Add the sqlite3_log_hook() interface for scheduling checkpoints.

FossilOrigin-Name: 9bda601455705475075e33bfa85687bce34b15ff

manifest

@@ -1,5 +1,5 @@
-C Add\ssome\scomments\sregarding\sfile-locks\sto\slog.c.
+C Add\sthe\ssqlite3_log_hook()\sinterface\sfor\sscheduling\scheckpoints.
-D 2010-04-17T18:50:28
+D 2010-04-19T18:03:52
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 4f2f967b7e58a35bb74fb7ec8ae90e0f4ca7868b
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -131,9 +131,9 @@ F src/journal.c b0ea6b70b532961118ab70301c00a33089f9315c
 F src/legacy.c a199d7683d60cef73089e892409113e69c23a99f
 F src/lempar.c 7f026423f4d71d989e719a743f98a1cbd4e6d99e
 F src/loadext.c 1c7a61ce1281041f437333f366a96aa0d29bb581
-F src/log.c fd6631f740b0cf2c8720477a036ffee8ca705c92
+F src/log.c a5bbeb05c456ee7ee9d4f3dba5e72bae2d9b6530
-F src/log.h 3cfec02156f5db3d233352897a47601930a29955
+F src/log.h b8c45a6348d9ef57c5205a08c611d57d07ee9feb
-F src/main.c c0e7192bad5b90544508b241eb2487ac661de890
+F src/main.c 867de6aa444abd97771b2b70472f448d65c1c77e
 F src/malloc.c a08f16d134f0bfab6b20c3cd142ebf3e58235a6a
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c 89d4ea8d5cdd55635cbaa48ad53132af6294cbb2
@@ -154,8 +154,8 @@ F src/os_common.h 240c88b163b02c21a9f21f87d49678a0aa21ff30
 F src/os_os2.c 75a8c7b9a00a2cf1a65f9fa4afbc27d46634bb2f
 F src/os_unix.c 5bf0015cebe2f21635da2af983c348eb88b3b4c1
 F src/os_win.c 1c7453c2df4dab26d90ff6f91272aea18bcf7053
-F src/pager.c 344eddf3c59eed4b4aca31abbf762d0e301ae44d
+F src/pager.c f9ad51dfa617131240ae77545c0083118324fc81
-F src/pager.h ce5d076f3860a5f2d7460c582cd68383343b33cf
+F src/pager.h aeaee9ceb4a4a6d15c2163ef4e11a7590fd54b59
 F src/parse.y ace5c7a125d9f2a410e431ee3209034105045f7e
 F src/pcache.c ace8f6a5ecd4711cc66a1b23053be7109bd437cf
 F src/pcache.h c683390d50f856d4cd8e24342ae62027d1bb6050
@@ -168,13 +168,13 @@ F src/resolve.c ac5f1a713cd1ae77f08b83cc69581e11bf5ae6f9
 F src/rowset.c 69afa95a97c524ba6faf3805e717b5b7ae85a697
 F src/select.c b7c9a40bc1567bceff52ad4b73108734ee4bf268
 F src/shell.c c40427c7245535a04a9cb4a417b6cc05c022e6a4
-F src/sqlite.h.in dc98616304e3e776008655671d81e3ad3028ada7
+F src/sqlite.h.in b9b0365613d4a99a0e6bc0ae6dbc73cc4a7e7cb7
 F src/sqlite3ext.h 69dfb8116af51b84a029cddb3b35062354270c89
-F src/sqliteInt.h bd7ff54663bdd5b57e0eb8b49aca5a3a3c60119a
+F src/sqliteInt.h 6ed0ed77103d00006d6a534c0239baf6decadb3f
 F src/sqliteLimit.h 3afab2291762b5d09ae20c18feb8e9fa935a60a6
 F src/status.c 4df6fe7dce2d256130b905847c6c60055882bdbe
 F src/table.c 2cd62736f845d82200acfa1287e33feb3c15d62e
-F src/tclsqlite.c ebf7a964f8311bc52266cf75afedae98cd743df3
+F src/tclsqlite.c e27e0457109d72c7404df08af1726ff6ddc3d92c
 F src/test1.c 8b4c246c41e75c3ff033edb2e8c2cf15820861ae
 F src/test2.c b6b43413d495addd039a88b87d65c839f86b18cb
 F src/test3.c 4c21700c73a890a47fc685c1097bfb661346ac94
@@ -217,8 +217,8 @@ F src/vacuum.c b1d542c8919d4d11119f78069e1906a1ad07e0ee
 F src/vdbe.c 2e2aaa765de667dd15e0462cf853efd1b2f97998
 F src/vdbe.h 471f6a3dcec4817ca33596fe7f6654d56c0e75f3
 F src/vdbeInt.h 19ebc8c2a2e938340051ee65af3f377fb99102d1
-F src/vdbeapi.c 11bcc381e81e797fcf3e81fa6a14ec16a04801cc
+F src/vdbeapi.c 466044df5bc916f778833e927165fd02cdef6086
-F src/vdbeaux.c 3028b2d50df39697e21263685349b5ff1333a29b
+F src/vdbeaux.c be6ca4bb330c7730b358dd627d6d632ca93482c9
 F src/vdbeblob.c 5327132a42a91e8b7acfb60b9d2c3b1c5c863e0e
 F src/vdbemem.c 2a82f455f6ca6f78b59fb312f96054c04ae0ead1
 F src/vdbetrace.c 864cef96919323482ebd9986f2132435115e9cc2
@@ -599,7 +599,7 @@ F test/substr.test 18f57c4ca8a598805c4d64e304c418734d843c1a
 F test/sync.test ded6b39d8d8ca3c0c5518516c6371b3316d3e3a3
 F test/table.test bf102a5669c4db7a41330802f24a4a81a4204f83
 F test/tableapi.test 7262a8cbaa9965d429f1cbd2747edc185fa56516
-F test/tclsqlite.test bf4227eb236a4c097aa7974a2bf7d3225acf34be
+F test/tclsqlite.test 7378a4e7474d9ffdb7c930086112b829e5955fb0
 F test/tempdb.test 1bf52da28a9c24e29717362a87722dff08feb72b
 F test/temptable.test f42121a0d29a62f00f93274464164177ab1cc24a
 F test/temptrigger.test b0273db072ce5f37cf19140ceb1f0d524bbe9f05
@@ -760,6 +760,7 @@ F test/vtab_err.test 0d4d8eb4def1d053ac7c5050df3024fd47a3fbd8
 F test/vtab_shared.test 0eff9ce4f19facbe0a3e693f6c14b80711a4222d
 F test/wal.test a56ff378f58b145fd3bf38c277fbfe792cd47bdd
 F test/walcrash.test 45cfbab30bb7cbe0b2e9d5cabe90dbcad10cb89b
+F test/walhook.test 76a559e262f0715c470bade4a8d8333035f8ee47
 F test/walslow.test 38076d5fad49e3678027be0f8110e6a32d531dc2
 F test/walthread.test 27e44ee6fd02f1f494a24f999c97086af3ab739d
 F test/where.test de337a3fe0a459ec7c93db16a519657a90552330
@@ -805,7 +806,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P 0ae91b0008b242a47385fc1f295c6b645483ee22
+P 9d51c3b754f0b94fea5ef3d669ad583b93b2b024
-R a205bea3ab4fa24118ce751726c3c719
+R 8eb45c9f56fe0d743248bffdfb606bc1
 U dan
-Z c979f9f88d66076be76b02e7ab3fa216
+Z e82f118f370901abf724c6ac84b89351

