From 735e7ee62ab6a9780054a5f3328471fc23f5b0be Mon Sep 17 00:00:00 2001 From: dan Date: Fri, 17 Nov 2023 17:10:37 +0000 Subject: [PATCH] When SQLITE_ENABLE_SETLK_TIMEOUT is defined, use a separate mutex in os_unix.c for each shm locking slot. FossilOrigin-Name: 4098df9652d90f2d22d5591d915d672c5413471f7916223510ba6fd932bfdd36 --- manifest | 17 ++-- manifest.uuid | 2 +- src/os_unix.c | 219 ++++++++++++++++++++++++++++++++++---------------- 3 files changed, 161 insertions(+), 77 deletions(-) diff --git a/manifest b/manifest index 2c1dd24e5f..21392b6b04 100644 --- a/manifest +++ b/manifest @@ -1,5 +1,5 @@ -C Fix\sharmless\scompiler\swarnings\sin\sdebugging\scode. -D 2023-11-17T12:22:42.597 +C When\sSQLITE_ENABLE_SETLK_TIMEOUT\sis\sdefined,\suse\sa\sseparate\smutex\sin\sos_unix.c\sfor\seach\sshm\slocking\sslot. +D 2023-11-17T17:10:37.075 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724 @@ -709,7 +709,7 @@ F src/os.h 1ff5ae51d339d0e30d8a9d814f4b8f8e448169304d83a7ed9db66a65732f3e63 F src/os_common.h 6c0eb8dd40ef3e12fe585a13e709710267a258e2c8dd1c40b1948a1d14582e06 F src/os_kv.c 4d39e1f1c180b11162c6dc4aa8ad34053873a639bac6baae23272fc03349986a F src/os_setup.h 6011ad7af5db4e05155f385eb3a9b4470688de6f65d6166b8956e58a3d872107 -F src/os_unix.c f8a557ff5b387ec599e8b84b7341e5a45ebdd579da03788364a34b9a9567faeb +F src/os_unix.c 1f6a930e8469b3709728690d089b55deb2fe605ba860941ddc21a2345e51bce4 F src/os_win.c 4a50a154aeebc66a1f8fb79c1ff6dd5fe3d005556533361e0d460d41cb6a45a8 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a F src/pager.c 987ab3a2cd9065d62e9955474470ff733445e2357432a67e3d0f5a8f9313e334 @@ -2140,8 +2140,11 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0 -P a9443dbfbe25e588b4adddde664ddf482f19f71c704fbf356d49cf3a6135e7fb -R dc0c90fa6e9a7208b4b533ec9a5980a8 -U drh -Z 5cf7a41ba5c0eb3c7c4392bc0e2744d2 +P ce6a75622ea5bca517bc6613e738aa670c9e1dd863596220eded5c2379c616c7 +R 277be03c0e13cb54ac8c8a3d23aba815 +T *branch * unix-setlk-timeout-mutexes +T *sym-unix-setlk-timeout-mutexes * +T -sym-trunk * +U dan +Z 8cc8841ac15d12b07622be01120eb3c1 # Remove this line to create a well-formed Fossil manifest. diff --git a/manifest.uuid b/manifest.uuid index 98bef54da7..5124df900b 100644 --- a/manifest.uuid +++ b/manifest.uuid @@ -1 +1 @@ -ce6a75622ea5bca517bc6613e738aa670c9e1dd863596220eded5c2379c616c7 \ No newline at end of file +4098df9652d90f2d22d5591d915d672c5413471f7916223510ba6fd932bfdd36 \ No newline at end of file diff --git a/src/os_unix.c b/src/os_unix.c index 3171b41fd6..82c81a4b12 100644 --- a/src/os_unix.c +++ b/src/os_unix.c @@ -4313,6 +4313,25 @@ static int unixGetpagesize(void){ ** Either unixShmNode.pShmMutex must be held or unixShmNode.nRef==0 and ** unixMutexHeld() is true when reading or writing any other field ** in this structure. +** +** aLock[SQLITE_SHM_NLOCK]: +** This array records the various locks held by clients on each of the +** SQLITE_SHM_NLOCK slots. If the aLock[] entry is set to 0, then no +** locks are held by the process on this slot. If