deadlock detection and claim a deadlock when progress can be
made. For those OSes we may loop for a while.
*/
-int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len)
+int tdb_allrecord_upgrade(struct tdb_context *tdb)
{
int count = 1000;
+
+ if (tdb->allrecord_lock.count != 1) {
+ TDB_LOG((tdb, TDB_DEBUG_ERROR,
+ "tdb_allrecord_upgrade failed: count %u too high\n",
+ tdb->allrecord_lock.count));
+ return -1;
+ }
+
+ if (tdb->allrecord_lock.off != 1) {
+ TDB_LOG((tdb, TDB_DEBUG_ERROR,
+ "tdb_allrecord_upgrade failed: already upgraded?\n"));
+ return -1;
+ }
+
while (count--) {
struct timeval tv;
- if (tdb_brlock(tdb, F_WRLCK, offset, len,
+ if (tdb_brlock(tdb, F_WRLCK, FREELIST_TOP, 0,
TDB_LOCK_WAIT|TDB_LOCK_PROBE) == 0) {
+ tdb->allrecord_lock.ltype = F_WRLCK;
+ tdb->allrecord_lock.off = 0;
return 0;
}
if (errno != EDEADLK) {
tv.tv_usec = 1;
select(0, NULL, NULL, NULL, &tv);
}
- TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock_upgrade failed at offset %d\n", offset));
+ TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_allrecord_upgrade failed\n"));
return -1;
}
+/* list -1 is the alloc list, otherwise a hash chain. */
+static tdb_off_t lock_offset(int list)
+{
+ return FREELIST_TOP + 4*list;
+}
-/* lock a list in the database. list -1 is the alloc list */
-static int _tdb_lock(struct tdb_context *tdb, int list, int ltype,
- enum tdb_lock_flags flags)
+static struct tdb_lock_type *find_nestlock(struct tdb_context *tdb,
+ tdb_off_t offset)
{
- struct tdb_lock_type *new_lck;
- int i;
+ unsigned int i;
- /* a allrecord lock allows us to avoid per chain locks */
- if (tdb->allrecord_lock.count &&
- (ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
- return 0;
+ for (i=0; i<tdb->num_lockrecs; i++) {
+ if (tdb->lockrecs[i].off == offset) {
+ return &tdb->lockrecs[i];
+ }
}
+ return NULL;
+}
- if (tdb->allrecord_lock.count) {
- tdb->ecode = TDB_ERR_LOCK;
- return -1;
- }
+/* lock an offset in the database. */
+int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
+ enum tdb_lock_flags flags)
+{
+ struct tdb_lock_type *new_lck;
- if (list < -1 || list >= (int)tdb->header.hash_size) {
+ if (offset >= lock_offset(tdb->header.hash_size)) {
tdb->ecode = TDB_ERR_LOCK;
- TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid list %d for ltype=%d\n",
- list, ltype));
+ TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid offset %u for ltype=%d\n",
+ offset, ltype));
return -1;
}
if (tdb->flags & TDB_NOLOCK)
return 0;
- for (i=0; i<tdb->num_lockrecs; i++) {
- if (tdb->lockrecs[i].list == list) {
- if (tdb->lockrecs[i].count == 0) {
- /*
- * Can't happen, see tdb_unlock(). It should
- * be an assert.
- */
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock: "
- "lck->count == 0 for list %d", list));
- }
- /*
- * Just increment the in-memory struct, posix locks
- * don't stack.
- */
- tdb->lockrecs[i].count++;
- return 0;
- }
+ new_lck = find_nestlock(tdb, offset);
+ if (new_lck) {
+ /*
+ * Just increment the in-memory struct, posix locks
+ * don't stack.