manifest.uuid

@@ -1 +1 @@
-9d51c3b754f0b94fea5ef3d669ad583b93b2b024
+9bda601455705475075e33bfa85687bce34b15ff

src/log.c

@@ -202,6 +202,14 @@ struct LogSummary {
 #define LOG_REGION_C 0x04
 #define LOG_REGION_D 0x08
 
+/*
+** Values for the third parameter to logLockRegion().
+*/
+#define LOG_UNLOCK  0             /* Unlock a range of bytes */
+#define LOG_RDLOCK  1             /* Put a SHARED lock on a range of bytes */
+#define LOG_WRLOCK  2             /* Put an EXCLUSIVE lock on a byte-range */
+#define LOG_WRLOCKW 3             /* Block on EXCLUSIVE lock on a byte-range */
+
 /*
 ** A single instance of this structure is allocated as part of each 
 ** connection to a database log. All structures associated with the 
@@ -225,6 +233,7 @@ struct Log {
   sqlite3_file *pFd;              /* File handle for log file */
   int isLocked;                   /* Non-zero if a snapshot is held open */
   int isWriteLocked;              /* True if this is the writer connection */
+  u32 iCallback;                  /* Value to pass to log callback (or 0) */
   LogSummaryHdr hdr;              /* Log summary header for current snapshot */
   LogLock lock;                   /* Lock held by this connection (if any) */
 };
@@ -647,29 +656,29 @@ finished:
 }
 
