X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftdb%2Flock.c;h=6f5799a8198f13dd06851aae03869c635035200e;hp=664081932c70e1ad42fd1df762e249f94ff2ed92;hb=e9989ef0758b3b660abf444d014c5b51a3a7c1b4;hpb=e9cc05b230fca341c6a27ea0efd6d749d95b5da7

diff --git a/ccan/tdb/lock.c b/ccan/tdb/lock.c
index 66408193..6f5799a8 100644
--- a/ccan/tdb/lock.c
+++ b/ccan/tdb/lock.c
@@ -33,17 +33,17 @@ void tdb_setalarm_sigptr(struct tdb_context *tdb, volatile sig_atomic_t *ptr)
 }
 
 static int fcntl_lock(struct tdb_context *tdb,
-		      int rw, off_t off, off_t len, bool wait)
+		      int rw, off_t off, off_t len, bool waitflag)
 {
 	struct flock fl;
-	
+
 	fl.l_type = rw;
 	fl.l_whence = SEEK_SET;
 	fl.l_start = off;
 	fl.l_len = len;
 	fl.l_pid = 0;
 
-	if (wait)
+	if (waitflag)
 		return fcntl(tdb->fd, F_SETLKW, &fl);
 	else
 		return fcntl(tdb->fd, F_SETLK, &fl);
@@ -163,7 +163,7 @@ int tdb_brlock(struct tdb_context *tdb,
 		 * EAGAIN is an expected return from non-blocking
 		 * locks. */
 		if (!(flags & TDB_LOCK_PROBE) && errno != EAGAIN) {
-			TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock failed (fd=%d) at offset %d rw_type=%d flags=%d len=%d\n", 
+			TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock failed (fd=%d) at offset %d rw_type=%d flags=%d len=%d\n",
 				 tdb->fd, offset, rw_type, flags, (int)len));
 		}
 		return -1;
@@ -185,7 +185,7 @@ int tdb_brunlock(struct tdb_context *tdb,
 	} while (ret == -1 && errno == EINTR);
 
 	if (ret == -1) {
-		TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brunlock failed (fd=%d) at offset %d rw_type=%d len=%d\n", 
+		TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brunlock failed (fd=%d) at offset %d rw_type=%d len=%d\n",
 			 tdb->fd, offset, rw_type, (int)len));
 	}
 	return ret;
@@ -218,51 +218,48 @@ int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len)
 	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 global lock allows us to avoid per chain locks */
-	if (tdb->global_lock.count && 
-	    (ltype == tdb->global_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->global_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(
@@ -276,13 +273,13 @@ static int _tdb_lock(struct tdb_context *tdb, int list, int ltype,
 
 	/* 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;
@@ -295,7 +292,19 @@ int tdb_lock(struct tdb_context *tdb, int list, int ltype)
 {
 	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)));
@@ -306,44 +315,37 @@ int tdb_lock(struct tdb_context *tdb, int list, int ltype)
 /* 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 */
-	if (tdb->global_lock.count && 
-	    (ltype == tdb->global_lock.ltype || ltype == F_RDLCK)) {
+	/* 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->global_lock.count) {
+	if (tdb->allrecord_lock.count) {
 		tdb->ecode = TDB_ERR_LOCK;
 		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;
@@ -364,8 +366,7 @@ static int _tdb_unlock(struct tdb_context *tdb, int list, int ltype,
 	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--;
 
@@ -395,7 +396,18 @@ static int _tdb_unlock(struct tdb_context *tdb, int list, int ltype,
 
 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);
 }
 
 /*
@@ -403,21 +415,7 @@ int tdb_unlock(struct tdb_context *tdb, int list, int ltype)
  */
 int tdb_transaction_lock(struct tdb_context *tdb, int ltype)
 {
-	if (tdb->global_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);
 }
 
