** logLockRegion() function.
*/
#define LOG_REGION_A 0x01
#define LOG_REGION_B 0x02
#define LOG_REGION_C 0x04
#define LOG_REGION_D 0x08









/*
** A single instance of this structure is allocated as part of each 
** connection to a database log. All structures associated with the 
** same log file are linked together into a list using LogLock.pNext
** starting at LogSummary.pLock.
**
** The mLock field of the structure describes the locks (if any) 
................................................................................

struct Log {
  LogSummary *pSummary;           /* Log file summary data */
  sqlite3_vfs *pVfs;              /* The VFS used to create pFd */
  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 */

  LogSummaryHdr hdr;              /* Log summary header for current snapshot */
  LogLock lock;                   /* Lock held by this connection (if any) */
};


/*
** This structure is used to implement an iterator that iterates through
................................................................................

finished:
  logSummaryWriteHdr(pSummary, &hdr);
  return rc;
}

/*
** Values for the third parameter to logLockRegion().
*/
#define LOG_UNLOCK  0
#define LOG_RDLOCK  1
#define LOG_WRLOCK  2
#define LOG_WRLOCKW 3

static int logLockFd(LogSummary *pSummary, int iStart, int nByte, int op){
  int aType[4] = { 
    F_UNLCK,                    /* LOG_UNLOCK */
    F_RDLCK,                    /* LOG_RDLOCK */
    F_WRLCK,                    /* LOG_WRLOCK */
    F_WRLCK                     /* LOG_WRLOCKW */
  };
  int aOp[4] = { 
    F_SETLK,                    /* LOG_UNLOCK */
    F_SETLK,                    /* LOG_RDLOCK */
    F_SETLK,                    /* LOG_WRLOCK */
    F_SETLKW                    /* LOG_WRLOCKW */
  };

  struct flock f;               /* Locking operation */
  int rc;                       /* Value returned by fcntl() */

  assert( ArraySize(aType)==ArraySize(aOp) );
  assert( op>=0 && op<ArraySize(aType) );

  memset(&f, 0, sizeof(f));
  f.l_type = aType[op];
  f.l_whence = SEEK_SET;
................................................................................
  }

  pLog->lock.mLock = mNew;
  sqlite3_mutex_leave(pSummary->mutex);
  return SQLITE_OK;
}






static int logLockDMH(LogSummary *pSummary, int eLock){

  assert( eLock==LOG_RDLOCK || eLock==LOG_WRLOCK );
  return logLockFd(pSummary, LOG_LOCK_DMH, 1, eLock);
}





static int logLockMutex(LogSummary *pSummary, int eLock){

  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.
*/
static int logSummaryInit(
  LogSummary *pSummary,           /* Log summary object to initialize */
................................................................................
  */
  rc = logLockDMH(pSummary, LOG_WRLOCK);
  if( rc==SQLITE_OK ){
    memset(pSummary->aData, 0, (LOGSUMMARY_HDR_NFIELD+2)*sizeof(u32) );
  }
  rc = logLockDMH(pSummary, LOG_RDLOCK);
  if( rc!=SQLITE_OK ){
    return SQLITE_IOERR;
  }

 out:
  logLockMutex(pSummary, LOG_UNLOCK);
  return rc;
}

................................................................................
  return SQLITE_OK;
}


/* 
** Set *pPgno to the size of the database file (or zero, if unknown).
*/
void sqlite3LogMaxpgno(Log *pLog, Pgno *pPgno){
  assert( pLog->isLocked );
  *pPgno = pLog->hdr.nPage;
}

/* 
** This function returns SQLITE_OK if the caller may write to the database.
** Otherwise, if the caller is operating on a snapshot that has already
................................................................................
  pLog->hdr.iCheck1 = aCksum[0];
  pLog->hdr.iCheck2 = aCksum[1];

  /* If this is a commit, update the log-summary header too. */
  if( isCommit && SQLITE_OK==(rc = logEnterMutex(pLog)) ){
    logSummaryWriteHdr(pLog->pSummary, &pLog->hdr);
    logLeaveMutex(pLog);