 /*
-** Values for the third parameter to logLockRegion().
+** Place, modify or remove a lock on the log-summary file associated 
+** with pSummary.
 */
-#define LOG_UNLOCK  0
+static int logLockFd(
-#define LOG_RDLOCK  1
+  LogSummary *pSummary,           /* The log-summary object to lock */
-#define LOG_WRLOCK  2
+  int iStart,                     /* First byte to lock */
-#define LOG_WRLOCKW 3
+  int nByte,                      /* Number of bytes to lock */
-
+  int op                          /* LOG_UNLOCK, RDLOCK, WRLOCK or WRLOCKW */
-static int logLockFd(LogSummary *pSummary, int iStart, int nByte, int op){
+){
   int aType[4] = { 
-    F_UNLCK,                    /* LOG_UNLOCK */
+    F_UNLCK,                      /* LOG_UNLOCK */
-    F_RDLCK,                    /* LOG_RDLOCK */
+    F_RDLCK,                      /* LOG_RDLOCK */
-    F_WRLCK,                    /* LOG_WRLOCK */
+    F_WRLCK,                      /* LOG_WRLOCK */
-    F_WRLCK                     /* LOG_WRLOCKW */
+    F_WRLCK                       /* LOG_WRLOCKW */
   };
   int aOp[4] = { 
-    F_SETLK,                    /* LOG_UNLOCK */
+    F_SETLK,                      /* LOG_UNLOCK */
-    F_SETLK,                    /* LOG_RDLOCK */
+    F_SETLK,                      /* LOG_RDLOCK */
-    F_SETLK,                    /* LOG_WRLOCK */
+    F_SETLK,                      /* LOG_WRLOCK */
-    F_SETLKW                    /* LOG_WRLOCKW */
+    F_SETLKW                      /* LOG_WRLOCKW */
   };
-
+  struct flock f;                 /* Locking operation */
-  struct flock f;               /* Locking operation */
+  int rc;                         /* Value returned by fcntl() */
-  int rc;                       /* Value returned by fcntl() */
 
   assert( ArraySize(aType)==ArraySize(aOp) );
   assert( op>=0 && op<ArraySize(aType) );
@@ -816,19 +825,28 @@ static int logLockRegion(Log *pLog, u32 mRegion, int op){
   return SQLITE_OK;
 }
 
+/*
+** Lock the DMH region, either with an EXCLUSIVE or SHARED lock. This
+** function is never called with LOG_UNLOCK - the only way the DMH region
+** is every completely unlocked is by by closing the file descriptor.
+*/
 static int logLockDMH(LogSummary *pSummary, int eLock){
+  assert( sqlite3_mutex_held(pSummary->mutex) );
   assert( eLock==LOG_RDLOCK || eLock==LOG_WRLOCK );
   return logLockFd(pSummary, LOG_LOCK_DMH, 1, eLock);
 }
 
+/*
+** Lock (or unlock) the MUTEX region. It is always locked using an
+** EXCLUSIVE, blocking lock.
+*/
 static int logLockMutex(LogSummary *pSummary, int eLock){
+  assert( sqlite3_mutex_held(pSummary->mutex) );
   assert( eLock==LOG_WRLOCKW || eLock==LOG_UNLOCK );
   logLockFd(pSummary, LOG_LOCK_MUTEX, 1, eLock);
   return SQLITE_OK;
 }
 
-
-
 /*
 ** This function intializes the connection to the log-summary identified
 ** by struct pSummary.
@@ -880,7 +898,7 @@ static int logSummaryInit(
   }
   rc = logLockDMH(pSummary, LOG_RDLOCK);
   if( rc!=SQLITE_OK ){
-    return SQLITE_IOERR;
+    rc = SQLITE_IOERR;
   }
 
  out:
@@ -1461,7 +1479,7 @@ int sqlite3LogRead(Log *pLog, Pgno pgno, int *pInLog, u8 *pOut){
 /* 
 ** Set *pPgno to the size of the database file (or zero, if unknown).
 */
-void sqlite3LogMaxpgno(Log *pLog, Pgno *pPgno){
+void sqlite3LogDbsize(Log *pLog, Pgno *pPgno){
   assert( pLog->isLocked );
   *pPgno = pLog->hdr.nPage;
 }
@@ -1646,9 +1664,10 @@ int sqlite3LogFrames(
   if( isCommit && SQLITE_OK==(rc = logEnterMutex(pLog)) ){
     logSummaryWriteHdr(pLog->pSummary, &pLog->hdr);
     logLeaveMutex(pLog);
+    pLog->iCallback = iFrame;
   }
 
