Use robust mutexes by default

Making it optional on pthreads just complicates things;
they're always robust on other implementations

diff --git a/libraries/liblmdb/lmdb.h b/libraries/liblmdb/lmdb.h
index 82a5410ab15b9d29703dfde620d26c628e455c7d..4236218bb50cc3beff4516e0004d3584cac365c4 100644 (file)
--- a/libraries/liblmdb/lmdb.h
+++ b/libraries/liblmdb/lmdb.h
@@ -50,12 +50,14 @@
  *
  *       Fix: Check for stale readers periodically, using the
  *       #mdb_reader_check function or the \ref mdb_stat_1 "mdb_stat" tool.
- *       Catch stale
- *       locks with option MDB_ROBUST if supported (non-BSD). Or just
- *       make all programs using the database close it; the lockfile
- *       is always reset on first open of the environment.
+ *       Stale writers will be cleared automatically on most systems:
+ *       - Windows - automatic
+ *       - BSD, systems using SysV semaphores - automatic
+ *       - Linux, systems using POSIX mutexes with Robust option - automatic
+ *       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_POSIX_SEM,
+ *     - On BSD systems or others configured with MDB_USE_SYSV_SEM,
  *       startup can fail due to semaphores owned by another userid.
  *
  *       Fix: Open and close the database as the user which owns the
@@ -290,8 +292,6 @@ typedef void (MDB_rel_func)(MDB_val *item, void *oldptr, void *newptr, void *rel
 #define MDB_NORDAHEAD  0x800000
        /** don't initialize malloc'd memory before writing to datafile */
 #define MDB_NOMEMINIT  0x1000000
-       /** catch stale locks if supported (not on BSD, needs robust mutexes) */
-#define MDB_ROBUST             0x2000000
 /** @} */
 
 /**    @defgroup       mdb_dbi_open    Database Flags
@@ -516,12 +516,6 @@ int  mdb_env_create(MDB_env **env);
         *              Open the environment in read-only mode. No write operations will be
         *              allowed. LMDB will still modify the lock file - except on read-only
         *              filesystems, where LMDB does not use locks.
-        *      <li>#MDB_ROBUST
-        *              Initialize the lockfile to catch stale locks if robust mutexes
-        *              are supported, so aborted processes will not block others.
-        *              Ignored when another process has the environment open. Unsupported
-        *              by liblmdb built with MDB_USE_POSIX_SEM (such as BSD systems).
-        *              Enabled by default on Windows. Some locking slowdown on Unix.
         *      <li>#MDB_WRITEMAP
         *              Use a writeable memory map unless MDB_RDONLY is set. This is faster
         *              and uses fewer mallocs, but loses protection from application bugs

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index a7e6dd7055e532c257332f6033783ff1840d6984..11cdc33d12afb658965eff66b241ffd6faebe535 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -200,7 +200,7 @@ union semun {
 #define MDB_DEVEL 0
 #endif
 
-#if MDB_DEVEL && (defined(_WIN32) || (defined(EOWNERDEAD) && !defined(MDB_USE_SYSV_SEM)))
+#if defined(WIN32) || (defined(EOWNERDEAD) && !defined(MDB_USE_SYSV_SEM))
 #define MDB_ROBUST_SUPPORTED   1
 #endif
 
@@ -670,8 +670,6 @@ typedef struct MDB_txbody {
                 *      when readers release their slots.
                 */
        unsigned        mtb_numreaders;
-               /** Flags which the lock file was initialized with. */
-       unsigned        mtb_flags;
 } MDB_txbody;
 
