From: drh Date: Thu, 20 May 2010 23:51:06 +0000 (+0000) Subject: Add a new xShmBarrier method to the VFS - a shared-memory fence operation. X-Git-Tag: version-3.7.2~355 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=286a28849332e8e32e711fe4fd0c49936978a839;p=thirdparty%2Fsqlite.git Add a new xShmBarrier method to the VFS - a shared-memory fence operation. Implement the same in both unix and win32. Use it to make the WAL subsystem more robust. FossilOrigin-Name: 1bd011c9fed5ef29fb616b4d0a52df3b82221b1f --- diff --git a/manifest b/manifest index 52aed1db63..4b9430e5b6 100644 --- a/manifest +++ b/manifest @@ -1,8 +1,8 @@ -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 -C Make\suse\sof\sthe\sextra\sinformation\sin\sthe\sWAL\sheader\sand\sframe\sheader\sto\nenhance\srobustness. -D 2010-05-20T21:21:10 +C Add\sa\snew\sxShmBarrier\smethod\sto\sthe\sVFS\s-\sa\sshared-memory\sfence\soperation.\nImplement\sthe\ssame\sin\sboth\sunix\sand\swin32.\s\sUse\sit\sto\smake\sthe\sWAL\ssubsystem\nmore\srobust. +D 2010-05-20T23:51:07 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0 F Makefile.in a5cad1f8f3e021356bfcc6c77dc16f6f1952bbc3 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654 @@ -151,12 +151,12 @@ F src/mutex_os2.c 20477db50cf3817c2f1cd3eb61e5c177e50231db F src/mutex_unix.c becb8c4e07616abf84650d3687d62a1461d5d9cd F src/mutex_w32.c fb1cf87c5a88b56c7df0d9ddb796ed9641046c3d F src/notify.c cbfa66a836da3a51567209636e6a94059c137930 -F src/os.c b994b2f4c9a2c406a20d43b59c22ed39a1e704d1 -F src/os.h 207c26793c9b518aa670480a3a262250dd3c98b1 +F src/os.c 2285265f7e8035ba77e8e8ec93adf3c3c61fc60e +F src/os.h efcc7f0072ae362b44eab8588b43a943da61504e F src/os_common.h a8f95b81eca8a1ab8593d23e94f8a35f35d4078f F src/os_os2.c 665876d5eec7585226b0a1cf5e18098de2b2da19 -F src/os_unix.c 6db01eb2c87856f9c9ea40d497941c54ae1b27ff -F src/os_win.c 3c8cafd2444f26504cf7af0e5f51ea568f88a67d +F src/os_unix.c 5c53b43c846ff417504e3000d331bd5326bb0b05 +F src/os_win.c 1e44ee84210b59db1e098bbbc66f6dee68e20d5f F src/pager.c d3284a6bbedeaa4ef3f5668af309d4381df97618 F src/pager.h 76466c3a5af56943537f68b1f16567101a0cd1d0 F src/parse.y ace5c7a125d9f2a410e431ee3209034105045f7e @@ -171,7 +171,7 @@ F src/resolve.c ac5f1a713cd1ae77f08b83cc69581e11bf5ae6f9 F src/rowset.c 69afa95a97c524ba6faf3805e717b5b7ae85a697 F src/select.c c03d8a0565febcde8c6a12c5d77d065fddae889b F src/shell.c fd4ccdb37c3b68de0623eb938a649e0990710714 -F src/sqlite.h.in ef766c813d377a0f3f5e6131d0a2667ecd6301c1 +F src/sqlite.h.in a7d351d5ae015179e7ef97a1060c7213b50efd9b F src/sqlite3ext.h 69dfb8116af51b84a029cddb3b35062354270c89 F src/sqliteInt.h c1ca9bed7c963343f90edaf0ec31b8ff4b43fb01 F src/sqliteLimit.h 196e2f83c3b444c4548fc1874f52f84fdbda40f3 @@ -183,7 +183,7 @@ F src/test2.c 31f1b9d076b4774a22d2605d0af1f34e14a9a7bd F src/test3.c 