-  return SQLITE_OK;
+  return rc;
 }
 
 /* 
@@ -1698,3 +1717,12 @@ int sqlite3LogCheckpoint(
   return rc;
 }
 
+int sqlite3LogCallback(Log *pLog){
+  u32 ret = 0;
+  if( pLog ){
+    ret = pLog->iCallback;
+    pLog->iCallback = 0;
+  }
+  return (int)ret;
+}
+

src/log.h

@@ -32,7 +32,7 @@ void sqlite3LogCloseSnapshot(Log *pLog);
 
 /* Read a page from the log, if it is present. */
 int sqlite3LogRead(Log *pLog, Pgno pgno, int *pInLog, u8 *pOut);
-void sqlite3LogMaxpgno(Log *pLog, Pgno *pPgno);
+void sqlite3LogDbsize(Log *pLog, Pgno *pPgno);
 
 /* Obtain or release the WRITER lock. */
 int sqlite3LogWriteLock(Log *pLog, int op);
@@ -50,4 +50,7 @@ int sqlite3LogCheckpoint(
   void *pBusyHandlerArg           /* Argument to pass to xBusyHandler */
 );
 
+/* Return the value to pass to a log callback. Or 0 for no callback. */
+int sqlite3LogCallback(Log *pLog);
+
 #endif /* _LOG_H_ */

src/main.c

@@ -1186,6 +1186,24 @@ void *sqlite3_rollback_hook(
   return pRet;
 }
 
+/*
+** Register a callback to be invoked each time a transaction is written
+** into the write-ahead-log by this database connection.
+*/
+void *sqlite3_log_hook(
+  sqlite3 *db,                    /* Attach the hook to this db handle */
+  int(*xCallback)(void *, sqlite3*, const char*, int),
+  void *pArg                      /* First argument passed to xCallback() */
+){
+  void *pRet;
+  sqlite3_mutex_enter(db->mutex);
+  pRet = db->pLogArg;
+  db->xLogCallback = xCallback;
+  db->pLogArg = pArg;
+  sqlite3_mutex_leave(db->mutex);
+  return pRet;
+}
+
 /*
 ** This function returns true if main-memory should be used instead of
 ** a temporary file for transient pager files and statement journals.

src/pager.c

@@ -2686,7 +2686,7 @@ int sqlite3PagerPagecount(Pager *pPager, int *pnPage){
     i64 n = 0;              /* File size in bytes returned by OsFileSize() */
 
     if( pagerUseLog(pPager) ){
-      sqlite3LogMaxpgno(pPager->pLog, &nPage);
+      sqlite3LogDbsize(pPager->pLog, &nPage);
     }
 
     if( nPage==0 ){
@@ -5709,4 +5709,8 @@ int sqlite3PagerCheckpoint(Pager *pPager){
   return rc;
 }
 
+int sqlite3PagerLogCallback(Pager *pPager){
+  return sqlite3LogCallback(pPager->pLog);
+}
+
 #endif /* SQLITE_OMIT_DISKIO */

src/pager.h

@@ -133,7 +133,9 @@ int sqlite3PagerRollback(Pager*);
 int sqlite3PagerOpenSavepoint(Pager *pPager, int n);
 int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint);
 int sqlite3PagerSharedLock(Pager *pPager);
+
 int sqlite3PagerCheckpoint(Pager *pPager);
+int sqlite3PagerLogCallback(Pager *pPager);
 
 /* Functions used to query pager state and configuration. */
 u8 sqlite3PagerIsreadonly(Pager*);

src/sqlite.h.in

@@ -5726,6 +5726,40 @@ int sqlite3_strnicmp(const char *, const char *, int);
 */
 void sqlite3_log(int iErrCode, const char *zFormat, ...);
 
