Size and performance optimization to dropCell() and freeSpace().

FossilOrigin-Name: bc1ec123ce05c9d16b0942f870381145dc9725764e47806939ff207a73066f4d

diff --git a/manifest b/manifest
index 79af87c73a322a91e8fb7d8ab225f38a526b43a9..80d60559cb177a50ebd8fa64fa5f5430798930ed 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Smaller\sand\sfaster\simplementation\sof\sthe\sfillInCell()\sroutine.
-D 2017-08-23T14:45:59.667
+C Size\sand\sperformance\soptimization\sto\sdropCell()\sand\sfreeSpace().
+D 2017-08-23T20:36:06.554
 F Makefile.in c644bbe8ebe4aae82ad6783eae6b6beea4c727b99ff97568b847ced5e2ac7afb
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 25b154da7f0b3d4924f27378c1f8d006285b80811f1ccf3ed953dbebf6282136
@@ -399,7 +399,7 @@ F src/auth.c 6277d63837357549fe14e723490d6dc1a38768d71c795c5eb5c0f8a99f918f73
 F src/backup.c faf17e60b43233c214aae6a8179d24503a61e83b
 F src/bitvec.c 17ea48eff8ba979f1f5b04cc484c7bb2be632f33
 F src/btmutex.c 0e9ce2d56159b89b9bc8e197e023ee11e39ff8ca
-F src/btree.c ea10ca63430533c358da32e5d2b8b22aa3c6a9e84f295139e4e5bb00f635726d
+F src/btree.c 45f3b8b3ad112d21afacfdfcbc1c362637bf080abb58c901104a8d3a6207a1bf
 F src/btree.h 32ef5d3f25dc70ef1ee9cecf84a023c21378f06a57cd701d2e866e141b150f09
 F src/btreeInt.h 55b702efce17e5d1941865464227d3802cfc9c7c832fac81d4c94dced47a71fc
 F src/build.c b47a0320c6d237718b8f493ac97d37d1071bce12aca668b15219187150c41295
@@ -1650,7 +1650,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P e69c0c8770d3cc2fcdc779c6290caf1575644d457326caa00327b9070251d620
-R 66591a7ad128e50f7a0c04de7cb52832
+P 77074990edef6c42bdfe7ccce1affc8ed64a86dde3ad4fa50b60ba0a6d851eea
+R 522ed57ec99b8b2e95cc60b01e62a8eb
 U drh
-Z 50b9a412665b926c36fcdf17b0a625f8
+Z 185127068afaca8c598b7b9a50979c09

diff --git a/manifest.uuid b/manifest.uuid
index 0e5f5791b52ae03805d1095020e0d795b694ee51..07ad7f8eec641b5e29a20b573f9307f271353186 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-77074990edef6c42bdfe7ccce1affc8ed64a86dde3ad4fa50b60ba0a6d851eea
\ No newline at end of file
+bc1ec123ce05c9d16b0942f870381145dc9725764e47806939ff207a73066f4d
\ No newline at end of file

diff --git a/src/btree.c b/src/btree.c
index b6e5fbc508ec07bf97a185f9d28257bfcaa4fb56..bd66a770494dd490649fc9b84c4729ccaaf9c98d 100644 (file)
--- a/src/btree.c
+++ b/src/btree.c
@@ -1505,7 +1505,7 @@ static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
     if( (x = size - nByte)>=0 ){
       testcase( x==4 );
       testcase( x==3 );
-      if( pc < pPg->cellOffset+2*pPg->nCell || size+pc > usableSize ){
+      if( size+pc > usableSize ){
         *pRc = SQLITE_CORRUPT_PGNO(pPg->pgno);
         return 0;
       }else if( x<4 ){
@@ -1640,7 +1640,7 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
   u8 hdr;                               /* Page header size.  0 or 100 */
   u8 nFrag = 0;                         /* Reduction in fragmentation */
   u16 iOrigSize = iSize;                /* Original value of iSize */
-  u32 iLast = pPage->pBt->usableSize-4; /* Largest possible freeblock offset */
+  u16 x;                                /* Offset to cell content area */
   u32 iEnd = iStart + iSize;            /* First byte past the iStart buffer */
   unsigned char *data = pPage->aData;   /* Page content */
 
@@ -1650,13 +1650,7 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
   assert( CORRUPT_DB || iEnd <= pPage->pBt->usableSize );
   assert( sqlite3_mutex_held(pPage->pBt->mutex) );
   assert( iSize>=4 );   /* Minimum cell size is 4 */
-  assert( iStart<=iLast );
-
-  /* Overwrite deleted information with zeros when the secure_delete
-  ** option is enabled */
-  if( pPage->pBt->btsFlags & BTS_FAST_SECURE ){
-    memset(&data[iStart], 0, iSize);
-  }
+  assert( iStart<=pPage->pBt->usableSize-4 );
 
   /* The list of freeblocks must be in ascending order.  Find the 
   ** spot on the list where iStart should be inserted.
@@ -1673,7 +1667,9 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
       }
       iPtr = iFreeBlk;
     }
-    if( iFreeBlk>iLast ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
+    if( iFreeBlk>pPage->pBt->usableSize-4 ){
+      return SQLITE_CORRUPT_PGNO(pPage->pgno);
+    }
     assert( iFreeBlk>iPtr || iFreeBlk==0 );
   
     /* At this point:
@@ -1709,19 +1705,25 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
     if( nFrag>data[hdr+7] ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
     data[hdr+7] -= nFrag;
   }
-  if( iStart==get2byte(&data[hdr+5]) ){
+  x = get2byte(&data[hdr+5]);
+  if( iStart<=x ){
     /* The new freeblock is at the beginning of the cell content area,
     ** so just extend the cell content area rather than create another
     ** freelist entry */
-    if( iPtr!=hdr+1 ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
+    if( iStart<x || iPtr!=hdr+1 ) return SQLITE_CORRUPT_PGNO(pPage->pgno);
     put2byte(&data[hdr+1], iFreeBlk);
     put2byte(&data[hdr+5], iEnd);
   }else{
     /* Insert the new freeblock into the freelist */
     put2byte(&data[iPtr], iStart);
-    put2byte(&data[iStart], iFreeBlk);
-    put2byte(&data[iStart+2], iSize);
   }
+  if( pPage->pBt->btsFlags & BTS_FAST_SECURE ){
+    /* Overwrite deleted information with zeros when the secure_delete
+    ** option is enabled */
+    memset(&data[iStart], 0, iSize);
+  }
+  put2byte(&data[iStart], iFreeBlk);
+  put2byte(&data[iStart+2], iSize);
   pPage->nFree += iOrigSize;
   return SQLITE_OK;
 }
@@ -6418,7 +6420,7 @@ static void dropCell(MemPage *pPage, int idx, int sz, int *pRC){
   hdr = pPage->hdrOffset;
   testcase( pc==get2byte(&data[hdr+5]) );
   testcase( pc+sz==pPage->pBt->usableSize );
-  if( pc < (u32)get2byte(&data[hdr+5]) || pc+sz > pPage->pBt->usableSize ){
+  if( pc+sz > pPage->pBt->usableSize ){
     *pRC = SQLITE_CORRUPT_BKPT;
     return;
   }