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Overview
Comment: | Additional field name changes and commit fixes associated with shared-memory locking in the unix VFS, to improve maintainability. No logic changes. |
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Timelines: | family | ancestors | descendants | both | trunk |
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SHA3-256: |
9280774a4bbc665d70f346d258768cbc |
User & Date: | drh 2018-10-02 19:58:08.325 |
Context
2018-10-02
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20:16 | Add an additional assert() verifying mutex invariants on the unixShmSystemLock() routine in the unix VFS. (check-in: cb1511065d user: drh tags: trunk) | |
19:58 | Additional field name changes and commit fixes associated with shared-memory locking in the unix VFS, to improve maintainability. No logic changes. (check-in: 9280774a4b user: drh tags: trunk) | |
19:36 | Fix comments and refactor some names associated with shared-memory locking in the Unix VFS. No logical changes. (check-in: 3e9f163527 user: drh tags: trunk) | |
Changes
Changes to src/os_unix.c.
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4211 4212 4213 4214 4215 4216 4217 | ** unixMutexHeld() must be true when creating or destroying ** this object or while reading or writing the following fields: ** ** nRef ** ** The following fields are read-only after the object is created: ** | | | | | 4211 4212 4213 4214 4215 4216 4217 4218 4219 4220 4221 4222 4223 4224 4225 4226 4227 4228 4229 4230 4231 4232 4233 4234 4235 4236 | ** unixMutexHeld() must be true when creating or destroying ** this object or while reading or writing the following fields: ** ** nRef ** ** The following fields are read-only after the object is created: ** ** hShm ** zFilename ** ** Either unixShmNode.pShmMutex must be held or unixShmNode.nRef==0 and ** unixMutexHeld() is true when reading or writing any other field ** in this structure. */ struct unixShmNode { unixInodeInfo *pInode; /* unixInodeInfo that owns this SHM node */ sqlite3_mutex *pShmMutex; /* Mutex to access this object */ char *zFilename; /* Name of the mmapped file */ int hShm; /* Open file descriptor */ int szRegion; /* Size of shared-memory regions */ u16 nRegion; /* Size of array apRegion */ u8 isReadonly; /* True if read-only */ u8 isUnlocked; /* True if no DMS lock held */ 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 */ |
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4291 4292 4293 4294 4295 4296 4297 | /* 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 ); | | | | 4291 4292 4293 4294 4295 4296 4297 4298 4299 4300 4301 4302 4303 4304 4305 4306 4307 4308 4309 4310 4311 | /* 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 ); if( pShmNode->hShm>=0 ){ /* Initialize the locking parameters */ f.l_type = lockType; f.l_whence = SEEK_SET; f.l_start = ofst; f.l_len = n; rc = osSetPosixAdvisoryLock(pShmNode->hShm, &f, pFile); rc = (rc!=(-1)) ? SQLITE_OK : SQLITE_BUSY; } /* Update the global lock state and do debug tracing */ #ifdef SQLITE_DEBUG { u16 mask; OSTRACE(("SHM-LOCK ")); |
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4371 4372 4373 4374 4375 4376 4377 | assert( unixMutexHeld() ); if( p && ALWAYS(p->nRef==0) ){ int nShmPerMap = unixShmRegionPerMap(); int i; assert( p->pInode==pFd->pInode ); sqlite3_mutex_free(p->pShmMutex); for(i=0; i<p->nRegion; i+=nShmPerMap){ | | | | | | 4371 4372 4373 4374 4375 4376 4377 4378 4379 4380 4381 4382 4383 4384 4385 4386 4387 4388 4389 4390 4391 4392 4393 4394 | assert( unixMutexHeld() ); if( p && ALWAYS(p->nRef==0) ){ int nShmPerMap = unixShmRegionPerMap(); int i; assert( p->pInode==pFd->pInode ); sqlite3_mutex_free(p->pShmMutex); for(i=0; i<p->nRegion; i+=nShmPerMap){ if( p->hShm>=0 ){ osMunmap(p->apRegion[i], p->szRegion); }else{ sqlite3_free(p->apRegion[i]); } } sqlite3_free(p->apRegion); if( p->hShm>=0 ){ robust_close(pFd, p->hShm, __LINE__); p->hShm = -1; } p->pInode->pShmNode = 0; sqlite3_free(p); } } /* |
