SQLite

  }
}

#ifdef SQLITE_DEBUG_SORTER_THREADS
static void vdbeSorterWorkDebug(SortSubtask *pTask, const char *zEvent){
  i64 t;
  int iTask = (pTask - pTask->pSorter->aTask);
  sqlite3OsCurrentTimeInt64(pTask->pSorter->db->pVfs, &t);
  fprintf(stderr, "%lld:%d %s\n", t, iTask, zEvent);
}
static void vdbeSorterRewindDebug(sqlite3 *db, const char *zEvent){
  i64 t;
  sqlite3OsCurrentTimeInt64(db->pVfs, &t);
  fprintf(stderr, "%lld:X %s\n", t, zEvent);
}
static void vdbeSorterPopulateDebug(
  SortSubtask *pTask,
  const char *zEvent
){
  i64 t;
  int iTask = (pTask - pTask->pSorter->aTask);
  sqlite3OsCurrentTimeInt64(pTask->pSorter->db->pVfs, &t);
  fprintf(stderr, "%lld:bg%d %s\n", t, iTask, zEvent);
}
static void vdbeSorterBlockDebug(
  SortSubtask *pTask,
  int bBlocked,
  const char *zEvent
){
  if( bBlocked ){
    i64 t;
    sqlite3OsCurrentTimeInt64(pTask->pSorter->db->pVfs, &t);
    fprintf(stderr, "%lld:main %s\n", t, zEvent);
  }
}
#else
# define vdbeSorterWorkDebug(x,y)
# define vdbeSorterRewindDebug(x,y)
# define vdbeSorterPopulateDebug(x,y)

    sqlite3VdbeSorterReset(db, pSorter);
    sqlite3_free(pSorter->list.aMemory);
    sqlite3DbFree(db, pSorter);
    pCsr->pSorter = 0;
  }
}

#if SQLITE_MAX_MMAP_SIZE>0
/*
** The first argument is a file-handle open on a temporary file. The file
** is guaranteed to be nByte bytes or smaller in size. This function
** attempts to extend the file to nByte bytes in size and to ensure that
** the VFS has memory mapped it.
**
** Whether or not the file does end up memory mapped of course depends on
** the specific VFS implementation.
*/
static void vdbeSorterExtendFile(sqlite3 *db, sqlite3_file *pFile, i64 nByte){
  if( nByte<=(i64)(db->nMaxSorterMmap) ){
    int rc = sqlite3OsTruncate(pFile, nByte);
    if( rc==SQLITE_OK ){
      void *p = 0;
      sqlite3OsFetch(pFile, 0, nByte, &p);
      sqlite3OsUnfetch(pFile, 0, p);
    }
  }
}
#else
# define vdbeSorterExtendFile(x,y,z) SQLITE_OK
#endif

/*
** Allocate space for a file-handle and open a temporary file. If successful,
** set *ppFile to point to the malloc'd file-handle and return SQLITE_OK.
** Otherwise, set *ppFile to 0 and return an SQLite error code.
*/
static int vdbeSorterOpenTempFile(
  sqlite3 *db,                    /* Database handle doing sort */
  i64 nExtend,                    /* Attempt to extend file to this size */
  sqlite3_file **ppFile
){
  int rc;
  rc = sqlite3OsOpenMalloc(db->pVfs, 0, ppFile,
      SQLITE_OPEN_TEMP_JOURNAL |
      SQLITE_OPEN_READWRITE    | SQLITE_OPEN_CREATE |
      SQLITE_OPEN_EXCLUSIVE    | SQLITE_OPEN_DELETEONCLOSE, &rc
  );
  if( rc==SQLITE_OK ){
    i64 max = SQLITE_MAX_MMAP_SIZE;
    sqlite3OsFileControlHint(*ppFile, SQLITE_FCNTL_MMAP_SIZE, (void*)&max);
    if( nExtend>0 ){
      vdbeSorterExtendFile(db, *ppFile, nExtend);
    }
  }
  return rc;
}

/*
** If it has not already been allocated, allocate the UnpackedRecord 
** structure at pTask->pUnpacked. Return SQLITE_OK if successful (or 