+ */
+ new_lck->count++;
+ return 0;
}
new_lck = (struct tdb_lock_type *)realloc(
/* Since fcntl locks don't nest, we do a lock for the first one,
and simply bump the count for future ones */
- if (tdb->methods->brlock(tdb, ltype, FREELIST_TOP+4*list, 1, flags)) {
+ if (tdb->methods->brlock(tdb, ltype, offset, 1, flags)) {
return -1;
}
- tdb->num_locks++;
-
- tdb->lockrecs[tdb->num_lockrecs].list = list;
+ tdb->lockrecs[tdb->num_lockrecs].off = offset;
tdb->lockrecs[tdb->num_lockrecs].count = 1;
tdb->lockrecs[tdb->num_lockrecs].ltype = ltype;
- tdb->num_lockrecs += 1;
+ tdb->num_lockrecs++;
return 0;
}
{
int ret;
- ret = _tdb_lock(tdb, list, ltype, TDB_LOCK_WAIT);
+ /* a allrecord lock allows us to avoid per chain locks */
+ if (tdb->allrecord_lock.count &&
+ (ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
+ return 0;
+ }
+
+ if (tdb->allrecord_lock.count) {
+ tdb->ecode = TDB_ERR_LOCK;
+ ret = -1;
+ } else {
+ ret = tdb_nest_lock(tdb, lock_offset(list), ltype,
+ TDB_LOCK_WAIT);
+ }
if (ret) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock failed on list %d "
"ltype=%d (%s)\n", list, ltype, strerror(errno)));
/* lock a list in the database. list -1 is the alloc list. non-blocking lock */
int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype)
{
- return _tdb_lock(tdb, list, ltype, TDB_LOCK_NOWAIT);
-}
-
-
-static int _tdb_unlock(struct tdb_context *tdb, int list, int ltype,
- bool mark_lock)
-{
- int ret = -1;
- int i;
- struct tdb_lock_type *lck = NULL;
-
- /* a global lock allows us to avoid per chain locks */
+ /* a allrecord lock allows us to avoid per chain locks */
if (tdb->allrecord_lock.count &&
(ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
return 0;
return -1;
}
+ return tdb_nest_lock(tdb, lock_offset(list), ltype, TDB_LOCK_NOWAIT);
+}
+
+
+int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype,
+ bool mark_lock)
+{
+ int ret = -1;
+ struct tdb_lock_type *lck;
+
if (tdb->flags & TDB_NOLOCK)
return 0;
/* Sanity checks */
- if (list < -1 || list >= (int)tdb->header.hash_size) {
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: list %d invalid (%d)\n", list, tdb->header.hash_size));
+ if (offset >= lock_offset(tdb->header.hash_size)) {
+ TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: offset %u invalid (%d)\n", offset, tdb->header.hash_size));
return ret;
}
- for (i=0; i<tdb->num_lockrecs; i++) {
- if (tdb->lockrecs[i].list == list) {
- lck = &tdb->lockrecs[i];
- break;
- }
- }
-
+ lck = find_nestlock(tdb, offset);
if ((lck == NULL) || (lck->count == 0)) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: count is 0\n"));
return -1;
if (mark_lock) {
ret = 0;
} else {
- ret = tdb->methods->brunlock(tdb, ltype,
- FREELIST_TOP+4*list, 1);
+ ret = tdb->methods->brunlock(tdb, ltype, offset, 1);
}
- tdb->num_locks--;
/*
* Shrink the array by overwriting the element just unlocked with the
* last array element.
*/
-
- if (tdb->num_lockrecs > 1) {
- *lck = tdb->lockrecs[tdb->num_lockrecs-1];
- }
- tdb->num_lockrecs -= 1;
+ *lck = tdb->lockrecs[--tdb->num_lockrecs];
/*
* We don't bother with realloc when the array shrinks, but if we have
int tdb_unlock(struct tdb_context *tdb, int list, int ltype)
{
- return _tdb_unlock(tdb, list, ltype, false);
+ /* a global lock allows us to avoid per chain locks */
+ if (tdb->allrecord_lock.count &&
+ (ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
+ return 0;
+ }
+
+ if (tdb->allrecord_lock.count) {
+ tdb->ecode = TDB_ERR_LOCK;
+ return -1;
+ }
+
+ return tdb_nest_unlock(tdb, lock_offset(list), ltype, false);
}
/*
*/
int tdb_transaction_lock(struct tdb_context *tdb, int ltype)
{
- if (tdb->allrecord_lock.count) {
- return 0;
- }
