Merge changes from wal2, including the fix to prevent non-PASSIVE checkpoints from...

FossilOrigin-Name: eb8449ea9ac8e29425f7127535a1db328d56c86382919fb1fcf42324b71de013

diff --cc manifest
index 94ba7c9f22d6a40badf4aa304e000af943a2b913,1c4be400ecd9948092b7b15e5f560204bed4b397..84b0a387affa6347e762e32151049d317e200ef7
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Merge\sthe\slatest\strunk\sfixes\sand\senhancements\sinto\sthe\sbedrock\sbranch.
- D 2024-12-07T23:29:06.209
 -C Update\sto\swalRestartLog()\sfunction\sto\smake\sit\sshorter\seasier\sto\smerge\swith\sbranch\s"bedrock".
 -D 2024-12-14T17:19:06.037
++C Merge\schanges\sfrom\swal2,\sincluding\sthe\sfix\sto\sprevent\snon-PASSIVE\scheckpoints\sfrom\sever\staking\sthe\swriter\slock.
++D 2024-12-14T17:36:12.410
  F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
  F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
  F LICENSE.md e108e1e69ae8e8a59e93c455654b8ac9356a11720d3345df2a4743e9590fb20d
@@@ -866,8 -860,8 +866,8 @@@ F src/vdbetrace.c fe0bc29ebd4e02c8bc5c1
  F src/vdbevtab.c fc46b9cbd759dc013f0b3724549cc0d71379183c667df3a5988f7e2f1bd485f3
  F src/vtab.c 316cd48e9320660db3047cd306cd056e4361180cebb4d0f10a39244e10c11422
  F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
- F src/wal.c 77f875970ad28d658d3804c21bd72918604267478f1ee7986cceb7e765f0ba35
 -F src/wal.c 2ec54ef10bb354fc61424c4b65f407e795abe07059001d0d1c5f99be5bb8b7bf
 -F src/wal.h 97b8a9903387401377b59507e86b93a148ef1ad4e5ce0f23659a12dcdce56af2
++F src/wal.c 3dfcce08758eec841bab07320c2b4e495c1c0621c2fd6327b3c3b19f52da48b6
 +F src/wal.h 8d02ab8c2a93a941f5898eb3345bf711c1d3f8f86f4be8d5428fb6c074962d8a
  F src/walker.c d5006d6b005e4ea7302ad390957a8d41ed83faa177e412f89bc5600a7462a014
  F src/where.c b34adb09fdb2a4f57a0bafd4194b501047ef383976fef9f0ac3f395f4881694d
  F src/whereInt.h 1e36ec50392f7cc3d93d1152d4338064cd522b87156a0739388b7e273735f0ca
@@@ -2023,9 -2002,9 +2023,9 @@@ F test/wal2recover2.test a7eece9892b125
  F test/wal2recover3.test 4a91689e165a38bc401736e6518188c2b0ff4fa1566d1810b8867536db128177
  F test/wal2rewrite.test 6ca6f631ffcf871240beab5f02608913fd075c6d0d31310b026c8383c65c9f9c
  F test/wal2rollback.test 23adc4a099b23f6aaea8b04fdca1c35861d887dd80f8be7da2d5273eb777e428
 -F test/wal2savepoint.test c380512ec1f97012cfc753e718bf3df38f51e7c319110e1cae25094a33b371c4
 +F test/wal2savepoint.test c2410acac73bfa63827f9346d060205080b747f0414ff27273d417dadfea28d0
- F test/wal2simple.test 320a08927f307d0ead26fa3fcef4e3f64279f49be9504f918cb33294f75aeec8
+ F test/wal2simple.test d2d94fe1f30700c9f30e46c16f1c3d7d245b861a1be2bfe5ead701484c6dd38e
 -F test/wal2snapshot.test 7a5f4629a3c43a43c3440b8b2ea9f07de91a46b0b9eea5f08f62b5bf5b6468df
 +F test/wal2snapshot.test f6c3945bea572fd8745774e95b8dca1e5832c696e2251bb0db33391ee567fe60
  F test/wal3.test 5de023bb862fd1eb9d2ad26fa8d9c43abb5370582e5b08b2ae0d6f93661bc310
  F test/wal4.test 4744e155cd6299c6bd99d3eab1c82f77db9cdb3c
  F test/wal5.test 9c11da7aeccd83a46d79a556ad11a18d3cb15aa9
@@@ -2239,8 -2216,8 +2239,8 @@@ F tool/version-info.c 3b36468a90faf1bbd
  F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee87c1b31a7
  F tool/warnings.sh 49a486c5069de041aedcbde4de178293e0463ae9918ecad7539eedf0ec77a139
  F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
- P e03dd0bd313817da7ebf2989e1a423d95503044310d9efa02610d4d3a5973996 d3ce95f7e0335b8522a1805ab602b64856ced3007c507ba42039c6183ef9ac3d
- R d8823e691da2b0f9a9ba0ce3199f7f80
- U drh
- Z 2951534e15570812952f9e1a2d7a743c
 -P 11d7865a56c1fbb978e3ba70ddc03c2a16080e2992c580e00e4c6c1fa47c043c
 -R 4b3e1430220bd396f41d373fd3638959
++P 08cfa7e8b3090151a56b3898ebf0526d765b4ab276d1186d8c3e850c9408899d 88d7fb2aef882fc41a4f9c1bdd2f0162289e90d62df50af1b0eb6994c5c94c28
++R f44d51de9edfea1408778c5a30d0bdec
+ U dan
 -Z 80dc095041f96e4782d4286427d7b68b
++Z 1f3094698fe34000e0ec18f27e27e594
  # Remove this line to create a well-formed Fossil manifest.

