/ Check-in [f8f72ecb]
Login
SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Fix harmless compiler warnings.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | threads
Files: files | file ages | folders
SHA1: f8f72ecb9052a4cace1db75879fb8b5131ea4f50
User & Date: drh 2014-04-18 13:40:07
Context
2014-04-18
13:57
Add to speedtest1.c the --threads option for setting the SQLITE_CONFIG_WORKER_THREADS configuration. check-in: 5fce40c4 user: drh tags: threads
13:40
Fix harmless compiler warnings. check-in: f8f72ecb user: drh tags: threads
12:38
Merge recent trunk changes into the threads branch. check-in: 8729aa3e user: drh tags: threads
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/vdbe.c.

4230
4231
4232
4233
4234
4235
4236

4237
4238
4239
4240
4241
4242
4243
....
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
....
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
  int nIgnore;

  pC = p->apCsr[pOp->p1];
  assert( isSorter(pC) );
  assert( pOp->p4type==P4_INT32 );
  pIn3 = &aMem[pOp->p3];
  nIgnore = pOp->p4.i;

  rc = sqlite3VdbeSorterCompare(pC, pIn3, nIgnore, &res);
  VdbeBranchTaken(res!=0,2);
  if( res ){
    pc = pOp->p2-1;
  }
  break;
};
................................................................................

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( isSorter(pC)==(pOp->opcode==OP_SorterSort) );
  res = 1;
  if( isSorter(pC) ){
    rc = sqlite3VdbeSorterRewind(db, pC, &res);
  }else{
    pCrsr = pC->pCursor;
    assert( pCrsr );
    rc = sqlite3BtreeFirst(pCrsr, &res);
    pC->deferredMoveto = 0;
    pC->cacheStatus = CACHE_STALE;
    pC->rowidIsValid = 0;
................................................................................
  pCrsr = pC->pCursor;
  if( pOp->p5 & OPFLAG_NCHANGE ) p->nChange++;
  assert( pCrsr!=0 );
  assert( pC->isTable==0 );
  rc = ExpandBlob(pIn2);
  if( rc==SQLITE_OK ){
    if( isSorter(pC) ){
      rc = sqlite3VdbeSorterWrite(db, pC, pIn2);
    }else{
      nKey = pIn2->n;
      zKey = pIn2->z;
      rc = sqlite3BtreeInsert(pCrsr, zKey, nKey, "", 0, 0, pOp->p3, 
          ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0)
          );
      assert( pC->deferredMoveto==0 );







>







 







|







 







|







4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
....
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
....
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
  int nIgnore;

  pC = p->apCsr[pOp->p1];
  assert( isSorter(pC) );
  assert( pOp->p4type==P4_INT32 );
  pIn3 = &aMem[pOp->p3];
  nIgnore = pOp->p4.i;
  res = 0;
  rc = sqlite3VdbeSorterCompare(pC, pIn3, nIgnore, &res);
  VdbeBranchTaken(res!=0,2);
  if( res ){
    pc = pOp->p2-1;
  }
  break;
};
................................................................................

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( isSorter(pC)==(pOp->opcode==OP_SorterSort) );
  res = 1;
  if( isSorter(pC) ){
    rc = sqlite3VdbeSorterRewind(pC, &res);
  }else{
    pCrsr = pC->pCursor;
    assert( pCrsr );
    rc = sqlite3BtreeFirst(pCrsr, &res);
    pC->deferredMoveto = 0;
    pC->cacheStatus = CACHE_STALE;
    pC->rowidIsValid = 0;
................................................................................
  pCrsr = pC->pCursor;
  if( pOp->p5 & OPFLAG_NCHANGE ) p->nChange++;
  assert( pCrsr!=0 );
  assert( pC->isTable==0 );
  rc = ExpandBlob(pIn2);
  if( rc==SQLITE_OK ){
    if( isSorter(pC) ){
      rc = sqlite3VdbeSorterWrite(pC, pIn2);
    }else{
      nKey = pIn2->n;
      zKey = pIn2->z;
      rc = sqlite3BtreeInsert(pCrsr, zKey, nKey, "", 0, 0, pOp->p3, 
          ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0)
          );
      assert( pC->deferredMoveto==0 );

Changes to src/vdbeInt.h.