*/
static void vdbePmaWriteVarint(PmaWriter *p, u64 iVal){
  int nByte; 
  u8 aByte[10];
  nByte = sqlite3PutVarint(aByte, iVal);
  vdbePmaWriteBlob(p, aByte, nByte);
}


























/*
** Write the current contents of in-memory linked-list pList to a level-0
** PMA in the temp file belonging to sub-task pTask. Return SQLITE_OK if 
** successful, or an SQLite error code otherwise.
**
** The format of a PMA is:

  vdbeSorterWorkDebug(pTask, "enter");
  memset(&writer, 0, sizeof(PmaWriter));
  assert( pList->szPMA>0 );

  /* If the first temporary PMA file has not been opened, open it now. */
  if( pTask->file.pFd==0 ){
    rc = vdbeSorterOpenTempFile(db, 0, &pTask->file.pFd);
    assert( rc!=SQLITE_OK || pTask->file.pFd );
    assert( pTask->file.iEof==0 );
    assert( pTask->nPMA==0 );
  }

  /* Try to get the file to memory map */
  if( rc==SQLITE_OK ){

static void vdbeIncrSetThreads(IncrMerger *pIncr, int bUseThread){
  if( bUseThread ){
    pIncr->bUseThread = 1;
    pIncr->pTask->file2.iEof -= pIncr->mxSz;
  }
}

#define INCRINIT_NORMAL 0
#define INCRINIT_TASK   1
#define INCRINIT_ROOT   2
static int vdbePmaReaderIncrInit(PmaReader *pIter, int eMode);

/*
** Initialize the merger argument passed as the second argument. Once this
** function returns, the first key of merged data may be read from the merger
** object in the usual fashion.
**
** If argument eMode is INCRINIT_ROOT, then it is assumed that any IncrMerge
** objects attached to the PmaReader objects that the merger reads from have
** already been populated, but that they have not yet populated aFile[0] and
** set the PmaReader objects up to read from it. In this case all that is
** required is to call vdbePmaReaderNext() on each iterator to point it at
** its first key.
**
** Otherwise, if eMode is any value other than INCRINIT_ROOT, then use 
** vdbePmaReaderIncrInit() to initialize each PmaReader that feeds data 
** to pMerger.
**
** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
*/
static int vdbeIncrInitMerger(
  SortSubtask *pTask, 
  MergeEngine *pMerger, 
  int eMode                       /* One of the INCRINIT_XXX constants */
){
  int rc = SQLITE_OK;             /* Return code */
  int i;                          /* For iterating through PmaReader objects */

  for(i=0; rc==SQLITE_OK && i<pMerger->nTree; i++){
    if( eMode==INCRINIT_ROOT ){
      rc = vdbePmaReaderNext(&pMerger->aIter[i]);
    }else{
      rc = vdbePmaReaderIncrInit(&pMerger->aIter[i], INCRINIT_NORMAL);
    }
  }

  for(i=pMerger->nTree-1; rc==SQLITE_OK && i>0; i--){
    rc = vdbeSorterDoCompare(pTask, pMerger, i);
  }

  return rc;
}

/*
** If the PmaReader passed as the first argument is not an incremental-reader
** (if pIter->pIncr==0), then this function is a no-op. Otherwise, it serves
** to open and/or initialize the temp file related fields of the IncrMerge
** object at (pIter->pIncr).
**
** If argument eMode is set to INCRINIT_NORMAL, then PmaReader iterators
** in the sub-tree headed by pIter are also initialized. Data is then loaded
** into the buffers belonging to this iterator, pIter, and it is set to
** point to the first key in its range.
**
** If argument eMode is set to INCRINIT_TASK, then PmaReader is guaranteed
** to be a multi-threaded iterator and this function is being called in a
** background thread. In this case all iterators in the sub-tree are 
** initialized as for INCRINIT_NORMAL and the aFile[1] buffer belonging to
** pIter is populated. However, the iterator itself is not set up to point
** to its first key. A call to vdbePmaReaderNext() is still required to do
** that. 
**
** The reason this function does not call vdbePmaReaderNext() immediately 
** in the INCRINIT_TASK case is that vdbePmaReaderNext() assumes that has
** to block on thread (pTask->thread) before accessing aFile[1]. But, since
** this entire function is being run by thread (pTask->thread), that will
** lead to the current background thread attempting to join itself.
**
** Finally, if argument eMode is set to INCRINIT_ROOT, it may be assumed
** that pIter->pIncr is a multi-threaded IncrMerge objects, and that all
** child-trees have already been initialized using IncrInit(INCRINIT_TASK).
** In this case vdbePmaReaderNext() is called on all child iterators and
** the current iterator set to point to the first key in its range.
**
** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
*/
static int vdbePmaReaderIncrInit(PmaReader *pIter, int eMode){
  int rc = SQLITE_OK;
  IncrMerger *pIncr = pIter->pIncr;
  if( pIncr ){
    SortSubtask *pTask = pIncr->pTask;
    sqlite3 *db = pTask->pSorter->db;

