test_async.c

最新的sqlite3.6.2源代码

*/
static int asyncLock(sqlite3_file *pFile, int eLock){
  int rc = SQLITE_OK;
  AsyncFileData *p = ((AsyncFile *)pFile)->pData;

  pthread_mutex_lock(&async.lockMutex);
  if( p->lock.eLock<eLock ){
    AsyncLock *pLock;
    AsyncFileLock *pIter;
    pLock = (AsyncLock *)sqlite3HashFind(&async.aLock, p->zName, p->nName);
    assert(pLock && pLock->pList);
    for(pIter=pLock->pList; pIter; pIter=pIter->pNext){
      if( pIter!=&p->lock && (
        (eLock==SQLITE_LOCK_EXCLUSIVE && pIter->eLock>=SQLITE_LOCK_SHARED) ||
        (eLock==SQLITE_LOCK_PENDING && pIter->eLock>=SQLITE_LOCK_RESERVED) ||
        (eLock==SQLITE_LOCK_RESERVED && pIter->eLock>=SQLITE_LOCK_RESERVED) ||
        (eLock==SQLITE_LOCK_SHARED && pIter->eLock>=SQLITE_LOCK_PENDING)
      )){
        rc = SQLITE_BUSY;
      }
    }
    if( rc==SQLITE_OK ){
      p->lock.eLock = eLock;
      p->lock.eAsyncLock = MAX(p->lock.eAsyncLock, eLock);
    }
    assert(p->lock.eAsyncLock>=p->lock.eLock);
    if( rc==SQLITE_OK ){
      rc = getFileLock(pLock);
    }
  }
  pthread_mutex_unlock(&async.lockMutex);

  ASYNC_TRACE(("LOCK %d (%s) rc=%d\n", eLock, p->zName, rc));
  return rc;
}
static int asyncUnlock(sqlite3_file *pFile, int eLock){
  AsyncFileData *p = ((AsyncFile *)pFile)->pData;
  AsyncFileLock *pLock = &p->lock;
  pthread_mutex_lock(&async.lockMutex);
  pLock->eLock = MIN(pLock->eLock, eLock);
  pthread_mutex_unlock(&async.lockMutex);
  return addNewAsyncWrite(p, ASYNC_UNLOCK, 0, eLock, 0);
}

/*
** This function is called when the pager layer first opens a database file
** and is checking for a hot-journal.
*/
static int asyncCheckReservedLock(sqlite3_file *pFile, int *pResOut){
  int ret = 0;
  AsyncFileLock *pIter;
  AsyncLock *pLock;
  AsyncFileData *p = ((AsyncFile *)pFile)->pData;

  pthread_mutex_lock(&async.lockMutex);
  pLock = (AsyncLock *)sqlite3HashFind(&async.aLock, p->zName, p->nName);
  for(pIter=pLock->pList; pIter; pIter=pIter->pNext){
    if( pIter->eLock>=SQLITE_LOCK_RESERVED ){
      ret = 1;
    }
  }
  pthread_mutex_unlock(&async.lockMutex);

  ASYNC_TRACE(("CHECK-LOCK %d (%s)\n", ret, p->zName));
  *pResOut = ret;
  return SQLITE_OK;
}

/* 
** This is a no-op, as the asynchronous backend does not support locking.
*/
static int asyncFileControl(sqlite3_file *id, int op, void *pArg){
  switch( op ){
    case SQLITE_FCNTL_LOCKSTATE: {
      pthread_mutex_lock(&async.lockMutex);
      *(int*)pArg = ((AsyncFile*)id)->pData->lock.eLock;
      pthread_mutex_unlock(&async.lockMutex);
      return SQLITE_OK;
    }
  }
  return SQLITE_ERROR;
}