438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
int sqlite3VdbeTransferError(Vdbe *p);

int sqlite3VdbeSorterInit(sqlite3 *, int, VdbeCursor *);
void sqlite3VdbeSorterReset(sqlite3 *, VdbeSorter *);
void sqlite3VdbeSorterClose(sqlite3 *, VdbeCursor *);
int sqlite3VdbeSorterRowkey(const VdbeCursor *, Mem *);
int sqlite3VdbeSorterNext(sqlite3 *, const VdbeCursor *, int *);
int sqlite3VdbeSorterRewind(sqlite3 *, const VdbeCursor *, int *);
int sqlite3VdbeSorterWrite(sqlite3 *, const VdbeCursor *, Mem *);
int sqlite3VdbeSorterCompare(const VdbeCursor *, Mem *, int, int *);

#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
  void sqlite3VdbeEnter(Vdbe*);
  void sqlite3VdbeLeave(Vdbe*);
#else
# define sqlite3VdbeEnter(X)







|
|







438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
int sqlite3VdbeTransferError(Vdbe *p);

int sqlite3VdbeSorterInit(sqlite3 *, int, VdbeCursor *);
void sqlite3VdbeSorterReset(sqlite3 *, VdbeSorter *);
void sqlite3VdbeSorterClose(sqlite3 *, VdbeCursor *);
int sqlite3VdbeSorterRowkey(const VdbeCursor *, Mem *);
int sqlite3VdbeSorterNext(sqlite3 *, const VdbeCursor *, int *);
int sqlite3VdbeSorterRewind(const VdbeCursor *, int *);
int sqlite3VdbeSorterWrite(const VdbeCursor *, Mem *);
int sqlite3VdbeSorterCompare(const VdbeCursor *, Mem *, int, int *);

#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
  void sqlite3VdbeEnter(Vdbe*);
  void sqlite3VdbeLeave(Vdbe*);
#else
# define sqlite3VdbeEnter(X)

Changes to src/vdbesort.c.

585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
...
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
...
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
....
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
....
1480
1481
1482
1483
1484
1485
1486

1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497

1498
1499
1500
1501
1502
1503
1504
....
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
....
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
....
1794
1795
1796
1797
1798
1799
1800

1801
1802
1803
1804
1805
1806
1807
1808
1809

1810
1811
1812
1813
1814
1815
1816
....
2155
2156
2157
2158
2159
2160
2161

2162
2163

2164
2165
2166
2167
2168

2169
2170
2171
2172
2173
2174
2175
....
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
....
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
**
** Or, if an error occurs, return an SQLite error code. The final value of
** *pp is undefined in this case.
*/
static int vdbeSorterMapFile(SortSubtask *pTask, SorterFile *pFile, u8 **pp){
  int rc = SQLITE_OK;
  if( pFile->iEof<=(i64)(pTask->pSorter->db->nMaxSorterMmap) ){
    rc = sqlite3OsFetch(pFile->pFd, 0, pFile->iEof, (void**)pp);
  }
  return rc;
}

/*
** Seek iterator pIter to offset iOff within file pFile. Return SQLITE_OK 
** if successful, or an SQLite error code if an error occurs.
................................................................................
#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;
................................................................................
    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)
# define vdbeSorterBlockDebug(x,y,z)
#endif

