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Use robust mutexes by default
Making it optional on pthreads just complicates things; they're always robust on other implementations
This commit is contained in:
Howard Chu
parent
58ddb5527b
commit
e3b6c359a9
2 changed files with 11 additions and 39 deletions
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@ -50,12 +50,14 @@
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*
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* Fix: Check for stale readers periodically, using the
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* #mdb_reader_check function or the \ref mdb_stat_1 "mdb_stat" tool.
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* Catch stale
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* locks with option MDB_ROBUST if supported (non-BSD). Or just
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* make all programs using the database close it; the lockfile
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* is always reset on first open of the environment.
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* Stale writers will be cleared automatically on most systems:
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* - Windows - automatic
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* - BSD, systems using SysV semaphores - automatic
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* - Linux, systems using POSIX mutexes with Robust option - automatic
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* Otherwise just make all programs using the database close it;
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* the lockfile is always reset on first open of the environment.
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*
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* - On BSD systems or others configured with MDB_USE_POSIX_SEM,
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* - On BSD systems or others configured with MDB_USE_SYSV_SEM,
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* startup can fail due to semaphores owned by another userid.
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*
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* Fix: Open and close the database as the user which owns the
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@ -290,8 +292,6 @@ typedef void (MDB_rel_func)(MDB_val *item, void *oldptr, void *newptr, void *rel
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#define MDB_NORDAHEAD 0x800000
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/** don't initialize malloc'd memory before writing to datafile */
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#define MDB_NOMEMINIT 0x1000000
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/** catch stale locks if supported (not on BSD, needs robust mutexes) */
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#define MDB_ROBUST 0x2000000
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/** @} */
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/** @defgroup mdb_dbi_open Database Flags
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@ -516,12 +516,6 @@ int mdb_env_create(MDB_env **env);
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* Open the environment in read-only mode. No write operations will be
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* allowed. LMDB will still modify the lock file - except on read-only
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* filesystems, where LMDB does not use locks.
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* <li>#MDB_ROBUST
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* Initialize the lockfile to catch stale locks if robust mutexes
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* are supported, so aborted processes will not block others.
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* Ignored when another process has the environment open. Unsupported
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* by liblmdb built with MDB_USE_POSIX_SEM (such as BSD systems).
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* Enabled by default on Windows. Some locking slowdown on Unix.
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* <li>#MDB_WRITEMAP
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* Use a writeable memory map unless MDB_RDONLY is set. This is faster
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* and uses fewer mallocs, but loses protection from application bugs
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@ -200,7 +200,7 @@ union semun {
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#define MDB_DEVEL 0
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#endif
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#if MDB_DEVEL && (defined(_WIN32) || (defined(EOWNERDEAD) && !defined(MDB_USE_SYSV_SEM)))
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#if defined(WIN32) || (defined(EOWNERDEAD) && !defined(MDB_USE_SYSV_SEM))
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#define MDB_ROBUST_SUPPORTED 1
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#endif
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@ -670,8 +670,6 @@ typedef struct MDB_txbody {
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* when readers release their slots.
