From 50dc8d972086dfbbc3ef3c7f664d58b5c44c4ac8 Mon Sep 17 00:00:00 2001
From: drh <>
Date: Thu, 6 Apr 2023 20:14:10 +0000
Subject: [PATCH] Increase the size of the cache of free blocks inside of
 pageFreeArray() to reduce the number of calls to freeSpace().

FossilOrigin-Name: 27c59f1ea789f3ff245f23e79ded5cd71c48e3a51ffbb8c220b51101a4e69fd7
---
 manifest      | 15 +++++++++------
 manifest.uuid |  2 +-
 src/btree.c   | 47 +++++++++++++++++++++++++++--------------------
 3 files changed, 37 insertions(+), 27 deletions(-)

diff --git a/manifest b/manifest
index a2e471df47..7b23595ea4 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Work\saround\sa\sharmless\sassertion\sfault\sassociated\swith\nsqlite3VdbeMemAboutToChange()\ssuch\sthat\sthe\sdetection\sof\sstale\svalues\nin\sregisters\sis\spreserved\sin\sdebugging\sbuilds,\sbut\swe\savoid\sa\sfalse-positive\nassertion\sfault\sin\scases\sinvolving\sa\svirtual\stable\swith\sa\sLIMIT\sclause\nin\san\sIN-operator\sloop.\ndbsqlfuzz\s3fd70d4ab4950acf1deb8f610a7a7c67cd38713b
-D 2023-04-06T17:29:38.736
+C Increase\sthe\ssize\sof\sthe\scache\sof\sfree\sblocks\sinside\sof\spageFreeArray()\sto\nreduce\sthe\snumber\sof\scalls\sto\sfreeSpace().
+D 2023-04-06T20:14:10.861
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -564,7 +564,7 @@ F src/auth.c f4fa91b6a90bbc8e0d0f738aa284551739c9543a367071f55574681e0f24f8cf
 F src/backup.c a2891172438e385fdbe97c11c9745676bec54f518d4447090af97189fd8e52d7
 F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
 F src/btmutex.c 6ffb0a22c19e2f9110be0964d0731d2ef1c67b5f7fabfbaeb7b9dabc4b7740ca
-F src/btree.c 023b41e0a4563880812288e32682538013287b7b82e0c24a57b0e26b6f0ef168
+F src/btree.c 1a5f31d548a68d2bd537919d8afa176540c3ea70787fe10d5873beb00f9db615
 F src/btree.h aa354b9bad4120af71e214666b35132712b8f2ec11869cb2315c52c81fad45cc
 F src/btreeInt.h a3268a60cbc91f578001f44ba40aae9c1b8aecbb0d2c095dd7fc54b0872ea4b8
 F src/build.c 8357d6ca9a8c9afc297c431df28bc2af407b47f3ef2311875276c944b30c4d54
@@ -2052,8 +2052,11 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 857d0f5e16ba69ac9e5ee581befca2f7ed933edfe6e36396b10dae7979b44a57
-R 2288ff5cfd8b0483680fe089706fc5b1
+P 56ea2c2fe6108d39833ac40957afab59ade01a216639d5bafdeeca53bbf4cd67
+R f4ea0d3a1a9bcf702848933fabd592b4
+T *branch * btree-freespace-opt
+T *sym-btree-freespace-opt *
+T -sym-trunk *
 U drh
-Z a25cf56afdc01321117f5bc71f12f074
+Z a279ebfc98f243d3f64ca427ad2184cf
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 01365fb8b8..38cf4ef4af 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-56ea2c2fe6108d39833ac40957afab59ade01a216639d5bafdeeca53bbf4cd67
\ No newline at end of file
+27c59f1ea789f3ff245f23e79ded5cd71c48e3a51ffbb8c220b51101a4e69fd7
\ No newline at end of file
diff --git a/src/btree.c b/src/btree.c
index 2f3063c3a3..86ff2b466f 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -7496,42 +7496,49 @@ static int pageFreeArray(
   u8 * const pEnd = &aData[pPg->pBt->usableSize];
   u8 * const pStart = &aData[pPg->hdrOffset + 8 + pPg->childPtrSize];
   int nRet = 0;
-  int i;
+  int i, j;
   int iEnd = iFirst + nCell;
-  u8 *pFree = 0;                  /* \__ Parameters for pending call to */
-  int szFree = 0;                 /* /   freeSpace()                    */
+  int nFree = 0;
+  int aOfst[10];
+  int aAfter[10];
 
   for(i=iFirst; i<iEnd; i++){
     u8 *pCell = pCArray->apCell[i];
     if( SQLITE_WITHIN(pCell, pStart, pEnd) ){
       int sz;
+      int iAfter;
+      int iOfst;
       /* No need to use cachedCellSize() here.  The sizes of all cells that
       ** are to be freed have already been computing while deciding which
       ** cells need freeing */
       sz = pCArray->szCell[i];  assert( sz>0 );
-      if( pFree!=(pCell + sz) ){
-        if( pFree ){
-          assert( pFree>aData && (pFree - aData)<65536 );
-          freeSpace(pPg, (u16)(pFree - aData), szFree);
+      iOfst = (u16)(pCell - aData);
+      iAfter = iOfst+sz;
+      for(j=0; j<nFree; j++){
+        if( aOfst[j]==iAfter ){
+          aOfst[j] = iOfst;
+          break;
+        }else if( aAfter[j]==iOfst ){
+          aAfter[j] = iAfter;
+          break;
         }
-        pFree = pCell;
-        szFree = sz;
-        if( pFree+sz>pEnd ){
-          return 0;
+      }
+      if( j>=nFree ){
+        if( nFree>=sizeof(aOfst)/sizeof(aOfst[0]) ){
+          for(j=0; j<nFree; j++){
+            freeSpace(pPg, aOfst[j], aAfter[j]-aOfst[j]);
+          }
+          nFree = 0;
         }
-      }else{
-        /* The current cell is adjacent to and before the pFree cell.
-        ** Combine the two regions into one to reduce the number of calls
-        ** to freeSpace(). */
-        pFree = pCell;
-        szFree += sz;
+        aOfst[nFree] = iOfst;
+        aAfter[nFree] = iAfter;
+        nFree++;
       }
       nRet++;
     }
   }
-  if( pFree ){
-    assert( pFree>aData && (pFree - aData)<65536 );
-    freeSpace(pPg, (u16)(pFree - aData), szFree);
+  for(j=0; j<nFree; j++){
+    freeSpace(pPg, aOfst[j], aAfter[j]-aOfst[j]);
   }
   return nRet;
 }
-- 
2.47.2