4c21700c73a890a47fc685c1097bfb661346ac94 F src/test4.c ad03bb987ddedce928f4258c1e7fa4109a73497d F src/test5.c cc55900118fa4add8ec9cf69fc4225a4662f76b1 -F src/test6.c 21f6ec70b5142c37846364e7da0580f7a05b0fc0 +F src/test6.c e524e36b10c4cd8fa08899f6245194045e78edbe F src/test7.c 3f2d63e4ccf97f8c2cf1a7fa0a3c8e2e2a354e6e F src/test8.c f959db9a22d882013b64c92753fa793b2ce3bdea F src/test9.c bea1e8cf52aa93695487badedd6e1886c321ea60 @@ -193,7 +193,7 @@ F src/test_backup.c c129c91127e9b46e335715ae2e75756e25ba27de F src/test_btree.c 47cd771250f09cdc6e12dda5bc71bc0b3abc96e2 F src/test_config.c 6210f501d358bde619ae761f06f123529c6ba24f F src/test_demovfs.c da81a5f7785bb352bda7911c332a983ec4f17f27 -F src/test_devsym.c 2c5221c047183e081da523bae16ae5d792c4caaf +F src/test_devsym.c 265e0c6a196e4b9cf880946b031483446a8033c3 F src/test_func.c 13b582345fb1185a93e46c53310fae8547dcce20 F src/test_hexio.c 1237f000ec7a491009b1233f5c626ea71bce1ea2 F src/test_init.c 5d624ffd0409d424cf9adbfe1f056b200270077c @@ -203,14 +203,14 @@ F src/test_journal.c 51da4dd6118ee843349592fde29429fab84a6243 F src/test_loadext.c df586c27176e3c2cb2e099c78da67bf14379a56e F src/test_malloc.c 2842c922b8e8d992aba722214952204ca025b411 F src/test_mutex.c ce06b59aca168cd8c520b77159a24352a7469bd3 -F src/test_onefile.c df4d7858b5cd1dffe92d36ec9dbad11f0037ffd1 -F src/test_osinst.c 33207e761effffc31a867f9d4a8bb1f52fe6ee92 +F src/test_onefile.c 4ce8c753c0240f010f0f2af89604875967d20945 +F src/test_osinst.c 9cac3f764c065a0ef9d341fffae0c29d6373dc82 F src/test_pcache.c 7bf828972ac0d2403f5cfa4cd14da41f8ebe73d8 F src/test_schema.c 8c06ef9ddb240c7a0fcd31bc221a6a2aade58bf0 F src/test_server.c bbba05c144b5fc4b52ff650a4328027b3fa5fcc6 F src/test_tclvar.c f4dc67d5f780707210d6bb0eb6016a431c04c7fa F src/test_thread.c aa9919c885a1fe53eafc73492f0898ee6c0a0726 -F src/test_vfs.c 7fc397aa5a52e2bf64fa0b46f3b9f40767150289 +F src/test_vfs.c a2d320ea9afc0d520b68eb4998f789b4f8007bfc F src/test_wsd.c 41cadfd9d97fe8e3e4e44f61a4a8ccd6f7ca8fe9 F src/tokenize.c 25ceb0f0a746ea1d0f9553787f3f0a56853cfaeb F src/trigger.c 8927588cb9e6d47f933b53bfe74200fbb504100d @@ -227,7 +227,7 @@ F src/vdbeblob.c 5327132a42a91e8b7acfb60b9d2c3b1c5c863e0e F src/vdbemem.c 2a82f455f6ca6f78b59fb312f96054c04ae0ead1 F src/vdbetrace.c 864cef96919323482ebd9986f2132435115e9cc2 F src/vtab.c a0f8a40274e4261696ef57aa806de2776ab72cda -F src/wal.c fd4377f7fe58cd5063b547b7f0f9a220d68335de +F src/wal.c 2352dd3a2bb271e5c76c9c4407f6590ae5e3768c F src/wal.h 434f76f51225bb614e43ccb6bd2341541ba6a06e F src/walker.c 3112bb3afe1d85dc52317cb1d752055e9a781f8f F src/where.c 75fee9e255b62f773fcadd1d1f25b6f63ac7a356 @@ -765,7 +765,7 @@ F test/vtab_alter.test 9e374885248f69e251bdaacf480b04a197f125e5 F test/vtab_err.test 0d4d8eb4def1d053ac7c5050df3024fd47a3fbd8 F test/vtab_shared.test 0eff9ce4f19facbe0a3e693f6c14b80711a4222d