/* 
** Return the device characteristics and sector-size of the device. It
** is not tricky to implement these correctly, as this backend might 
** not have an open file handle at this point.
*/
static int asyncSectorSize(sqlite3_file *pFile){
  return 512;
}
static int asyncDeviceCharacteristics(sqlite3_file *pFile){
  return 0;
}

static int unlinkAsyncFile(AsyncFileData *pData){
  AsyncLock *pLock;
  AsyncFileLock **ppIter;
  int rc = SQLITE_OK;

  pLock = sqlite3HashFind(&async.aLock, pData->zName, pData->nName);
  for(ppIter=&pLock->pList; *ppIter; ppIter=&((*ppIter)->pNext)){
    if( (*ppIter)==&pData->lock ){
      *ppIter = pData->lock.pNext;
      break;
    }
  }
  if( !pLock->pList ){
    if( pLock->pFile ){
      sqlite3OsClose(pLock->pFile);
    }
    sqlite3_free(pLock);
    sqlite3HashInsert(&async.aLock, pData->zName, pData->nName, 0);
    if( !sqliteHashFirst(&async.aLock) ){
      sqlite3HashClear(&async.aLock);
    }
  }else{
    rc = getFileLock(pLock);
  }

  return rc;
}

/*
** Open a file.
*/
static int asyncOpen(
  sqlite3_vfs *pAsyncVfs,
  const char *zName,
  sqlite3_file *pFile,
  int flags,
  int *pOutFlags
){
  static sqlite3_io_methods async_methods = {
    1,                               /* iVersion */
    asyncClose,                      /* xClose */
    asyncRead,                       /* xRead */
    asyncWrite,                      /* xWrite */
    asyncTruncate,                   /* xTruncate */
    asyncSync,                       /* xSync */
    asyncFileSize,                   /* xFileSize */
    asyncLock,                       /* xLock */
    asyncUnlock,                     /* xUnlock */
    asyncCheckReservedLock,          /* xCheckReservedLock */
    asyncFileControl,                /* xFileControl */
    asyncSectorSize,                 /* xSectorSize */
    asyncDeviceCharacteristics       /* xDeviceCharacteristics */
  };

  sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
  AsyncFile *p = (AsyncFile *)pFile;
  int nName = strlen(zName)+1;
  int rc = SQLITE_OK;
  int nByte;
  AsyncFileData *pData;
  AsyncLock *pLock = 0;
  char *z;
  int isExclusive = (flags&SQLITE_OPEN_EXCLUSIVE);

  nByte = (
    sizeof(AsyncFileData) +        /* AsyncFileData structure */
    2 * pVfs->szOsFile +           /* AsyncFileData.pBaseRead and pBaseWrite */
    nName                          /* AsyncFileData.zName */
  ); 
  z = sqlite3_malloc(nByte);
  if( !z ){
    return SQLITE_NOMEM;
  }
  memset(z, 0, nByte);
  pData = (AsyncFileData*)z;
  z += sizeof(pData[0]);
  pData->pBaseRead = (sqlite3_file*)z;
  z += pVfs->szOsFile;
  pData->pBaseWrite = (sqlite3_file*)z;
  z += pVfs->szOsFile;
  pData->zName = z;
  pData->nName = nName;
  pData->close.pFileData = pData;
  pData->close.op = ASYNC_CLOSE;
  memcpy(pData->zName, zName, nName);

  if( !isExclusive ){
    rc = sqlite3OsOpen(pVfs, zName, pData->pBaseRead, flags, pOutFlags);
    if( rc==SQLITE_OK && ((*pOutFlags)&SQLITE_OPEN_READWRITE) ){
      rc = sqlite3OsOpen(pVfs, zName, pData->pBaseWrite, flags, 0);
    }
  }

  pthread_mutex_lock(&async.lockMutex);

