diff options
Diffstat (limited to 'src/os_unix.c')
| -rw-r--r-- | src/os_unix.c | 100 |
1 files changed, 68 insertions, 32 deletions
diff --git a/src/os_unix.c b/src/os_unix.c index d991ec9d5..006b0d182 100644 --- a/src/os_unix.c +++ b/src/os_unix.c @@ -4594,11 +4594,9 @@ struct unixShmFile { sqlite3_mutex *mutexBuf; /* Mutex to access zBuf[] */ sqlite3_mutex *mutexRecov; /* The RECOVER mutex */ char *zFilename; /* Name of the file */ - int size; /* Size of the file */ int h; /* Open file descriptor */ - char *pMMapBuf; /* Where currently mmapped() */ - int nReadPrefix; /* Number of SQLITE_SHM_READ_PREFIX locks */ - int nReadFull; /* Number of SQLITE_SHM_READ_FULL locks */ + int szMap; /* Size of the mapping of file into memory */ + char *pMMapBuf; /* Where currently mmapped(). NULL if unmapped */ int nRef; /* Number of unixShm objects pointing to this */ unixShm *pFirst; /* All unixShm objects pointing to this */ unixShmFile *pNext; /* Next in list of all unixShmFile objects */ @@ -4995,8 +4993,6 @@ static int unixShmOpen( } pFile->fid.dev = sStat.st_dev; pFile->fid.ino = sStat.st_ino; - pFile->size = (int)sStat.st_size; - pFile->size = (pFile->size/SQLITE_UNIX_SHM_INCR)*SQLITE_UNIX_SHM_INCR; /* Check to see if another process is holding the dead-man switch. ** If not, truncate the file to zero length. @@ -5010,7 +5006,6 @@ static int unixShmOpen( rc = SQLITE_IOERR; goto shm_open_err; } - pFile->size = 0; } rc = unixShmSystemLock(pFile, F_RDLCK, UNIX_SHM_DMS); if( rc ) goto shm_open_err; @@ -5078,46 +5073,86 @@ static int unixShmClose(sqlite3_shm *pSharedMem){ } /* -** Query and/or changes the size of a shared-memory segment. -** The reqSize parameter is the new size of the segment, or -1 to -** do just a query. The size of the segment after resizing is -** written into pNewSize. A writer lock is held on the shared memory -** segment while resizing it. +** Query and/or changes the size of the underlying storage for +** a shared-memory segment. The reqSize parameter is the new size +** of the underlying storage, or -1 to do just a query. The size +** of the underlying storage (after resizing if resizing occurs) is +** written into pNewSize. ** -** If ppBuffer is not NULL, the a reader lock is acquired on the shared -** memory segment and *ppBuffer is made to point to the start of the -** shared memory segment. xShmRelease() must be called to release the -** lock. +** This routine does not (necessarily) change the size of the mapping +** of the underlying storage into memory. Use xShmGet() to change +** the mapping size. +** +** The reqSize parameter is the minimum size requested. The implementation +** is free to expand the storage to some larger amount if it chooses. */ static int unixShmSize( sqlite3_shm *pSharedMem, /* Pointer returned by unixShmOpen() */ int reqSize, /* Requested size. -1 for query only */ - int *pNewSize, /* Write new size here */ - void **ppBuf /* Write new buffer origin here */ + int *pNewSize /* Write new size here */ ){ unixShm *p = (unixShm*)pSharedMem; unixShmFile *pFile = p->pFile; int rc = SQLITE_OK; + struct stat sStat; - sqlite3_mutex_enter(pFile->mutexBuf); - sqlite3_mutex_enter(pFile->mutex); if( reqSize>=0 ){ reqSize = (reqSize + SQLITE_UNIX_SHM_INCR - 1)/SQLITE_UNIX_SHM_INCR; reqSize *= SQLITE_UNIX_SHM_INCR; - if( reqSize!=pFile->size ){ - if( pFile->pMMapBuf ) munmap(pFile->pMMapBuf, pFile->size); - rc = ftruncate(pFile->h, reqSize); - if( rc ){ - pFile->pMMapBuf = 0; - pFile->size = 0; - }else{ - pFile->pMMapBuf = mmap(0, reqSize, PROT_READ|PROT_WRITE, MAP_SHARED, - pFile->h, 0); - pFile->size = pFile->pMMapBuf ? reqSize : 0; - } + rc = ftruncate(pFile->h, reqSize); + } + if( fstat(pFile->h, &sStat)==0 ){ + *pNewSize = (int)sStat.st_size; + }else{ + *pNewSize = 0; + rc = SQLITE_IOERR; + } + return rc; +} + + +/* +** Map the shared storage into memory. The minimum size of the +** mapping should be reqMapSize if reqMapSize is positive. If +** reqMapSize is zero or negative, the implementation can choose +** whatever mapping size is convenient. +** +** *ppBuf is made to point to the memory which is a mapping of the +** underlying storage. This segment is locked. unixShmRelease() +** must be called to release the lock. +** +** *pNewMapSize is set to the size of the mapping. +** +** *ppBuf and *pNewMapSize might be NULL and zero if no space has +** yet been allocated to the underlying storage. +*/ +static int unixShmGet( + sqlite3_shm *pSharedMem, /* Pointer returned by unixShmOpen() */ + int reqMapSize, /* Requested size of mapping. -1 means don't care */ + int *pNewMapSize, /* Write new size of mapping here */ + void **ppBuf /* Write mapping buffer origin here */ +){ + unixShm *p = (unixShm*)pSharedMem; + unixShmFile *pFile = p->pFile; + int rc = SQLITE_OK; + + sqlite3_mutex_enter(pFile->mutexBuf); + sqlite3_mutex_enter(pFile->mutex); + if( pFile->szMap==0 || reqMapSize>pFile->szMap ){ + int actualSize; + if( unixShmSize(pSharedMem, -1, &actualSize)==SQLITE_OK + && reqMapSize<actualSize + ){ + reqMapSize = actualSize; + } + if( pFile->pMMapBuf ){ + munmap(pFile->pMMapBuf, pFile->szMap); } + pFile->pMMapBuf = mmap(0, reqMapSize, PROT_READ|PROT_WRITE, MAP_SHARED, + pFile->h, 0); + pFile->szMap = pFile->pMMapBuf ? reqMapSize : 0; } - *pNewSize = pFile->size; + *pNewMapSize = pFile->szMap; *ppBuf = pFile->pMMapBuf; sqlite3_mutex_leave(pFile->mutex); return rc; @@ -6490,6 +6525,7 @@ int sqlite3_os_init(void){ unixGetLastError, /* xGetLastError */ \ unixShmOpen, /* xShmOpen */ \ unixShmSize, /* xShmSize */ \ + unixShmGet, /* xShmGet */ \ unixShmRelease, /* xShmRelease */ \ 0, /* xShmPush */ \ 0, /* xShmPull */ \ |