libctdb: implement synchronous readrecordlock interface.

Because this doesn't use a generic callback, it's not quite as trivial
as the other sync wrappers.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>


(This used to be ctdb commit 1f20b938d46d4fcd50d2b473c1ab8dc31d178d2d)

3 files changed, 57 insertions, 1 deletions

diff --git a/ctdb/include/ctdb.h b/ctdb/include/ctdb.h
index a9ee63ff25..c5e6f935e4 100644
--- a/ctdb/include/ctdb.h
+++ b/ctdb/include/ctdb.h
@@ -475,6 +475,7 @@ void ctdb_detachdb(struct ctdb_connection *ctdb, struct ctdb_db *db);
 
 /**
  * ctdb_readrecordlock - read and lock a record (synchronous)
+ * @ctdb: the ctdb_connection from ctdb_connect.
  * @ctdb_db: the database handle from ctdb_attachdb/ctdb_attachdb_recv.
  * @key: the key of the record to lock.
  * @req: a pointer to the request, if one is needed.
@@ -482,7 +483,8 @@ void ctdb_detachdb(struct ctdb_connection *ctdb, struct ctdb_db *db);
  * Do a ctdb_readrecordlock_send and wait for it to complete.
  * Returns NULL on failure.
  */
-struct ctdb_lock *ctdb_readrecordlock(struct ctdb_db *ctdb_db, TDB_DATA key,
+struct ctdb_lock *ctdb_readrecordlock(struct ctdb_connection *ctdb,
+				      struct ctdb_db *ctdb_db, TDB_DATA key,
 				      TDB_DATA *data);
 
 
diff --git a/ctdb/libctdb/ctdb.c b/ctdb/libctdb/ctdb.c
index 096a9264f0..23acef4ada 100644
--- a/ctdb/libctdb/ctdb.c
+++ b/ctdb/libctdb/ctdb.c
@@ -794,6 +794,7 @@ static void readrecordlock_retry(struct ctdb_connection *ctdb,
 		/* Now it's their responsibility to free lock & request! */
 		req->extra_destructor = NULL;
 		lock->callback(lock->ctdb_db, lock, data, private);
+		ctdb_request_free(ctdb, req);
 		return;
 	}
 
diff --git a/ctdb/libctdb/sync.c b/ctdb/libctdb/sync.c
index 43db2cf6b5..2e6ba9926f 100644
--- a/ctdb/libctdb/sync.c
+++ b/ctdb/libctdb/sync.c
@@ -115,3 +115,56 @@ bool ctdb_getpnn(struct ctdb_connection *ctdb,
 	}
 	return ret;
 }
+
+struct rrl_info {
+	bool done;
+	struct ctdb_lock *lock;
+	TDB_DATA *data;
+};
+
+static void rrl_callback(struct ctdb_db *ctdb_db,
+			 struct ctdb_lock *lock,
+			 TDB_DATA data,
+			 struct rrl_info *rrl)
+{
+	rrl->done = true;
+	rrl->lock = lock;
+	*rrl->data = data;
+}
+
+struct ctdb_lock *ctdb_readrecordlock(struct ctdb_connection *ctdb,
+				      struct ctdb_db *ctdb_db, TDB_DATA key,
+				      TDB_DATA *data)
+{
+	struct pollfd fds;
+	struct rrl_info rrl;
+
+	rrl.done = false;
+	rrl.lock = NULL;
+	rrl.data = data;
+
+	/* Immediate failure is easy. */
+	if (!ctdb_readrecordlock_async(ctdb_db, key, rrl_callback, &rrl))
+		return NULL;
+
+	/* Immediate success is easy. */
+	if (!rrl.done) {
+		/* Otherwise wait until callback called. */
+		fds.fd = ctdb_get_fd(ctdb);
+		while (!rrl.done) {
+			fds.events = ctdb_which_events(ctdb);
+			if (poll(&fds, 1, -1) < 0) {
+				/* Signalled is OK, other error is bad. */
+				if (errno == EINTR)
+					continue;
+				DEBUG(ctdb, LOG_ERR,
+				      "ctdb_readrecordlock: poll failed");
+				return NULL;
+			}
+			if (!ctdb_service(ctdb, fds.revents)) {
+				break;
+			}
+		}
+	}
+	return rrl.lock;
+}