F test/wal.test 90afd254ece957a716751b1c35fac02d6353c2a7 -F test/wal2.test ed0d505726343408b8f88b281dadc95ba0a00ba2 +F test/wal2.test c9f470f7e4f09274a7a4d35dbbae8587115c6e19 F test/walbak.test e7650a26eb4b8abeca9b145b1af1e63026dde432 F test/walcrash.test f6d5fb2bb108876f04848720a488065d9deef69f F test/walfault.test 98df47444944a6db2161eed5cef71d6c00bcb8c3 @@ -816,14 +816,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f -P 669706431f186f92fdc0856a6206419a1e843f46 -R 7ce0bc2b62787cca31ab42b34ac1e9ef +P 9580ecb7e3beb1949a71784a3dcd1823a88e4a9d +R 6169e39cb99c7a86e9c9e7505a7068ac U drh -Z 335bcf01b684b4b622e461b91e26e309 +Z b1a49e07405386f7203bad3d085615ae -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) -iD8DBQFL9afIoxKgR168RlERAma7AJ9zhPYbudAO43Ry1pxCArWXbiP7QwCffSB2 -UDhUaZ/h1EszzPxcYgfA5bo= -=RESX +iD8DBQFL9cruoxKgR168RlERAkAFAJ9xRzU75gC9SA4GXt3kPWkhCqvfpACdF9xG +lxuM43sIwrUxctG6rY11InI= +=HHWB -----END PGP SIGNATURE----- diff --git a/manifest.uuid b/manifest.uuid index ba5b221dc8..767cd5e0f2 100644 --- a/manifest.uuid +++ b/manifest.uuid @@ -1 +1 @@ -9580ecb7e3beb1949a71784a3dcd1823a88e4a9d \ No newline at end of file +1bd011c9fed5ef29fb616b4d0a52df3b82221b1f \ No newline at end of file diff --git a/src/os.c b/src/os.c index 44848fdbb8..0593654007 100644 --- a/src/os.c +++ b/src/os.c @@ -113,6 +113,9 @@ int sqlite3OsShmRelease(sqlite3_file *id){ int sqlite3OsShmLock(sqlite3_file *id, int desiredLock, int *pGotLock){ return id->pMethods->xShmLock(id, desiredLock, pGotLock); } +void sqlite3OsShmBarrier(sqlite3_file *id){ + id->pMethods->xShmBarrier(id); +} int sqlite3OsShmClose(sqlite3_file *id, int deleteFlag){ return id->pMethods->xShmClose(id, deleteFlag); } diff --git a/src/os.h b/src/os.h index 8a08acc721..ba00c44ed2 100644 --- a/src/os.h +++ b/src/os.h @@ -248,6 +248,7 @@ int sqlite3OsShmSize(sqlite3_file *id, int, int*); int sqlite3OsShmGet(sqlite3_file *id, int, int*, void volatile**); int sqlite3OsShmRelease(sqlite3_file *id); int sqlite3OsShmLock(sqlite3_file *id, int, int*); +void sqlite3OsShmBarrier(sqlite3_file *id); int sqlite3OsShmClose(sqlite3_file *id, int); /* diff --git a/src/os_unix.c b/src/os_unix.c index ecdd261d25..0a302a455c 100644 --- a/src/os_unix.c +++ b/src/os_unix.c @@ -3883,12 +3883,31 @@ static int unixShmLock( return rc; } +/* +** Implement a memory barrier or memory fence on shared memory. +** +** All loads and stores begun before the barrier must complete before +** any load or store begun after the barrier. +*/ +static void unixShmBarrier( + sqlite3_file *fd /* Database file holding the shared memory */ +){ +#ifdef __GNUC__ + __sync_synchronize(); +#else + unixMutexEnter(); + unixMutexLeave(); +#endif +} + + #else # define unixShmOpen 0 # define unixShmSize 0 # define unixShmGet 0 # define unixShmRelease 0 # define unixShmLock 