SQLite

      }
    }
 
    if( rc!=SQLITE_OK ){
      (void)sqlite3PagerWalWriteLock(pPager, 0);
      unlockBtreeIfUnused(pBt);
    }
#if defined(SQLITE_ENABLE_SETLK_TIMEOUT)
    if( rc==SQLITE_BUSY_TIMEOUT ){
      /* If a blocking lock timed out, break out of the loop here so that
      ** the busy-handler is not invoked.  */
      break;
    }
#endif
  }while( (rc&0xFF)==SQLITE_BUSY && pBt->inTransaction==TRANS_NONE &&
          btreeInvokeBusyHandler(pBt) );
  sqlite3PagerWalDb(pPager, 0);
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
  if( rc==SQLITE_BUSY_TIMEOUT ) rc = SQLITE_BUSY;
#endif

  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
  assert( pShmNode->hShm>=0 || pDbFd->pInode->bProcessLock==1 );
  assert( pShmNode->hShm<0 || pDbFd->pInode->bProcessLock==0 );

  /* Check that, if this to be a blocking lock, no locks that occur later
  ** in the following list than the lock being obtained are already held:
  **
  **   1. Recovery lock (ofst==2).
  **   2. Checkpointer lock (ofst==1).
  **   3. Write lock (ofst==0).
  **   4. Read locks (ofst>=3 && ofst<SQLITE_SHM_NLOCK).
  **
  ** In other words, if this is a blocking lock, none of the locks that
  ** occur later in the above list than the lock being obtained may be
  ** held.


  */
#if defined(SQLITE_ENABLE_SETLK_TIMEOUT) && defined(SQLITE_DEBUG)
  {
    u16 lockMask = (p->exclMask|p->sharedMask);
    assert( (flags & SQLITE_SHM_UNLOCK) || pDbFd->iBusyTimeout==0 || (
          (ofst!=2 || lockMask==0)
       && (ofst!=1 || lockMask==0 || lockMask==2)
       && (ofst!=0 || lockMask<3)
       && (ofst<3  || lockMask<(1<<ofst))
    ));
  }
#endif

    */
    if( !ret && GetLastError()==ERROR_IO_PENDING ){
      DWORD nDelay = (nMs==0 ? INFINITE : nMs);
      DWORD res = osWaitForSingleObject(ovlp.hEvent, nDelay);
      if( res==WAIT_OBJECT_0 ){
        ret = TRUE;
      }else if( res==WAIT_TIMEOUT ){
#if SQLITE_ENABLE_SETLK_TIMEOUT==1
        rc = SQLITE_BUSY_TIMEOUT;
#else
        rc = SQLITE_BUSY;
#endif
      }else{
        /* Some other error has occurred */
        rc = SQLITE_IOERR_LOCK;
      }

      /* If it is still pending, cancel the LockFileEx() call. */
      osCancelIo(hFile);

       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );

  /* Check that, if this to be a blocking lock, no locks that occur later
  ** in the following list than the lock being obtained are already held:
  **
  **   1. Recovery lock (ofst==2).
  **   2. Checkpointer lock (ofst==1).
  **   3. Write lock (ofst==0).
  **   4. Read locks (ofst>=3 && ofst<SQLITE_SHM_NLOCK).
  **
  ** In other words, if this is a blocking lock, none of the locks that
  ** occur later in the above list than the lock being obtained may be
  ** held.


  */
#if defined(SQLITE_ENABLE_SETLK_TIMEOUT) && defined(SQLITE_DEBUG)
  {
    u16 lockMask = (p->exclMask|p->sharedMask);
    assert( (flags & SQLITE_SHM_UNLOCK) || pDbFd->iBusyTimeout==0 || (
          (ofst!=2 || lockMask==0)
       && (ofst!=1 || lockMask==0 || lockMask==2)
       && (ofst!=0 || lockMask<3)
       && (ofst<3  || lockMask<(1<<ofst))
    ));
  }
#endif

  int (*xGet)(Pager*,Pgno,DbPage**,int); /* Routine to fetch a patch */
  char *pTmpSpace;            /* Pager.pageSize bytes of space for tmp use */
  PCache *pPCache;            /* Pointer to page cache object */
#ifndef SQLITE_OMIT_WAL
  Wal *pWal;                  /* Write-ahead log used by "journal_mode=wal" */
  char *zWal;                 /* File name for write-ahead log */
#endif
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
  sqlite3 *dbWal;
#endif
};

