From: dan <dan@noemail.net>
Date: Tue, 28 Nov 2017 13:39:41 +0000 (+0000)
Subject: Lock the wal file for all snapshot transactions, even if they would not
X-Git-Tag: version-3.22.0~174
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=05573e41a8d11caf5c407dd8fea1e71f11d8a4a1;p=thirdparty%2Fsqlite.git

Lock the wal file for all snapshot transactions, even if they would not
otherwise require this, preventing checkpointers and writers from wrapping the
wal file. This means that if one connection has an open snapshot transaction
it is guaranteed that a second connection can open a transaction on the same
snapshot.

FossilOrigin-Name: b81a31495bd27c1d96f7df653da3502054240cb5acf66b860da7f0f9b422a524
---

05573e41a8d11caf5c407dd8fea1e71f11d8a4a1
diff --cc manifest
index 58ec6b9026,c550d72b06..0d6ebb2ca6
--- a/manifest
+++ b/manifest
@@@ -1,10 -1,10 +1,10 @@@
- C Add\sexperimental\sfeature\sto\sdetect\sthreading\sbugs\sin\sapps\sthat\suse\nSQLITE_CONFIG_MULTITHREADED.\sEnabled\sat\scompile\stime\susing\nSQLITE_ENABLE_MULTITHREADED_CHECKS.
- D 2017-11-28T07:52:00.416
 -C Experimental\schange\sso\sthat\ssnapshot\stransactions\salways\slock\sthe\swal\sfile\s-\npreventing\swriters\sor\struncate-checkpointers\sfrom\swrapping\sit.
 -D 2017-09-23T07:46:54.932
 -F Makefile.in 4bc36d913c2e3e2d326d588d72f618ac9788b2fd4b7efda61102611a6495c3ff
++C Lock\sthe\swal\sfile\sfor\sall\ssnapshot\stransactions,\seven\sif\sthey\swould\snot\notherwise\srequire\sthis,\spreventing\scheckpointers\sand\swriters\sfrom\swrapping\sthe\nwal\sfile.\sThis\smeans\sthat\sif\sone\sconnection\shas\san\sopen\ssnapshot\stransaction\nit\sis\sguaranteed\sthat\sa\ssecond\sconnection\scan\sopen\sa\stransaction\son\sthe\ssame\nsnapshot.
++D 2017-11-28T13:39:41.135
 +F Makefile.in 6a879cbf01e37f9eac131414955f71774b566502d9a57ded1b8585b507503cb8
  F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 -F Makefile.msc 6033b51b6aea702ea059f6ab2d47b1d3cef648695f787247dd4fb395fe60673f
 +F Makefile.msc e5d7606238f55816da99f719969598df5b091aa2e9a6935c9412fcae8f53fc44
  F README.md f5c87359573c4d255425e588a56554b50fdcc2afba4e017a2e02a43701456afd
 -F VERSION f81232df28e2d3ff049feefad5fbd5489cc33697f6bd2ecf61af7f0dde3b83d0
 +F VERSION 0c10cdfed866fdd2d80434f64f042c3330f1daaed12e54287beb104f04b3faaf
  F aclocal.m4 a5c22d164aff7ed549d53a90fa56d56955281f50
  F art/sqlite370.eps aa97a671332b432a54e1d74ff5e8775be34200c2
  F art/sqlite370.ico af56c1d00fee7cd4753e8631ed60703ed0fc6e90
@@@ -544,20 -530,20 +544,20 @@@ F src/vdbe.c 3393b508d9ad084ffce232a7c5
  F src/vdbe.h d50cadf12bcf9fb99117ef392ce1ea283aa429270481426b6e8b0280c101fd97
  F src/vdbeInt.h 1fe00770144c12c4913128f35262d11527ef3284561baaab59b947a41c08d0d9
  F src/vdbeapi.c 9c670ca0dcc1cd86373aa353b747b26fe531ca5cd4331690c611d1f03842e2a1
 -F src/vdbeaux.c 831a77aaa7aa43005f1c9bf3e9eb6506f4865e1cf99943ccdcd3be5d2dd8a3c7
 -F src/vdbeblob.c 635a79b60340a6a14a622ea8dcb081f0a66b1ac3836870c587f232eec08c0286
 -F src/vdbemem.c 5c1533bf756918b4e46b2ed2bb82c29c7c651e1e37bbd0a0d8731a68787598ff
 +F src/vdbeaux.c b02a1f842c0e916285643b8475b7189f10b76f9e7edb5e2353a913c7980f90b5
 +F src/vdbeblob.c f5c70f973ea3a9e915d1693278a5f890dc78594300cf4d54e64f2b0917c94191
 +F src/vdbemem.c 6e6082377183b8fd8d6f2bce45250b4c2e89bfeb534a094cd8612dae8aaa2fda
  F src/vdbesort.c 731a09e5cb9e96b70c394c1b7cf3860fbe84acca7682e178615eb941a3a0ef2f
  F src/vdbetrace.c 48e11ebe040c6b41d146abed2602e3d00d621d7ebe4eb29b0a0f1617fd3c2f6c
 -F src/vtab.c f1d5c23132fb0247af3e86146404112283ddedb6c518de0d4edc91cfb36970ef
 +F src/vtab.c 0e4885495172e1bdf54b12cce23b395ac74ef5729031f15e1bc1e3e6b360ed1a
  F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
- F src/wal.c beeb71e4eab65dbf0d95f2717efc6ca3c0f5b3090ce67f3de63828f39a6ff053
 -F src/wal.c 0ceefa9f2a0cb00033d312a04c2d5c2005a6404a6fccab22743de9b3c363154b