  }

  return SQLITE_OK;
}

/* 
** Checkpoint the database:
**
**   1. Wait for an EXCLUSIVE lock on regions B and C.
**   2. Wait for an EXCLUSIVE lock on region A.
................................................................................
    rc = logCheckpoint(pLog, pFd, sync_flags, zBuf);
  }

  /* Release the locks. */
  logLockRegion(pLog, LOG_REGION_A|LOG_REGION_B|LOG_REGION_C, LOG_UNLOCK);
  return rc;
}

** logLockRegion() function.
*/
#define LOG_REGION_A 0x01
#define LOG_REGION_B 0x02
#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 
** same log file are linked together into a list using LogLock.pNext
** starting at LogSummary.pLock.
**
** The mLock field of the structure describes the locks (if any) 
................................................................................

struct Log {
  LogSummary *pSummary;           /* Log file summary data */
  sqlite3_vfs *pVfs;              /* The VFS used to create pFd */
  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) */
};


/*
** This structure is used to implement an iterator that iterates through
................................................................................

finished:
  logSummaryWriteHdr(pSummary, &hdr);
  return rc;
}

/*
** Place, modify or remove a lock on the log-summary file associated 
** with pSummary.
*/
static int logLockFd(
  LogSummary *pSummary,           /* The log-summary object to lock */
  int iStart,                     /* First byte to lock */
  int nByte,                      /* Number of bytes to lock */
  int op                          /* LOG_UNLOCK, RDLOCK, WRLOCK or WRLOCKW */
){
  int aType[4] = { 
    F_UNLCK,                      /* LOG_UNLOCK */
    F_RDLCK,                      /* LOG_RDLOCK */
    F_WRLCK,                      /* LOG_WRLOCK */
    F_WRLCK                       /* LOG_WRLOCKW */
  };
  int aOp[4] = { 
    F_SETLK,                      /* LOG_UNLOCK */
    F_SETLK,                      /* LOG_RDLOCK */
    F_SETLK,                      /* LOG_WRLOCK */
    F_SETLKW                      /* LOG_WRLOCKW */
  };
  struct flock f;                 /* Locking operation */
  int rc;                         /* Value returned by fcntl() */

  assert( ArraySize(aType)==ArraySize(aOp) );
  assert( op>=0 && op<ArraySize(aType) );

  memset(&f, 0, sizeof(f));
  f.l_type = aType[op];
  f.l_whence = SEEK_SET;
................................................................................
  }

  pLog->lock.mLock = mNew;
  sqlite3_mutex_leave(pSummary->mutex);
  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.
*/
static int logSummaryInit(
  LogSummary *pSummary,           /* Log summary object to initialize */
................................................................................
  */
  rc = logLockDMH(pSummary, LOG_WRLOCK);
  if( rc==SQLITE_OK ){
    memset(pSummary->aData, 0, (LOGSUMMARY_HDR_NFIELD+2)*sizeof(u32) );
  }
  rc = logLockDMH(pSummary, LOG_RDLOCK);
  if( rc!=SQLITE_OK ){
    rc = SQLITE_IOERR;
  }

 out:
  logLockMutex(pSummary, LOG_UNLOCK);
  return rc;
}

................................................................................
  return SQLITE_OK;
}


/* 
** Set *pPgno to the size of the database file (or zero, if unknown).
*/
void sqlite3LogDbsize(Log *pLog, Pgno *pPgno){
  assert( pLog->isLocked );
  *pPgno = pLog->hdr.nPage;
}

/* 
** This function returns SQLITE_OK if the caller may write to the database.
** Otherwise, if the caller is operating on a snapshot that has already
................................................................................
  pLog->hdr.iCheck1 = aCksum[0];
  pLog->hdr.iCheck2 = aCksum[1];

