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Overview
Comment:Change the windows backend to retry read and write requests if the encounter ERROR_LOCK_VIOLATION and ERROR_SHARING_VIOLATION errors - which we think sometimes happens due to aggressive anti-virus software.
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SHA1: c20aca06610407c197ea50ea77c2591aacf2252a
User & Date: drh 2011-07-11 18:17:56
Original Comment: Change the windows backend to retry read and write requests if the encounter ERROR_LOCK_VIOLATION and ERROR_SHARING_VIOLATION errors - which we think sometimes happens due to agressive anti-virus software.
Context
2011-07-11
23:45
Update the TCL commands for setting windows manditory locks. Add test cases for manditory lock delays under windows. check-in: 03af4c17 user: drh tags: trunk
18:17
Change the windows backend to retry read and write requests if the encounter ERROR_LOCK_VIOLATION and ERROR_SHARING_VIOLATION errors - which we think sometimes happens due to aggressive anti-virus software. check-in: c20aca06 user: drh tags: trunk
2011-07-09
16:17
Fix harmless compiler warnings on unix. check-in: 90b1aea1 user: drh tags: trunk
Changes
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Changes to src/os_win.c.

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  sqlite3_log(errcode,
      "os_win.c:%d: (%d) %s(%s) - %s",
      iLine, iErrno, zFunc, zPath, zMsg
  );

  return errcode;
}




























#if SQLITE_OS_WINCE
/*************************************************************************
** This section contains code for WinCE only.
*/
/*
** WindowsCE does not have a localtime() function.  So create a
................................................................................
  sqlite3_file *id,          /* File to read from */
  void *pBuf,                /* Write content into this buffer */
  int amt,                   /* Number of bytes to read */
  sqlite3_int64 offset       /* Begin reading at this offset */
){
  winFile *pFile = (winFile*)id;  /* file handle */
  DWORD nRead;                    /* Number of bytes actually read from file */


  assert( id!=0 );
  SimulateIOError(return SQLITE_IOERR_READ);
  OSTRACE(("READ %d lock=%d\n", pFile->h, pFile->locktype));

  if( seekWinFile(pFile, offset) ){
    return SQLITE_FULL;
  }
  if( !ReadFile(pFile->h, pBuf, amt, &nRead, 0) ){

    pFile->lastErrno = GetLastError();
    return winLogError(SQLITE_IOERR_READ, "winRead", pFile->zPath);
  }
  if( nRead<(DWORD)amt ){
    /* Unread parts of the buffer must be zero-filled */
    memset(&((char*)pBuf)[nRead], 0, amt-nRead);
    return SQLITE_IOERR_SHORT_READ;
................................................................................
  OSTRACE(("WRITE %d lock=%d\n", pFile->h, pFile->locktype));

  rc = seekWinFile(pFile, offset);
  if( rc==0 ){
    u8 *aRem = (u8 *)pBuf;        /* Data yet to be written */
    int nRem = amt;               /* Number of bytes yet to be written */
    DWORD nWrite;                 /* Bytes written by each WriteFile() call */



    while( nRem>0 && WriteFile(pFile->h, aRem, nRem, &nWrite, 0) && nWrite>0 ){




      aRem += nWrite;
      nRem -= nWrite;
    }
    if( nRem>0 ){
      pFile->lastErrno = GetLastError();
      rc = 1;
    }







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  sqlite3_log(errcode,
      "os_win.c:%d: (%d) %s(%s) - %s",
      iLine, iErrno, zFunc, zPath, zMsg
  );

  return errcode;
}

/*
** The number of times that a ReadFile() or WriteFile() will be retried
** following a locking error.
*/
#ifndef SQLITE_WIN32_IOERR_RETRY
# define SQLITE_WIN32_IOERR_RETRY 5
#endif

/*
** If a ReadFile() or WriteFile() error occurs, invoke this routine
** to see if it should be retried.  Return TRUE to retry.  Return FALSE
** to give up with an error.
*/
static int retryIoerr(int *pnRetry){
  DWORD e;
  if( *pnRetry>=SQLITE_WIN32_IOERR_RETRY ){
    return 0;
  }
  e = GetLastError();
  if( e==ERROR_LOCK_VIOLATION || e==ERROR_SHARING_VIOLATION ){
    Sleep(50 + 50*(*pnRetry));
    ++*pnRetry;
    return 1;
  }
  return 0;
}

#if SQLITE_OS_WINCE
/*************************************************************************
** This section contains code for WinCE only.
*/
/*
** WindowsCE does not have a localtime() function.  So create a
................................................................................
  sqlite3_file *id,          /* File to read from */
  void *pBuf,                /* Write content into this buffer */
  int amt,                   /* Number of bytes to read */
  sqlite3_int64 offset       /* Begin reading at this offset */
){
  winFile *pFile = (winFile*)id;  /* file handle */
  DWORD nRead;                    /* Number of bytes actually read from file */
  int nRetry = 0;                 /* Number of retrys */

  assert( id!=0 );
  SimulateIOError(return SQLITE_IOERR_READ);
  OSTRACE(("READ %d lock=%d\n", pFile->h, pFile->locktype));

  if( seekWinFile(pFile, offset) ){
    return SQLITE_FULL;
  }
  while( !ReadFile(pFile->h, pBuf, amt, &nRead, 0) ){
    if( retryIoerr(&nRetry) ) continue;
    pFile->lastErrno = GetLastError();
    return winLogError(SQLITE_IOERR_READ, "winRead", pFile->zPath);
  }
  if( nRead<(DWORD)amt ){
    /* Unread parts of the buffer must be zero-filled */
    memset(&((char*)pBuf)[nRead], 0, amt-nRead);
    return SQLITE_IOERR_SHORT_READ;
................................................................................
  OSTRACE(("WRITE %d lock=%d\n", pFile->h, pFile->locktype));

  rc = seekWinFile(pFile, offset);
  if( rc==0 ){
    u8 *aRem = (u8 *)pBuf;        /* Data yet to be written */
    int nRem = amt;               /* Number of bytes yet to be written */
    DWORD nWrite;                 /* Bytes written by each WriteFile() call */
    int nRetry = 0;               /* Number of retries */

    while( nRem>0 ){
      if( !WriteFile(pFile->h, aRem, nRem, &nWrite, 0) ){
        if( retryIoerr(&nRetry) ) continue;
        break;
      }
      if( nWrite<=0 ) break;
      aRem += nWrite;
      nRem -= nWrite;
    }
    if( nRem>0 ){
      pFile->lastErrno = GetLastError();
      rc = 1;
    }