SQLite4  Check-in [0f28f8317b]

  lsm_db *pDb,
  Freelist *pFreelist
){
  int rc;
  int nVal = 0;
  void *pVal = 0;
  assert( lsmShmAssertWorker(pDb) );

  /* Load the blob of data from the LSM. If that is successful (and the
  ** blob is greater than zero bytes in size), decode the contents and
  ** merge them into the current contents of *pFreelist.  */
  rc = lsmSortedLoadFreelist(pDb, &pVal, &nVal);
  if( pVal ){
    u32 *aFree = (u32 *)pVal;
    int nFree = nVal / sizeof(int);

**   exist - since it would always overlap with the meta pages. If the 
**   page-size is (say) 512 bytes, then the first usable page in the database
**   is page 33.
**
**   It is assumed that the first two meta pages and the data that follows
**   them are located on different disk sectors. So that if a power failure 
**   while writing to a meta page there is no risk of damage to the other
**   meta page or any other part of the database file. TODO: This may need
**   to be revisited.
**
** Blocks:
**
**   The database file is also divided into blocks. The default block size is
**   2MB. When writing to the database file, an attempt is made to write data
**   in contiguous block-sized chunks.
**
**   The first and last page on each block are special in that they are 4 
**   bytes smaller than all other pages. This is because the last four bytes 
**   of space on the first and last pages of each block are reserved for
**   pointers to other blocks (i.e. a 32-bit block number).
**
** Runs:
**
**   A run is a sequence of pages that the upper layer uses to store a 
**   sorted array of database keys (and accompanying data - values, FC 
**   pointers and so on). Given a page within a run, it is possible to

** THE LOG FILE 
**
** This file opens and closes the log file. But it does not contain any
** logic related to the log file format. Instead, it exports the following
** functions that are used by the code in lsm_log.c to read and write the
** log file:
**
**     lsmFsOpenLog
**     lsmFsWriteLog
**     lsmFsSyncLog
**     lsmFsReadLog
**     lsmFsTruncateLog
**     lsmFsCloseAndDeleteLog
**
*/

}

/*
** Write the contents of string buffer pStr into the log file, starting at
** offset iOff.
*/
int lsmFsWriteLog(FileSystem *pFS, i64 iOff, LsmString *pStr){
  assert( pFS->fdLog );
  return lsmEnvWrite(pFS->pEnv, pFS->fdLog, iOff, pStr->z, pStr->n);
}

/*
** fsync() the log file.
*/
int lsmFsSyncLog(FileSystem *pFS){
  assert( pFS->fdLog );
  return lsmEnvSync(pFS->pEnv, pFS->fdLog);
}

/*
** Read nRead bytes of data starting at offset iOff of the log file. Append
** the results to string buffer pStr.
*/
int lsmFsReadLog(FileSystem *pFS, i64 iOff, int nRead, LsmString *pStr){
  int rc;                         /* Return code */
  assert( pFS->fdLog );
  rc = lsmStringExtend(pStr, nRead);
  if( rc==LSM_OK ){
    rc = lsmEnvRead(pFS->pEnv, pFS->fdLog, iOff, &pStr->z[pStr->n], nRead);
    pStr->n += nRead;
  }
  return rc;
}

    }else{
      *pRc = lsmEnvOpen(pFS->pEnv, zName, &pFile);
    }
    lsmFree(pFS->pEnv, zName);
  }
  return pFile;
}

/*
** If it is not already open, this function opens the log file. It returns
** LSM_OK if successful (or if the log file was already open) or an LSM
** error code otherwise.
**
** The log file must be opened before any of the following may be called:
**
**     lsmFsWriteLog
**     lsmFsSyncLog
**     lsmFsReadLog
*/
int lsmFsOpenLog(FileSystem *pFS){
  int rc = LSM_OK;
  if( 0==pFS->fdLog ){ pFS->fdLog = fsOpenFile(pFS, 1, &rc); }
  return rc;
}

/*
** Open a connection to a database stored within the file-system (the
** "system of files").
*/
int lsmFsOpen(lsm_db *pDb, const char *zDb){
  FileSystem *pFS;

    /* Allocate the hash-table here. At some point, it should be changed
    ** so that it can grow dynamicly. */
    pFS->nCacheMax = 2048;
    pFS->nHash = 4096;
    pFS->apHash = lsmMallocZeroRc(pDb->pEnv, sizeof(Page *) * pFS->nHash, &rc);

    /* Open the database file */
    pFS->fdDb = fsOpenFile(pFS, 0, &rc);


    if( rc!=LSM_OK ){
      lsmFsClose(pFS);
      pFS = 0;
    }
  }

*/
int lsmLogBegin(lsm_db *pDb){
  int rc = LSM_OK;
  LogWriter *pNew;
  LogRegion *aReg;

  if( pDb->bUseLog==0 ) return LSM_OK;
  rc = lsmFsOpenLog(pDb->pFS);
  pNew = lsmMallocZeroRc(pDb->pEnv, sizeof(LogWriter), &rc);
  if( pNew ){
    lsmStringInit(&pNew->buf, pDb->pEnv);
    rc = lsmStringExtend(&pNew->buf, 2);
  }
  if( rc!=LSM_OK ){
    assert( pNew==0 || pNew->buf.z==0 );

  LsmString buf2;                 /* Value buffer */
  LogReader reader;               /* Log reader object */
  int rc = LSM_OK;                /* Return code */
  int nCommit = 0;                /* Number of transactions to recover */
  int iPass;
  int nJump = 0;                  /* Number of LSM_LOG_JUMP records in pass 0 */
  DbLog *pLog;

  rc = lsmFsOpenLog(pDb->pFS);
  if( rc!=LSM_OK ) return rc;

  lsmTreeInit(pDb);
  pLog = &pDb->treehdr.log;
  lsmCheckpointLogoffset(pDb->pShmhdr->aWorker, pLog);

  logReaderInit(pDb, pLog, 1, &reader);
  lsmStringInit(&buf1, pDb->pEnv);

    ** than one purpose - to open both the database and log files, and 
    ** perhaps to unlink the log file during disconnection. An absolute
    ** path is required to ensure that the correct files are operated
    ** on even if the application changes the cwd.  */
    rc = getFullpathname(pDb->pEnv, zFilename, &zFull);
    assert( rc==LSM_OK || zFull==0 );

    /* Open the database file. */





    if( rc==LSM_OK ){
      rc = lsmFsOpen(pDb, zFull);
    }

    /* Connect to the database */
    if( rc==LSM_OK ){
      rc = lsmDbDatabaseConnect(pDb, zFilename);