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*/
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unsigned mtb_numreaders;
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/** Flags which the lock file was initialized with. */
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unsigned mtb_flags;
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} MDB_txbody;
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/** The actual reader table definition. */
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@ -684,7 +682,6 @@ typedef struct MDB_txninfo {
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#define mti_rmname mt1.mtb.mtb_rmname
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#define mti_txnid mt1.mtb.mtb_txnid
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#define mti_numreaders mt1.mtb.mtb_numreaders
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#define mti_flags mt1.mtb.mtb_flags
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char pad[(sizeof(MDB_txbody)+CACHELINE-1) & ~(CACHELINE-1)];
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} mt1;
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union {
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@ -4338,7 +4335,6 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
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if (!env->me_rmutex) goto fail_errno;
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env->me_wmutex = CreateMutex(&mdb_all_sa, FALSE, env->me_txns->mti_wmname);
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if (!env->me_wmutex) goto fail_errno;
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env->me_flags |= MDB_ROBUST;
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#elif defined(MDB_USE_SYSV_SEM)
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union semun semu;
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unsigned short vals[2] = {1, 1};
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@ -4361,23 +4357,18 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
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if ((rc = pthread_mutexattr_init(&mattr))
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|| (rc = pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED))
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#ifdef MDB_ROBUST_SUPPORTED
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|| ((env->me_flags & MDB_ROBUST) &&
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(rc = pthread_mutexattr_setrobust(&mattr, PTHREAD_MUTEX_ROBUST)))
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|| (rc = pthread_mutexattr_setrobust(&mattr, PTHREAD_MUTEX_ROBUST))
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#endif
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|| (rc = pthread_mutex_init(&env->me_txns->mti_rmutex, &mattr))
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|| (rc = pthread_mutex_init(&env->me_txns->mti_wmutex, &mattr)))
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goto fail;
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pthread_mutexattr_destroy(&mattr);
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#endif /* _WIN32 || MDB_USE_SYSV_SEM */
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#ifndef MDB_ROBUST_SUPPORTED
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env->me_flags &= ~MDB_ROBUST;
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#endif
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env->me_txns->mti_magic = MDB_MAGIC;
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env->me_txns->mti_format = MDB_LOCK_FORMAT;
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env->me_txns->mti_txnid = 0;
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env->me_txns->mti_numreaders = 0;
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env->me_txns->mti_flags = env->me_flags;
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} else {
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if (env->me_txns->mti_magic != MDB_MAGIC) {
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@ -4395,8 +4386,6 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
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if (rc && rc != EACCES && rc != EAGAIN) {
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goto fail;
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}
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env->me_flags = (env->me_flags & ~MDB_ROBUST) |
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(env->me_txns->mti_flags & MDB_ROBUST);
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#ifdef _WIN32
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env->me_rmutex = OpenMutex(SYNCHRONIZE, FALSE, env->me_txns->mti_rmname);
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if (!env->me_rmutex) goto fail_errno;
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@ -4440,13 +4429,8 @@ fail:
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* environment and re-opening it with the new flags.
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*/
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#define CHANGEABLE (MDB_NOSYNC|MDB_NOMETASYNC|MDB_MAPASYNC|MDB_NOMEMINIT)
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#define CHANGELESS (MDB_FIXEDMAP|MDB_NOSUBDIR|MDB_RDONLY|ROBUST_FLAG| \
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#define CHANGELESS (MDB_FIXEDMAP|MDB_NOSUBDIR|MDB_RDONLY| \
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MDB_WRITEMAP|MDB_NOTLS|MDB_NOLOCK|MDB_NORDAHEAD)
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#ifdef MDB_ROBUST_SUPPORTED
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#define ROBUST_FLAG MDB_ROBUST
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#else
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#define ROBUST_FLAG 0
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#endif
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#if VALID_FLAGS & PERSISTENT_FLAGS & (CHANGEABLE|CHANGELESS)
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# error "Persistent DB flags & env flags overlap, but both go in mm_flags"
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@ -9481,7 +9465,7 @@ static int mdb_reader_check0(MDB_env *env, int rlocked, int *dead)
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*/
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static int mdb_mutex_failed(MDB_env *env, mdb_mutex_t *mutex, int rc)
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{
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int toggle, rlocked, rc2;
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int rlocked, rc2;
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#ifndef _WIN32
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enum { WAIT_ABANDONED = EOWNERDEAD };
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#endif
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@ -9491,12 +9475,6 @@ static int mdb_mutex_failed(MDB_env *env, mdb_mutex_t *mutex, int rc)
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rc = MDB_SUCCESS;
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rlocked = (mutex == MDB_MUTEX(env, r));
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if (!rlocked) {
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/* Keep mti_txnid updated, otherwise next writer can
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* overwrite data which latest meta page refers to.
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* TODO: Instead revert any aborted commit and sync?
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*/
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toggle = mdb_env_pick_meta(env);
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env->me_txns->mti_txnid = env->me_metas[toggle]->mm_txnid;
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/* env is hosed if the dead thread was ours */
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if (env->me_txn) {
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env->me_flags |= MDB_FATAL_ERROR;
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