From 58ddb5527bd4868bb7017cfe2051bc2e24bcf5a8 Mon Sep 17 00:00:00 2001 From: Howard Chu Date: Sun, 20 Jul 2014 11:08:55 -0700 Subject: [PATCH] Use SysV semaphores instead of POSIX Since they can cleanup after themselves on process exit --- libraries/liblmdb/mdb.c | 167 ++++++++++++++++++----------------- libraries/liblmdb/mdb_copy.c | 2 +- 2 files changed, 88 insertions(+), 81 deletions(-) diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c index 6179b57868..a7e6dd7055 100644 --- a/libraries/liblmdb/mdb.c +++ b/libraries/liblmdb/mdb.c @@ -102,7 +102,7 @@ extern int cacheflush(char *addr, int nbytes, int cache); #endif #if defined(__APPLE__) || defined (BSD) -# define MDB_USE_POSIX_SEM 1 +# define MDB_USE_SYSV_SEM 1 # define MDB_FDATASYNC fsync #elif defined(ANDROID) # define MDB_FDATASYNC fsync @@ -110,11 +110,18 @@ extern int cacheflush(char *addr, int nbytes, int cache); #ifndef _WIN32 #include -#ifdef MDB_USE_POSIX_SEM -# define MDB_USE_HASH 1 -#include -#endif -#endif +#ifdef MDB_USE_SYSV_SEM +#include +#include +#ifdef _SEM_SEMUN_UNDEFINED +union semun { + int val; + struct semid_ds *buf; + unsigned short *array; +}; +#endif /* _SEM_SEMUN_UNDEFINED */ +#endif /* MDB_USE_SYSV_SEM */ +#endif /* !_WIN32 */ #ifdef USE_VALGRIND #include @@ -193,7 +200,7 @@ extern int cacheflush(char *addr, int nbytes, int cache); #define MDB_DEVEL 0 #endif -#if MDB_DEVEL && (defined(_WIN32) || (defined(EOWNERDEAD) && !defined(MDB_USE_POSIX_SEM))) +#if MDB_DEVEL && (defined(_WIN32) || (defined(EOWNERDEAD) && !defined(MDB_USE_SYSV_SEM))) #define MDB_ROBUST_SUPPORTED 1 #endif @@ -254,25 +261,30 @@ typedef HANDLE mdb_mutex_t; /** For MDB_LOCK_FORMAT: True if readers take a pid lock in the lockfile */ #define MDB_PIDLOCK 1 -#ifdef MDB_USE_POSIX_SEM +#ifdef MDB_USE_SYSV_SEM -typedef sem_t *mdb_mutex_t; -#define MDB_MUTEX(env, rw) ((env)->me_##rw##mutex) +typedef struct mdb_mutex { + int semid; + int semnum; +} mdb_mutex_t; + +#define MDB_MUTEX(env, rw) (&(env)->me_##rw##mutex) #define LOCK_MUTEX0(mutex) mdb_sem_wait(mutex) -#define UNLOCK_MUTEX(mutex) sem_post(mutex) +#define UNLOCK_MUTEX(mutex) do { struct sembuf sb = { mutex->semnum, 1, SEM_UNDO }; semop(mutex->semid, &sb, 1); } while(0) static int -mdb_sem_wait(sem_t *sem) +mdb_sem_wait(mdb_mutex_t *sem) { int rc; - while ((rc = sem_wait(sem)) && (rc = errno) == EINTR) ; + struct sembuf sb = { sem->semnum, -1, SEM_UNDO }; + while ((rc = semop(sem->semid, &sb, 1)) && (rc = errno) == EINTR) ; return rc; } #else /** Pointer/HANDLE type of shared mutex/semaphore. */ -typedef pthread_mutex_t *mdb_mutex_t; +typedef pthread_mutex_t mdb_mutex_t; /** Mutex for the reader table (rw = r) or write transaction (rw = w). */ #define MDB_MUTEX(env, rw) (&(env)->me_txns->mti_##rw##mutex) @@ -283,7 +295,7 @@ typedef pthread_mutex_t *mdb_mutex_t; /** Unlock the reader or writer mutex. */ #define UNLOCK_MUTEX(mutex) pthread_mutex_unlock(mutex) -#endif /* MDB_USE_POSIX_SEM */ +#endif /* MDB_USE_SYSV_SEM */ /** Get the error code for the last failed system function. */ @@ -308,8 +320,10 @@ typedef pthread_mutex_t *mdb_mutex_t; #define GET_PAGESIZE(x) ((x) = sysconf(_SC_PAGE_SIZE)) #endif -#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM) +#if defined(_WIN32) #define MNAME_LEN 32 +#elif defined(MDB_USE_SYSV_SEM) +#define MNAME_LEN 0 #else #define MNAME_LEN (sizeof(pthread_mutex_t)) #endif @@ -323,7 +337,7 @@ typedef pthread_mutex_t *mdb_mutex_t; #define LOCK_MUTEX(rc, env, mutex) \ (((rc) = LOCK_MUTEX0(mutex)) && \ ((rc) = mdb_mutex_failed(env, mutex, rc))) -static int mdb_mutex_failed(MDB_env *env, mdb_mutex_t mutex, int rc); +static int mdb_mutex_failed(MDB_env *env, mdb_mutex_t *mutex, int rc); #else #define LOCK_MUTEX(rc, env, mutex) ((rc) = LOCK_MUTEX0(mutex)) #define mdb_mutex_failed(env, mutex, rc) (rc) @@ -636,8 +650,10 @@ typedef struct MDB_txbody { uint32_t mtb_magic; /** Format of this lock file. Must be set to #MDB_LOCK_FORMAT. */ uint32_t mtb_format; -#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM) +#if defined(_WIN32) char mtb_rmname[MNAME_LEN]; +#elif defined(MDB_USE_SYSV_SEM) + int mtb_semid; #else /** Mutex protecting access to this table. * This is the #MDB_MUTEX(env,r) reader table lock. @@ -672,9 +688,11 @@ typedef struct MDB_txninfo { char pad[(sizeof(MDB_txbody)+CACHELINE-1) & ~(CACHELINE-1)]; } mt1; union { -#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM) +#if defined(_WIN32) char mt2_wmname[MNAME_LEN]; #define mti_wmname mt2.mt2_wmname +#elif defined(MDB_USE_SYSV_SEM) +#define mti_semid mt1.mtb.mtb_semid #else pthread_mutex_t mt2_wmutex; #define mti_wmutex mt2.mt2_wmutex @@ -1157,8 +1175,8 @@ struct MDB_env { #ifdef _WIN32 int me_pidquery; /**< Used in OpenProcess */ #endif -#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM) - /* Windows mutexes/POSIX semaphores do not reside in shared mem */ +#if defined(_WIN32) || defined(MDB_USE_SYSV_SEM) + /* Windows mutexes/SysV semaphores do not reside in shared mem */ mdb_mutex_t me_rmutex; mdb_mutex_t me_wmutex; #endif @@ -1212,7 +1230,7 @@ static int mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, static int mdb_env_read_header(MDB_env *env, MDB_meta *meta); static int mdb_env_pick_meta(const MDB_env *env); static int mdb_env_write_meta(MDB_txn *txn); -#if !(defined(_WIN32) || defined(MDB_USE_POSIX_SEM)) /* Drop unused excl arg */ +#if !