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Overview
Comment:Before writing data to a new database segment, make sure the data is held in heap (not mmap'd) memory. Otherwise, the write may cause the file to grow and the mapping to be released and remapped, leaving an invalid pointer.
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SHA1: 3ba1c3f58959792c2630c7a6a8ecadaf613ac574
User & Date: dan 2012-11-05 14:33:04
Context
2012-11-05
14:56
Merge range-delete-fixes branch with trunk. check-in: 7605250294 user: dan tags: trunk
14:33
Before writing data to a new database segment, make sure the data is held in heap (not mmap'd) memory. Otherwise, the write may cause the file to grow and the mapping to be released and remapped, leaving an invalid pointer. Leaf check-in: 3ba1c3f589 user: dan tags: range-delete-fixes
10:23
Fix a bug in compressed database mode causing an incorrect page number to be assigned to a page record when the end of the previous record is aligned with the end of a database block. check-in: e6a71a8583 user: dan tags: range-delete-fixes
Changes
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Changes to src/lsm_sorted.c.

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  return rc;
}

static int mergeWorkerWrite(
  MergeWorker *pMW,               /* Merge worker object to write into */
  int eType,                      /* One of SORTED_SEPARATOR, WRITE or DELETE */
  void *pKey, int nKey,           /* Key value */
  MultiCursor *pCsr,              /* Read value (if any) from here */
  int iVal,
  int iPtr                        /* Absolute value of page pointer, or 0 */
){
  int rc = LSM_OK;                /* Return code */
  Merge *pMerge;                  /* Persistent part of level merge state */
  int nHdr;                       /* Space required for this record header */
  Page *pPg;                      /* Page to write to */
  u8 *aData;                      /* Data buffer for page pWriter->pPage */
................................................................................
  int nRec;                       /* Number of records on page pPg */
  int iFPtr;                      /* Value of pointer in footer of pPg */
  int iRPtr = 0;                  /* Value of pointer written into record */
  int iOff;                       /* Current write offset within page pPg */
  Segment *pSeg;                  /* Segment being written */
  int flags = 0;                  /* If != 0, flags value for page footer */
  int bFirst = 0;                 /* True for first key of output run */
  void *pVal;
  int nVal;

  pMerge = pMW->pLevel->pMerge;    
  pSeg = &pMW->pLevel->lhs;

  if( pSeg->iFirst==0 && pMW->pPage==0 ){
    rc = mergeWorkerFirstPage(pMW);
    bFirst = 1;
................................................................................
  ** The header space is:
  **
  **     1) record type - 1 byte.
  **     2) Page-pointer-offset - 1 varint
  **     3) Key size - 1 varint
  **     4) Value size - 1 varint (only if LSM_INSERT flag is set)
  */
  if( rc==LSM_OK ){
    rc = multiCursorGetVal(pCsr, iVal, &pVal, &nVal);
  }
  if( rc==LSM_OK ){
    nHdr = 1 + lsmVarintLen32(iRPtr) + lsmVarintLen32(nKey);
    if( rtIsWrite(eType) ) nHdr += lsmVarintLen32(nVal);

    /* If the entire header will not fit on page pPg, or if page pPg is 
    ** marked read-only, advance to the next page of the output run. */
    iOff = pMerge->iOutputOff;
    if( iOff<0 || pPg==0 || iOff+nHdr > SEGMENT_EOF(nData, nRec+1) ){
      iFPtr = *pCsr->pPrevMergePtr;
      iRPtr = iPtr - iFPtr;
      iOff = 0;
      nRec = 0;
      rc = mergeWorkerNextPage(pMW, iFPtr);
      pPg = pMW->pPage;
    }
  }
................................................................................
    if( rtIsWrite(eType) ) iOff += lsmVarintPut32(&aData[iOff], nVal);   /* 4 */
    pMerge->iOutputOff = iOff;

    /* Write the key and data into the segment. */
    assert( iFPtr==pageGetPtr(aData, nData) );
    rc = mergeWorkerData(pMW, 0, iFPtr+iRPtr, pKey, nKey);
    if( rc==LSM_OK && rtIsWrite(eType) ){
      if( rtTopic(eType)==0 ) rc = multiCursorGetVal(pCsr, iVal, &pVal, &nVal);
      if( rc==LSM_OK ){
        rc = mergeWorkerData(pMW, 0, iFPtr+iRPtr, pVal, nVal);
      }
    }
  }

  return rc;
................................................................................
        }
      }
    }