0 +# define unixShmBarrier 0 # define unixShmClose 0 #endif /* #ifndef SQLITE_OMIT_WAL */ @@ -3952,6 +3971,7 @@ static const sqlite3_io_methods METHOD = { \ unixShmGet, /* xShmGet */ \ unixShmRelease, /* xShmRelease */ \ unixShmLock, /* xShmLock */ \ + unixShmBarrier, /* xShmBarrier */ \ unixShmClose /* xShmClose */ \ }; \ static const sqlite3_io_methods *FINDER##Impl(const char *z, unixFile *p){ \ diff --git a/src/os_win.c b/src/os_win.c index ac82c8d6e6..6e908c38e3 100644 --- a/src/os_win.c +++ b/src/os_win.c @@ -2078,12 +2078,27 @@ static int winShmLock( return rc; } +/* +** Implement a memory barrier or memory fence on shared memory. +** +** All loads and stores begun before the barrier must complete before +** any load or store begun after the barrier. +*/ +static void winShmBarrier( + sqlite3_file *fd /* Database holding the shared memory */ +){ + /* MemoryBarrier(); // does not work -- do not know why not */ + winShmEnterMutex(); + winShmLeaveMutex(); +} + #else # define winShmOpen 0 # define winShmSize 0 # define winShmGet 0 # define winShmRelease 0 # define winShmLock 0 +# define winShmBarrier 0 # define winShmClose 0 #endif /* #ifndef SQLITE_OMIT_WAL */ /* @@ -2113,6 +2128,7 @@ static const sqlite3_io_methods winIoMethod = { winShmGet, /* xShmGet */ winShmRelease, /* xShmRelease */ winShmLock, /* xShmLock */ + winShmBarrier, /* xShmBarrier */ winShmClose /* xShmClose */ }; diff --git a/src/sqlite.h.in b/src/sqlite.h.in index 4c149a6845..0256399037 100644 --- a/src/sqlite.h.in +++ b/src/sqlite.h.in @@ -659,6 +659,7 @@ struct sqlite3_io_methods { int (*xShmGet)(sqlite3_file*, int reqSize, int *pSize, void volatile**); int (*xShmRelease)(sqlite3_file*); int (*xShmLock)(sqlite3_file*, int desiredLock, int *gotLock); + void (*xShmBarrier)(sqlite3_file*); int (*xShmClose)(sqlite3_file*, int deleteFlag); /* Methods above are valid for version 2 */ /* Additional methods may be added in future releases */ diff --git a/src/test6.c b/src/test6.c index 98db74aabb..743e7ca016 100644 --- a/src/test6.c +++ b/src/test6.c @@ -543,6 +543,9 @@ static int cfShmRelease(sqlite3_file *pFile){ static int cfShmLock(sqlite3_file *pFile, int desired, int *pGot){ return sqlite3OsShmLock(((CrashFile*)pFile)->pRealFile, desired, pGot); } +static void cfShmBarrier(sqlite3_file *pFile){ + sqlite3OsShmBarrier(((CrashFile*)pFile)->pRealFile); +} static int cfShmClose(sqlite3_file *pFile, int delFlag){ return sqlite3OsShmClose(((CrashFile*)pFile)->pRealFile, delFlag); } @@ -567,6 +570,7 @@ static const sqlite3_io_methods CrashFileVtab = { cfShmGet, /* xShmGet */ cfShmRelease, /* xShmRelease */ cfShmLock, /* xShmLock */ + cfShmBarrier, /* xShmBarrier */ cfShmClose /* xShmClose */ }; diff --git a/src/test_devsym.c b/src/test_devsym.c index 3dab67abe9..196dccf286 100644 --- a/src/test_devsym.c +++ b/src/test_devsym.c @@ -55,6 +55,7 @@ static int devsymShmSize(sqlite3_file*,int,int*); static int devsymShmGet(sqlite3_file*,int,int*,volatile void**); static int devsymShmRelease(sqlite3_file*); static int devsymShmLock(sqlite3_file*,int,int*); +static void devsymShmBarrier(sqlite3_file*); static int devsymShmClose(sqlite3_file*,int); /* @@ -123,6 +124,7 @@ static sqlite3_io_methods devsym_io_methods = { devsymShmGet, /* xShmGet */ devsymShmRelease, /* xShmRelease */ devsymShmLock, /* xShmLock */ + devsymShmBarrier, /* xShmBarrier */ devsymShmClose /* xShmClose */ }; @@ -265,6 +267,10 @@ static int devsymShmLock(sqlite3_file *pFile, int desired, int *pGot){ devsym_file *p = (devsym_file *)pFile; return sqlite3OsShmLock(p->pReal, desired, pGot); } +static void devsymShmBarrier(sqlite3_file *pFile){ + devsym_file *p = (devsym_file *)pFile; + sqlite3OsShmBarrier(p->pReal); +} static int devsymShmClose(sqlite3_file *pFile, int delFlag){ devsym_file *p = (devsym_file *)pFile; return sqlite3OsShmClose(p->pReal, delFlag); diff --git a/src/test_onefile.c b/src/test_onefile.c index 520dffcb71..ea6c972603 100644 --- a/src/test_onefile.c +++ b/src/test_onefile.c @@ -223,8 +223,8 @@ static sqlite3_io_methods fs_io_methods = { 0, /* xShmOpen */ 0, /* xShmSize */ 0, /* xShmLock */ - 0, /* xShmClose */ - 0, /* xShmDelete */ + 0, /* xShmBarrier */ + 0 /* xShmClose */ }; @@ -245,8 +245,8 @@ static sqlite3_io_methods tmp_io_methods = { 0, /* xShmOpen */ 0, /* xShmSize */ 0, /* xShmLock */ - 0, /* xShmClose */ - 0, /* xShmDelete */ + 0, /* xShmBarrier */ + 0 /* xShmClose */ }; /* Useful macros used in several places */ diff --git a/src/test_osinst.c b/src/test_osinst.c index 0c8d311e38..f5e541c2d6 100644 --- a/src/test_osinst.c +++ b/src/test_osinst.c @@ -98,10 +98,11 @@ #define OS_SHMGET 23 #define OS_SHMRELEASE 24 #define OS_SHMLOCK 25 -#define OS_SHMSIZE 26 -#define OS_ANNOTATE 27 +#define OS_SHMBARRIER 26 +#define OS_SHMSIZE 27 +#define OS_ANNOTATE 28 -#define OS_NUMEVENTS 28 +#define OS_NUMEVENTS 29 #define VFSLOG_BUFFERSIZE 8192 @@ -150,6 +151,7 @@ static int vfslogShmSize(sqlite3_file *pFile, int reqSize, int *pNewSize); static int vfslogShmGet(sqlite3_file *pFile, int,int*,volatile void **); static int vfslogShmRelease(sqlite3_file *pFile); static int vfslogShmLock(sqlite3_file *pFile, int desiredLock, int *gotLock); +static void vfslogShmBarrier(sqlite3_file*); static int vfslogShmClose(sqlite3_file *pFile, int deleteFlag); /* @@ -206,6 +208,7 @@ static sqlite3_io_methods vfslog_io_methods = { vfslogShmGet, /* xShmGet */ vfslogShmRelease, /* xShmRelease */ vfslogShmLock, /* xShmLock */ + vfslogShmBarrier, /* xShmBarrier */ vfslogShmClose /* xShmClose */ }; @@ -455,6 +458,14 @@ static int vfslogShmLock(sqlite3_file *pFile, int desiredLock, int *gotLock){ vfslog_call(p->pVfslog, OS_SHMLOCK, p->iFileId, t, rc, 