SQLite4
Check-in [d4c5a3bad7edad16f7f06666e9c15ee59beffe53]
Not logged in

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

Overview
SHA1 Hash:d4c5a3bad7edad16f7f06666e9c15ee59beffe53
Date: 2012-11-29 19:14:46
User: dan
Comment:Avoid reading and checksumming an entire meta-page every time a write transaction is opened.
Tags And Properties
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/lsmInt.h

704
705
706
707
708
709
710


711
712
713
714
715
716
717
int lsmEnvLock(lsm_env *pEnv, lsm_file *pFile, int iLock, int eLock);

int lsmEnvShmMap(lsm_env *, lsm_file *, int, int, void **); 
void lsmEnvShmBarrier(lsm_env *);
void lsmEnvShmUnmap(lsm_env *, lsm_file *, int);

void lsmEnvSleep(lsm_env *, int);



/*
** End of functions from "lsm_file.c".
**************************************************************************/

/* 
** Functions from file "lsm_sorted.c".







>
>







704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
int lsmEnvLock(lsm_env *pEnv, lsm_file *pFile, int iLock, int eLock);

int lsmEnvShmMap(lsm_env *, lsm_file *, int, int, void **); 
void lsmEnvShmBarrier(lsm_env *);
void lsmEnvShmUnmap(lsm_env *, lsm_file *, int);

void lsmEnvSleep(lsm_env *, int);

int lsmFsReadSyncedId(lsm_db *db, int, i64 *piVal);

/*
** End of functions from "lsm_file.c".
**************************************************************************/

/* 
** Functions from file "lsm_sorted.c".

Changes to src/lsm_file.c

1221
1222
1223
1224
1225
1226
1227
































1228
1229
1230
1231
1232
1233
1234
    }else{
      p->nData = pFS->nPagesize;
    }
    pFS->nOut += (p->nRef==0);
    p->nRef++;
  }
  *ppPg = p;
































  return rc;
}


static int fsRunEndsBetween(
  Segment *pRun, 
  Segment *pIgnore, 







>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>







1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
    }else{
      p->nData = pFS->nPagesize;
    }
    pFS->nOut += (p->nRef==0);
    p->nRef++;
  }
  *ppPg = p;
  return rc;
}

/*
** Read the 64-bit checkpoint id of the checkpoint currently stored on meta
** page iMeta of the database file. If no error occurs, store the id value
** in *piVal and return LSM_OK. Otherwise, return an LSM error code and leave
** *piVal unmodified.
**
** If a checkpointer connection is currently updating meta-page iMeta, or an
** earlier checkpointer crashed while doing so, the value read into *piVal
** may be garbage. It is the callers responsibility to deal with this.
*/
int lsmFsReadSyncedId(lsm_db *db, int iMeta, i64 *piVal){
  FileSystem *pFS = db->pFS;
  int rc = LSM_OK;

  assert( iMeta==1 || iMeta==2 );
  if( pFS->bUseMmap ){
    fsGrowMapping(pFS, iMeta*LSM_META_PAGE_SIZE, &rc);
    if( rc==LSM_OK ){
      *piVal = (i64)lsmGetU64(&((u8 *)pFS->pMap)[(iMeta-1)*LSM_META_PAGE_SIZE]);
    }
  }else{
    MetaPage *pMeta = 0;
    rc = lsmFsMetaPageGet(pFS, 0, iMeta, &pMeta);
    if( rc==LSM_OK ){
      *piVal = (i64)lsmGetU64(pMeta->aData);
      lsmFsMetaPageRelease(pMeta);
    }
  }

  return rc;
}


static int fsRunEndsBetween(
  Segment *pRun, 
  Segment *pIgnore, 

Changes to src/lsm_log.c

298
299
300
301
302
303
304


305

306












307
308
309
310
311
312
313
314
315
316
317
318
319
320

321
322
323
324
325
326
327
/*
** If possible, reclaim log file space. Log file space is reclaimed after
** a snapshot that points to the same data in the database file is synced
** into the db header.
*/
static int logReclaimSpace(lsm_db *pDb){
  int rc = LSM_OK;