  /* If this is a commit, update the log-summary header too. */
  if( isCommit && SQLITE_OK==(rc = logEnterMutex(pLog)) ){
    logSummaryWriteHdr(pLog->pSummary, &pLog->hdr);
    logLeaveMutex(pLog);
    pLog->iCallback = iFrame;
  }

  return rc;
}

/* 
** Checkpoint the database:
**
**   1. Wait for an EXCLUSIVE lock on regions B and C.
**   2. Wait for an EXCLUSIVE lock on region A.
................................................................................
    rc = logCheckpoint(pLog, pFd, sync_flags, zBuf);
  }

  /* Release the locks. */
  logLockRegion(pLog, LOG_REGION_A|LOG_REGION_B|LOG_REGION_C, LOG_UNLOCK);
  return rc;
}

int sqlite3LogCallback(Log *pLog){
  u32 ret = 0;
  if( pLog ){
    ret = pLog->iCallback;
    pLog->iCallback = 0;
  }
  return (int)ret;
}

/* Used by readers to open (lock) and close (unlock) a snapshot. */
int sqlite3LogOpenSnapshot(Log *pLog, int *);
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);

/* Obtain or release the WRITER lock. */
int sqlite3LogWriteLock(Log *pLog, int op);

/* Write a frame or frames to the log. */
int sqlite3LogFrames(Log *pLog, int, PgHdr *, Pgno, int, int);

................................................................................
  Log *pLog,                      /* Log connection */
  sqlite3_file *pFd,              /* File descriptor open on db file */
  int sync_flags,                 /* Flags to sync db file with (or 0) */
  u8 *zBuf,                       /* Temporary buffer to use */
  int (*xBusyHandler)(void *),    /* Pointer to busy-handler function */
  void *pBusyHandlerArg           /* Argument to pass to xBusyHandler */
);




#endif /* _LOG_H_ */

/* Used by readers to open (lock) and close (unlock) a snapshot. */
int sqlite3LogOpenSnapshot(Log *pLog, int *);
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 sqlite3LogDbsize(Log *pLog, Pgno *pPgno);

/* Obtain or release the WRITER lock. */
int sqlite3LogWriteLock(Log *pLog, int op);

/* Write a frame or frames to the log. */
int sqlite3LogFrames(Log *pLog, int, PgHdr *, Pgno, int, int);

................................................................................
  Log *pLog,                      /* Log connection */
  sqlite3_file *pFd,              /* File descriptor open on db file */
  int sync_flags,                 /* Flags to sync db file with (or 0) */
  u8 *zBuf,                       /* Temporary buffer to use */
  int (*xBusyHandler)(void *),    /* Pointer to busy-handler function */
  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_ */

  sqlite3_mutex_enter(db->mutex);
  pRet = db->pRollbackArg;
  db->xRollbackCallback = xCallback;
  db->pRollbackArg = 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.
** The value returned depends on the value of db->temp_store (runtime
** parameter) and the compile time value of SQLITE_TEMP_STORE. The
** following table describes the relationship between these two values

  sqlite3_mutex_enter(db->mutex);
  pRet = db->pRollbackArg;
  db->xRollbackCallback = xCallback;
  db->pRollbackArg = pArg;
  sqlite3_mutex_leave(db->mutex);
  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.
** The value returned depends on the value of db->temp_store (runtime
** parameter) and the compile time value of SQLITE_TEMP_STORE. The
** following table describes the relationship between these two values

  if( pPager->dbSizeValid ){
    nPage = pPager->dbSize;
  }else{
    int rc;                 /* Error returned by OsFileSize() */
    i64 n = 0;              /* File size in bytes returned by OsFileSize() */

    if( pagerUseLog(pPager) ){
      sqlite3LogMaxpgno(pPager->pLog, &nPage);
    }

    if( nPage==0 ){
      assert( isOpen(pPager->fd) || pPager->tempFile );
      if( isOpen(pPager->fd) ){
        if( SQLITE_OK!=(rc = sqlite3OsFileSize(pPager->fd, &n)) ){
          pager_error(pPager, rc);
................................................................................
    rc = sqlite3LogCheckpoint(pPager->pLog, pPager->fd, 
        (pPager->noSync ? 0 : pPager->sync_flags),
        zBuf, pPager->xBusyHandler, pPager->pBusyHandlerArg
    );
  }
  return rc;
}