    /* If this is a separator key and we know that the output pointer has not
    ** changed, there is no point in writing an output record. Otherwise,
    ** proceed. */
    if( rtIsSeparator(eType)==0 || iPtr!=0 ){
      /* Write the record into the main run. */







      if( rc==LSM_OK ){
        rc = mergeWorkerWrite(pMW, eType, pKey, nKey, pCsr, iVal, iPtr);
      }
    }
  }

  /* Advance the cursor to the next input record (assuming one exists). */
  assert( lsmMCursorValid(pMW->pCsr) );
  if( rc==LSM_OK ) rc = lsmMCursorNext(pMW->pCsr);







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  return rc;
}

static int mergeWorkerWrite(
  MergeWorker *pMW,               /* Merge worker object to write into */
  int eType,                      /* One of SORTED_SEPARATOR, WRITE or DELETE */
  void *pKey, int nKey,           /* Key value */
  void *pVal, int nVal,           /* Value value */

  int iPtr                        /* Absolute value of page pointer, or 0 */
){
  int rc = LSM_OK;                /* Return code */
  Merge *pMerge;                  /* Persistent part of level merge state */
  int nHdr;                       /* Space required for this record header */
  Page *pPg;                      /* Page to write to */
  u8 *aData;                      /* Data buffer for page pWriter->pPage */
................................................................................
  int nRec;                       /* Number of records on page pPg */
  int iFPtr;                      /* Value of pointer in footer of pPg */
  int iRPtr = 0;                  /* Value of pointer written into record */
  int iOff;                       /* Current write offset within page pPg */
  Segment *pSeg;                  /* Segment being written */
  int flags = 0;                  /* If != 0, flags value for page footer */
  int bFirst = 0;                 /* True for first key of output run */



  pMerge = pMW->pLevel->pMerge;    
  pSeg = &pMW->pLevel->lhs;

  if( pSeg->iFirst==0 && pMW->pPage==0 ){
    rc = mergeWorkerFirstPage(pMW);
    bFirst = 1;
................................................................................
  ** The header space is:
  **
  **     1) record type - 1 byte.
  **     2) Page-pointer-offset - 1 varint
  **     3) Key size - 1 varint
  **     4) Value size - 1 varint (only if LSM_INSERT flag is set)
  */



  if( rc==LSM_OK ){
    nHdr = 1 + lsmVarintLen32(iRPtr) + lsmVarintLen32(nKey);
    if( rtIsWrite(eType) ) nHdr += lsmVarintLen32(nVal);

    /* If the entire header will not fit on page pPg, or if page pPg is 
    ** marked read-only, advance to the next page of the output run. */
    iOff = pMerge->iOutputOff;
    if( iOff<0 || pPg==0 || iOff+nHdr > SEGMENT_EOF(nData, nRec+1) ){
      iFPtr = *pMW->pCsr->pPrevMergePtr;
      iRPtr = iPtr - iFPtr;
      iOff = 0;
      nRec = 0;
      rc = mergeWorkerNextPage(pMW, iFPtr);
      pPg = pMW->pPage;
    }
  }
................................................................................
    if( rtIsWrite(eType) ) iOff += lsmVarintPut32(&aData[iOff], nVal);   /* 4 */
    pMerge->iOutputOff = iOff;

    /* Write the key and data into the segment. */
    assert( iFPtr==pageGetPtr(aData, nData) );
    rc = mergeWorkerData(pMW, 0, iFPtr+iRPtr, pKey, nKey);
    if( rc==LSM_OK && rtIsWrite(eType) ){

      if( rc==LSM_OK ){
        rc = mergeWorkerData(pMW, 0, iFPtr+iRPtr, pVal, nVal);
      }
    }
  }

  return rc;
................................................................................
        }
      }
    }

    /* If this is a separator key and we know that the output pointer has not
    ** changed, there is no point in writing an output record. Otherwise,
    ** proceed. */
    if( rc==LSM_OK && (rtIsSeparator(eType)==0 || iPtr!=0) ){
      /* Write the record into the main run. */
      void *pVal; int nVal;
      rc = multiCursorGetVal(pCsr, iVal, &pVal, &nVal);
      if( pVal && rc==LSM_OK ){
        assert( nVal>=0 );
        rc = sortedBlobSet(pDb->pEnv, &pCsr->val, pVal, nVal);
        pVal = pCsr->val.pData;
      }
      if( rc==LSM_OK ){
        rc = mergeWorkerWrite(pMW, eType, pKey, nKey, pVal, nVal, iPtr);
      }
    }
  }

  /* Advance the cursor to the next input record (assuming one exists). */
  assert( lsmMCursorValid(pMW->pCsr) );
  if( rc==LSM_OK ) rc = lsmMCursorNext(pMW->pCsr);