it is set to -1, then +** some client holds an EXCLUSIVE lock on the locking slot. If the aLock[] +** value is set to a positive value, then it is the number of shared +** locks currently held on the slot. +** +** aMutex[SQLITE_SHM_NLOCK]: +** Normally, when SQLITE_ENABLE_SETLK_TIMEOUT is not defined, mutex +** pShmMutex is used to protect the aLock[] array and the right to +** call fcntl() on unixShmNode.hShm to obtain or release locks. +** +** If SQLITE_ENABLE_SETLK_TIMEOUT is defined though, we use an array +** of mutexes - one for each locking slot. To read or write locking +** slot aLock[iSlot], the caller must hold the corresponding mutex +** aMutex[iSlot]. Similarly, to call fcntl() to obtain or release a +** lock corresponding to slot iSlot, mutex aMutex[iSlot] must be held. */ struct unixShmNode { unixInodeInfo *pInode; /* unixInodeInfo that owns this SHM node */ @@ -4326,10 +4345,11 @@ struct unixShmNode { char **apRegion; /* Array of mapped shared-memory regions */ int nRef; /* Number of unixShm objects pointing to this */ unixShm *pFirst; /* All unixShm objects pointing to this */ +#ifdef SQLITE_ENABLE_SETLK_TIMEOUT + sqlite3_mutex *aMutex[SQLITE_SHM_NLOCK]; +#endif int aLock[SQLITE_SHM_NLOCK]; /* # shared locks on slot, -1==excl lock */ #ifdef SQLITE_DEBUG - u8 exclMask; /* Mask of exclusive locks held */ - u8 sharedMask; /* Mask of shared locks held */ u8 nextShmId; /* Next available unixShm.id value */ #endif }; @@ -4412,16 +4432,29 @@ static int unixShmSystemLock( struct flock f; /* The posix advisory locking structure */ int rc = SQLITE_OK; /* Result code form fcntl() */ - /* Access to the unixShmNode object is serialized by the caller */ pShmNode = pFile->pInode->pShmNode; - assert( pShmNode->nRef==0 || sqlite3_mutex_held(pShmNode->pShmMutex) ); - assert( pShmNode->nRef>0 || unixMutexHeld() ); + + /* Assert that the correct mutex or mutexes are held. */ + if( pShmNode->nRef==0 ){ + assert( ofst==UNIX_SHM_DMS && n==1 && unixMutexHeld() ); + }else{ +#ifdef SQLITE_ENABLE_SETLK_TIMEOUT + int ii; + for(ii=ofst-UNIX_SHM_BASE; iiaMutex[ii]) ); + } +#else + assert( sqlite3_mutex_held(pShmNode->pShmMutex) ); + assert( pShmNode->nRef>0 ); +#endif + } /* Shared locks never span more than one byte */ assert( n==1 || lockType!=F_RDLCK ); /* Locks are within range */ assert( n>=1 && n<=SQLITE_SHM_NLOCK ); + assert( ofst>=UNIX_SHM_BASE && ofst<=(UNIX_SHM_DMS+SQLITE_SHM_NLOCK) ); if( pShmNode->hShm>=0 ){ int res; @@ -4440,39 +4473,28 @@ static int unixShmSystemLock( } } - /* Update the global lock state and do debug tracing */ + /* Do debug tracing */ #ifdef SQLITE_DEBUG - { u16 mask; OSTRACE(("SHM-LOCK ")); - mask = ofst>31 ? 0xffff : (1<<(ofst+n)) - (1<exclMask &= ~mask; - pShmNode->sharedMask &= ~mask; + OSTRACE(("unlock %d..%d ok\n", ofst, ofst+n-1)); }else if( lockType==F_RDLCK ){ - OSTRACE(("read-lock %d ok", ofst)); - pShmNode->exclMask &= ~mask; - pShmNode->sharedMask |= mask; + OSTRACE(("read-lock %d..