From: drh <drh@noemail.net>
Date: Mon, 13 Nov 2017 05:51:37 +0000 (+0000)
Subject: Remove some branches in walTryBeginRead() that were
X-Git-Tag: version-3.22.0~199^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2e9b0923aca34aa5d18a3be65f7e082c45758cc3;p=thirdparty%2Fsqlite.git

Remove some branches in walTryBeginRead() that were
added by check-in [ce5d13c2de] but became unreachable with the addition
of logic in check-in [18b26843] that enabled read-only clients to parse
the WAL file into a heap-memory WAL-index, thus guaranteeing that the
WAL-index header is always available.

FossilOrigin-Name: 9c6b38b9a96c11bdf9db4ea025720a4f49dcb723fa2e2776edc8453bce85c7e3
---

diff --git a/manifest b/manifest
index 2fbd04081b..fc71ea63a6 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C In\swal.c:\simproved\scomments,\snew\sassert()\sand\stestcase()\smacros,\sand\nreplace\ssome\smagic\snumbers\swith\sappropriate\ssymbolic\sconstants.
-D 2017-11-11T20:11:01.646
+C Remove\ssome\sbranches\sin\swalTryBeginRead()\sthat\swere\s\nadded\sby\scheck-in\s[ce5d13c2de]\sbut\sbecame\sunreachable\swith\sthe\saddition\nof\slogic\sin\scheck-in\s[18b26843]\sthat\senabled\sread-only\sclients\sto\sparse\nthe\sWAL\sfile\sinto\sa\sheap-memory\sWAL-index,\sthus\sguaranteeing\sthat\sthe\s\nWAL-index\sheader\sis\salways\savailable.
+D 2017-11-13T05:51:37.627
 F Makefile.in 5bae3f2f3d42f2ad52b141562d74872c97ac0fca6c54953c91bb150a0e6427a8
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 3a5cb477ec3ce5274663b693164e349db63348667cd45bad78cc13d580b691e2
@@ -543,7 +543,7 @@ F src/vdbesort.c 731a09e5cb9e96b70c394c1b7cf3860fbe84acca7682e178615eb941a3a0ef2
 F src/vdbetrace.c 48e11ebe040c6b41d146abed2602e3d00d621d7ebe4eb29b0a0f1617fd3c2f6c
 F src/vtab.c 0e4885495172e1bdf54b12cce23b395ac74ef5729031f15e1bc1e3e6b360ed1a
 F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
-F src/wal.c 213ddce034c354e640294e77b28097db2a7e10e16c12f6a1158bd7fbcc8e730c
+F src/wal.c 31ae1a82afccf02e2ff220add690d057dd7e25d9d7ec0b53fe57f2d62a4ba510
 F src/wal.h 8de5d2d3de0956d6f6cb48c83a4012d5f227b8fe940f3a349a4b7e85ebcb492a
 F src/walker.c d591e8a9ccf60abb010966b354fcea4aa08eba4d83675c2b281a8764c76cc22f
 F src/where.c b7a075f5fb3d912a891dcc3257f538372bb4a1622dd8ca7d752ad95ce8949ba4
@@ -1669,7 +1669,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 346388007de585083dc67ad865b91db7c7d7b78c10a06f8bb7c48767c326c47e
-R cc8d47b78b14e89aa0bda73b44dcaa29
+P 13ec8a77a47aa471af587459f4094da0d06674c5960f0d34777bcb3d38bc413b
+R be755a48b3ce9c3ee36556946fccdf2c
 U drh
-Z f012da86d6540243e580ab3866be51e7
+Z a296aa345abf23e8a36cfa010f746e55
diff --git a/manifest.uuid b/manifest.uuid
index cbdfc58fda..0dbf02629b 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-13ec8a77a47aa471af587459f4094da0d06674c5960f0d34777bcb3d38bc413b
\ No newline at end of file
+9c6b38b9a96c11bdf9db4ea025720a4f49dcb723fa2e2776edc8453bce85c7e3
\ No newline at end of file
diff --git a/src/wal.c b/src/wal.c
index 6fddf39076..382be4e0c8 100644
--- a/src/wal.c
+++ b/src/wal.c
@@ -2418,6 +2418,9 @@ static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
 
   assert( pWal->readLock<0 );     /* Not currently locked */
 
+  /* useWal may only be set for read/write connections */
+  assert( (pWal->readOnly & WAL_SHM_RDONLY)==0 || useWal==0 );
+
   /* Take steps to avoid spinning forever if there is a protocol error.
   **
   ** Circumstances that cause a RETRY should only last for the briefest
@@ -2484,9 +2487,9 @@ static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
   }
 
   assert( pWal->nWiData>0 );
-  assert( pWal->apWiData[0] || (pWal->readOnly & WAL_SHM_RDONLY) );
-  pInfo = pWal->apWiData[0] ? walCkptInfo(pWal) : 0;
-  if( !useWal && (pInfo==0 || pInfo->nBackfill==pWal->hdr.mxFrame)
+  assert( pWal->apWiData[0]!=0 );
+  pInfo = walCkptInfo(pWal);
+  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)))
@@ -2498,9 +2501,7 @@ static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
     rc = walLockShared(pWal, WAL_READ_LOCK(0));
     walShmBarrier(pWal);
     if( rc==SQLITE_OK ){
-      if( pInfo
-       && memcmp((void *)walIndexHdr(pWal), &pWal->hdr, sizeof(WalIndexHdr)) 
-      ){
+      if( memcmp((void *)walIndexHdr(pWal), &pWal->hdr, sizeof(WalIndexHdr)) ){
         /* It is not safe to allow the reader to continue here if frames
         ** may have been appended to the log before READ_LOCK(0) was obtained.
         ** When holding READ_LOCK(0), the reader ignores the entire log file,