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Add tracing logic to the shared-cache locks in btree.c. The tracing is

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off by default.  Enable by changing a single "#if 0" into "#if 1" and
recompiling.  Debugging code only - no changes to release builds.

FossilOrigin-Name: f2b943f97ad7e47848ac6df3a3a1eba134b9e63c4a631f8eaf8bda77cc02ba7b
This commit is contained in:
drh
2024-02-01 14:17:01 +00:00
parent d87299cece
commit 1d09f4d018
3 changed files with 55 additions and 7 deletions
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48
src/btree.c
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@@ -151,8 +151,47 @@ int corruptPageError(int lineno, MemPage *p){
# define SQLITE_CORRUPT_PAGE(pMemPage) SQLITE_CORRUPT_PGNO(pMemPage->pgno)
#endif
/* Default value for SHARED_LOCK_TRACE macro if shared-cache is disabled
** or if the lock tracking is disabled. This is always the value for
** release builds.
*/
#define SHARED_LOCK_TRACE(X,MSG,TAB,TYPE) /*no-op*/
#ifndef SQLITE_OMIT_SHARED_CACHE
#if 0
/* ^---- Change to 1 and recompile to enable shared-lock tracing
** for debugging purposes.
**
** Print all shared-cache locks on a BtShared. Debugging use only.
*/
static void sharedLockTrace(
BtShared *pBt,
const char *zMsg,
int iRoot,
int eLockType
){
BtLock *pLock;
if( iRoot>0 ){
printf("%s-%p %u%s:", zMsg, pBt, iRoot, eLockType==READ_LOCK?"R":"W");
}else{
printf("%s-%p:", zMsg, pBt);
}
for(pLock=pBt->pLock; pLock; pLock=pLock->pNext){
printf(" %p/%u%s", pLock->pBtree, pLock->iTable,
pLock->eLock==READ_LOCK ? "R" : "W");
while( pLock->pNext && pLock->pBtree==pLock->pNext->pBtree ){
pLock = pLock->pNext;
printf(",%u%s", pLock->iTable, pLock->eLock==READ_LOCK ? "R" : "W");
}
}
printf("\n");
fflush(stdout);
}
#undef SHARED_LOCK_TRACE
#define SHARED_LOCK_TRACE(X,MSG,TAB,TYPE) sharedLockTrace(X,MSG,TAB,TYPE)
#endif /* Shared-lock tracing */
#ifdef SQLITE_DEBUG
/*
**** This function is only used as part of an assert() statement. ***
@@ -229,6 +268,8 @@ static int hasSharedCacheTableLock(
iTab = iRoot;
}
SHARED_LOCK_TRACE(pBtree->pBt,"hasLock",iRoot,eLockType);
/* Search for the required lock. Either a write-lock on root-page iTab, a
** write-lock on the schema table, or (if the client is reading) a
** read-lock on iTab will suffice. Return 1 if any of these are found. */
@@ -362,6 +403,8 @@ static int setSharedCacheTableLock(Btree *p, Pgno iTable, u8 eLock){
BtLock *pLock = 0;
BtLock *pIter;
SHARED_LOCK_TRACE(pBt,"setLock", iTable, eLock);
assert( sqlite3BtreeHoldsMutex(p) );
assert( eLock==READ_LOCK || eLock==WRITE_LOCK );
assert( p->db!=0 );
@@ -429,6 +472,8 @@ static void clearAllSharedCacheTableLocks(Btree *p){
assert( p->sharable || 0==*ppIter );
assert( p->inTrans>0 );
SHARED_LOCK_TRACE(pBt, "clearAllLocks", 0, 0);
while( *ppIter ){
BtLock *pLock = *ppIter;
assert( (pBt->btsFlags & BTS_EXCLUSIVE)==0 || pBt->pWriter==pLock->pBtree );
@@ -467,6 +512,9 @@ static void clearAllSharedCacheTableLocks(Btree *p){
*/
static void downgradeAllSharedCacheTableLocks(Btree *p){
BtShared *pBt = p->pBt;
SHARED_LOCK_TRACE(pBt, "downgradeLocks", 0, 0);
if( pBt->pWriter==p ){
BtLock *pLock;
pBt->pWriter = 0;