- if (tdb->transaction_lock_count > 0) {
- tdb->transaction_lock_count++;
- return 0;
- }
-
- if (tdb->methods->brlock(tdb, ltype, TRANSACTION_LOCK, 1, TDB_LOCK_WAIT) == -1) {
- TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_lock: failed to get transaction lock\n"));
- tdb->ecode = TDB_ERR_LOCK;
- return -1;
- }
- tdb->transaction_lock_count++;
- return 0;
+ return tdb_nest_lock(tdb, TRANSACTION_LOCK, ltype, TDB_LOCK_WAIT);
}
/*
*/
int tdb_transaction_unlock(struct tdb_context *tdb, int ltype)
{
- int ret;
- if (tdb->allrecord_lock.count) {
- return 0;
- }
- if (tdb->transaction_lock_count > 1) {
- tdb->transaction_lock_count--;
- return 0;
- }
- ret = tdb->methods->brunlock(tdb, ltype, TRANSACTION_LOCK, 1);
- if (ret == 0) {
- tdb->transaction_lock_count = 0;
- }
- return ret;
+ return tdb_nest_unlock(tdb, TRANSACTION_LOCK, ltype, false);
}
-
-
-/* lock/unlock entire database */
-static int _tdb_lockall(struct tdb_context *tdb, int ltype,
- enum tdb_lock_flags flags)
+/* lock/unlock entire database. It can only be upgradable if you have some
+ * other way of guaranteeing exclusivity (ie. transaction write lock). */
+int tdb_allrecord_lock(struct tdb_context *tdb, int ltype,
+ enum tdb_lock_flags flags, bool upgradable)
{
/* There are no locks on read-only dbs */
if (tdb->read_only || tdb->traverse_read) {
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
-
- if (tdb->num_locks != 0) {
+
+ if (tdb_have_extra_locks(tdb)) {
/* can't combine global and chain locks */
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
- if (tdb->methods->brlock(tdb, ltype,
- FREELIST_TOP, 4*tdb->header.hash_size,
- flags)) {
+ if (upgradable && ltype != F_RDLCK) {
+ /* tdb error: you can't upgrade a write lock! */
+ tdb->ecode = TDB_ERR_LOCK;
+ return -1;
+ }
+
+ if (tdb->methods->brlock(tdb, ltype, FREELIST_TOP, 0, flags)) {
if (flags & TDB_LOCK_WAIT) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lockall failed (%s)\n", strerror(errno)));
}
}
tdb->allrecord_lock.count = 1;
- tdb->allrecord_lock.ltype = ltype;
+ /* If it's upgradable, it's actually exclusive so we can treat
+ * it as a write lock. */
+ tdb->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype;
+ tdb->allrecord_lock.off = upgradable;
return 0;
}
/* unlock entire db */
-static int _tdb_unlockall(struct tdb_context *tdb, int ltype, bool mark_lock)
+int tdb_allrecord_unlock(struct tdb_context *tdb, int ltype, bool mark_lock)
{
/* There are no locks on read-only dbs */
if (tdb->read_only || tdb->traverse_read) {
return -1;
}
- if (tdb->allrecord_lock.ltype != ltype || tdb->allrecord_lock.count == 0) {
+ if (tdb->allrecord_lock.count == 0) {
+ tdb->ecode = TDB_ERR_LOCK;
+ return -1;
+ }
+
+ /* Upgradable locks are marked as write locks. */
+ if (tdb->allrecord_lock.ltype != ltype
+ && (!tdb->allrecord_lock.off || ltype != F_RDLCK)) {
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
}
if (!mark_lock &&
- tdb->methods->brunlock(tdb, ltype,
- FREELIST_TOP, 4*tdb->header.hash_size)) {
+ tdb->methods->brunlock(tdb, ltype, FREELIST_TOP, 0)) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlockall failed (%s)\n", strerror(errno)));
return -1;
}
int tdb_lockall(struct tdb_context *tdb)
{
tdb_trace(tdb, "tdb_lockall");
- return _tdb_lockall(tdb, F_WRLCK, TDB_LOCK_WAIT);
+ return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false);
}
/* lock entire database with write lock - mark only */
int tdb_lockall_mark(struct tdb_context *tdb)
{
tdb_trace(tdb, "tdb_lockall_mark");
- return _tdb_lockall(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY);
+ return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY, false);
}
/* unlock entire database with write lock - unmark only */