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4422 4423 4424 4425 4426 4427 4428 | ** process might open and use the *-shm file without truncating it. ** And if the *-shm file has been corrupted by a power failure or ** system crash, the database itself may also become corrupt. */ lock.l_whence = SEEK_SET; lock.l_start = UNIX_SHM_DMS; lock.l_len = 1; lock.l_type = F_WRLCK; | | | | 4422 4423 4424 4425 4426 4427 4428 4429 4430 4431 4432 4433 4434 4435 4436 4437 4438 4439 4440 4441 4442 4443 4444 | ** process might open and use the *-shm file without truncating it. ** And if the *-shm file has been corrupted by a power failure or ** system crash, the database itself may also become corrupt. */ lock.l_whence = SEEK_SET; lock.l_start = UNIX_SHM_DMS; lock.l_len = 1; lock.l_type = F_WRLCK; if( osFcntl(pShmNode->hShm, F_GETLK, &lock)!=0 ) { rc = SQLITE_IOERR_LOCK; }else if( lock.l_type==F_UNLCK ){ if( pShmNode->isReadonly ){ pShmNode->isUnlocked = 1; rc = SQLITE_READONLY_CANTINIT; }else{ rc = unixShmSystemLock(pDbFd, F_WRLCK, UNIX_SHM_DMS, 1); if( rc==SQLITE_OK && robust_ftruncate(pShmNode->hShm, 0) ){ rc = unixLogError(SQLITE_IOERR_SHMOPEN,"ftruncate",pShmNode->zFilename); } } }else if( lock.l_type==F_WRLCK ){ rc = SQLITE_BUSY; } |
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4536 4537 4538 4539 4540 4541 4542 | sqlite3_snprintf(nShmFilename, zShm, SQLITE_SHM_DIRECTORY "/sqlite-shm-%x-%x", (u32)sStat.st_ino, (u32)sStat.st_dev); #else sqlite3_snprintf(nShmFilename, zShm, "%s-shm", zBasePath); sqlite3FileSuffix3(pDbFd->zPath, zShm); #endif | | | | | | | | 4536 4537 4538 4539 4540 4541 4542 4543 4544 4545 4546 4547 4548 4549 4550 4551 4552 4553 4554 4555 4556 4557 4558 4559 4560 4561 4562 4563 4564 4565 4566 4567 4568 4569 4570 4571 4572 4573 4574 4575 4576 4577 4578 | sqlite3_snprintf(nShmFilename, zShm, SQLITE_SHM_DIRECTORY "/sqlite-shm-%x-%x", (u32)sStat.st_ino, (u32)sStat.st_dev); #else sqlite3_snprintf(nShmFilename, zShm, "%s-shm", zBasePath); sqlite3FileSuffix3(pDbFd->zPath, zShm); #endif pShmNode->hShm = -1; pDbFd->pInode->pShmNode = pShmNode; pShmNode->pInode = pDbFd->pInode; if( sqlite3GlobalConfig.bCoreMutex ){ pShmNode->pShmMutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST); if( pShmNode->pShmMutex==0 ){ rc = SQLITE_NOMEM_BKPT; goto shm_open_err; } } if( pInode->bProcessLock==0 ){ if( 0==sqlite3_uri_boolean(pDbFd->zPath, "readonly_shm", 0) ){ pShmNode->hShm = robust_open(zShm, O_RDWR|O_CREAT,(sStat.st_mode&0777)); } if( pShmNode->hShm<0 ){ pShmNode->hShm = robust_open(zShm, O_RDONLY, (sStat.st_mode&0777)); if( pShmNode->hShm<0 ){ rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShm); goto shm_open_err; } pShmNode->isReadonly = 1; } /* If this process is running as root, make sure that the SHM file ** is owned by the same user that owns the original database. Otherwise, ** the original owner will not be able to connect. */ robustFchown(pShmNode->hShm, sStat.st_uid, sStat.st_gid); rc = unixLockSharedMemory(pDbFd, pShmNode); if( rc!=SQLITE_OK && rc!=SQLITE_READONLY_CANTINIT ) goto shm_open_err; } } /* Make the new connection a child of the unixShmNode */ |
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4650 4651 4652 4653 4654 4655 4656 | if( pShmNode->isUnlocked ){ rc = unixLockSharedMemory(pDbFd, pShmNode); if( rc!=SQLITE_OK ) goto shmpage_out; pShmNode->isUnlocked = 0; } assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 ); assert( pShmNode->pInode==pDbFd->pInode ); | | | | | | 4650 4651 4652 4653 4654 4655 4656 4657 4658 4659 4660 4661 4662 4663 4664 4665 4666 4667 4668 4669 4670 4671 4672 4673 4674 4675 4676 4677 4678 4679 4680 4681 4682 | if( pShmNode->isUnlocked ){ rc = unixLockSharedMemory(pDbFd, pShmNode); if( rc!=SQLITE_OK ) goto shmpage_out; pShmNode->isUnlocked = 0; } assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 ); assert( pShmNode->pInode==pDbFd->pInode ); assert( pShmNode->hShm>=0 || pDbFd->pInode->bProcessLock==1 ); assert( pShmNode->hShm<0 || pDbFd->pInode->bProcessLock==0 ); /* Minimum number of regions required to be mapped. */ nReqRegion = ((iRegion+nShmPerMap) / nShmPerMap) * nShmPerMap; if( pShmNode->nRegion<nReqRegion ){ char **apNew; /* New apRegion[] array */ int nByte = nReqRegion*szRegion; /* Minimum required file size */ struct stat sStat; /* Used by fstat() */ pShmNode->szRegion = szRegion; if( pShmNode->hShm>=0 ){ /* The requested region is not mapped into this processes address space. ** Check to see if it has been allocated (i.e. if the wal-index file is ** large enough to contain the requested region). */ if( osFstat(pShmNode->hShm, &sStat) ){ rc = SQLITE_IOERR_SHMSIZE; goto shmpage_out; } if( sStat.st_size<nByte ){ /* The requested memory region does not exist. If bExtend is set to ** false, exit early. *pp will be set to NULL and SQLITE_OK returned. |