diff --cc manifest.uuid
index f87133fbe64a73d8a419eb43dd4d4ef22533a136,50f2864eed320324e08b5be2c973fafa79cd7741..be068ab9d02ad0f3439484912e8bae6a8e97da2a
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 08cfa7e8b3090151a56b3898ebf0526d765b4ab276d1186d8c3e850c9408899d
 -88d7fb2aef882fc41a4f9c1bdd2f0162289e90d62df50af1b0eb6994c5c94c28
++eb8449ea9ac8e29425f7127535a1db328d56c86382919fb1fcf42324b71de013

diff --cc src/wal.c
index 8eb3912bfea1b03a39a3cbf8b2968ac015540154,ddb0b9dd6213e986c240375d5b97bd17e12c786d..1f2db82f05a0727ebfbe48e9e10a848ea688a465
--- 1/src/wal.c
--- 2/src/wal.c
+++ b/src/wal.c
@@@ -4952,32 -4599,42 +4953,55 @@@ static int walRestartLog(Wal *pWal)
        nWalSize = MAX(nWalSize, 1);
      }
  
-     assert( 1==WAL_LOCK_PART1 );
-     assert( 4==WAL_LOCK_PART2 );
-     assert( 1+(iApp*3)==WAL_LOCK_PART1 || 1+(iApp*3)==WAL_LOCK_PART2 );
-     if( pWal->readLock==1+(iApp*3)
++    /* With a BEGIN CONCURRENT transaction, it is possible for a connection
++    ** to hold the WAL_LOCK_PART1 lock even if iApp==1 (or WAL_LOCK_PART2
++    ** when iApp==0). This is because a connection running concurrent to this
++    ** one may have switched the wal file after this connection took the
++    ** read lock.
++    **
++    ** This is not a problem, as if this happens it means the current lock 
++    ** is more restrictive, not less, than required. And a BEGIN CONCURRENT
++    ** transaction cannot be committed and downgraded to a read-transaction,
++    ** so there is no chance of continuing while holding the wrong lock.
++    */
+     assert( iApp==0 || pWal->readLock==WAL_LOCK_PART2 
 -                    || pWal->readLock==WAL_LOCK_PART2_FULL1 );
++                    || pWal->readLock==WAL_LOCK_PART2_FULL1 
++                    || pWal->readLock==WAL_LOCK_PART1 );
+     assert( iApp==1 || pWal->readLock==WAL_LOCK_PART1 
 -                    || pWal->readLock==WAL_LOCK_PART1_FULL2 );
++                    || pWal->readLock==WAL_LOCK_PART1_FULL2 
++                    || pWal->readLock==WAL_LOCK_PART2 );
+ 
+     /* Switch to wal file !iApp if 
+     **
+     **   (a) Wal file iApp (the current wal file) contains >= nWalSize frames.
+     **   (b) This client is not reading from wal file !iApp.