#if SQLITE_MAX_WORKER_THREADS>0
/*
** Join thread pTask->thread.
................................................................................
** 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
................................................................................
    }
    *pbEof = (pMerger->aIter[pMerger->aTree[1]].pFile==0);
  }

  return rc;
}


/*
** The main routine for background threads that write level-0 PMAs.
*/
static void *vdbeSorterFlushThread(void *pCtx){
  SortSubtask *pTask = (SortSubtask*)pCtx;
  int rc;                         /* Return code */
  assert( pTask->bDone==0 );
  rc = vdbeSorterListToPMA(pTask, &pTask->list);
  pTask->bDone = 1;
  return SQLITE_INT_TO_PTR(rc);
}


/*
** Flush the current contents of VdbeSorter.list to a new PMA, possibly
** using a background thread.
*/
static int vdbeSorterFlushPMA(VdbeSorter *pSorter){
#if SQLITE_MAX_WORKER_THREADS==0
................................................................................
      }

      rc = vdbeSorterCreateThread(pTask, vdbeSorterFlushThread, pCtx);
    }
  }

  return rc;
#endif
}

/*
** Add a record to the sorter.
*/
int sqlite3VdbeSorterWrite(
  sqlite3 *db,                    /* Database handle */
  const VdbeCursor *pCsr,         /* Sorter cursor */
  Mem *pVal                       /* Memory cell containing record */
){
  VdbeSorter *pSorter = pCsr->pSorter;
  int rc = SQLITE_OK;             /* Return Code */
  SorterRecord *pNew;             /* New list element */

................................................................................
      );
      pSorter->list.aMemory = aNew;
      pSorter->nMemory = nNew;
    }

    pNew = (SorterRecord*)&pSorter->list.aMemory[pSorter->iMemory];
    pSorter->iMemory += ROUND8(nReq);
    pNew->u.iNext = (u8*)(pSorter->list.pList) - pSorter->list.aMemory;
  }else{
    pNew = (SorterRecord *)sqlite3Malloc(nReq);
    if( pNew==0 ){
      return SQLITE_NOMEM;
    }
    pNew->u.pNext = pSorter->list.pList;
  }
................................................................................
  }else{
    vdbeMergeEngineFree(pMerger);
    rc = SQLITE_NOMEM;
  }
  return rc;
}


/*
** Set the "use-threads" flag on object pIncr.
*/
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);

/*
................................................................................
**
** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
*/
static int vdbeSorterSetupMerge(VdbeSorter *pSorter){
  int rc;                         /* Return code */
  SortSubtask *pTask0 = &pSorter->aTask[0];
  MergeEngine *pMain = 0;

  sqlite3 *db = pTask0->pSorter->db;
  int iTask;


  rc = vdbeSorterMergeTreeBuild(pSorter, &pMain);
  if( rc==SQLITE_OK ){
#if SQLITE_MAX_WORKER_THREADS
    if( pSorter->bUseThreads ){

      PmaReader *pIter;
      SortSubtask *pLast = &pSorter->aTask[pSorter->nTask-1];
      rc = vdbeSortAllocUnpacked(pLast);
      if( rc==SQLITE_OK ){
        pIter = (PmaReader*)sqlite3DbMallocZero(db, sizeof(PmaReader));
        pSorter->pReader = pIter;
      }
................................................................................


/*
** Once the sorter has been populated by calls to sqlite3VdbeSorterWrite,
** this function is called to prepare for iterating through the records
** in sorted order.
*/
int sqlite3VdbeSorterRewind(sqlite3 *db, const VdbeCursor *pCsr, int *pbEof){
  VdbeSorter *pSorter = pCsr->pSorter;
  int rc = SQLITE_OK;             /* Return code */

  assert( pSorter );

  /* If no data has been written to disk, then do not do so now. Instead,
  ** sort the VdbeSorter.pRecord list. The vdbe layer will read data directly
................................................................................
  if( pSorter->list.pList ){
    rc = vdbeSorterFlushPMA(pSorter);
  }

  /* Join all threads */
  rc = vdbeSorterJoinAll(pSorter, rc);

  vdbeSorterRewindDebug(db, "rewind");