/*
** Indexes for use with Pager.aStat[]. The Pager.aStat[] array contains
** the values accessed by passing SQLITE_DBSTATUS_CACHE_HIT, CACHE_MISS
** or CACHE_WRITE to sqlite3_db_status().
*/

  ** (e.g. due to malloc() failure), return an error code.
  */
  if( rc==SQLITE_OK ){
    rc = sqlite3WalOpen(pPager->pVfs,
        pPager->fd, pPager->zWal, pPager->exclusiveMode,
        pPager->journalSizeLimit, &pPager->pWal
    );
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
    if( rc==SQLITE_OK ){
      sqlite3WalDb(pPager->pWal, pPager->dbWal);
    }
#endif
  }
  pagerFixMaplimit(pPager);

  return rc;
}

}

/*
** Set the database handle used by the wal layer to determine if
** blocking locks are required.
*/
void sqlite3PagerWalDb(Pager *pPager, sqlite3 *db){
  pPager->dbWal = db;
  if( pagerUseWal(pPager) ){
    sqlite3WalDb(pPager->pWal, db);
  }
}
#endif

#ifdef SQLITE_ENABLE_SNAPSHOT

  if( !useWal ){
    assert( rc==SQLITE_OK );
    if( pWal->bShmUnreliable==0 ){
      rc = walIndexReadHdr(pWal, pChanged);
    }
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT

    if( rc==SQLITE_BUSY_TIMEOUT ){
      rc = SQLITE_BUSY;
      *pCnt |= WAL_RETRY_BLOCKED_MASK;
    }
#endif
    if( rc==SQLITE_BUSY ){
      /* If there is not a recovery running in another thread or process
      ** then convert BUSY errors to WAL_RETRY.  If recovery is known to
      ** be running, convert BUSY to BUSY_RECOVERY.  There is a race here
      ** which might cause WAL_RETRY to be returned even if BUSY_RECOVERY
      ** would be technically correct.  But the race is benign since with
      ** WAL_RETRY this routine will be called again and will probably be
      ** right on the second iteration.
      */
      walEnableBlocking(pWal);
      if( pWal->apWiData[0]==0 ){
        /* This branch is taken when the xShmMap() method returns SQLITE_BUSY.
        ** We assume this is a transient condition, so return WAL_RETRY. The
        ** xShmMap() implementation used by the default unix and win32 VFS
        ** modules may return SQLITE_BUSY due to a race condition in the
        ** code that determines whether or not the shared-memory region
        ** must be zeroed before the requested page is returned.
        */
        rc = WAL_RETRY;
      }else if( SQLITE_OK==(rc = walLockShared(pWal, WAL_RECOVER_LOCK)) ){
        walUnlockShared(pWal, WAL_RECOVER_LOCK);
        rc = WAL_RETRY;
      }else if( rc==SQLITE_BUSY ){
        rc = SQLITE_BUSY_RECOVERY;
      }
    }
    walDisableBlocking(pWal);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    else if( pWal->bShmUnreliable ){
      return walBeginShmUnreliable(pWal, pChanged);
    }
  }

  file size test.db-wal
} 0

do_test 1.8 {
  execsql BEGIN db3
  list [catch { sqlite3_snapshot_open_blob db3 main $snap } msg] $msg
} {1 SQLITE_ERROR_SNAPSHOT}

db3 close
db2 close

#-------------------------------------------------------------------------
reset_db
do_execsql_test 2.0 {
  PRAGMA journal_mode = wal;
  CREATE TABLE t1(a, b);
  INSERT INTO t1 VALUES(1, 2);