%d ok\n", ofst, ofst+n-1)); }else{ assert( lockType==F_WRLCK ); - OSTRACE(("write-lock %d ok", ofst)); - pShmNode->exclMask |= mask; - pShmNode->sharedMask &= ~mask; + OSTRACE(("write-lock %d..%d ok\n", ofst, ofst+n-1)); } }else{ if( lockType==F_UNLCK ){ - OSTRACE(("unlock %d failed", ofst)); + OSTRACE(("unlock %d..%d failed\n", ofst, ofst+n-1)); }else if( lockType==F_RDLCK ){ - OSTRACE(("read-lock failed")); + OSTRACE(("read-lock %d..%d failed\n", ofst, ofst+n-1)); }else{ assert( lockType==F_WRLCK ); - OSTRACE(("write-lock %d failed", ofst)); + OSTRACE(("write-lock %d..%d failed\n", ofst, ofst+n-1)); } } - OSTRACE((" - afterwards %03x,%03x\n", - pShmNode->sharedMask, pShmNode->exclMask)); - } #endif return rc; @@ -4509,6 +4531,11 @@ static void unixShmPurge(unixFile *pFd){ int i; assert( p->pInode==pFd->pInode ); sqlite3_mutex_free(p->pShmMutex); +#ifdef SQLITE_ENABLE_SETLK_TIMEOUT + for(i=0; iaMutex[i]); + } +#endif for(i=0; inRegion; i+=nShmPerMap){ if( p->hShm>=0 ){ osMunmap(p->apRegion[i], p->szRegion); @@ -4689,6 +4716,18 @@ static int unixOpenSharedMemory(unixFile *pDbFd){ rc = SQLITE_NOMEM_BKPT; goto shm_open_err; } +#ifdef SQLITE_ENABLE_SETLK_TIMEOUT + { + int ii; + for(ii=0; iiaMutex[ii] = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST); + if( pShmNode->aMutex[ii]==0 ){ + rc = SQLITE_NOMEM_BKPT; + goto shm_open_err; + } + } + } +#endif } if( pInode->bProcessLock==0 ){ @@ -4910,9 +4949,11 @@ shmpage_out: */ #ifdef SQLITE_DEBUG static int assertLockingArrayOk(unixShmNode *pShmNode){ +#ifdef SQLITE_ENABLE_SETLK_TIMEOUT + return 1; +#else unixShm *pX; int aLock[SQLITE_SHM_NLOCK]; - assert( sqlite3_mutex_held(pShmNode->pShmMutex) ); memset(aLock, 0, sizeof(aLock)); for(pX=pShmNode->pFirst; pX; pX=pX->pNext){ @@ -4930,13 +4971,14 @@ static int assertLockingArrayOk(unixShmNode *pShmNode){ assert( 0==memcmp(pShmNode->aLock, aLock, sizeof(aLock)) ); return (memcmp(pShmNode->aLock, aLock, sizeof(aLock))==0); +#endif } #endif /* ** Change the lock state for a shared-memory segment. ** -** Note that the relationship between SHAREd and EXCLUSIVE locks is a little +** Note that the relationship between SHARED and EXCLUSIVE locks is a little ** different here than in posix. In xShmLock(), one can go from unlocked ** to shared and back or from unlocked to exclusive and back. But one may ** not go from shared to exclusive or from exclusive to shared. @@ -4951,7 +4993,7 @@ static int unixShmLock( unixShm *p; /* The shared memory being locked */ unixShmNode *pShmNode; /* The underlying file iNode */ int rc = SQLITE_OK; /* Result code */ - u16 mask; /* Mask of locks to take or release */ + u16 mask = (1<<(ofst+n)) - (1<pShm; @@ -4997,18 +5039,51 @@ static int unixShmLock( } #endif - mask = (1<<(ofst+n)) - (1<1 || mask==(1<pShmMutex); - assert( assertLockingArrayOk(pShmNode) ); - if( flags & SQLITE_SHM_UNLOCK ){ - if( (p->exclMask|p->sharedMask) & mask ){ - int ii; - int bUnlock = 1; + /* Check if there is any work to do. There are three cases: + ** + ** a) An unlock operation where there are locks to unlock, + ** b) An shared lock where the requested lock is not already held + ** c) An exclusive lock where the requested lock is not already held + ** + ** The SQLite core never requests an exclusive lock that it already holds. + ** This is assert()ed below. + */ + assert( flags!