#endif /* SQLITE_OMIT_DISKIO */

  if( pPager->dbSizeValid ){
    nPage = pPager->dbSize;
  }else{
    int rc;                 /* Error returned by OsFileSize() */
    i64 n = 0;              /* File size in bytes returned by OsFileSize() */

    if( pagerUseLog(pPager) ){
      sqlite3LogDbsize(pPager->pLog, &nPage);
    }

    if( nPage==0 ){
      assert( isOpen(pPager->fd) || pPager->tempFile );
      if( isOpen(pPager->fd) ){
        if( SQLITE_OK!=(rc = sqlite3OsFileSize(pPager->fd, &n)) ){
          pager_error(pPager, rc);
................................................................................
    rc = sqlite3LogCheckpoint(pPager->pLog, pPager->fd, 
        (pPager->noSync ? 0 : pPager->sync_flags),
        zBuf, pPager->xBusyHandler, pPager->pBusyHandlerArg
    );
  }
  return rc;
}

int sqlite3PagerLogCallback(Pager *pPager){
  return sqlite3LogCallback(pPager->pLog);
}

#endif /* SQLITE_OMIT_DISKIO */

int sqlite3PagerCommitPhaseOne(Pager*,const char *zMaster, int);
int sqlite3PagerSync(Pager *pPager);
int sqlite3PagerCommitPhaseTwo(Pager*);
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);


/* Functions used to query pager state and configuration. */
u8 sqlite3PagerIsreadonly(Pager*);
int sqlite3PagerRefcount(Pager*);
int sqlite3PagerMemUsed(Pager*);
const char *sqlite3PagerFilename(Pager*);
const sqlite3_vfs *sqlite3PagerVfs(Pager*);

int sqlite3PagerCommitPhaseOne(Pager*,const char *zMaster, int);
int sqlite3PagerSync(Pager *pPager);
int sqlite3PagerCommitPhaseTwo(Pager*);
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*);
int sqlite3PagerRefcount(Pager*);
int sqlite3PagerMemUsed(Pager*);
const char *sqlite3PagerFilename(Pager*);
const sqlite3_vfs *sqlite3PagerVfs(Pager*);

** To avoid deadlocks and other threading problems, the sqlite3_log() routine
** will not use dynamically allocated memory.  The log message is stored in
** a fixed-length buffer on the stack.  If the log message is longer than
** a few hundred characters, it will be truncated to the length of the
** buffer.
*/
void sqlite3_log(int iErrCode, const char *zFormat, ...);



































/*
** Undo the hack that converts floating point types to integer for
** builds on processors without floating point support.
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# undef double
#endif

#ifdef __cplusplus
}  /* End of the 'extern "C"' block */
#endif
#endif

** To avoid deadlocks and other threading problems, the sqlite3_log() routine
** will not use dynamically allocated memory.  The log message is stored in
** a fixed-length buffer on the stack.  If the log message is longer than
** a few hundred characters, it will be truncated to the length of the
** buffer.
*/
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.
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# undef double
#endif

#ifdef __cplusplus
}  /* End of the 'extern "C"' block */
#endif
#endif

  void *pProfileArg;                        /* Argument to profile function */
  void *pCommitArg;                 /* Argument to xCommitCallback() */   
  int (*xCommitCallback)(void*);    /* Invoked at every commit. */
  void *pRollbackArg;               /* Argument to xRollbackCallback() */   
  void (*xRollbackCallback)(void*); /* Invoked at every commit. */
  void *pUpdateArg;
  void (*xUpdateCallback)(void*,int, const char*,const char*,sqlite_int64);


  void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*);
  void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*);
  void *pCollNeededArg;
  sqlite3_value *pErr;          /* Most recent error message */
  char *zErrMsg;                /* Most recent error message (UTF-8 encoded) */
  char *zErrMsg16;              /* Most recent error message (UTF-16 encoded) */
  union {