  /* Assuming no errors have occurred, set up a merger structure to 
  ** incrementally read and merge all remaining PMAs.  */
  assert( pSorter->pReader==0 );
  if( rc==SQLITE_OK ){
    rc = vdbeSorterSetupMerge(pSorter);
    *pbEof = 0;
  }

  vdbeSorterRewindDebug(db, "rewinddone");
  return rc;
}

/*
** Advance to the next element in the sorter.
*/
int sqlite3VdbeSorterNext(sqlite3 *db, const VdbeCursor *pCsr, int *pbEof){







|







 







|

|







 







|







 







|







 







>











>







 







|






<







 







|







 







>









>







 







>

<
>





>







 







|







 







|









|







585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
...
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
...
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
....
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
....
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
....
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572

1573
1574
1575
1576
1577
1578
1579
....
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
....
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
....
2158
2159
2160
2161
2162
2163
2164
2165
2166

2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
....
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
....
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
**
** Or, if an error occurs, return an SQLite error code. The final value of
** *pp is undefined in this case.
*/
static int vdbeSorterMapFile(SortSubtask *pTask, SorterFile *pFile, u8 **pp){
  int rc = SQLITE_OK;
  if( pFile->iEof<=(i64)(pTask->pSorter->db->nMaxSorterMmap) ){
    rc = sqlite3OsFetch(pFile->pFd, 0, (int)pFile->iEof, (void**)pp);
  }
  return rc;
}

/*
** Seek iterator pIter to offset iOff within file pFile. Return SQLITE_OK 
** if successful, or an SQLite error code if an error occurs.
................................................................................
#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(const char *zEvent){
  i64 t;
  sqlite3OsCurrentTimeInt64(sqlite3_vfs_find(0), &t);
  fprintf(stderr, "%lld:X %s\n", t, zEvent);
}
static void vdbeSorterPopulateDebug(
  SortSubtask *pTask,
  const char *zEvent
){
  i64 t;
................................................................................
    i64 t;
    sqlite3OsCurrentTimeInt64(pTask->pSorter->db->pVfs, &t);
    fprintf(stderr, "%lld:main %s\n", t, zEvent);
  }
}
#else
# define vdbeSorterWorkDebug(x,y)
# define vdbeSorterRewindDebug(y)
# define vdbeSorterPopulateDebug(x,y)
# define vdbeSorterBlockDebug(x,y,z)
#endif

#if SQLITE_MAX_WORKER_THREADS>0
/*
** Join thread pTask->thread.
................................................................................
** 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, (int)nByte, &p);
      sqlite3OsUnfetch(pFile, 0, p);
    }
  }
}
#else
# define vdbeSorterExtendFile(x,y,z) SQLITE_OK
#endif
................................................................................
    }
    *pbEof = (pMerger->aIter[pMerger->aTree[1]].pFile==0);
  }

  return rc;
}

#if SQLITE_MAX_WORKER_THREADS>0
/*
** The main routine for background threads that write level-0 PMAs.
*/
static void *vdbeSorterFlushThread(void *pCtx){
  SortSubtask *pTask = (SortSubtask*)pCtx;
  int rc;                         /* Return code */
  assert( pTask->bDone==0 );
  rc = vdbeSorterListToPMA(pTask, &pTask->list);
  pTask->bDone = 1;
  return SQLITE_INT_TO_PTR(rc);
}
#endif /* SQLITE_MAX_WORKER_THREADS>0 */

/*
** Flush the current contents of VdbeSorter.list to a new PMA, possibly
** using a background thread.
*/
static int vdbeSorterFlushPMA(VdbeSorter *pSorter){
#if SQLITE_MAX_WORKER_THREADS==0
................................................................................
      }

      rc = vdbeSorterCreateThread(pTask, vdbeSorterFlushThread, pCtx);
    }
  }

  return rc;
#endif /* SQLITE_MAX_WORKER_THREADS!=0 */
}

/*
** Add a record to the sorter.
*/
int sqlite3VdbeSorterWrite(

  const VdbeCursor *pCsr,         /* Sorter cursor */
  Mem *pVal                       /* Memory cell containing record */
){
  VdbeSorter *pSorter = pCsr->pSorter;
  int rc = SQLITE_OK;             /* Return Code */
  SorterRecord *pNew;             /* New list element */