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4696 4697 4698 4699 4700 4701 4702 | static const int pgsz = 4096; int iPg; /* Write to the last byte of each newly allocated or extended page */ assert( (nByte % pgsz)==0 ); for(iPg=(sStat.st_size/pgsz); iPg<(nByte/pgsz); iPg++){ int x = 0; | | | 4696 4697 4698 4699 4700 4701 4702 4703 4704 4705 4706 4707 4708 4709 4710 | static const int pgsz = 4096; int iPg; /* Write to the last byte of each newly allocated or extended page */ assert( (nByte % pgsz)==0 ); for(iPg=(sStat.st_size/pgsz); iPg<(nByte/pgsz); iPg++){ int x = 0; if( seekAndWriteFd(pShmNode->hShm, iPg*pgsz + pgsz-1,"",1,&x)!=1 ){ const char *zFile = pShmNode->zFilename; rc = unixLogError(SQLITE_IOERR_SHMSIZE, "write", zFile); goto shmpage_out; } } } } |
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4719 4720 4721 4722 4723 4724 4725 | goto shmpage_out; } pShmNode->apRegion = apNew; while( pShmNode->nRegion<nReqRegion ){ int nMap = szRegion*nShmPerMap; int i; void *pMem; | | | | 4719 4720 4721 4722 4723 4724 4725 4726 4727 4728 4729 4730 4731 4732 4733 4734 4735 4736 | goto shmpage_out; } pShmNode->apRegion = apNew; while( pShmNode->nRegion<nReqRegion ){ int nMap = szRegion*nShmPerMap; int i; void *pMem; if( pShmNode->hShm>=0 ){ pMem = osMmap(0, nMap, pShmNode->isReadonly ? PROT_READ : PROT_READ|PROT_WRITE, MAP_SHARED, pShmNode->hShm, szRegion*(i64)pShmNode->nRegion ); if( pMem==MAP_FAILED ){ rc = unixLogError(SQLITE_IOERR_SHMMAP, "mmap", pShmNode->zFilename); goto shmpage_out; } }else{ pMem = sqlite3_malloc64(szRegion); |
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4785 4786 4787 4788 4789 4790 4791 | assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK ); assert( n>=1 ); assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED) || flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE) || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED) || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) ); assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 ); | | | | 4785 4786 4787 4788 4789 4790 4791 4792 4793 4794 4795 4796 4797 4798 4799 4800 | assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK ); assert( n>=1 ); assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED) || flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE) || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED) || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) ); assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 ); assert( pShmNode->hShm>=0 || pDbFd->pInode->bProcessLock==1 ); assert( pShmNode->hShm<0 || pDbFd->pInode->bProcessLock==0 ); mask = (1<<(ofst+n)) - (1<<ofst); assert( n>1 || mask==(1<<ofst) ); sqlite3_mutex_enter(pShmNode->pShmMutex); if( flags & SQLITE_SHM_UNLOCK ){ u16 allMask = 0; /* Mask of locks held by siblings */ |
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4929 4930 4931 4932 4933 4934 4935 | /* If pShmNode->nRef has reached 0, then close the underlying ** shared-memory file, too */ assert( unixFileMutexNotheld(pDbFd) ); unixEnterMutex(); assert( pShmNode->nRef>0 ); pShmNode->nRef--; if( pShmNode->nRef==0 ){ | | | 4929 4930 4931 4932 4933 4934 4935 4936 4937 4938 4939 4940 4941 4942 4943 | /* If pShmNode->nRef has reached 0, then close the underlying ** shared-memory file, too */ assert( unixFileMutexNotheld(pDbFd) ); unixEnterMutex(); assert( pShmNode->nRef>0 ); pShmNode->nRef--; if( pShmNode->nRef==0 ){ if( deleteFlag && pShmNode->hShm>=0 ){ osUnlink(pShmNode->zFilename); } unixShmPurge(pDbFd); } unixLeaveMutex(); return SQLITE_OK; |
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