From: Hallvard Furuseth Date: Mon, 12 Jan 2015 20:02:29 +0000 (+0100) Subject: Make SysV semaphores robust. Cleanup MDB_ROBUST. X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=631970e485a37d8fc270d8de41ecfe76d8521b70;p=openldap Make SysV semaphores robust. Cleanup MDB_ROBUST. --- diff --git a/libraries/liblmdb/lmdb.h b/libraries/liblmdb/lmdb.h index 9efdfb3963..f37d8f5897 100644 --- a/libraries/liblmdb/lmdb.h +++ b/libraries/liblmdb/lmdb.h @@ -109,7 +109,9 @@ * The transaction becomes "long-lived" as above until a check * for stale readers is performed or the lockfile is reset, * since the process may not remove it from the lockfile. - * Except write-transactions on Unix with MDB_ROBUST or on Windows. + * + * This does not apply to write transactions if the system clears + * stale writers, see above. * * - If you do that anyway, do a periodic check for stale readers. Or * close the environment once in a while, so the lockfile can get reset. diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c index 84cd8a35a0..f0fe6154b2 100644 --- a/libraries/liblmdb/mdb.c +++ b/libraries/liblmdb/mdb.c @@ -208,7 +208,7 @@ union semun { #define MDB_DEVEL 0 #endif -#if defined(_WIN32) || (defined(EOWNERDEAD) && !defined(MDB_USE_SYSV_SEM)) +#if defined(_WIN32) || defined(MDB_USE_SYSV_SEM) || defined(EOWNERDEAD) #define MDB_ROBUST_SUPPORTED 1 #endif @@ -222,6 +222,16 @@ union semun { # define mdb_func_ "" #endif +/* Internal error codes, not exposed outside liblmdb */ +#define MDB_NO_ROOT (MDB_LAST_ERRCODE + 10) +#ifdef _WIN32 +#define MDB_OWNERDEAD ((int) WAIT_ABANDONED) +#elif defined MDB_USE_SYSV_SEM +#define MDB_OWNERDEAD (MDB_LAST_ERRCODE + 11) +#else +#define MDB_OWNERDEAD EOWNERDEAD +#endif + #ifdef _WIN32 #define MDB_USE_HASH 1 #define MDB_PIDLOCK 0 @@ -237,7 +247,6 @@ typedef HANDLE mdb_mutex_t; #define pthread_key_delete(x) TlsFree(x) #define pthread_getspecific(x) TlsGetValue(x) #define pthread_setspecific(x,y) (TlsSetValue(x,y) ? 0 : ErrCode()) -#define pthread_mutex_consistent(mutex) 0 #define pthread_mutex_unlock(x) ReleaseMutex(*x) #define pthread_mutex_lock(x) WaitForSingleObject(*x, INFINITE) #define pthread_cond_signal(x) SetEvent(*x) @@ -247,6 +256,7 @@ typedef HANDLE mdb_mutex_t; #define MDB_MUTEX(env, rw) ((env)->me_##rw##mutex) #define LOCK_MUTEX0(mutex) WaitForSingleObject(mutex, INFINITE) #define UNLOCK_MUTEX(mutex) ReleaseMutex(mutex) +#define mdb_mutex_consistent(mutex) 0 #define getpid() GetCurrentProcessId() #define MDB_FDATASYNC(fd) (!FlushFileBuffers(fd)) #define MDB_MSYNC(addr,len,flags) (!FlushViewOfFile(addr,len)) @@ -274,6 +284,7 @@ typedef HANDLE mdb_mutex_t; typedef struct mdb_mutex { int semid; int semnum; + int *locked; } mdb_mutex_t; #define MDB_MUTEX(env, rw) (&(env)->me_##rw##mutex) @@ -281,19 +292,28 @@ typedef struct mdb_mutex { #define UNLOCK_MUTEX(mutex) do { \ struct sembuf sb = { 0, 1, SEM_UNDO }; \ sb.sem_num = (mutex)->semnum; \ + *(mutex)->locked = 0; \ semop((mutex)->semid, &sb, 1); \ } while(0) static int mdb_sem_wait(mdb_mutex_t *sem) { - int rc; - struct sembuf sb = { 0, -1, SEM_UNDO }; - sb.sem_num = sem->semnum; - while ((rc = semop(sem->semid, &sb, 1)) && (rc = errno) == EINTR) ; - return rc; + int rc, *locked = sem->locked; + struct sembuf sb = { 0, -1, SEM_UNDO }; + sb.sem_num = sem->semnum; + do { + if (!semop(sem->semid, &sb, 1)) { + rc = *locked ? MDB_OWNERDEAD : MDB_SUCCESS; + *locked = 1; + break; + } + } while ((rc = errno) == EINTR); + return rc; } +#define mdb_mutex_consistent(mutex) 0 + #else /** Pointer/HANDLE type of shared mutex/semaphore. */ @@ -308,6 +328,9 @@ typedef pthread_mutex_t mdb_mutex_t; /** Unlock the reader or writer mutex. */ #define UNLOCK_MUTEX(mutex) pthread_mutex_unlock(mutex) + /** Mark mutex-protected data as repaired, after death of previous owner. + */ +#define mdb_mutex_consistent(mutex) pthread_mutex_consistent(mutex) #endif /* MDB_USE_SYSV_SEM */ /** Get the error code for the last failed system function. @@ -336,11 +359,17 @@ typedef pthread_mutex_t mdb_mutex_t; #if defined(_WIN32) #define MNAME_LEN 32 #elif defined(MDB_USE_SYSV_SEM) -#define MNAME_LEN 0 +#define MNAME_LEN (sizeof(int)) #else #define MNAME_LEN (sizeof(pthread_mutex_t)) #endif +#ifdef MDB_USE_SYSV_SEM +#define SYSV_SEM_FLAG 1 /**< SysV sems in lockfile format */ +#else +#define SYSV_SEM_FLAG 0 +#endif + /** @} */ #ifdef MDB_ROBUST_SUPPORTED @@ -667,6 +696,7 @@ typedef struct MDB_txbody { char mtb_rmname[MNAME_LEN]; #elif defined(MDB_USE_SYSV_SEM) int mtb_semid; + int mtb_rlocked; #else /** Mutex protecting access to this table. * This is the #MDB_MUTEX(env,r) reader table lock. @@ -695,22 +725,25 @@ typedef struct MDB_txninfo { #define mti_rmname mt1.mtb.mtb_rmname #define mti_txnid mt1.mtb.mtb_txnid #define mti_numreaders mt1.mtb.mtb_numreaders - char pad[(sizeof(MDB_txbody)+CACHELINE-1) & ~(CACHELINE-1)]; - } mt1; #ifdef MDB_USE_SYSV_SEM #define mti_semid mt1.mtb.mtb_semid -#else +#define mti_rlocked mt1.mtb.mtb_rlocked +#endif + char pad[(sizeof(MDB_txbody)+CACHELINE-1) & ~(CACHELINE-1)]; + } mt1; union { #if defined(_WIN32) char mt2_wmname[MNAME_LEN]; #define mti_wmname mt2.mt2_wmname +#elif defined MDB_USE_SYSV_SEM + int mt2_wlocked; +#define mti_wlocked mt2.mt2_wlocked #else pthread_mutex_t mt2_wmutex; #define mti_wmutex mt2.mt2_wmutex #endif char pad[(MNAME_LEN+CACHELINE-1) & ~(CACHELINE-1)]; } mt2; -#endif MDB_reader mti_readers[1]; } MDB_txninfo; @@ -719,7 +752,7 @@ typedef struct MDB_txninfo { ((uint32_t) \ ((MDB_LOCK_VERSION) \ /* Flags which describe functionality */ \ - + (((MNAME_LEN) == 0) << 18) /* MDB_USE_SYSV_SEM */ \ + + (SYSV_SEM_FLAG << 18) \ + (((MDB_PIDLOCK) != 0) << 16))) /** @} */ @@ -2596,17 +2629,8 @@ mdb_txn_renew0(MDB_txn *txn) if (ti) { if (LOCK_MUTEX(rc, env, MDB_MUTEX(env, w))) return rc; -#ifdef MDB_USE_SYSV_SEM - meta = env->me_metas[ mdb_env_pick_meta(env) ]; - txn->mt_txnid = meta->mm_txnid; - /* Update mti_txnid like mdb_mutex_failed() would, - * in case last writer crashed before updating it. - */ - ti->mti_txnid = txn->mt_txnid; -#else txn->mt_txnid = ti->mti_txnid; meta = env->me_metas[txn->mt_txnid & 1]; -#endif } else { meta = env->me_metas[ mdb_env_pick_meta(env) ]; txn->mt_txnid = meta->mm_txnid; @@ -4358,6 +4382,10 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl) int fdflags; # define MDB_CLOEXEC 0 #endif +#endif +#ifdef MDB_USE_SYSV_SEM + int semid; + union semun semu; #endif int rc; off_t size, rsize; @@ -4472,17 +4500,10 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl) env->me_wmutex = CreateMutex(&mdb_all_sa, FALSE, env->me_txns->mti_wmname); if (!env->me_wmutex) goto fail_errno; #elif defined(MDB_USE_SYSV_SEM) - union semun semu; unsigned short vals[2] = {1, 1}; - int semid = semget(IPC_PRIVATE, 2, mode); + semid = semget(IPC_PRIVATE, 2, mode); if (semid < 0) goto fail_errno; - - env->me_rmutex.semid = semid; - env->me_wmutex.semid = semid; - env->me_rmutex.semnum = 0; - env->me_wmutex.semnum = 1; - semu.array = vals; if (semctl(semid, 0, SETALL, semu) < 0) goto fail_errno; @@ -4509,8 +4530,6 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl) } else { #ifdef MDB_USE_SYSV_SEM struct semid_ds buf; - union semun semu; - int semid; #endif if (env->me_txns->mti_magic != MDB_MAGIC) { DPUTS("lock region has invalid magic"); @@ -4535,20 +4554,23 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl) #elif defined(MDB_USE_SYSV_SEM) semid = env->me_txns->mti_semid; semu.buf = &buf; - /* check for read access */ if (semctl(semid, 0, IPC_STAT, semu) < 0) goto fail_errno; /* check for write access */ if (semctl(semid, 0, IPC_SET, semu) < 0) goto fail_errno; - - env->me_rmutex.semid = semid; - env->me_wmutex.semid = semid; - env->me_rmutex.semnum = 0; - env->me_wmutex.semnum = 1; #endif } +#ifdef MDB_USE_SYSV_SEM + env->me_rmutex.semid = semid; + env->me_wmutex.semid = semid; + env->me_rmutex.semnum = 0; + env->me_wmutex.semnum = 1; + env->me_rmutex.locked = &env->me_txns->mti_rlocked; + env->me_wmutex.locked = &env->me_txns->mti_wlocked; +#endif + return MDB_SUCCESS; fail_errno: @@ -6140,7 +6162,6 @@ int mdb_cursor_put(MDB_cursor *mc, MDB_val *key, MDB_val *data, unsigned int flags) { - enum { MDB_NO_ROOT = MDB_LAST_ERRCODE+10 }; /* internal code */ MDB_env *env; MDB_node *leaf = NULL; MDB_page *fp, *mp; @@ -9593,7 +9614,7 @@ static int mdb_reader_check0(MDB_env *env, int rlocked, int *dead) #ifdef MDB_ROBUST_SUPPORTED /** Handle #LOCK_MUTEX0() failure. - * With #MDB_ROBUST, try to repair the lock file if the mutex owner died. + * Try to repair the lock file if the mutex owner died. * @param[in] env the environment handle * @param[in] mutex LOCK_MUTEX0() mutex * @param[in] rc LOCK_MUTEX0() error (nonzero) @@ -9602,11 +9623,8 @@ static int mdb_reader_check0(MDB_env *env, int rlocked, int *dead) static int mdb_mutex_failed(MDB_env *env, mdb_mutex_t *mutex, int rc) { int toggle, rlocked, rc2; -#ifndef _WIN32 - enum { WAIT_ABANDONED = EOWNERDEAD }; -#endif - if (rc == (int) WAIT_ABANDONED) { + if (rc == MDB_OWNERDEAD) { /* We own the mutex. Clean up after dead previous owner. */ rc = MDB_SUCCESS; rlocked = (mutex == MDB_MUTEX(env, r)); @@ -9627,7 +9645,7 @@ static int mdb_mutex_failed(MDB_env *env, mdb_mutex_t *mutex, int rc) (rc ? "this process' env is hosed" : "recovering"))); rc2 = mdb_reader_check0(env, rlocked, NULL); if (rc2 == 0) - rc2 = pthread_mutex_consistent(mutex); + rc2 = mdb_mutex_consistent(mutex); if (rc || (rc = rc2)) { DPRINTF(("LOCK_MUTEX recovery failed, %s", mdb_strerror(rc))); UNLOCK_MUTEX(mutex);