+/*
+** Experimental WAL callback interface.
+**
+** The [sqlite3_log_hook()] function is used to register a callback that
+** will be invoked each time a database connection commits data to a
+** write-ahead-log (i.e. whenever a transaction is committed in
+** journal_mode=WAL mode). 
+**
+** The callback is invoked by SQLite after the commit has taken place and 
+** the associated write-lock on the database released, so the implementation 
+** may read, write or checkpoint the database as required.
+**
+** The first parameter passed to the callback function when it is invoked
+** is a copy of the third parameter passed to sqlite3_log_hook() when
+** registering the callback. The second is a copy of the database handle.
+** The third parameter is the name of the database that was written to -
+** either "main" or the name of an ATTACHed database. The fourth parameter
+** is the number of pages currently in the log file, including those that
+** were just committed.
+**
+** If an invocation of the callback function returns non-zero, then a
+** checkpoint is automatically run on the database. If zero is returned,
+** no special action is taken.
+**
+** A single database handle may have at most a single log callback 
+** registered at one time. Calling [sqlite3_log_hook()] replaces any
+** previously registered log callback. 
+*/
+void *sqlite3_log_hook(
+  sqlite3*, 
+  int(*)(void *,sqlite3*,const char*,int),
+  void*
+);
+
 /*
 ** Undo the hack that converts floating point types to integer for
 ** builds on processors without floating point support.

src/sqliteInt.h

@@ -823,6 +823,8 @@ struct sqlite3 {
   void (*xRollbackCallback)(void*); /* Invoked at every commit. */
   void *pUpdateArg;
   void (*xUpdateCallback)(void*,int, const char*,const char*,sqlite_int64);
+  int (*xLogCallback)(void *, sqlite3 *, const char *, u32);
+  void *pLogArg;
   void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*);
   void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*);
   void *pCollNeededArg;

src/tclsqlite.c

@@ -123,6 +123,7 @@ struct SqliteDb {
   SqlFunc *pFunc;            /* List of SQL functions */
   Tcl_Obj *pUpdateHook;      /* Update hook script (if any) */
   Tcl_Obj *pRollbackHook;    /* Rollback hook script (if any) */
+  Tcl_Obj *pLogHook;         /* WAL hook script (if any) */
   Tcl_Obj *pUnlockNotify;    /* Unlock notify script (if any) */
   SqlCollate *pCollate;      /* List of SQL collation functions */
   int rc;                    /* Return code of most recent sqlite3_exec() */
@@ -485,6 +486,9 @@ static void DbDeleteCmd(void *db){
   if( pDb->pRollbackHook ){
     Tcl_DecrRefCount(pDb->pRollbackHook);
   }
+  if( pDb->pLogHook ){
+    Tcl_DecrRefCount(pDb->pLogHook);
+  }
   if( pDb->pCollateNeeded ){
     Tcl_DecrRefCount(pDb->pCollateNeeded);
   }
@@ -589,6 +593,32 @@ static void DbRollbackHandler(void *clientData){
   }
 }
 