int tdb_lockall_unmark(struct tdb_context *tdb)
{
tdb_trace(tdb, "tdb_lockall_unmark");
- return _tdb_unlockall(tdb, F_WRLCK, true);
+ return tdb_allrecord_unlock(tdb, F_WRLCK, true);
}
/* lock entire database with write lock - nonblocking varient */
int tdb_lockall_nonblock(struct tdb_context *tdb)
{
- int ret = _tdb_lockall(tdb, F_WRLCK, TDB_LOCK_NOWAIT);
+ int ret = tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_NOWAIT, false);
tdb_trace_ret(tdb, "tdb_lockall_nonblock", ret);
return ret;
}
int tdb_unlockall(struct tdb_context *tdb)
{
tdb_trace(tdb, "tdb_unlockall");
- return _tdb_unlockall(tdb, F_WRLCK, false);
+ return tdb_allrecord_unlock(tdb, F_WRLCK, false);
}
/* lock entire database with read lock */
int tdb_lockall_read(struct tdb_context *tdb)
{
tdb_trace(tdb, "tdb_lockall_read");
- return _tdb_lockall(tdb, F_RDLCK, TDB_LOCK_WAIT);
+ return tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, false);
}
/* lock entire database with read lock - nonblock varient */
int tdb_lockall_read_nonblock(struct tdb_context *tdb)
{
- int ret = _tdb_lockall(tdb, F_RDLCK, TDB_LOCK_NOWAIT);
+ int ret = tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_NOWAIT, false);
tdb_trace_ret(tdb, "tdb_lockall_read_nonblock", ret);
return ret;
}
int tdb_unlockall_read(struct tdb_context *tdb)
{
tdb_trace(tdb, "tdb_unlockall_read");
- return _tdb_unlockall(tdb, F_RDLCK, false);
+ return tdb_allrecord_unlock(tdb, F_RDLCK, false);
}
/* lock/unlock one hash chain. This is meant to be used to reduce
/* mark a chain as locked without actually locking it. Warning! use with great caution! */
int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key)
{
- int ret = _tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK,
- TDB_LOCK_MARK_ONLY);
+ int ret = tdb_nest_lock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
+ F_WRLCK, TDB_LOCK_MARK_ONLY);
tdb_trace_1rec(tdb, "tdb_chainlock_mark", key);
return ret;
}
int tdb_chainlock_unmark(struct tdb_context *tdb, TDB_DATA key)
{
tdb_trace_1rec(tdb, "tdb_chainlock_unmark", key);
- return _tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK, true);
+ return tdb_nest_unlock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
+ F_WRLCK, true);
}
int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key)
count++;
return (count == 1 ? tdb->methods->brunlock(tdb, F_RDLCK, off, 1) : 0);
}
+
+bool tdb_have_extra_locks(struct tdb_context *tdb)
+{
+ unsigned int extra = tdb->num_lockrecs;
+
+ /* A transaction holds the lock for all records. */
+ if (!tdb->transaction && tdb->allrecord_lock.count) {
+ return true;
+ }
+
+ /* We always hold the active lock if CLEAR_IF_FIRST. */
+ if (find_nestlock(tdb, ACTIVE_LOCK)) {
+ extra--;
+ }
+
+ /* In a transaction, we expect to hold the transaction lock */
+ if (tdb->transaction && find_nestlock(tdb, TRANSACTION_LOCK)) {
+ extra--;
+ }
+
+ return extra;
+}
+
+/* The transaction code uses this to remove all locks. Note that this
+ may include OPEN_LOCK. */
+void tdb_release_extra_locks(struct tdb_context *tdb)
+{
+ unsigned int i, extra = 0;
+
+ if (tdb->allrecord_lock.count != 0) {
+ tdb_brunlock(tdb, tdb->allrecord_lock.ltype, FREELIST_TOP, 0);
+ tdb->allrecord_lock.count = 0;
+ }
+
+ for (i=0;i<tdb->num_lockrecs;i++) {
+ struct tdb_lock_type *lck = &tdb->lockrecs[i];
+
+ /* Don't release transaction or active locks! */
+ if (tdb->transaction && lck->off == TRANSACTION_LOCK) {
+ tdb->lockrecs[extra++] = *lck;
+ } else if (lck->off == ACTIVE_LOCK) {
+ tdb->lockrecs[extra++] = *lck;
+ } else {
+ tdb_brunlock(tdb, lck->ltype, lck->off, 1);
+ }
+ }
+ tdb->num_lockrecs = extra;
+ if (tdb->num_lockrecs == 0) {
+ SAFE_FREE(tdb->lockrecs);
+ }
+}
projects / ccan / blobdiff