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Overview
Comment:Simplify the winRead and winWrite VFS functions to reduce the number of system calls.
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SHA1: 10ce846759f6f22e70bb9b67bea7a0c2b8a156fe
User & Date: mistachkin 2012-03-30 12:27:55
Context
2012-03-30
14:01
Merge the latest trunk changes into the winrt branch. check-in: a1a85b84 user: drh tags: winrt
12:27
Simplify the winRead and winWrite VFS functions to reduce the number of system calls. check-in: 10ce8467 user: mistachkin tags: winrt
2012-03-23
12:28
Update MSVC makefile to support compiling for WinRT using one setting. check-in: c10794bf user: mistachkin tags: winrt
Changes
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Changes to src/os_win.c.

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    ){
       sqlite3_win32_sleep(100);  /* Wait a little before trying again */
    }
    sqlite3_free(pFile->zDeleteOnClose);
  }
#endif
  OSTRACE(("CLOSE %d %s\n", pFile->h, rc ? "ok" : "failed"));



  OpenCounter(-1);
  return rc ? SQLITE_OK
            : winLogError(SQLITE_IOERR_CLOSE, osGetLastError(),
                          "winClose", pFile->zPath);
}

/*
................................................................................
*/
static int winRead(
  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( !osReadFile(pFile->h, pBuf, amt, &nRead, 0) ){

    DWORD lastErrno;
    if( retryIoerr(&nRetry, &lastErrno) ) continue;
    pFile->lastErrno = lastErrno;
    return winLogError(SQLITE_IOERR_READ, pFile->lastErrno,
             "winRead", pFile->zPath);
  }
  logIoerr(nRetry);
................................................................................
*/
static int winWrite(
  sqlite3_file *id,               /* File to write into */
  const void *pBuf,               /* The bytes to be written */
  int amt,                        /* Number of bytes to write */
  sqlite3_int64 offset            /* Offset into the file to begin writing at */
){
  int rc;                         /* True if error has occured, else false */
  winFile *pFile = (winFile*)id;  /* File handle */
  int nRetry = 0;                 /* Number of retries */

  assert( amt>0 );
  assert( pFile );
  SimulateIOError(return SQLITE_IOERR_WRITE);
  SimulateDiskfullError(return SQLITE_FULL);

  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 */
    DWORD lastErrno = NO_ERROR;   /* Value returned by GetLastError() */





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






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







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    ){
       sqlite3_win32_sleep(100);  /* Wait a little before trying again */
    }
    sqlite3_free(pFile->zDeleteOnClose);
  }
#endif
  OSTRACE(("CLOSE %d %s\n", pFile->h, rc ? "ok" : "failed"));
  if( rc ){
    pFile->h = NULL;
  }
  OpenCounter(-1);
  return rc ? SQLITE_OK
            : winLogError(SQLITE_IOERR_CLOSE, osGetLastError(),
                          "winClose", pFile->zPath);
}

/*
................................................................................
*/
static int winRead(
  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 */
){
  OVERLAPPED overlapped;          /* The offset for ReadFile. */
  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));

  memset(&overlapped, 0, sizeof(OVERLAPPED));
  overlapped.Offset = (LONG)(offset & 0xffffffff);

  overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
  while( !osReadFile(pFile->h, pBuf, amt, &nRead, &overlapped) &&
         osGetLastError()!=ERROR_HANDLE_EOF ){
    DWORD lastErrno;
    if( retryIoerr(&nRetry, &lastErrno) ) continue;
    pFile->lastErrno = lastErrno;
    return winLogError(SQLITE_IOERR_READ, pFile->lastErrno,
             "winRead", pFile->zPath);
  }
  logIoerr(nRetry);
................................................................................
*/
static int winWrite(
  sqlite3_file *id,               /* File to write into */
  const void *pBuf,               /* The bytes to be written */
  int amt,                        /* Number of bytes to write */
  sqlite3_int64 offset            /* Offset into the file to begin writing at */
){
  int rc = 0;                     /* True if error has occured, else false */
  winFile *pFile = (winFile*)id;  /* File handle */
  int nRetry = 0;                 /* Number of retries */

  assert( amt>0 );
  assert( pFile );
  SimulateIOError(return SQLITE_IOERR_WRITE);
  SimulateDiskfullError(return SQLITE_FULL);

  OSTRACE(("WRITE %d lock=%d\n", pFile->h, pFile->locktype));

  {
    OVERLAPPED overlapped;        /* The offset for WriteFile. */
    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 */
    DWORD lastErrno = NO_ERROR;   /* Value returned by GetLastError() */

    memset(&overlapped, 0, sizeof(OVERLAPPED));
    overlapped.Offset = (LONG)(offset & 0xffffffff);
    overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);

    while( nRem>0 ){
      if( !osWriteFile(pFile->h, aRem, nRem, &nWrite, &overlapped) ){
        if( retryIoerr(&nRetry, &lastErrno) ) continue;
        break;
      }
      if( nWrite<=0 ){
        lastErrno = osGetLastError();
        break;
      }
      offset += nWrite;
      overlapped.Offset = (LONG)(offset & 0xffffffff);
      overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
      aRem += nWrite;
      nRem -= nWrite;
    }
    if( nRem>0 ){
      pFile->lastErrno = lastErrno;
      rc = 1;
    }