  void *pProfileArg;                        /* Argument to profile function */
  void *pCommitArg;                 /* Argument to xCommitCallback() */   
  int (*xCommitCallback)(void*);    /* Invoked at every commit. */
  void *pRollbackArg;               /* Argument to xRollbackCallback() */   
  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;
  sqlite3_value *pErr;          /* Most recent error message */
  char *zErrMsg;                /* Most recent error message (UTF-8 encoded) */
  char *zErrMsg16;              /* Most recent error message (UTF-16 encoded) */
  union {

  char *zProgress;           /* The progress callback routine */
  char *zAuth;               /* The authorization callback routine */
  int disableAuth;           /* Disable the authorizer if it exists */
  char *zNull;               /* Text to substitute for an SQL NULL value */
  SqlFunc *pFunc;            /* List of SQL functions */
  Tcl_Obj *pUpdateHook;      /* Update hook script (if any) */
  Tcl_Obj *pRollbackHook;    /* Rollback 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() */
  Tcl_Obj *pCollateNeeded;   /* Collation needed script */
  SqlPreparedStmt *stmtList; /* List of prepared statements*/
  SqlPreparedStmt *stmtLast; /* Last statement in the list */
  int maxStmt;               /* The next maximum number of stmtList */
................................................................................
  }
  if( pDb->pUpdateHook ){
    Tcl_DecrRefCount(pDb->pUpdateHook);
  }
  if( pDb->pRollbackHook ){
    Tcl_DecrRefCount(pDb->pRollbackHook);
  }



  if( pDb->pCollateNeeded ){
    Tcl_DecrRefCount(pDb->pCollateNeeded);
  }
  Tcl_Free((char*)pDb);
}

/*
................................................................................
static void DbRollbackHandler(void *clientData){
  SqliteDb *pDb = (SqliteDb*)clientData;
  assert(pDb->pRollbackHook);
  if( TCL_OK!=Tcl_EvalObjEx(pDb->interp, pDb->pRollbackHook, 0) ){
    Tcl_BackgroundError(pDb->interp);
  }
}



























#if defined(SQLITE_TEST) && defined(SQLITE_ENABLE_UNLOCK_NOTIFY)
static void setTestUnlockNotifyVars(Tcl_Interp *interp, int iArg, int nArg){
  char zBuf[64];
  sprintf(zBuf, "%d", iArg);
  Tcl_SetVar(interp, "sqlite_unlock_notify_arg", zBuf, TCL_GLOBAL_ONLY);
  sprintf(zBuf, "%d", nArg);
................................................................................
  static const char *DB_strs[] = {
    "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",
    "version",            0                    
  };
  enum DB_enum {
    DB_AUTHORIZER,        DB_BACKUP,           DB_BUSY,
    DB_CACHE,             DB_CHANGES,          DB_CLOSE,
    DB_COLLATE,           DB_COLLATION_NEEDED, DB_COMMIT_HOOK,
    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_PROFILE,           DB_PROGRESS,         DB_REKEY,
    DB_RESTORE,           DB_ROLLBACK_HOOK,    DB_STATUS,
    DB_TIMEOUT,           DB_TOTAL_CHANGES,    DB_TRACE,
    DB_TRANSACTION,       DB_UNLOCK_NOTIFY,    DB_UPDATE_HOOK,
    DB_VERSION,
  };
  /* don't leave trailing commas on DB_enum, it confuses the AIX xlc compiler */

  if( objc<2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "SUBCOMMAND ...");
    return TCL_ERROR;
  }
................................................................................
      }
    }
#endif
    break;
  }

  /*

  **    $db update_hook ?script?
  **    $db rollback_hook ?script?
  */

  case DB_UPDATE_HOOK: 
  case DB_ROLLBACK_HOOK: {

    /* set ppHook to point at pUpdateHook or pRollbackHook, depending on 
    ** whether [$db update_hook] or [$db rollback_hook] was invoked.
    */
    Tcl_Obj **ppHook; 
    if( choice==DB_UPDATE_HOOK ){
      ppHook = &pDb->pUpdateHook;