  if( rc==SQLITE_OK ){
    pLock = sqlite3HashFind(&async.aLock, pData->zName, pData->nName);
    if( !pLock ){
      pLock = sqlite3MallocZero(pVfs->szOsFile + sizeof(AsyncLock));
      if( pLock ){
        AsyncLock *pDelete;
#ifdef ENABLE_FILE_LOCKING
        if( flags&SQLITE_OPEN_MAIN_DB ){
          pLock->pFile = (sqlite3_file *)&pLock[1];
          rc = sqlite3OsOpen(pVfs, zName, pLock->pFile, flags, 0);
          if( rc!=SQLITE_OK ){
            sqlite3_free(pLock);
            pLock = 0;
          }
        }
#endif
        pDelete = sqlite3HashInsert(
          &async.aLock, pData->zName, pData->nName, (void *)pLock
        );
        if( pDelete ){
          rc = SQLITE_NOMEM;
          sqlite3_free(pLock);
        }
      }else{
        rc = SQLITE_NOMEM;
      }
    }
  }

  if( rc==SQLITE_OK ){
    HashElem *pElem;
    p->pMethod = &async_methods;
    p->pData = pData;

    /* Link AsyncFileData.lock into the linked list of 
    ** AsyncFileLock structures for this file.
    */
    pData->lock.pNext = pLock->pList;
    pLock->pList = &pData->lock;

    pElem = sqlite3HashFindElem(&async.aLock, pData->zName, pData->nName);
    pData->zName = (char *)sqliteHashKey(pElem);
  }else{
    sqlite3OsClose(pData->pBaseRead);
    sqlite3OsClose(pData->pBaseWrite);
    sqlite3_free(pData);
  }

  pthread_mutex_unlock(&async.lockMutex);

  if( rc==SQLITE_OK ){
    incrOpenFileCount();
  }

  if( rc==SQLITE_OK && isExclusive ){
    rc = addNewAsyncWrite(pData, ASYNC_OPENEXCLUSIVE, (i64)flags, 0, 0);
    if( rc==SQLITE_OK ){
      if( pOutFlags ) *pOutFlags = flags;
    }else{
      pthread_mutex_lock(&async.lockMutex);
      unlinkAsyncFile(pData);
      pthread_mutex_unlock(&async.lockMutex);
      sqlite3_free(pData);
    }
  }
  return rc;
}

/*
** Implementation of sqlite3OsDelete. Add an entry to the end of the 
** write-op queue to perform the delete.
*/
static int asyncDelete(sqlite3_vfs *pAsyncVfs, const char *z, int syncDir){
  return addNewAsyncWrite(0, ASYNC_DELETE, syncDir, strlen(z)+1, z);
}

/*
** Implementation of sqlite3OsAccess. This method holds the mutex from
** start to finish.
*/
static int asyncAccess(
  sqlite3_vfs *pAsyncVfs, 
  const char *zName, 
  int flags,
  int *pResOut
){
  int rc;
  int ret;
  AsyncWrite *p;
  sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;

  assert(flags==SQLITE_ACCESS_READWRITE 
      || flags==SQLITE_ACCESS_READ 
      || flags==SQLITE_ACCESS_EXISTS 
  );

  pthread_mutex_lock(&async.queueMutex);
  rc = sqlite3OsAccess(pVfs, zName, flags, &ret);
  if( rc==SQLITE_OK && flags==SQLITE_ACCESS_EXISTS ){
    for(p=async.pQueueFirst; p; p = p->pNext){
      if( p->op==ASYNC_DELETE && 0==strcmp(p->zBuf, zName) ){
        ret = 0;
      }else if( p->op==ASYNC_OPENEXCLUSIVE 
             && 0==strcmp(p->pFileData->zName, zName) 
      ){
        ret = 1;
      }
    }
  }
  ASYNC_TRACE(("ACCESS(%s): %s = %d\n", 
    flags==SQLITE_ACCESS_READWRITE?"read-write":
    flags==SQLITE_ACCESS_READ?"read":"exists"
    , zName, ret)
  );
  pthread_mutex_unlock(&async.queueMutex);
  *pResOut = ret;
  return rc;
}

/*
** Fill in zPathOut with the full path to the file identified by zPath.
*/
static int asyncFullPathname(
  sqlite3_vfs *pAsyncVfs, 
  const char *zPath, 
  int nPathOut,
  char *zPathOut
){
  int rc;
  sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
  rc = sqlite3OsFullPathname(pVfs, zPath, nPathOut, zPathOut);

