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From GitBox <...@apache.org>
Subject [GitHub] maoling commented on a change in pull request #825: ZOOKEEPER-2474:add a way for client to reattach to a session when using ZKClientConfig
Date Wed, 20 Feb 2019 02:26:31 GMT
maoling commented on a change in pull request #825: ZOOKEEPER-2474:add a way for client to
reattach to a session when using ZKClientConfig
URL: https://github.com/apache/zookeeper/pull/825#discussion_r258311354
 
 

 ##########
 File path: zookeeper-server/src/main/java/org/apache/zookeeper/ZooKeeper.java
 ##########
 @@ -1140,17 +1140,94 @@ public ZooKeeper(String connectString, int sessionTimeout, Watcher
watcher,
     public ZooKeeper(String connectString, int sessionTimeout, Watcher watcher,
             long sessionId, byte[] sessionPasswd, boolean canBeReadOnly,
             HostProvider aHostProvider) throws IOException {
-        LOG.info("Initiating client connection, connectString=" + connectString
-                + " sessionTimeout=" + sessionTimeout
-                + " watcher=" + watcher
-                + " sessionId=" + Long.toHexString(sessionId)
-                + " sessionPasswd="
-                + (sessionPasswd == null ? "<null>" : "<hidden>"));
+    	this(connectString, sessionTimeout, watcher, sessionId, sessionPasswd,
+    			canBeReadOnly, aHostProvider, null);
+    }
+
+    /**
+     * To create a ZooKeeper client object, the application needs to pass a
+     * connection string containing a comma separated list of host:port pairs,
+     * each corresponding to a ZooKeeper server.
+     * <p>
+     * Session establishment is asynchronous. This constructor will initiate
+     * connection to the server and return immediately - potentially (usually)
+     * before the session is fully established. The watcher argument specifies
+     * the watcher that will be notified of any changes in state. This
+     * notification can come at any point before or after the constructor call
+     * has returned.
+     * <p>
+     * The instantiated ZooKeeper client object will pick an arbitrary server
+     * from the connectString and attempt to connect to it. If establishment of
+     * the connection fails, another server in the connect string will be tried
+     * (the order is non-deterministic, as we random shuffle the list), until a
+     * connection is established. The client will continue attempts until the
+     * session is explicitly closed (or the session is expired by the server).
+     * <p>
+     * Added in 3.2.0: An optional "chroot" suffix may also be appended to the
+     * connection string. This will run the client commands while interpreting
+     * all paths relative to this root (similar to the unix chroot command).
+     * <p>
+     * Use {@link #getSessionId} and {@link #getSessionPasswd} on an established
+     * client connection, these values must be passed as sessionId and
+     * sessionPasswd respectively if reconnecting. Otherwise, if not
+     * reconnecting, use the other constructor which does not require these
+     * parameters.
+     * <p>
+     * For backward compatibility, there is another version
+     * {@link #ZooKeeper(String, int, Watcher, long, byte[], boolean)} which uses
+     * default {@link StaticHostProvider}
+     *
+     * @param connectString
+     *            comma separated host:port pairs, each corresponding to a zk
+     *            server. e.g. "127.0.0.1:3000,127.0.0.1:3001,127.0.0.1:3002"
+     *            If the optional chroot suffix is used the example would look
+     *            like: "127.0.0.1:3000,127.0.0.1:3001,127.0.0.1:3002/app/a"
+     *            where the client would be rooted at "/app/a" and all paths
+     *            would be relative to this root - ie getting/setting/etc...
+     *            "/foo/bar" would result in operations being run on
+     *            "/app/a/foo/bar" (from the server perspective).
+     * @param sessionTimeout
+     *            session timeout in milliseconds
+     * @param watcher
+     *            a watcher object which will be notified of state changes, may
+     *            also be notified for node events
+     * @param sessionId
+     *            specific session id to use if reconnecting
+     * @param sessionPasswd
+     *            password for this session
+     * @param canBeReadOnly
+     *            (added in 3.4) whether the created client is allowed to go to
+     *            read-only mode in case of partitioning. Read-only mode
+     *            basically means that if the client can't find any majority
+     *            servers but there's partitioned server it could reach, it
+     *            connects to one in read-only mode, i.e. read requests are
+     *            allowed while write requests are not. It continues seeking for
+     *            majority in the background.
+     * @param aHostProvider
+     *            use this as HostProvider to enable custom behaviour.
+     * @param clientConfig
+     *            (added in 3.5.2) passing this conf object gives each client the flexibility
of
 
 Review comment:
   > nit:3.5.2, is should be 3.5.3
   
   Look around the code in the `zookeeper.java`,all the info shows that the clientConfig was
added in 3.5.2 ?
   >   we could also add a @SInCE 3.5.3 javadoc tag
   
   Agreed!

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