(defined(_WIN32) || defined(MDB_USE_SYSV_SEM)) /* Drop unused excl arg */ # define mdb_env_close0(env, excl) mdb_env_close1(env) #endif static void mdb_env_close0(MDB_env *env, int excl); @@ -2510,7 +2528,7 @@ mdb_txn_renew0(MDB_txn *txn) } else { MDB_PID_T pid = env->me_pid; MDB_THR_T tid = pthread_self(); - mdb_mutex_t rmutex = MDB_MUTEX(env, r); + mdb_mutex_t *rmutex = MDB_MUTEX(env, r); if (!env->me_live_reader) { rc = mdb_reader_pid(env, Pidset, pid); @@ -3695,9 +3713,9 @@ mdb_env_create(MDB_env **env) e->me_fd = INVALID_HANDLE_VALUE; e->me_lfd = INVALID_HANDLE_VALUE; e->me_mfd = INVALID_HANDLE_VALUE; -#ifdef MDB_USE_POSIX_SEM - e->me_rmutex = SEM_FAILED; - e->me_wmutex = SEM_FAILED; +#ifdef MDB_USE_SYSV_SEM + e->me_rmutex.semid = -1; + e->me_wmutex.semid = -1; #endif e->me_pid = getpid(); GET_PAGESIZE(e->me_os_psize); @@ -4080,8 +4098,8 @@ mdb_env_excl_lock(MDB_env *env, int *excl) if (!rc) { *excl = 1; } else -# ifdef MDB_USE_POSIX_SEM - if (*excl < 0) /* always true when !MDB_USE_POSIX_SEM */ +# ifdef MDB_USE_SYSV_SEM + if (*excl < 0) /* always true when !MDB_USE_SYSV_SEM */ # endif { lock_info.l_type = F_RDLCK; @@ -4321,41 +4339,23 @@ 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; env->me_flags |= MDB_ROBUST; -#elif defined(MDB_USE_POSIX_SEM) - struct stat stbuf; - struct { - dev_t dev; - ino_t ino; - } idbuf; - MDB_val val; - char encbuf[11]; +#elif defined(MDB_USE_SYSV_SEM) + union semun semu; + unsigned short vals[2] = {1, 1}; + int semid = semget(IPC_PRIVATE, 2, mode); + if (semid < 0) + goto fail_errno; -#if defined(__NetBSD__) -#define MDB_SHORT_SEMNAMES 1 /* limited to 14 chars */ -#endif - if (fstat(env->me_lfd, &stbuf)) goto fail_errno; - idbuf.dev = stbuf.st_dev; - idbuf.ino = stbuf.st_ino; - val.mv_data = &idbuf; - val.mv_size = sizeof(idbuf); - mdb_hash_enc(&val, encbuf); -#ifdef MDB_SHORT_SEMNAMES - encbuf[9] = '\0'; /* drop name from 15 chars to 14 chars */ -#endif - sprintf(env->me_txns->mti_rmname, "/MDBr%s", encbuf); - sprintf(env->me_txns->mti_wmname, "/MDBw%s", encbuf); - /* Clean up after a previous run, if needed: Try to - * remove both semaphores before doing anything else. - */ - sem_unlink(env->me_txns->mti_rmname); - sem_unlink(env->me_txns->mti_wmname); - env->me_rmutex = sem_open(env->me_txns->mti_rmname, - O_CREAT|O_EXCL, mode, 1); - if (env->me_rmutex == SEM_FAILED) goto fail_errno; - env->me_wmutex = sem_open(env->me_txns->mti_wmname, - O_CREAT|O_EXCL, mode, 1); - if (env->me_wmutex == SEM_FAILED) goto fail_errno; -#else /* MDB_USE_POSIX_SEM */ + 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; + env->me_txns->mti_semid = semid; +#else /* MDB_USE_SYSV_SEM */ pthread_mutexattr_t mattr; if ((rc = pthread_mutexattr_init(&mattr)) @@ -4368,7 +4368,7 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl) || (rc = pthread_mutex_init(&env->me_txns->mti_wmutex, &mattr))) goto fail; pthread_mutexattr_destroy(&mattr); -#endif /* _WIN32 || MDB_USE_POSIX_SEM */ +#endif /* _WIN32 || MDB_USE_SYSV_SEM */ #ifndef MDB_ROBUST_SUPPORTED env->me_flags &= ~MDB_ROBUST; #endif @@ -4402,11 +4402,23 