 /*
@@ -425,19 +423,7 @@ int tdb_transaction_lock(struct tdb_context *tdb, int ltype)
  */
 int tdb_transaction_unlock(struct tdb_context *tdb, int ltype)
 {
-	int ret;
-	if (tdb->global_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);
 }
 
 
@@ -453,18 +439,18 @@ static int _tdb_lockall(struct tdb_context *tdb, int ltype,
 		return -1;
 	}
 
-	if (tdb->global_lock.count && tdb->global_lock.ltype == ltype) {
-		tdb->global_lock.count++;
+	if (tdb->allrecord_lock.count && tdb->allrecord_lock.ltype == ltype) {
+		tdb->allrecord_lock.count++;
 		return 0;
 	}
 
-	if (tdb->global_lock.count) {
+	if (tdb->allrecord_lock.count) {
 		/* a global lock of a different type exists */
 		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;
@@ -479,8 +465,8 @@ static int _tdb_lockall(struct tdb_context *tdb, int ltype,
 		return -1;
 	}
 
-	tdb->global_lock.count = 1;
-	tdb->global_lock.ltype = ltype;
+	tdb->allrecord_lock.count = 1;
+	tdb->allrecord_lock.ltype = ltype;
 
 	return 0;
 }
@@ -496,13 +482,13 @@ static int _tdb_unlockall(struct tdb_context *tdb, int ltype, bool mark_lock)
 		return -1;
 	}
 
-	if (tdb->global_lock.ltype != ltype || tdb->global_lock.count == 0) {
+	if (tdb->allrecord_lock.ltype != ltype || tdb->allrecord_lock.count == 0) {
 		tdb->ecode = TDB_ERR_LOCK;
 		return -1;
 	}
 
-	if (tdb->global_lock.count > 1) {
-		tdb->global_lock.count--;
+	if (tdb->allrecord_lock.count > 1) {
+		tdb->allrecord_lock.count--;
 		return 0;
 	}
 
@@ -513,8 +499,8 @@ static int _tdb_unlockall(struct tdb_context *tdb, int ltype, bool mark_lock)
 		return -1;
 	}
 
-	tdb->global_lock.count = 0;
-	tdb->global_lock.ltype = 0;
+	tdb->allrecord_lock.count = 0;
+	tdb->allrecord_lock.ltype = 0;
 
 	return 0;
 }
@@ -599,8 +585,8 @@ int tdb_chainlock_nonblock(struct tdb_context *tdb, TDB_DATA key)
 /* 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;
 }
@@ -609,7 +595,8 @@ int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key)
 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)
@@ -632,10 +619,12 @@ int tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key)
 	return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
 }
 
+
+
 /* record lock stops delete underneath */
 int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off)
 {
-	if (tdb->global_lock.count) {
+	if (tdb->allrecord_lock.count) {
 		return 0;
 	}
 	return off ? tdb->methods->brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0;
@@ -666,7 +655,7 @@ int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off)
 	struct tdb_traverse_lock *i;
 	uint32_t count = 0;
 
-	if (tdb->global_lock.count) {
+	if (tdb->allrecord_lock.count) {
 		return 0;
 	}
 
@@ -677,3 +666,47 @@ int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off)
 			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;
+
+	if (tdb->allrecord_lock.count) {
+		return true;
+	}
+
+	/* 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, 4*tdb->header.hash_size);
+		tdb->allrecord_lock.count = 0;
+	}
+
+	for (i=0;i<tdb->num_lockrecs;i++) {
+		struct tdb_lock_type *lck = &tdb->lockrecs[i];
+
+		if (tdb->transaction && lck->off == TRANSACTION_LOCK) {
+			tdb->lockrecs[extra++] = *lck;
+		} else {
+			tdb_brunlock(tdb, lck->ltype, lck->off, 1);
+		}
+	}
+	tdb->num_locks = extra;
+	tdb->num_lockrecs = extra;
+	if (tdb->num_lockrecs == 0) {
+		SAFE_FREE(tdb->lockrecs);
+	}
+}