++F src/wal.c 5a3f464edd64596f601683ed321d12e6fd93c5fb9afdfb3653d6ffd0fee9c48f
  F src/wal.h 8de5d2d3de0956d6f6cb48c83a4012d5f227b8fe940f3a349a4b7e85ebcb492a
 -F src/walker.c 3ccfa8637f95355bff61144e01a615b8ef26f79c312880848da73f03367da1e6
 -F src/where.c 21eea981920a13fd3c0ac3d6c128d0a34b22cbec064e4f0603375fe1ffe26ca6
 +F src/walker.c da987a20d40145c0a03c07d8fefcb2ed363becc7680d0500d9c79915591f5b1f
 +F src/where.c 9752b68e03e2044f0faa4708fabb0189769067b660bffa931e1fd65736269659
  F src/whereInt.h 82c04c5075308abbac59180c8bad5ecb45b07453981f60a53f3c7dee21e1e971
 -F src/wherecode.c e8c2ece5843ea56e6c90277d421f2d628f3f7b7c976642369cc519f008e1d2b1
 -F src/whereexpr.c 4953ca4e769c047d0a00a1ba9085849626b1f3a6e89f6befcf5c38fa0722acdd
 +F src/wherecode.c 611fcabd05592ed2febd7d182f9621425b0466c5232d70e0981c842d429356d5
 +F src/whereexpr.c 427ea8e96ec24f2a7814c67b8024ad664a9c7656264c4566c34743cb23186e46
  F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
  F test/affinity2.test a6d901b436328bd67a79b41bb0ac2663918fe3bd
  F test/affinity3.test 6a101af2fc945ce2912f6fe54dd646018551710d
@@@ -1222,7 -1205,8 +1222,8 @@@ F test/skipscan3.test ec5bab3f81c7038b4
  F test/skipscan5.test 67817a4b6857c47e0e33ba3e506da6f23ef68de2
  F test/skipscan6.test 5866039d03a56f5bd0b3d172a012074a1d90a15b
  F test/snapshot.test 85735bd997a4f6d710140c28fd860519a299649f
 -F test/snapshot2.test 867652ed4a13282dce218723535fad1c7b44c3c4
 +F test/snapshot2.test 925e42427e923262db63c9d7155183f889e3e99feaedec4075f659e51608344f
+ F test/snapshot3.test 9719443594a04778861bd20d12596c5f880af177d6cd62f111da3198cafc6096
  F test/snapshot_fault.test 52c5e97ebd218846a8ae2da4d147d3e77d71f963
  F test/soak.test 0b5b6375c9f4110c828070b826b3b4b0bb65cd5f
  F test/softheap1.test 843cd84db9891b2d01b9ab64cef3e9020f98d087
@@@ -1678,8 -1656,10 +1679,8 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P e6b89304695be371978e65dddd710c8bd563c66b9c94d23165142b6c235c82e1 12a23c0a66fac5c9674120b390f6abaeaba3f7ff04693b281af1eefb93d6f47c
- R dd8aff31239aebcaa5e5379a4673912d
- T +closed 12a23c0a66fac5c9674120b390f6abaeaba3f7ff04693b281af1eefb93d6f47c
 -P 2c03d8b8f028b6a736aaf2cf8b28a51b3434cf341c95cf3a80469e0a24acdd98
 -R 44e3d692cd4dca7384d5a55f548b9b05
 -T *branch * snapshots-lock-wal
 -T *sym-snapshots-lock-wal *
 -T -sym-trunk *
++P 40b598c8392f030f6ed8c63ce81cb0426bb3984397c19c756215f6a569a40164 d71eeaab9ecdeed772047498b781be1f0be0655af284b94cf676bb408ceea8b1
++R e37ca38ceb47340e2d23476ad044f736
++T +closed d71eeaab9ecdeed772047498b781be1f0be0655af284b94cf676bb408ceea8b1
  U dan
- Z bdded6a608898929c58df7d45769809f
 -Z 91f0de7cf02d66dc9c74cc874f9821f7
++Z a9d291c094a58941f666434dce6709fb
diff --cc manifest.uuid
index 2cef934b2b,b33987e64e..1c080520c0
--- a/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 40b598c8392f030f6ed8c63ce81cb0426bb3984397c19c756215f6a569a40164
 -d71eeaab9ecdeed772047498b781be1f0be0655af284b94cf676bb408ceea8b1
++b81a31495bd27c1d96f7df653da3502054240cb5acf66b860da7f0f9b422a524
diff --cc src/wal.c
index 376151e1a8,73a6db0e02..7b49f3dab4
--- a/src/wal.c
+++ b/src/wal.c
@@@ -2484,18 -2245,12 +2484,17 @@@ static int walTryBeginRead(Wal *pWal, i
      if( rc!=SQLITE_OK ){
        return rc;
      }
 +    else if( pWal->bShmUnreliable ){
 +      return walBeginShmUnreliable(pWal, pChanged);
 +    }
    }
  
 +  assert( pWal->nWiData>0 );
 +  assert( pWal->apWiData[0]!=0 );
    pInfo = walCkptInfo(pWal);
 -  if( !useWal && pInfo->nBackfill==pWal->hdr.mxFrame 
 +  if( !useWal && pInfo->nBackfill==pWal->hdr.mxFrame
  #ifdef SQLITE_ENABLE_SNAPSHOT
-    && (pWal->pSnapshot==0 || pWal->hdr.mxFrame==0
-      || 0==memcmp(&pWal->hdr, pWal->pSnapshot, sizeof(WalIndexHdr)))
+    && (pWal->pSnapshot==0 || pWal->hdr.mxFrame==0)
  #endif
    ){
      /* The WAL has been completely backfilled (or it is empty).