+static int DbLogHandler(
+  void *clientData, 
+  sqlite3 *db, 
+  const char *zDb, 
+  int nEntry
+){
+  int ret = 0;
+  Tcl_Obj *p;
+  SqliteDb *pDb = (SqliteDb*)clientData;
+  Tcl_Interp *interp = pDb->interp;
+  assert(pDb->pLogHook);
+
+  p = Tcl_DuplicateObj(pDb->pLogHook);
+  Tcl_IncrRefCount(p);
+  Tcl_ListObjAppendElement(interp, p, Tcl_NewStringObj(zDb, -1));
+  Tcl_ListObjAppendElement(interp, p, Tcl_NewIntObj(nEntry));
+  if( TCL_OK!=Tcl_EvalObjEx(interp, p, 0) 
+   || TCL_OK!=Tcl_GetIntFromObj(interp, Tcl_GetObjResult(interp), &ret)
+  ){
+    Tcl_BackgroundError(interp);
+  }
+  Tcl_DecrRefCount(p);
+
+  return ret;
+}
+
 #if defined(SQLITE_TEST) && defined(SQLITE_ENABLE_UNLOCK_NOTIFY)
 static void setTestUnlockNotifyVars(Tcl_Interp *interp, int iArg, int nArg){
   char zBuf[64];
@@ -1540,12 +1570,12 @@ static int DbObjCmd(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
     "complete",           "copy",              "enable_load_extension",
     "errorcode",          "eval",              "exists",
     "function",           "incrblob",          "interrupt",
-    "last_insert_rowid",  "nullvalue",         "onecolumn",
+    "last_insert_rowid",  "log_hook",          "nullvalue",
-    "profile",            "progress",          "rekey",
+    "onecolumn",          "profile",           "progress",
-    "restore",            "rollback_hook",     "status",
+    "rekey",              "restore",           "rollback_hook",     
-    "timeout",            "total_changes",     "trace",
+    "status",             "timeout",           "total_changes",     
-    "transaction",        "unlock_notify",     "update_hook",
+    "trace",              "transaction",       "unlock_notify",     
-    "version",            0                    
+    "update_hook",        "version",            0                    
   };
   enum DB_enum {
     DB_AUTHORIZER,        DB_BACKUP,           DB_BUSY,
@@ -1554,12 +1584,12 @@ static int DbObjCmd(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
     DB_COMPLETE,          DB_COPY,             DB_ENABLE_LOAD_EXTENSION,
     DB_ERRORCODE,         DB_EVAL,             DB_EXISTS,
     DB_FUNCTION,          DB_INCRBLOB,         DB_INTERRUPT,
-    DB_LAST_INSERT_ROWID, DB_NULLVALUE,        DB_ONECOLUMN,
+    DB_LAST_INSERT_ROWID, DB_LOG_HOOK,         DB_NULLVALUE,
-    DB_PROFILE,           DB_PROGRESS,         DB_REKEY,
+    DB_ONECOLUMN,         DB_PROFILE,          DB_PROGRESS,
-    DB_RESTORE,           DB_ROLLBACK_HOOK,    DB_STATUS,
+    DB_REKEY,             DB_RESTORE,          DB_ROLLBACK_HOOK,    
-    DB_TIMEOUT,           DB_TOTAL_CHANGES,    DB_TRACE,
+    DB_STATUS,            DB_TIMEOUT,          DB_TOTAL_CHANGES,    
-    DB_TRANSACTION,       DB_UNLOCK_NOTIFY,    DB_UPDATE_HOOK,
+    DB_TRACE,             DB_TRANSACTION,      DB_UNLOCK_NOTIFY,    
-    DB_VERSION,
+    DB_UPDATE_HOOK,       DB_VERSION
   };
   /* don't leave trailing commas on DB_enum, it confuses the AIX xlc compiler */
 
@@ -2730,9 +2760,11 @@ static int DbObjCmd(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
   }
 
   /*
+  **    $db log_hook ?script?
   **    $db update_hook ?script?
   **    $db rollback_hook ?script?
   */
+  case DB_LOG_HOOK: 
   case DB_UPDATE_HOOK: 
   case DB_ROLLBACK_HOOK: {
 
@@ -2742,6 +2774,8 @@ static int DbObjCmd(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
     Tcl_Obj **ppHook; 
     if( choice==DB_UPDATE_HOOK ){
       ppHook = &pDb->pUpdateHook;
+    }else if( choice==DB_LOG_HOOK ){
+      ppHook = &pDb->pLogHook;
     }else{
       ppHook = &pDb->pRollbackHook;
     }
@@ -2767,6 +2801,7 @@ static int DbObjCmd(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
 
     sqlite3_update_hook(pDb->db, (pDb->pUpdateHook?DbUpdateHandler:0), pDb);
     sqlite3_rollback_hook(pDb->db,(pDb->pRollbackHook?DbRollbackHandler:0),pDb);
+    sqlite3_log_hook(pDb->db,(pDb->pLogHook?DbLogHandler:0),pDb);
 
     break;
   }

src/vdbeapi.c

@@ -306,6 +306,23 @@ void sqlite3_result_error_nomem(sqlite3_context *pCtx){
   pCtx->s.db->mallocFailed = 1;
 }
 
+static int doLogCallbacks(sqlite3 *db){
+  int i;
+  int rc = SQLITE_OK;
+  for(i=0; i<db->nDb; i++){
+    Btree *pBt = db->aDb[i].pBt;
+    if( pBt ){
+      int nEntry = sqlite3PagerLogCallback(sqlite3BtreePager(pBt));
+      if( db->xLogCallback && nEntry>0 && rc==SQLITE_OK
+       && db->xLogCallback(db->pLogArg, db, db->aDb[i].zName, nEntry)
+      ){
+        rc = sqlite3PagerCheckpoint(sqlite3BtreePager(pBt));
+      }
+    }
+  }
+  return rc;
+}
+
 /*
 ** Execute the statement pStmt, either until a row of data is ready, the
 ** statement is completely executed or an error occurs.
@@ -387,6 +404,14 @@ static int sqlite3Step(Vdbe *p){
   }
 #endif
 