  /* Because of the way intra-process file locking works, this backend
  ** needs to return a canonical path. The following block assumes the
  ** file-system uses unix style paths. 
  */
  if( rc==SQLITE_OK ){
    int iIn;
    int iOut = 0;
    int nPathOut = strlen(zPathOut);

    for(iIn=0; iIn<nPathOut; iIn++){

      /* Replace any occurences of "//" with "/" */
      if( iIn<=(nPathOut-2) && zPathOut[iIn]=='/' && zPathOut[iIn+1]=='/'
      ){
        continue;
      }

      /* Replace any occurences of "/./" with "/" */
      if( iIn<=(nPathOut-3) 
       && zPathOut[iIn]=='/' && zPathOut[iIn+1]=='.' && zPathOut[iIn+2]=='/'
      ){
        iIn++;
        continue;
      }

      /* Replace any occurences of "<path-component>/../" with "" */
      if( iOut>0 && iIn<=(nPathOut-4) 
       && zPathOut[iIn]=='/' && zPathOut[iIn+1]=='.' 
       && zPathOut[iIn+2]=='.' && zPathOut[iIn+3]=='/'
      ){
        iIn += 3;
        iOut--;
        for( ; iOut>0 && zPathOut[iOut-1]!='/'; iOut--);
        continue;
      }

      zPathOut[iOut++] = zPathOut[iIn];
    }
    zPathOut[iOut] = '\0';
  }

  return rc;
}
static void *asyncDlOpen(sqlite3_vfs *pAsyncVfs, const char *zPath){
  sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
  return pVfs->xDlOpen(pVfs, zPath);
}
static void asyncDlError(sqlite3_vfs *pAsyncVfs, int nByte, char *zErrMsg){
  sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
  pVfs->xDlError(pVfs, nByte, zErrMsg);
}
static void *asyncDlSym(
  sqlite3_vfs *pAsyncVfs, 
  void *pHandle, 
  const char *zSymbol
){
  sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
  return pVfs->xDlSym(pVfs, pHandle, zSymbol);
}
static void asyncDlClose(sqlite3_vfs *pAsyncVfs, void *pHandle){
  sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
  pVfs->xDlClose(pVfs, pHandle);
}
static int asyncRandomness(sqlite3_vfs *pAsyncVfs, int nByte, char *zBufOut){
  sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
  return pVfs->xRandomness(pVfs, nByte, zBufOut);
}
static int asyncSleep(sqlite3_vfs *pAsyncVfs, int nMicro){
  sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
  return pVfs->xSleep(pVfs, nMicro);
}
static int asyncCurrentTime(sqlite3_vfs *pAsyncVfs, double *pTimeOut){
  sqlite3_vfs *pVfs = (sqlite3_vfs *)pAsyncVfs->pAppData;
  return pVfs->xCurrentTime(pVfs, pTimeOut);
}

static sqlite3_vfs async_vfs = {
  1,                    /* iVersion */
  sizeof(AsyncFile),    /* szOsFile */
  0,                    /* mxPathname */
  0,                    /* pNext */
  "async",              /* zName */
  0,                    /* pAppData */
  asyncOpen,            /* xOpen */
  asyncDelete,          /* xDelete */
  asyncAccess,          /* xAccess */
  asyncFullPathname,    /* xFullPathname */
  asyncDlOpen,          /* xDlOpen */
  asyncDlError,         /* xDlError */
  asyncDlSym,           /* xDlSym */
  asyncDlClose,         /* xDlClose */
  asyncRandomness,      /* xDlError */
  asyncSleep,           /* xDlSym */
  asyncCurrentTime      /* xDlClose */
};

/*
** Call this routine to enable or disable the
** asynchronous IO features implemented in this file. 
**
** This routine is not even remotely threadsafe.  Do not call
** this routine while any SQLite database connections are open.
*/
static void asyncEnable(int enable){
  if( enable ){
    if( !async_vfs.pAppData ){
      static int hashTableInit = 0;
      async_vfs.pAppData = (void *)sqlite3_vfs_find(0);