  if( pDb->pShmhdr->iMetaPage ){

    DbLog *pLog = &pDb->treehdr.log;












    i64 iSnapshotId = 0;
    i64 iOff = 0;
    rc = lsmCheckpointSynced(pDb, &iSnapshotId, &iOff, 0);
    if( rc==LSM_OK && pLog->iSnapshotId<iSnapshotId ){
      int iRegion;
      for(iRegion=0; iRegion<3; iRegion++){
        LogRegion *p = &pLog->aRegion[iRegion];
        if( iOff>=p->iStart && iOff<=p->iEnd ) break;
        p->iStart = 0;
        p->iEnd = 0;
      }
      assert( iRegion<3 );
      pLog->aRegion[iRegion].iStart = iOff;
      pLog->iSnapshotId = iSnapshotId;

    }
  }
  return rc;
}

/*
** This function is called when a write-transaction is first opened. It







>
>
|
>

>
>
>
>
>
>
>
>
>
>
>
>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
>







298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
/*
** If possible, reclaim log file space. Log file space is reclaimed after
** a snapshot that points to the same data in the database file is synced
** into the db header.
*/
static int logReclaimSpace(lsm_db *pDb){
  int rc = LSM_OK;
  int iMeta;

  iMeta = (int)pDb->pShmhdr->iMetaPage;
  if( iMeta==1 || iMeta==2 ){
    DbLog *pLog = &pDb->treehdr.log;
    i64 iSyncedId;

    /* Read the snapshot-id of the snapshot stored on meta-page iMeta. Note
    ** that in theory, the value read is untrustworthy (due to a race 
    ** condition - see comments above lsmFsReadSyncedId()). So it is only 
    ** ever used to conclude that no log space can be reclaimed. If it seems
    ** to indicate that it may be possible to reclaim log space, a
    ** second call to lsmCheckpointSynced() (which does return trustworthy
    ** values) is made below to confirm.  */
    rc = lsmFsReadSyncedId(pDb, iMeta, &iSyncedId);

    if( rc==LSM_OK && pLog->iSnapshotId!=iSyncedId ){
      i64 iSnapshotId = 0;
      i64 iOff = 0;
      rc = lsmCheckpointSynced(pDb, &iSnapshotId, &iOff, 0);
      if( rc==LSM_OK && pLog->iSnapshotId<iSnapshotId ){
        int iRegion;
        for(iRegion=0; iRegion<3; iRegion++){
          LogRegion *p = &pLog->aRegion[iRegion];
          if( iOff>=p->iStart && iOff<=p->iEnd ) break;
          p->iStart = 0;
          p->iEnd = 0;
        }
        assert( iRegion<3 );
        pLog->aRegion[iRegion].iStart = iOff;
        pLog->iSnapshotId = iSnapshotId;
      }
    }
  }
  return rc;
}

/*
** This function is called when a write-transaction is first opened. It

Changes to src/lsm_sorted.c

338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
u32 lsmGetU32(u8 *aOut){
  return ((u32)aOut[0] << 24) 
       + ((u32)aOut[1] << 16) 
       + ((u32)aOut[2] << 8) 
       + ((u32)aOut[3]);
}

u32 lsmGetU64(u8 *aOut){
  return ((u64)aOut[0] << 56) 
       + ((u64)aOut[1] << 48) 
       + ((u64)aOut[2] << 40) 
       + ((u64)aOut[3] << 32) 
       + ((u64)aOut[4] << 24)
       + ((u32)aOut[5] << 16) 
       + ((u32)aOut[6] << 8) 







|







338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
u32 lsmGetU32(u8 *aOut){
  return ((u32)aOut[0] << 24) 
       + ((u32)aOut[1] << 16) 
       + ((u32)aOut[2] << 8) 
       + ((u32)aOut[3]);
}

u64 lsmGetU64(u8 *aOut){
  return ((u64)aOut[0] << 56) 
       + ((u64)aOut[1] << 48) 
       + ((u64)aOut[2] << 40) 
       + ((u64)aOut[3] << 32) 
       + ((u64)aOut[4] << 24)
       + ((u32)aOut[5] << 16) 
       + ((u32)aOut[6] << 8)