Restore support for Posix semaphores

diff --git a/libraries/liblmdb/Makefile b/libraries/liblmdb/Makefile
index 2d0983eff04457c8f0e8d2cf785f23de46ca6606..a8ea9706fa504bc66f81bbaadc32a03f0e80fa39 100644 (file)
--- a/libraries/liblmdb/Makefile
+++ b/libraries/liblmdb/Makefile
@@ -8,7 +8,7 @@
 # platforms; you should not need to change any of these.
 # Read their descriptions in mdb.c if you do:
 #
-# - MDB_USE_POSIX_SEM
+# - MDB_USE_POSIX_MUTEX, MDB_USE_POSIX_SEM, MDB_USE_SYSV_SEM
 # - MDB_DSYNC
 # - MDB_FDATASYNC
 # - MDB_FDATASYNC_WORKS

diff --git a/libraries/liblmdb/lmdb.h b/libraries/liblmdb/lmdb.h
index e9a01a5cb9a67f649f87aa3ad8ff4db9b3b3011f..deb6812578a0d365396e6f9012a8312f7c99939d 100644 (file)
--- a/libraries/liblmdb/lmdb.h
+++ b/libraries/liblmdb/lmdb.h
@@ -57,7 +57,8 @@
  *       Otherwise just make all programs using the database close it;
  *       the lockfile is always reset on first open of the environment.
  *
- *     - On BSD systems or others configured with MDB_USE_SYSV_SEM,
+ *     - On BSD systems or others configured with MDB_USE_SYSV_SEM or
+ *       MDB_USE_POSIX_SEM,
  *       startup can fail due to semaphores owned by another userid.
  *
  *       Fix: Open and close the database as the user which owns the

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 0fc3ab7242f23932eb9c200dc78e46016c07dce1..2d2486d02bd4accd6a8390f5f8affcf88e1d986d 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -110,7 +110,9 @@ extern int cacheflush(char *addr, int nbytes, int cache);
 #endif
 
 #if defined(__APPLE__) || defined (BSD)
+# if !(defined(MDB_USE_POSIX_MUTEX) || defined(MDB_USE_POSIX_SEM))
 # define MDB_USE_SYSV_SEM      1
+# endif
 # define MDB_FDATASYNC         fsync
 #elif defined(ANDROID)
 # define MDB_FDATASYNC         fsync
@@ -118,7 +120,10 @@ extern int cacheflush(char *addr, int nbytes, int cache);
 
 #ifndef _WIN32
 #include <pthread.h>
-#ifdef MDB_USE_SYSV_SEM
+#ifdef MDB_USE_POSIX_SEM
+# define MDB_USE_HASH          1
+#include <semaphore.h>
+#elif defined(MDB_USE_SYSV_SEM)
 #include <sys/ipc.h>
 #include <sys/sem.h>
 #ifdef _SEM_SEMUN_UNDEFINED
@@ -130,10 +135,10 @@ union semun {
 #endif /* _SEM_SEMUN_UNDEFINED */
 #else
 #define MDB_USE_POSIX_MUTEX    1
-#endif /* MDB_USE_SYSV_SEM */
+#endif /* MDB_USE_POSIX_SEM */
 #endif /* !_WIN32 */
 
-#if defined(_WIN32) + defined(MDB_USE_SYSV_SEM) \
+#if defined(_WIN32) + defined(MDB_USE_POSIX_SEM) + defined(MDB_USE_SYSV_SEM) \
        + defined(MDB_USE_POSIX_MUTEX) != 1
 # error "Ambiguous shared-lock implementation"
 #endif
@@ -285,7 +290,21 @@ typedef HANDLE mdb_mutex_t, mdb_mutexref_t;
        /** For MDB_LOCK_FORMAT: True if readers take a pid lock in the lockfile */
 #define MDB_PIDLOCK                    1
 
-#ifdef MDB_USE_SYSV_SEM
+#ifdef MDB_USE_POSIX_SEM
+
+typedef sem_t *mdb_mutex_t, *mdb_mutexref_t;
+#define LOCK_MUTEX0(mutex)             mdb_sem_wait(mutex)
+#define UNLOCK_MUTEX(mutex)            sem_post(mutex)
+
+static int
+mdb_sem_wait(sem_t *sem)
+{
+   int rc;
+   while ((rc = sem_wait(sem)) && (rc = errno) == EINTR) ;
+   return rc;
+}
+
+#elif defined MDB_USE_SYSV_SEM
 
 typedef struct mdb_mutex {
        int semid;
@@ -339,7 +358,7 @@ typedef pthread_mutex_t mdb_mutex_t[1], *mdb_mutexref_t;
        /** 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 */
+#endif /* MDB_USE_POSIX_SEM || MDB_USE_SYSV_SEM */
 
        /** Get the error code for the last failed system function.
         */
@@ -364,7 +383,7 @@ typedef pthread_mutex_t mdb_mutex_t[1], *mdb_mutexref_t;
 #define        GET_PAGESIZE(x) ((x) = sysconf(_SC_PAGE_SIZE))
 #endif
 
-#if defined(_WIN32)
+#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM)
 #define MNAME_LEN      32
 #elif defined(MDB_USE_SYSV_SEM)
 #define MNAME_LEN      (sizeof(int))
@@ -705,7 +724,7 @@ 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)
+#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM)
        char    mtb_rmname[MNAME_LEN];
 #elif defined(MDB_USE_SYSV_SEM)
        int     mtb_semid;
@@ -745,7 +764,7 @@ typedef struct MDB_txninfo {
                char pad[(sizeof(MDB_txbody)+CACHELINE-1) & ~(CACHELINE-1)];
        } mt1;
        union {
-#if defined(_WIN32)
+#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM)
                char mt2_wmname[MNAME_LEN];
 #define        mti_wmname      mt2.mt2_wmname
 #elif defined MDB_USE_SYSV_SEM
@@ -3840,7 +3859,10 @@ 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_SYSV_SEM
+#ifdef MDB_USE_POSIX_SEM
+       e->me_rmutex = SEM_FAILED;
+       e->me_wmutex = SEM_FAILED;
+#elif defined MDB_USE_SYSV_SEM
        e->me_rmutex->semid = -1;
        e->me_wmutex->semid = -1;
 #endif
@@ -4556,6 +4578,40 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
                if (!env->me_rmutex) goto fail_errno;
                env->me_wmutex = CreateMutex(&mdb_all_sa, FALSE, env->me_txns->mti_wmname);
                if (!env->me_wmutex) goto fail_errno;
+#elif defined(MDB_USE_POSIX_SEM)
+               struct stat stbuf;
+               struct {
+                       dev_t dev;
+                       ino_t ino;
+               } idbuf;
+               MDB_val val;
+               char encbuf[11];
+
+#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;
 #elif defined(MDB_USE_SYSV_SEM)
                unsigned short vals[2] = {1, 1};
                key_t key = ftok(lpath, 'M');
@@ -4580,7 +4636,7 @@ 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_SYSV_SEM */
+#endif /* _WIN32 || ... */
 
                env->me_txns->mti_magic = MDB_MAGIC;
                env->me_txns->mti_format = MDB_LOCK_FORMAT;
@@ -4611,6 +4667,11 @@ 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)
                semid = env->me_txns->mti_semid;
                semu.buf = &buf;
@@ -4864,6 +4925,21 @@ 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);
+                       /* 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);
+                       }
+               }
 #elif defined(MDB_USE_SYSV_SEM)
                if (env->me_rmutex->semid != -1) {
                        /* If we have the filelock:  If we are the