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl) if (!env->me_rmutex) goto fail_errno; env->me_wmutex = OpenMutex(SYNCHRONIZE, FALSE, env->me_txns->mti_wmname); if (!env->me_wmutex) goto fail_errno; -#elif defined(MDB_USE_POSIX_SEM) - env->me_rmutex = sem_open(env->me_txns->mti_rmname, 0); - if (env->me_rmutex == SEM_FAILED) goto fail_errno; - env->me_wmutex = sem_open(env->me_txns->mti_wmname, 0); - if (env->me_wmutex == SEM_FAILED) goto fail_errno; +#elif defined(MDB_USE_SYSV_SEM) + struct semid_ds buf; + union semun semu; + int 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 } return MDB_SUCCESS; @@ -4642,20 +4654,15 @@ mdb_env_close0(MDB_env *env, int excl) /* Windows automatically destroys the mutexes when * the last handle closes. */ -#elif defined(MDB_USE_POSIX_SEM) - if (env->me_rmutex != SEM_FAILED) { - sem_close(env->me_rmutex); - if (env->me_wmutex != SEM_FAILED) - sem_close(env->me_wmutex); +#elif defined(MDB_USE_SYSV_SEM) + if (env->me_rmutex.semid != -1) { /* If we have the filelock: If we are the * only remaining user, clean up semaphores. */ if (excl == 0) mdb_env_excl_lock(env, &excl); - if (excl > 0) { - sem_unlink(env->me_txns->mti_rmname); - sem_unlink(env->me_txns->mti_wmname); - } + if (excl > 0) + semctl(env->me_rmutex.semid, 0, IPC_RMID); } #endif munmap((void *)env->me_txns, (env->me_maxreaders-1)*sizeof(MDB_reader)+sizeof(MDB_txninfo)); @@ -8664,7 +8671,7 @@ static int ESECT mdb_env_copyfd0(MDB_env *env, HANDLE fd) { MDB_txn *txn = NULL; - mdb_mutex_t wmutex = NULL; + mdb_mutex_t *wmutex = NULL; int rc; size_t wsize; char *ptr; @@ -9415,7 +9422,7 @@ mdb_reader_check(MDB_env *env, int *dead) /** As #mdb_reader_check(). rlocked = . */ static int mdb_reader_check0(MDB_env *env, int rlocked, int *dead) { - mdb_mutex_t rmutex = rlocked ? NULL : MDB_MUTEX(env, r); + mdb_mutex_t *rmutex = rlocked ? NULL : MDB_MUTEX(env, r); unsigned int i, j, rdrs; MDB_reader *mr; MDB_PID_T *pids, pid; @@ -9472,7 +9479,7 @@ static int mdb_reader_check0(MDB_env *env, int rlocked, int *dead) * @param[in] rc LOCK_MUTEX0() error (nonzero) * @return 0 on success with the mutex locked, or an error code on failure. */ -static int mdb_mutex_failed(MDB_env *env, mdb_mutex_t mutex, int rc) +static int mdb_mutex_failed(MDB_env *env, mdb_mutex_t *mutex, int rc) { int toggle, rlocked, rc2; #ifndef _WIN32 diff --git a/libraries/liblmdb/mdb_copy.c b/libraries/liblmdb/mdb_copy.c index e7f965c03a..af0a941110 100644 --- a/libraries/liblmdb/mdb_copy.c +++ b/libraries/liblmdb/mdb_copy.c @@ -64,7 +64,7 @@ int main(int argc,char * argv[]) act = "opening environment"; rc = mdb_env_create(&env); if (rc == MDB_SUCCESS) { - rc = mdb_env_open(env, argv[1], flags, 0664); + rc = mdb_env_open(env, argv[1], flags, 0600); } if (rc == MDB_SUCCESS) { act = "copying"; -- 2.39.5