=(SQLITE_SHM_EXCLUSIVE|SQLITE_SHM_LOCK) + || 0==(p->exclMask & mask) + ); + if( ((flags & SQLITE_SHM_UNLOCK) && ((p->exclMask|p->sharedMask) & mask)) + || (flags==(SQLITE_SHM_SHARED|SQLITE_SHM_LOCK) && 0==(p->sharedMask & mask)) + || (flags==(SQLITE_SHM_EXCLUSIVE|SQLITE_SHM_LOCK)) + ){ - for(ii=ofst; ii((p->sharedMask & (1<aMutex[iMutex]); + } +#else + sqlite3_mutex_enter(pShmNode->pShmMutex); +#endif + + if( flags & SQLITE_SHM_UNLOCK ){ + /* Case (a) - unlock. */ + int bUnlock = 1; + assert( (p->exclMask & p->sharedMask)==0 ); + assert( (flags & SQLITE_SHM_EXCLUSIVE)==0 || (p->exclMask & mask)==mask ); + assert( (flags & SQLITE_SHM_SHARED)==0 || (p->sharedMask & mask)==mask ); + + /* If this is a SHARED lock being unlocked, it is possible that other + ** clients within this process are holding the same SHARED lock. In + ** this case, set bUnlock to 0 so that the posix lock is not removed + ** from the file-descriptor below. */ + if( flags & SQLITE_SHM_SHARED ){ + assert( n==1 ); + assert( aLock[ofst]>=1 ); + if( aLock[ofst]>1 ){ bUnlock = 0; + aLock[ofst]--; + p->sharedMask &= ~mask; } } @@ -5016,23 +5091,15 @@ static int unixShmLock( rc = unixShmSystemLock(pDbFd, F_UNLCK, ofst+UNIX_SHM_BASE, n); if( rc==SQLITE_OK ){ memset(&aLock[ofst], 0, sizeof(int)*n); + p->sharedMask &= ~mask; + p->exclMask &= ~mask; } - }else if( ALWAYS(p->sharedMask & (1<1 ); - aLock[ofst]--; } + }else if( flags & SQLITE_SHM_SHARED ){ + /* Case (b) - a shared lock. */ - /* Undo the local locks */ - if( rc==SQLITE_OK ){ - p->exclMask &= ~mask; - p->sharedMask &= ~mask; - } - } - }else if( flags & SQLITE_SHM_SHARED ){ - assert( n==1 ); - assert( (p->exclMask & (1<sharedMask & mask)==0 ){ if( aLock[ofst]<0 ){ + /* An exclusive lock is held by some other connection. BUSY. */ rc = SQLITE_BUSY; }else if( aLock[ofst]==0 ){ rc = unixShmSystemLock(pDbFd, F_RDLCK, ofst+UNIX_SHM_BASE, n); @@ -5043,34 +5110,48 @@ static int unixShmLock( p->sharedMask |= mask; aLock[ofst]++; } - } - }else{ - /* Make sure no sibling connections hold locks that will block this - ** lock. If any do, return SQLITE_BUSY right away. */ - int ii; - for(ii=ofst; iisharedMask & mask)==0 ); - if( ALWAYS((p->exclMask & (1<exclMask & mask)==0 ); + + /* Make sure no sibling connections hold locks that will block this + ** lock. If any do, return SQLITE_BUSY right away. */ + for(ii=ofst; iisharedMask & mask)==0 ); - p->exclMask |= mask; - for(ii=ofst; iiexclMask |= mask; + for(ii=ofst; iiaMutex[iMutex]); + } +#else + sqlite3_mutex_leave(pShmNode->pShmMutex); +#endif } - assert( assertLockingArrayOk(pShmNode) ); - sqlite3_mutex_leave(pShmNode->pShmMutex); + OSTRACE(("SHM-LOCK shmid-%d, pid-%d got %03x,%03x\n", p->id, osGetpid(0), p->sharedMask, p->exclMask)); return rc; -- 2.39.5