    assert( eMode==INCRINIT_NORMAL || pIncr->bUseThread==1 );
    rc = vdbeIncrInitMerger(pTask, pIncr->pMerger, eMode);

    /* Set up the required files for pIncr. A multi-theaded IncrMerge object
    ** requires two temp files to itself, whereas a single-threaded object
    ** only requires a region of pTask->file2. */
    if( rc==SQLITE_OK ){
      int mxSz = pIncr->mxSz;
      if( pIncr->bUseThread==0 ){
        if( pTask->file2.pFd==0 ){

          assert( pTask->file2.iEof>0 );

          rc = vdbeSorterOpenTempFile(db, pTask->file2.iEof, &pTask->file2.pFd);
          pTask->file2.iEof = 0;

        }
        if( rc==SQLITE_OK ){
          pIncr->aFile[1].pFd = pTask->file2.pFd;
          pIncr->iStartOff = pTask->file2.iEof;
          pTask->file2.iEof += mxSz;
        }
      }else{
        rc = vdbeSorterOpenTempFile(db, mxSz, &pIncr->aFile[0].pFd);
        if( rc==SQLITE_OK ){
          rc = vdbeSorterOpenTempFile(db, mxSz, &pIncr->aFile[1].pFd);
        }
      }
    }

    if( rc==SQLITE_OK && pIncr->bUseThread ){
      /* Use the current thread to populate aFile[1], even though this
      ** iterator is multi-threaded. The reason being that this function
      ** is already running in background thread pIncr->pTask->thread. */
      assert( eMode==INCRINIT_ROOT || eMode==INCRINIT_TASK );
      rc = vdbeIncrPopulate(pIncr);
    }

    if( rc==SQLITE_OK && eMode!=INCRINIT_TASK ){
      rc = vdbePmaReaderNext(pIter);
    }
  }
  return rc;
}

#if SQLITE_MAX_WORKER_THREADS>0
/*
** The main routine for vdbePmaReaderIncrInit() operations run in 
** background threads.
*/
static void *vdbePmaReaderBgInit(void *pCtx){
  PmaReader *pReader = (PmaReader*)pCtx;
  void *pRet = SQLITE_INT_TO_PTR(vdbePmaReaderIncrInit(pReader,INCRINIT_TASK));
  pReader->pIncr->pTask->bDone = 1;
  return pRet;
}

/*
** Use a background thread to invoke vdbePmaReaderIncrInit(INCRINIT_TASK) 
** on the the PmaReader object passed as the first argument.
**
** This call will initialize the various fields of the pIter->pIncr 
** structure and, if it is a multi-threaded IncrMerger, launch a 
** background thread to populate aFile[1].
*/
static int vdbePmaReaderBgIncrInit(PmaReader *pIter){

              if( p->pIncr ){ rc = vdbePmaReaderBgIncrInit(p); }
            }
          }
        }
        pMain = 0;
      }
      if( rc==SQLITE_OK ){
        int eMode = (pSorter->nTask>1 ? INCRINIT_ROOT : INCRINIT_NORMAL);
        rc = vdbePmaReaderIncrInit(pIter, eMode);
      }
    }else
#endif
    {
      rc = vdbeIncrInitMerger(pTask0, pMain, INCRINIT_NORMAL);
      pSorter->pMerger = pMain;
      pMain = 0;
    }
  }

  if( rc!=SQLITE_OK ){
    vdbeMergeEngineFree(pMain);