[sheepdog] [PATCH] multi-sheep cluster in one zookeeper support

[Yu Yang]

An optional "chroot" suffix can be appended to the connection
string(or hosts list). This will run the client commands while
interpreting all paths relative to this root.
Different sheep clusters have their own root znode,
so one zk can support muilt-sheep cluster.
If it is not set, the default root is /sheepdog,
which is compatible with old versions.

Signed-off-by: Yu Yang <yuyang at cmss.chinamobile.com>
---
 sheep/cluster/zookeeper.c |   49 ++++++++++++++++++++++++++++++++++++++++-----
 sheep/sheep.c             |    6 ++++--
 2 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/sheep/cluster/zookeeper.c b/sheep/cluster/zookeeper.c
index e2ee248..5b706a3 100644
--- a/sheep/cluster/zookeeper.c
+++ b/sheep/cluster/zookeeper.c
@@ -28,10 +28,10 @@
 #define SESSION_TIMEOUT 30000		/* millisecond */
 
 #define BASE_ZNODE "/sheepdog"
-#define QUEUE_ZNODE BASE_ZNODE "/queue"
-#define MEMBER_ZNODE BASE_ZNODE "/member"
-#define MASTER_ZNODE BASE_ZNODE "/master"
-#define LOCK_ZNODE BASE_ZNODE "/lock"
+#define QUEUE_ZNODE "/queue"
+#define MEMBER_ZNODE "/member"
+#define MASTER_ZNODE "/master"
+#define LOCK_ZNODE "/lock"
 
 static int zk_timeout = SESSION_TIMEOUT;
 static int my_master_seq;
@@ -641,7 +641,6 @@ static inline void build_node_list(void)
 
 static int zk_queue_init(void)
 {
-	RETURN_IF_ERROR(zk_init_node(BASE_ZNODE), "path %s", BASE_ZNODE);
 	RETURN_IF_ERROR(zk_init_node(MASTER_ZNODE), "path %s", MASTER_ZNODE);
 	RETURN_IF_ERROR(zk_init_node(QUEUE_ZNODE), "path %s", QUEUE_ZNODE);
 	RETURN_IF_ERROR(zk_init_node(MEMBER_ZNODE), "path %s", MEMBER_ZNODE);
@@ -1378,6 +1377,39 @@ static void zk_unlock(uint64_t lock_id)
 	sd_debug("unlock %"PRIu64, lock_id);
 }
 
+static int zk_prepare_root(const char *hosts)
+{
+	char root[MAX_NODE_STR_LEN];
+	char conn[MAX_NODE_STR_LEN];
+	const char *p = strchr(hosts, '/');
+	int interval, max_retry, retry;
+	int i = 0;
+	strcpy(root, p);
+	while (hosts != p)
+		conn[i++] = *hosts++;
+	conn[i] = '\0';
+
+	zhandle = zookeeper_init(conn, zk_watcher, zk_timeout, NULL, NULL, 0);
+	if (!zhandle) {
+		sd_err("failed to initialize zk server %s", conn);
+		return -1;
+	}
+
+	interval = 100;
+	retry = 0;
+	max_retry = zk_timeout / interval;
+	while (zoo_state(zhandle) != ZOO_CONNECTED_STATE) {
+		usleep(interval * 1000);
+		if (++retry >= max_retry) {
+			sd_err("failed to connect to zk server %s "
+					"after %d retries", conn, retry);
+			return -1;
+		}
+	}
+	RETURN_IF_ERROR(zk_init_node(root), "path %s", root);
+	return 0;
+}
+
 static int zk_init(const char *option)
 {
 	char *hosts, *to, *p;
@@ -1397,6 +1429,13 @@ static int zk_init(const char *option)
 		p = strstr(hosts, "timeout");
 		*--p = '\0';
 	}
+	if (!strchr(hosts, '/'))
+			strcat(hosts, BASE_ZNODE);
+	if (zk_prepare_root(hosts) != 0) {
+		sd_err("failed to initialize zk server %s", hosts);
+		return -1;
+	}
+
 	sd_info("version %d.%d.%d, address %s, timeout %d", ZOO_MAJOR_VERSION,
 		ZOO_MINOR_VERSION, ZOO_PATCH_VERSION, hosts, zk_timeout);
 	zhandle = zookeeper_init(hosts, zk_watcher, zk_timeout, NULL, NULL, 0);
diff --git a/sheep/sheep.c b/sheep/sheep.c
index 7d5fa0f..6f0c3ef 100644
--- a/sheep/sheep.c
+++ b/sheep/sheep.c
@@ -70,10 +70,12 @@ static const char cluster_help[] =
 "\tzookeeper: use zookeeper driver, need extra arguments\n"
 "\n\tzookeeper arguments: address-list,timeout=value (default as 3000)\n"
 "\nExample:\n\t"
-"$ sheep -c zookeeper:IP1:PORT1,IP2:PORT2,IP3:PORT3,timeout=1000 ...\n"
+"$ sheep -c zookeeper:IP1:PORT1,IP2:PORT2,IP3:PORT3/clustername,timeout=1000 ...\n"
 "This tries to use 3 node zookeeper cluster, which can be reached by\n"
 "IP1:PORT1, IP2:PORT2, IP3:PORT3 to manage membership and broadcast message\n"
-"and set the timeout of node heartbeat as 1000 milliseconds\n";
+"and set the timeout of node heartbeat as 1000 milliseconds.\n"
+"The suffix /clustername is for multi-sheep cluster support,\n"
+"its default value is /sheepdog.\n";
 
 static const char cache_help[] =
 "Available arguments:\n"
-- 
1.7.9.5