    }else{
      ppHook = &pDb->pRollbackHook;
    }

    if( objc!=2 && objc!=3 ){
       Tcl_WrongNumArgs(interp, 2, objv, "?SCRIPT?");
       return TCL_ERROR;
................................................................................
        *ppHook = objv[2];
        Tcl_IncrRefCount(*ppHook);
      }
    }

    sqlite3_update_hook(pDb->db, (pDb->pUpdateHook?DbUpdateHandler:0), pDb);
    sqlite3_rollback_hook(pDb->db,(pDb->pRollbackHook?DbRollbackHandler:0),pDb);


    break;
  }

  /*    $db version
  **
  ** Return the version string for this database.

  char *zProgress;           /* The progress callback routine */
  char *zAuth;               /* The authorization callback routine */
  int disableAuth;           /* Disable the authorizer if it exists */
  char *zNull;               /* Text to substitute for an SQL NULL value */
  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() */
  Tcl_Obj *pCollateNeeded;   /* Collation needed script */
  SqlPreparedStmt *stmtList; /* List of prepared statements*/
  SqlPreparedStmt *stmtLast; /* Last statement in the list */
  int maxStmt;               /* The next maximum number of stmtList */
................................................................................
  }
  if( pDb->pUpdateHook ){
    Tcl_DecrRefCount(pDb->pUpdateHook);
  }
  if( pDb->pRollbackHook ){
    Tcl_DecrRefCount(pDb->pRollbackHook);
  }
  if( pDb->pLogHook ){
    Tcl_DecrRefCount(pDb->pLogHook);
  }
  if( pDb->pCollateNeeded ){
    Tcl_DecrRefCount(pDb->pCollateNeeded);
  }
  Tcl_Free((char*)pDb);
}

/*
................................................................................
static void DbRollbackHandler(void *clientData){
  SqliteDb *pDb = (SqliteDb*)clientData;
  assert(pDb->pRollbackHook);
  if( TCL_OK!=Tcl_EvalObjEx(pDb->interp, pDb->pRollbackHook, 0) ){
    Tcl_BackgroundError(pDb->interp);
  }
}

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];
  sprintf(zBuf, "%d", iArg);
  Tcl_SetVar(interp, "sqlite_unlock_notify_arg", zBuf, TCL_GLOBAL_ONLY);
  sprintf(zBuf, "%d", nArg);
................................................................................
  static const char *DB_strs[] = {
    "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",        "version",            0                    
  };
  enum DB_enum {
    DB_AUTHORIZER,        DB_BACKUP,           DB_BUSY,
    DB_CACHE,             DB_CHANGES,          DB_CLOSE,
    DB_COLLATE,           DB_COLLATION_NEEDED, DB_COMMIT_HOOK,
    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_LOG_HOOK,         DB_NULLVALUE,
    DB_ONECOLUMN,         DB_PROFILE,          DB_PROGRESS,
    DB_REKEY,             DB_RESTORE,          DB_ROLLBACK_HOOK,    
    DB_STATUS,            DB_TIMEOUT,          DB_TOTAL_CHANGES,    
    DB_TRACE,             DB_TRANSACTION,      DB_UNLOCK_NOTIFY,    
    DB_UPDATE_HOOK,       DB_VERSION
  };
  /* don't leave trailing commas on DB_enum, it confuses the AIX xlc compiler */

  if( objc<2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "SUBCOMMAND ...");
    return TCL_ERROR;
  }
................................................................................
      }
    }
#endif
    break;
  }

  /*
  **    $db log_hook ?script?
  **    $db update_hook ?script?
  **    $db rollback_hook ?script?
  */
  case DB_LOG_HOOK: 
  case DB_UPDATE_HOOK: 
  case DB_ROLLBACK_HOOK: {

    /* set ppHook to point at pUpdateHook or pRollbackHook, depending on 
    ** whether [$db update_hook] or [$db rollback_hook] was invoked.
    */
    Tcl_Obj **ppHook; 
    if( choice==DB_UPDATE_HOOK ){
      ppHook = &pDb->pUpdateHook;
    }else if( choice==DB_LOG_HOOK ){
      ppHook = &pDb->pLogHook;
    }else{
      ppHook = &pDb->pRollbackHook;
    }

    if( objc!=2 && objc!=3 ){
       Tcl_WrongNumArgs(interp, 2, objv, "?SCRIPT?");
       return TCL_ERROR;
................................................................................
        *ppHook = objv[2];
        Tcl_IncrRefCount(*ppHook);
      }
    }

    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;
  }

  /*    $db version
  **
  ** Return the version string for this database.

