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Remove some branches in walTryBeginRead() that were

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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
This commit is contained in:
drh
2017-11-13 05:51:37 +00:00
parent c05a063c68
commit 2e9b0923ac
3 changed files with 14 additions and 13 deletions
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13
src/wal.c
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@@ -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,