+  if( rc==SQLITE_DONE ){
+    assert( p->rc==SQLITE_OK );
+    p->rc = doLogCallbacks(db);
+    if( p->rc!=SQLITE_OK ){
+      rc = SQLITE_ERROR;
+    }
+  }
+
   db->errCode = rc;
   if( SQLITE_NOMEM==sqlite3ApiExit(p->db, p->rc) ){
     p->rc = SQLITE_NOMEM;

src/vdbeaux.c

@@ -1651,7 +1651,7 @@ static int vdbeCommit(sqlite3 *db, Vdbe *p){
   ** one database file has an open write transaction, a master journal
   ** file is required for an atomic commit.
   */ 
-  for(i=0; i<db->nDb; i++){ 
+  for(i=0; i<db->nDb; i++){
     Btree *pBt = db->aDb[i].pBt;
     if( sqlite3BtreeIsInTrans(pBt) ){
       needXcommit = 1;

test/tclsqlite.test

@@ -35,7 +35,7 @@ do_test tcl-1.1 {
 do_test tcl-1.2 {
   set v [catch {db bogus} msg]
   lappend v $msg
-} {1 {bad option "bogus": must be authorizer, backup, busy, cache, changes, close, collate, collation_needed, commit_hook, complete, copy, enable_load_extension, errorcode, eval, exists, function, incrblob, interrupt, last_insert_rowid, nullvalue, onecolumn, profile, progress, rekey, restore, rollback_hook, status, timeout, total_changes, trace, transaction, unlock_notify, update_hook, or version}}
+} {1 {bad option "bogus": must be authorizer, backup, busy, cache, changes, close, collate, collation_needed, commit_hook, complete, copy, enable_load_extension, errorcode, eval, exists, function, incrblob, interrupt, last_insert_rowid, log_hook, nullvalue, onecolumn, profile, progress, rekey, restore, rollback_hook, status, timeout, total_changes, trace, transaction, unlock_notify, update_hook, or version}}
 do_test tcl-1.2.1 {
   set v [catch {db cache bogus} msg]
   lappend v $msg

test/walhook.test

@@ -0,0 +1,73 @@
+# 2010 April 19
+#
+# 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.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+proc sqlite3_wal {args} {
+  eval sqlite3 $args
+  [lindex $args 0] eval { 
+    PRAGMA journal_mode = wal;
+    PRAGMA synchronous = normal;
+    PRAGMA page_size = 1024;
+  }
+}
+sqlite3_wal db test.db
+db log_hook log_hook
+
+set ::log_hook [list]
+proc log_hook {zDb nEntry} {
+  lappend ::log_hook $zDb $nEntry
+  return 0
+}
+
+do_test walhook-1.1 {
+  execsql { CREATE TABLE t1(i PRIMARY KEY, j) }
+  set ::log_hook
+} {main 3}
+do_test walhook-1.2 {
+  set ::log_hook [list]
+  execsql { INSERT INTO t1 VALUES(1, 'one') }
+  set ::log_hook
+} {main 5}
+do_test walhook-1.3 {
+  proc log_hook {args} { return 1 }
+  execsql { INSERT INTO t1 VALUES(2, 'two') }
+  file size test.db
+} [expr 3*1024]
+
+do_test walhook-1.4 {
+  proc log_hook {zDb nEntry} { 
+    execsql { PRAGMA checkpoint }
+    return 0
+  }
+  execsql { CREATE TABLE t2(a, b) }
+  file size test.db
+} [expr 4*1024]
+
+do_test walhook-1.5 {
+  sqlite3_wal db2 test.db
+  proc log_hook {zDb nEntry} { 
+    execsql { PRAGMA checkpoint } db2
+    return 0
+  }
+  execsql { CREATE TABLE t3(a PRIMARY KEY, b) }
+  file size test.db
+} [expr 6*1024]
+
+catch { db2 close }
+catch { db close }
+finish_test
+