................................................................................
      );
      pSorter->list.aMemory = aNew;
      pSorter->nMemory = nNew;
    }

    pNew = (SorterRecord*)&pSorter->list.aMemory[pSorter->iMemory];
    pSorter->iMemory += ROUND8(nReq);
    pNew->u.iNext = (int)((u8*)(pSorter->list.pList) - pSorter->list.aMemory);
  }else{
    pNew = (SorterRecord *)sqlite3Malloc(nReq);
    if( pNew==0 ){
      return SQLITE_NOMEM;
    }
    pNew->u.pNext = pSorter->list.pList;
  }
................................................................................
  }else{
    vdbeMergeEngineFree(pMerger);
    rc = SQLITE_NOMEM;
  }
  return rc;
}

#if SQLITE_MAX_WORKER_THREADS>0
/*
** Set the "use-threads" flag on object pIncr.
*/
static void vdbeIncrSetThreads(IncrMerger *pIncr, int bUseThread){
  if( bUseThread ){
    pIncr->bUseThread = 1;
    pIncr->pTask->file2.iEof -= pIncr->mxSz;
  }
}
#endif /* SQLITE_MAX_WORKER_THREADS>0 */

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

/*
................................................................................
**
** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
*/
static int vdbeSorterSetupMerge(VdbeSorter *pSorter){
  int rc;                         /* Return code */
  SortSubtask *pTask0 = &pSorter->aTask[0];
  MergeEngine *pMain = 0;
#if SQLITE_MAX_WORKER_THREADS
  sqlite3 *db = pTask0->pSorter->db;

#endif

  rc = vdbeSorterMergeTreeBuild(pSorter, &pMain);
  if( rc==SQLITE_OK ){
#if SQLITE_MAX_WORKER_THREADS
    if( pSorter->bUseThreads ){
      int iTask;
      PmaReader *pIter;
      SortSubtask *pLast = &pSorter->aTask[pSorter->nTask-1];
      rc = vdbeSortAllocUnpacked(pLast);
      if( rc==SQLITE_OK ){
        pIter = (PmaReader*)sqlite3DbMallocZero(db, sizeof(PmaReader));
        pSorter->pReader = pIter;
      }
................................................................................


/*
** Once the sorter has been populated by calls to sqlite3VdbeSorterWrite,
** this function is called to prepare for iterating through the records
** in sorted order.
*/
int sqlite3VdbeSorterRewind(const VdbeCursor *pCsr, int *pbEof){
  VdbeSorter *pSorter = pCsr->pSorter;
  int rc = SQLITE_OK;             /* Return code */

  assert( pSorter );

  /* If no data has been written to disk, then do not do so now. Instead,
  ** sort the VdbeSorter.pRecord list. The vdbe layer will read data directly
................................................................................
  if( pSorter->list.pList ){
    rc = vdbeSorterFlushPMA(pSorter);
  }

  /* Join all threads */
  rc = vdbeSorterJoinAll(pSorter, rc);

  vdbeSorterRewindDebug("rewind");

  /* Assuming no errors have occurred, set up a merger structure to 
  ** incrementally read and merge all remaining PMAs.  */
  assert( pSorter->pReader==0 );
  if( rc==SQLITE_OK ){
    rc = vdbeSorterSetupMerge(pSorter);
    *pbEof = 0;
  }

  vdbeSorterRewindDebug("rewinddone");
  return rc;
}

/*
** Advance to the next element in the sorter.
*/
int sqlite3VdbeSorterNext(sqlite3 *db, const VdbeCursor *pCsr, int *pbEof){