Add a timeout to tdb_lock_bystring(). Ensure we never have more than

MAX_PRINT_JOBS in a queue.
Jeremy.
(This used to be commit 9fe3c0b90d4bff2217e3cb5a34b4683ca314c06e)

3 files changed, 49 insertions, 6 deletions

diff --git a/source3/tdb/tdb.c b/source3/tdb/tdb.c
index 4143ac7781..c57d23cb6f 100644
--- a/source3/tdb/tdb.c
+++ b/source3/tdb/tdb.c
@@ -208,6 +208,10 @@ static int tdb_brlock(TDB_CONTEXT *tdb, tdb_off offset,
 			TDB_LOG((tdb, 5,"tdb_brlock failed (fd=%d) at offset %d rw_type=%d lck_type=%d\n", 
 				 tdb->fd, offset, rw_type, lck_type));
 		}
+		/* Was it an alarm timeout ? */
+		if (errno == EINTR && palarm_fired && *palarm_fired)
+			return TDB_ERRCODE(TDB_ERR_LOCK_TIMEOUT, -1);
+		/* Otherwise - generic lock error. */
 		/* errno set by fcntl */
 		return TDB_ERRCODE(TDB_ERR_LOCK, -1);
 	}
diff --git a/source3/tdb/tdb.h b/source3/tdb/tdb.h
index 42b88aeb16..dda89d0355 100644
--- a/source3/tdb/tdb.h
+++ b/source3/tdb/tdb.h
@@ -44,7 +44,7 @@ extern "C" {
 
 /* error codes */
 enum TDB_ERROR {TDB_SUCCESS=0, TDB_ERR_CORRUPT, TDB_ERR_IO, TDB_ERR_LOCK, 
-		TDB_ERR_OOM, TDB_ERR_EXISTS, TDB_ERR_NOEXIST, TDB_ERR_NOLOCK };
+		TDB_ERR_OOM, TDB_ERR_EXISTS, TDB_ERR_NOEXIST, TDB_ERR_NOLOCK, TDB_ERR_LOCK_TIMEOUT };
 
 #ifndef u32
 #define u32 unsigned
diff --git a/source3/tdb/tdbutil.c b/source3/tdb/tdbutil.c
index 1a3a8bb9a5..e7650033b8 100644
--- a/source3/tdb/tdbutil.c
+++ b/source3/tdb/tdbutil.c
@@ -24,18 +24,57 @@
 /* these are little tdb utility functions that are meant to make
    dealing with a tdb database a little less cumbersome in Samba */
 
+static SIG_ATOMIC_T gotalarm;
+
+/***************************************************************
+ Signal function to tell us we timed out.
+****************************************************************/
+
+static void gotalarm_sig(void)
+{
+	gotalarm = 1;
+}
+
+/****************************************************************************
+ Lock a chain with timeout (in seconds).
+****************************************************************************/
+
+int tdb_chainlock_with_timeout( TDB_CONTEXT *tdb, TDB_DATA key, unsigned int timeout)
+{
+	/* Allow tdb_chainlock to be interrupted by an alarm. */
+	int ret;
+	gotalarm = 0;
+	tdb_set_lock_alarm(&gotalarm);
+
+	if (timeout) {
+		CatchSignal(SIGALRM, SIGNAL_CAST gotalarm_sig);
+		alarm(timeout);
+	}
+
+	ret = tdb_chainlock(tdb, key);
+
+	if (timeout) {
+		alarm(0);
+		CatchSignal(SIGALRM, SIGNAL_CAST SIG_IGN);
+		if (gotalarm)
+			return -1;
+	}
+
+	return ret;
+}
+
 /****************************************************************************
- Lock a chain by string.
+ Lock a chain by string. Return -1 if timeout or lock failed.
 ****************************************************************************/
 
-int tdb_lock_bystring(TDB_CONTEXT *tdb, char *keyval)
+int tdb_lock_bystring(TDB_CONTEXT *tdb, char *keyval, unsigned int timeout)
 {
 	TDB_DATA key;
 
 	key.dptr = keyval;
 	key.dsize = strlen(keyval)+1;
 	
-	return tdb_chainlock(tdb, key);
+	return tdb_chainlock_with_timeout(tdb, key, timeout);
 }
 
 /****************************************************************************
@@ -230,7 +269,7 @@ int32 tdb_change_int32_atomic(TDB_CONTEXT *tdb, char *keystr, int32 *oldval, int
 	int32 val;
 	int32 ret = -1;
 
-	if (tdb_lock_bystring(tdb, keystr) == -1)
+	if (tdb_lock_bystring(tdb, keystr,0) == -1)
 		return -1;
 
 	if ((val = tdb_fetch_int32(tdb, keystr)) == -1) {
@@ -271,7 +310,7 @@ BOOL tdb_change_uint32_atomic(TDB_CONTEXT *tdb, char *keystr, uint32 *oldval, ui
 	uint32 val;
 	BOOL ret = False;
 
-	if (tdb_lock_bystring(tdb, keystr) == -1)
+	if (tdb_lock_bystring(tdb, keystr,0) == -1)
 		return False;
 
 	if (!tdb_fetch_uint32(tdb, keystr, &val)) {