# 2025 May 30
#
# 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.
#
#***********************************************************************
#
# TESTRUNNER: slow
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/lock_common.tcl
set testprefix walsetlk_recover

ifcapable !wal {finish_test ; return }
# ifcapable !setlk_timeout {finish_test ; return }

do_execsql_test 1.0 {
  PRAGMA journal_mode = wal;
  CREATE TABLE t1(a, b);
  INSERT INTO t1 VALUES(1, 2);
  INSERT INTO t1 VALUES(3, 4);
  INSERT INTO t1 VALUES(5, 6);
} {wal}

db_save_and_close
db_restore

testfixture_nb myvar {

  testvfs tvfs -fullshm 1
  sqlite3 db test.db -vfs tvfs
  tvfs script vfs_callback
  tvfs filter xRead

  set ::done 0
  proc vfs_callback {method file args} {
    if {$::done==0 && [string match *wal $file]} {
      after 4000
      set ::done 1
    }
    return "SQLITE_OK"
  }

  db eval {
    SELECT * FROM t1
  }

  db close
}

# Give the [testfixture_nb] command time to start
after 1000 {set xyz 1}
vwait xyz

testvfs tvfs -fullshm 1
sqlite3 db test.db -vfs tvfs

tvfs script sleep_callback
tvfs filter xSleep
set ::sleep_count 0
proc sleep_callback {args} {
  incr ::sleep_count
}

sqlite3 db test.db -vfs tvfs
db timeout 500
set tm [lindex [time {
  catch {
    db eval {SELECT * FROM t1}
  } msg
}] 0]

do_test 1.2         { set ::msg } {database is locked}
do_test 1.3.($::tm) { expr $::tm>400000 && $::tm<2000000 } 1

vwait myvar

do_execsql_test 1.4 {
  SELECT * FROM t1
} {1 2 3 4 5 6}

db close
tvfs delete

# All SQLite builds should pass the tests above. SQLITE_ENABLE_SETLK_TIMEOUT=1
# builds do so without calling the VFS xSleep method.
if {$::sqlite_options(setlk_timeout)==1} {
  do_test 1.5.1 {
    set ::sleep_count
  } 0
} else {
  do_test 1.5.2 {
    expr $::sleep_count>0
  } 1
}

finish_test

# 2025 May 30
#
# 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.
#
#***********************************************************************
#
# TESTRUNNER: slow
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/lock_common.tcl
set testprefix walsetlk_snapshot

ifcapable !wal {finish_test ; return }
ifcapable !snapshot {finish_test; return}

db close
testvfs tvfs -fullshm 1
sqlite3 db test.db -vfs tvfs
tvfs script sleep_callback
tvfs filter xSleep
set ::sleep_count 0
proc sleep_callback {args} {
  incr ::sleep_count
}

do_execsql_test 1.0 {
  PRAGMA journal_mode = wal;
  CREATE TABLE t1(a, b);
  INSERT INTO t1 VALUES(1, 2);
  INSERT INTO t1 VALUES(3, 4);
  INSERT INTO t1 VALUES(5, 6);
} {wal}

do_test 1.1 {
  db eval BEGIN
  set ::snap [sqlite3_snapshot_get db main]
  db eval {
    INSERT INTO t1 VALUES(7, 8);
    COMMIT;
  }
} {}

testfixture_nb myvar {

  testvfs tvfs -fullshm 1
  sqlite3 db test.db -vfs tvfs
  tvfs script vfs_callback
  tvfs filter {xWrite}

  set ::done 0
  proc vfs_callback {args} {
    if {$::done==0} {
      after 4000
      set ::done 1
    }
    return "SQLITE_OK"
  }

  db eval {
    PRAGMA wal_checkpoint;
  }

  db close
}

# Give the [testfixture_nb] command time to start
after 1000 {set xyz 1}
vwait xyz

db timeout 500
set tm [lindex [time {
  catch {
    db eval BEGIN
      sqlite3_snapshot_open db main $::snap
  } msg
}] 0]

do_test 1.2 { set ::msg } {SQLITE_BUSY}
do_test 1.3.($::tm) { expr $::tm<2000000 } 1

do_execsql_test 1.4 {
  SELECT * FROM t1
} {1 2 3 4 5 6 7 8}

sqlite3_snapshot_free $::snap

vwait myvar

# All SQLite builds should pass the tests above. SQLITE_ENABLE_SETLK_TIMEOUT=1
# builds do so without calling the VFS xSleep method.
if {$::sqlite_options(setlk_timeout)==1} {
  do_test 1.5.1 {
    set ::sleep_count
  } 0
} else {
  do_test 1.5.2 {
    expr $::sleep_count>0
  } 1
}

finish_test