+     **   (c) No other client is reading from wal file !iApp.
+     **
+     ** Condition (b) guarantees that wal file !iApp is either empty or
+     ** completely checkpointed. 
+     */
+     assert( (0*3)+1==WAL_LOCK_PART1 ); /* iApp==0 -> require WAL_LOCK_PART1 */
+     assert( (1*3)+1==WAL_LOCK_PART2 ); /* iApp==1 -> require WAL_LOCK_PART2 */
+     if( pWal->readLock==(iApp*3)+1
       && walidxGetMxFrame(&pWal->hdr, iApp)>=nWalSize 
      ){
-       volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
-       u32 mxFrame = walidxGetMxFrame(&pWal->hdr, !iApp);
-       if( mxFrame==0 || pInfo->nBackfill ){
-         rc = wal2RestartOk(pWal, iApp);
-         if( rc==SQLITE_OK ){
-           int iNew = !iApp;
-           pWal->nCkpt++;
-           walidxSetFile(&pWal->hdr, iNew);
-           walidxSetMxFrame(&pWal->hdr, iNew, 0);
-           sqlite3Put4byte((u8*)&pWal->hdr.aSalt[0], pWal->hdr.aFrameCksum[0]);
-           sqlite3Put4byte((u8*)&pWal->hdr.aSalt[1], pWal->hdr.aFrameCksum[1]);
-           walIndexWriteHdr(pWal);
-           pInfo->nBackfill = 0;
-           wal2RestartFinished(pWal, iApp);
-           walUnlockShared(pWal, WAL_READ_LOCK(pWal->readLock));
-           pWal->readLock = iNew ? WAL_LOCK_PART2_FULL1 : WAL_LOCK_PART1_FULL2;
-           rc = walLockShared(pWal, WAL_READ_LOCK(pWal->readLock));
-         }else if( rc==SQLITE_BUSY ){
-           rc = SQLITE_OK;
-         }
+       rc = wal2RestartOk(pWal, iApp);
+       if( rc==SQLITE_OK ){
+         volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
+         int iNew = !iApp;
+         pWal->nCkpt++;
+         walidxSetFile(&pWal->hdr, iNew);
+         walidxSetMxFrame(&pWal->hdr, iNew, 0);
+         sqlite3Put4byte((u8*)&pWal->hdr.aSalt[0], pWal->hdr.aFrameCksum[0]);
+         sqlite3Put4byte((u8*)&pWal->hdr.aSalt[1], pWal->hdr.aFrameCksum[1]);
+         walIndexWriteHdr(pWal);
+         pInfo->nBackfill = 0;
+         wal2RestartFinished(pWal, iApp);
+         walUnlockShared(pWal, WAL_READ_LOCK(pWal->readLock));
+         pWal->readLock = iNew ? WAL_LOCK_PART2_FULL1 : WAL_LOCK_PART1_FULL2;
+         rc = walLockShared(pWal, WAL_READ_LOCK(pWal->readLock));
+       }else if( rc==SQLITE_BUSY ){
+         rc = SQLITE_OK;
        }
      }
    }else if( pWal->readLock==0 ){