        /** The actual reader table definition. */
@@ -684,7 +682,6 @@ 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
-#define mti_flags      mt1.mtb.mtb_flags
                char pad[(sizeof(MDB_txbody)+CACHELINE-1) & ~(CACHELINE-1)];
        } mt1;
        union {
@@ -4338,7 +4335,6 @@ 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;
-               env->me_flags |= MDB_ROBUST;
 #elif defined(MDB_USE_SYSV_SEM)
                union semun semu;
                unsigned short vals[2] = {1, 1};
@@ -4361,23 +4357,18 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
                if ((rc = pthread_mutexattr_init(&mattr))
                        || (rc = pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED))
 #ifdef MDB_ROBUST_SUPPORTED
-                       || ((env->me_flags & MDB_ROBUST) &&
-                               (rc = pthread_mutexattr_setrobust(&mattr, PTHREAD_MUTEX_ROBUST)))
+                       || (rc = pthread_mutexattr_setrobust(&mattr, PTHREAD_MUTEX_ROBUST))
 #endif
                        || (rc = pthread_mutex_init(&env->me_txns->mti_rmutex, &mattr))
                        || (rc = pthread_mutex_init(&env->me_txns->mti_wmutex, &mattr)))
                        goto fail;
                pthread_mutexattr_destroy(&mattr);
 #endif /* _WIN32 || MDB_USE_SYSV_SEM */
-#ifndef MDB_ROBUST_SUPPORTED
-               env->me_flags &= ~MDB_ROBUST;
-#endif
 
                env->me_txns->mti_magic = MDB_MAGIC;
                env->me_txns->mti_format = MDB_LOCK_FORMAT;
                env->me_txns->mti_txnid = 0;
                env->me_txns->mti_numreaders = 0;
-               env->me_txns->mti_flags = env->me_flags;
 
        } else {
                if (env->me_txns->mti_magic != MDB_MAGIC) {
@@ -4395,8 +4386,6 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
                if (rc && rc != EACCES && rc != EAGAIN) {
                        goto fail;
                }
-               env->me_flags = (env->me_flags & ~MDB_ROBUST) |
-                       (env->me_txns->mti_flags & MDB_ROBUST);
 #ifdef _WIN32
                env->me_rmutex = OpenMutex(SYNCHRONIZE, FALSE, env->me_txns->mti_rmname);
                if (!env->me_rmutex) goto fail_errno;
@@ -4440,13 +4429,8 @@ fail:
         *      environment and re-opening it with the new flags.
         */
 #define        CHANGEABLE      (MDB_NOSYNC|MDB_NOMETASYNC|MDB_MAPASYNC|MDB_NOMEMINIT)
-#define        CHANGELESS      (MDB_FIXEDMAP|MDB_NOSUBDIR|MDB_RDONLY|ROBUST_FLAG| \
+#define        CHANGELESS      (MDB_FIXEDMAP|MDB_NOSUBDIR|MDB_RDONLY| \
        MDB_WRITEMAP|MDB_NOTLS|MDB_NOLOCK|MDB_NORDAHEAD)
-#ifdef MDB_ROBUST_SUPPORTED
-#define ROBUST_FLAG MDB_ROBUST
-#else
-#define ROBUST_FLAG 0
-#endif
 
 #if VALID_FLAGS & PERSISTENT_FLAGS & (CHANGEABLE|CHANGELESS)
 # error "Persistent DB flags & env flags overlap, but both go in mm_flags"
@@ -9481,7 +9465,7 @@ 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;
+       int rlocked, rc2;
 #ifndef _WIN32
        enum { WAIT_ABANDONED = EOWNERDEAD };
 #endif
@@ -9491,12 +9475,6 @@ static int mdb_mutex_failed(MDB_env *env, mdb_mutex_t *mutex, int rc)
                rc = MDB_SUCCESS;
                rlocked = (mutex == MDB_MUTEX(env, r));
                if (!rlocked) {
-                       /* Keep mti_txnid updated, otherwise next writer can
-                        * overwrite data which latest meta page refers to.
-                        * TODO: Instead revert any aborted commit and sync?
-                        */
-                       toggle = mdb_env_pick_meta(env);
-                       env->me_txns->mti_txnid = env->me_metas[toggle]->mm_txnid;
                        /* env is hosed if the dead thread was ours */
                        if (env->me_txn) {
                                env->me_flags |= MDB_FATAL_ERROR;