1 files changed, 118 insertions, 0 deletions
diff --git a/ctdb/common/ctdb_lockwait.c b/ctdb/common/ctdb_lockwait.c
new file mode 100644
index 0000000000..304a0a413e
--- /dev/null
+++ b/ctdb/common/ctdb_lockwait.c
@@ -0,0 +1,118 @@
+/* 
+   wait for a tdb chain lock
+
+   Copyright (C) Andrew Tridgell  2006
+
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2 of the License, or (at your option) any later version.
+
+   This library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this library; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+*/
+
+#include "includes.h"
+#include "lib/events/events.h"
+#include "system/filesys.h"
+#include "system/wait.h"
+#include "popt.h"
+#include "../include/ctdb_private.h"
+#include "db_wrap.h"
+#include "lib/tdb/include/tdb.h"
+
+
+struct lockwait_handle {
+	struct fd_event *fde;
+	int fd[2];
+	pid_t child;
+	void *private_data;
+	void (*callback)(void *);
+};
+
+static void lockwait_handler(struct event_context *ev, struct fd_event *fde, 
+			     uint16_t flags, void *private_data)
+{
+	struct lockwait_handle *h = talloc_get_type(private_data, 
+						     struct lockwait_handle);
+	void (*callback)(void *) = h->callback;
+	void *p = h->private_data;
+	pid_t child = h->child;
+	talloc_set_destructor(h, NULL);
+	close(h->fd[0]);
+	talloc_free(h);	
+	callback(p);
+	waitpid(child, NULL, 0);
+}
+
+static int lockwait_destructor(struct lockwait_handle *h)
+{
+	close(h->fd[0]);
+	kill(h->child, SIGKILL);
+	waitpid(h->child, NULL, 0);
+	return 0;
+}
+
+/*
+  setup a non-blocking chainlock on a tdb record. If this function
+  returns NULL then it could not get the chainlock. Otherwise it
+  returns a opaque handle, and will call callback() once it has
+  managed to get the chainlock. You can cancel it by using talloc_free
+  on the returned handle.
+
+  It is the callers responsibility to unlock the chainlock once
+  acquired
+ */
+struct lockwait_handle *ctdb_lockwait(struct ctdb_db_context *ctdb_db,
+				      TDB_DATA key,
+				      void (*callback)(void *), void *private_data)
+{
+	struct lockwait_handle *h;
+	int ret;
+
+	h = talloc_zero(ctdb_db, struct lockwait_handle);
+	if (h == NULL) {
+		return NULL;
+	}
+
+	ret = pipe(h->fd);
+	if (ret != 0) {
+		talloc_free(h);
+		return NULL;
+	}
+
+	h->child = fork();
+	if (h->child == (pid_t)-1) {
+		close(h->fd[0]);
+		close(h->fd[1]);
+		talloc_free(h);
+		return NULL;
+	}
+
+	h->callback = callback;
+	h->private_data = private_data;
+
+	if (h->child == 0) {
+		struct tdb_context *tdb = ctdb_db->ltdb->tdb;
+		/* in child */
+		tdb_chainlock(tdb, key);
+		_exit(0);
+	}
+
+	close(h->fd[1]);
+	talloc_set_destructor(h, lockwait_destructor);
+
+	h->fde = event_add_fd(ctdb_db->ctdb->ev, h, h->fd[0], EVENT_FD_READ, lockwait_handler, h);
+	if (h->fde == NULL) {
+		talloc_free(h);
+		return NULL;
+	}
+
+	return h;
+}