & SQLITE_OPEN_MAIN_DB ){
-      sqlite3_mutex_enter(pRbuVfs->mutex);
-      pFd->pMainNext = pRbuVfs->pMain;
-      pRbuVfs->pMain = pFd;
-      sqlite3_mutex_leave(pRbuVfs->mutex);
+      rbuMainlistAdd(pFd);
     }
   }else{
     sqlite3_free(pFd->zDel);
@@ -4672,7 +4720,7 @@ static int rbuVfsAccess(
   **      file opened instead.
   */
   if( rc==SQLITE_OK && flags==SQLITE_ACCESS_EXISTS ){
-    rbu_file *pDb = rbuFindMaindb(pRbuVfs, zPath);
+    rbu_file *pDb = rbuFindMaindb(pRbuVfs, zPath, 1);
     if( pDb && pDb->pRbu && pDb->pRbu->eStage==RBU_STAGE_OAL ){
       if( *pResOut ){
         rc = SQLITE_CANTOPEN;
diff --git a/manifest b/manifest
index 3cea376d3c..8c7dc34921 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sa\spotential\scrash\sthat\scan\soccur\swhile\sreading\san\sindex\sfrom\sa\scorrupt\ndatabase\sfile.\s\sThe\scorruption\sis\sa\srecord-header-size\sthat\sis\slarger\sthan\n0x7fffffff.\s\sProblem\sdetected\sby\sOSSFuzz\sagainst\sGDAL\sand\sreported\sto\sus\s\n(with\sa\ssuggested\sfix)\sby\sEven\sRouault.\s\sThe\stest\scase\sis\sin\sTH3.
-D 2018-10-01T13:54:30.911
+C Speed\sup\sxAccess()\scalls\smade\son\san\sRBU\sVFS\swhen\sthere\sare\slots\sof\sopen\nconnections.
+D 2018-10-01T17:33:35.846
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 01e95208a78b57d056131382c493c963518f36da4c42b12a97eb324401b3a334
@@ -348,7 +348,7 @@ F ext/rbu/rbusplit.test 69271c790732b28bd465551d80b0a9a3f074e189896ee8490ce56d22
 F ext/rbu/rbutemplimit.test cd553a9288d515d0b5f87d277e76fd18c4aa740b761e7880fab11ce986ea18d1
 F ext/rbu/rbuvacuum.test ff357e9b556ca7ad4673da0ff7f244def919ff858e0f9f350d3e30fdd83a62a8
 F ext/rbu/rbuvacuum2.test 2074ab14fe66e1c7e7210c62562650dcd215bbaa
-F ext/rbu/sqlite3rbu.c f438fea899d15d13ff3e3133242b9e378c37b5a3d76add8c342c68bdd65c6819
+F ext/rbu/sqlite3rbu.c 71f8c09948d09ec9c5a8dbe7127e8ef61ef0853e698b2650be2485ac7b9c75c8
 F ext/rbu/sqlite3rbu.h b42bcd4d8357268c6c39ab2a60b29c091e89328fa8cc49c8fac5ab8d007e79b2
 F ext/rbu/test_rbu.c baa23eb28457580673d2175e5f0c29ced0cd320ee819b13ad362398c53b96e90
 F ext/repair/README.md 92f5e8aae749a4dae14f02eea8e1bb42d4db2b6ce5e83dbcdd6b1446997e0c15
@@ -1770,7 +1770,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P c52f457e56eb9d573eb67093731eb231aaf6fd6dbdc397e6f948b82736fbe3ab
-R c75c41f8def35162ce620ba59792b15c
-U drh
-Z 2db3890d5903ac5d614f7b18f951a8a9
+P 8ac2cdda68f92b0352bc7f0b4be5fca4bb58565ca65055fb34153cc284ed6922
+R a63f057a754c642de8f2617ecd7043d5
+U dan
+Z c6e86f7777ba1872e2992f69103701bb
diff --git a/manifest.uuid b/manifest.uuid
index d9b29688df..8b77660070 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-8ac2cdda68f92b0352bc7f0b4be5fca4bb58565ca65055fb34153cc284ed6922
\ No newline at end of file
+310b4b65b8c8ee080760c7efb4c7e20244c6063a5dba37a4f40490105aafd29f
\ No newline at end of file