0, 0); return rc; } +static void vfslogShmBarrier(sqlite3_file *pFile){ + sqlite3_uint64 t; + VfslogFile *p = (VfslogFile *)pFile; + t = vfslog_time(); + p->pReal->pMethods->xShmBarrier(p->pReal); + t = vfslog_time() - t; + vfslog_call(p->pVfslog, OS_SHMBARRIER, p->iFileId, t, SQLITE_OK, 0, 0); +} static int vfslogShmClose(sqlite3_file *pFile, int deleteFlag){ int rc; sqlite3_uint64 t; @@ -781,6 +792,7 @@ static const char *vfslog_eventname(int eEvent){ case OS_SHMSIZE: zEvent = "xShmSize"; break; case OS_SHMRELEASE: zEvent = "xShmRelease"; break; case OS_SHMLOCK: zEvent = "xShmLock"; break; + case OS_SHMBARRIER: zEvent = "xShmBarrier"; break; case OS_ANNOTATE: zEvent = "annotation"; break; } diff --git a/src/test_vfs.c b/src/test_vfs.c index f4dec59511..f95587931e 100644 --- a/src/test_vfs.c +++ b/src/test_vfs.c @@ -103,6 +103,7 @@ static int tvfsShmSize(sqlite3_file*, int , int *); static int tvfsShmGet(sqlite3_file*, int , int *, volatile void **); static int tvfsShmRelease(sqlite3_file*); static int tvfsShmLock(sqlite3_file*, int , int *); +static void tvfsShmBarrier(sqlite3_file*); static int tvfsShmClose(sqlite3_file*, int); static sqlite3_io_methods tvfs_io_methods = { @@ -124,6 +125,7 @@ static sqlite3_io_methods tvfs_io_methods = { tvfsShmGet, /* xShmGet */ tvfsShmRelease, /* xShmRelease */ tvfsShmLock, /* xShmLock */ + tvfsShmBarrier, /* xShmBarrier */ tvfsShmClose /* xShmClose */ }; @@ -269,6 +271,7 @@ static int tvfsOpen( pMethods->xShmRelease = 0; pMethods->xShmClose = 0; pMethods->xShmLock = 0; + pMethods->xShmBarrier = 0; } pFile->pMethods = pMethods; } @@ -569,6 +572,17 @@ static int tvfsShmLock( return rc; } +static void tvfsShmBarrier(sqlite3_file *pFile){ + int rc = SQLITE_OK; + TestvfsFile *pFd = (TestvfsFile *)pFile; + Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData); + + tvfsExecTcl(p, "xShmBarrier", + Tcl_NewStringObj(pFd->pShm->zFile, -1), pFd->pShmId, 0 + ); + tvfsResultCode(p, &rc); +} + static int tvfsShmClose( sqlite3_file *pFile, int deleteFlag diff --git a/src/wal.c b/src/wal.c index 5e4c927a77..65c711d8f1 100644 --- a/src/wal.c +++ b/src/wal.c @@ -207,7 +207,10 @@ typedef struct WalIterator WalIterator; /* -** The following object holds an exact copy of the wal-index header. +** The following object holds a copy of the wal-index header content. +** +** The actual header in the wal-index consists of two copies of this +** object. */ struct WalIndexHdr { u32 iChange; /* Counter incremented each transaction */ @@ -223,7 +226,7 @@ struct WalIndexHdr { ** only support mandatory file-locks, we do not read or write data ** from the region of the file on which locks are applied. */ -#define WALINDEX_LOCK_OFFSET (sizeof(WalIndexHdr)) +#define WALINDEX_LOCK_OFFSET (sizeof(WalIndexHdr)*2) #define WALINDEX_LOCK_RESERVED 8 /* Size of header before each frame in wal */ @@ -306,13 +309,13 @@ static void walChecksumBytes( u32 *aOut /* OUT: Final checksum value output */ ){ u32 s1, s2; + u8 *aEnd = (u8*)&a[nByte]; if( aIn ){ s1 = aIn[0]; s2 = aIn[1]; }else{ s1 = s2 = 0; } - u8 *aEnd = (u8*)&a[nByte]; assert( nByte>=8 ); assert( (nByte&0x00000003)==0 ); @@ -355,10 +358,14 @@ static int walSetLock(Wal *pWal, int desiredStatus){ ** The checksum on pWal->hdr is updated before it is written. */ static void walIndexWriteHdr(Wal *pWal){ + WalIndexHdr *aHdr; walChecksumBytes((u8*)&pWal->hdr, sizeof(pWal->hdr) - sizeof(pWal->hdr.aCksum), 0, pWal->hdr.aCksum); - memcpy((void*)pWal->pWiData, &pWal->hdr, sizeof(pWal->hdr)); + aHdr = (WalIndexHdr*)pWal->pWiData; + memcpy(&aHdr[1], &pWal->hdr, sizeof(pWal->hdr)); + sqlite3OsShmBarrier(pWal->pDbFd); + memcpy(&aHdr[0], &pWal->hdr, sizeof(pWal->hdr)); } /* @@ -1118,8 +1125,9 @@ int sqlite3WalClose( ** is read successfully and the checksum verified, return zero. */ int walIndexTryHdr(Wal *pWal, int *pChanged){ - u32 aCksum[2]; - WalIndexHdr hdr; + u32 aCksum[2]; /* Checksum on the header content */ + WalIndexHdr hdr1, hdr2; /* Two copies of the header content */ + WalIndexHdr *aHdr; /* Header in shared memory */ assert( pWal->pWiData ); if( pWal->szWIndex==0 ){ @@ -1135,15 +1143,24 @@ int walIndexTryHdr(Wal *pWal, int *pChanged){ ** file, meaning it is possible that an inconsistent snapshot is read ** from the file. If this happens, return non-zero. */ - memcpy(&hdr, (void*)pWal->pWiData, sizeof(hdr)); - walChecksumBytes((u8*)&hdr, sizeof(hdr)-sizeof(hdr.aCksum), 0, aCksum); - if( aCksum[0]!=hdr.aCksum[0] || aCksum[1]!=hdr.aCksum[1] ){ + aHdr = (WalIndexHdr*)pWal->pWiData; + memcpy(&hdr1, &aHdr[0], sizeof(hdr1)); + sqlite3OsShmBarrier(pWal->pDbFd); + memcpy(&hdr2, &aHdr[1], sizeof(hdr2)); + + if( memcmp(&hdr1, &hdr2, sizeof(hdr1))!=0 ){ + /* Dirty read */ + return 1; + } + walChecksumBytes((u8*)&hdr1, sizeof(hdr1)-sizeof(hdr1.aCksum), 0, aCksum); + if( aCksum[0]!=hdr1.aCksum[0] || aCksum[1]!=hdr1.aCksum[1] ){ + /* Malformed header */ return 1; } - if( memcmp(&pWal->hdr, &hdr, sizeof(WalIndexHdr)) ){ + if( memcmp(&pWal->hdr, &hdr1, sizeof(WalIndexHdr)) ){ *pChanged = 1; - memcpy(&pWal->hdr, &hdr, sizeof(WalIndexHdr)); + memcpy(&pWal->hdr, &hdr1, sizeof(WalIndexHdr)); pWal->szPage = pWal->hdr.szPage; } diff --git a/test/wal2.test b/test/wal2.test index 3248bdbc7e..ead8cbbb17 100644 --- a/test/wal2.test +++ b/test/wal2.test @@ -25,11 +25,11 @@ proc set_tvfs_hdr {file args} { set blob [tvfs shm $file] if {[llength $args]} { - set blob [binary format i8a* [lindex $args 0] [string range $blob 32 end]] + set blob [binary format i16a* [lindex $args 0] [string range $blob 64 end]] tvfs shm $file $blob } - binary scan $blob i8 ints + binary scan $blob i16 ints return $ints }