/* An SQLITE_NOMEM error. */
void sqlite3_result_error_nomem(sqlite3_context *pCtx){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetNull(&pCtx->s);
  pCtx->isError = SQLITE_NOMEM;
  pCtx->s.db->mallocFailed = 1;
}


















/*
** Execute the statement pStmt, either until a row of data is ready, the
** statement is completely executed or an error occurs.
**
** This routine implements the bulk of the logic behind the sqlite_step()
** API.  The only thing omitted is the automatic recompile if a 
................................................................................

    sqlite3OsCurrentTime(db->pVfs, &rNow);
    elapseTime = (u64)((rNow - (int)rNow)*3600.0*24.0*1000000000.0);
    elapseTime -= p->startTime;
    db->xProfile(db->pProfileArg, p->zSql, elapseTime);
  }
#endif









  db->errCode = rc;
  if( SQLITE_NOMEM==sqlite3ApiExit(p->db, p->rc) ){
    p->rc = SQLITE_NOMEM;
  }
end_of_step:
  /* At this point local variable rc holds the value that should be 

/* An SQLITE_NOMEM error. */
void sqlite3_result_error_nomem(sqlite3_context *pCtx){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetNull(&pCtx->s);
  pCtx->isError = SQLITE_NOMEM;
  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.
**
** This routine implements the bulk of the logic behind the sqlite_step()
** API.  The only thing omitted is the automatic recompile if a 
................................................................................

    sqlite3OsCurrentTime(db->pVfs, &rNow);
    elapseTime = (u64)((rNow - (int)rNow)*3600.0*24.0*1000000000.0);
    elapseTime -= p->startTime;
    db->xProfile(db->pProfileArg, p->zSql, elapseTime);
  }
#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;
  }
end_of_step:
  /* At this point local variable rc holds the value that should be 

  /* This loop determines (a) if the commit hook should be invoked and
  ** (b) how many database files have open write transactions, not 
  ** including the temp database. (b) is important because if more than 
  ** 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++){ 
    Btree *pBt = db->aDb[i].pBt;
    if( sqlite3BtreeIsInTrans(pBt) ){
      needXcommit = 1;
      if( i!=1 ) nTrans++;
    }
  }

  /* This loop determines (a) if the commit hook should be invoked and
  ** (b) how many database files have open write transactions, not 
  ** including the temp database. (b) is important because if more than 
  ** 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++){
    Btree *pBt = db->aDb[i].pBt;
    if( sqlite3BtreeIsInTrans(pBt) ){
      needXcommit = 1;
      if( i!=1 ) nTrans++;
    }
  }

  set v [catch {sqlite3 bogus} msg]
  regsub {really_sqlite3} $msg {sqlite3} msg
  lappend v $msg
} [list 1 "wrong # args: should be \"$r\""]
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}}
do_test tcl-1.2.1 {
  set v [catch {db cache bogus} msg]
  lappend v $msg
} {1 {bad option "bogus": must be flush or size}}
do_test tcl-1.2.2 {
  set v [catch {db cache} msg]
  lappend v $msg

  set v [catch {sqlite3 bogus} msg]
  regsub {really_sqlite3} $msg {sqlite3} msg
  lappend v $msg
} [list 1 "wrong # args: should be \"$r\""]
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, 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
} {1 {bad option "bogus": must be flush or size}}
do_test tcl-1.2.2 {
  set v [catch {db cache} msg]
  lappend v $msg

# 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