Java tutorial
package org.apache.blur.zookeeper; /** * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.io.IOException; import java.util.List; import org.apache.blur.log.Log; import org.apache.blur.log.LogFactory; import org.apache.blur.trace.Trace; import org.apache.blur.trace.Tracer; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.KeeperException.Code; import org.apache.zookeeper.Op; import org.apache.zookeeper.OpResult; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.ZooKeeper; import org.apache.zookeeper.data.ACL; import org.apache.zookeeper.data.Stat; public class ZooKeeperClient extends ZooKeeper { private static final Log LOG = LogFactory.getLog(ZooKeeperClient.class); private final int internalSessionTimeout; public ZooKeeperClient(String connectString, int sessionTimeout, Watcher watcher) throws IOException { super(connectString, sessionTimeout, watcher); internalSessionTimeout = sessionTimeout; } public ZooKeeperClient(String connectString, int sessionTimeout, Watcher watcher, boolean canBeReadOnly) throws IOException { super(connectString, sessionTimeout, watcher, canBeReadOnly); internalSessionTimeout = sessionTimeout; } public ZooKeeperClient(String connectString, int sessionTimeout, Watcher watcher, long sessionId, byte[] sessionPasswd, boolean canBeReadOnly) throws IOException { super(connectString, sessionTimeout, watcher, sessionId, sessionPasswd, canBeReadOnly); internalSessionTimeout = sessionTimeout; } public ZooKeeperClient(String connectString, int sessionTimeout, Watcher watcher, long sessionId, byte[] sessionPasswd) throws IOException { super(connectString, sessionTimeout, watcher, sessionId, sessionPasswd); internalSessionTimeout = sessionTimeout; } static abstract class ZKExecutor<T> { String _name; ZKExecutor(String name) { _name = name; } abstract T execute() throws KeeperException, InterruptedException; } public <T> T execute(ZKExecutor<T> executor) throws KeeperException, InterruptedException { final long timestmap = System.currentTimeMillis(); int sessionTimeout = getSessionTimeout(); if (sessionTimeout == 0) { sessionTimeout = internalSessionTimeout; } while (true) { Tracer trace = Trace.trace("remote call - zookeeper", Trace.param("method", executor._name), Trace.param("toString", executor.toString())); try { return executor.execute(); } catch (KeeperException e) { if (e.code() == Code.CONNECTIONLOSS && timestmap + sessionTimeout >= System.currentTimeMillis()) { LOG.warn("Connection loss"); ZkUtils.pause(this); continue; } throw e; } finally { trace.done(); } } } @Override public String create(final String path, final byte[] data, final List<ACL> acl, final CreateMode createMode) throws KeeperException, InterruptedException { return execute(new ZKExecutor<String>("create") { @Override String execute() throws KeeperException, InterruptedException { LOG.debug("ZK Call - create [{0}] [{1}] [{2}] [{3}]", path, data, acl, createMode); return ZooKeeperClient.super.create(path, data, acl, createMode); } }); } @Override public void delete(final String path, final int version) throws InterruptedException, KeeperException { execute(new ZKExecutor<Void>("delete") { @Override Void execute() throws KeeperException, InterruptedException { LOG.debug("ZK Call - delete [{0}] [{1}]", path, version); ZooKeeperClient.super.delete(path, version); return null; } }); } @Override public List<OpResult> multi(final Iterable<Op> ops) throws InterruptedException, KeeperException { return execute(new ZKExecutor<List<OpResult>>("multi") { @Override List<OpResult> execute() throws KeeperException, InterruptedException { return ZooKeeperClient.super.multi(ops); } }); } @Override public Stat exists(final String path, final Watcher watcher) throws KeeperException, InterruptedException { return execute(new ZKExecutor<Stat>("exists") { @Override Stat execute() throws KeeperException, InterruptedException { LOG.debug("ZK Call - exists [{0}] [{1}]", path, watcher); return ZooKeeperClient.super.exists(path, watcher); } }); } @Override public Stat exists(final String path, final boolean watch) throws KeeperException, InterruptedException { return execute(new ZKExecutor<Stat>("exists") { @Override Stat execute() throws KeeperException, InterruptedException { LOG.debug("ZK Call - exists [{0}] [{1}]", path, watch); return ZooKeeperClient.super.exists(path, watch); } }); } @Override public byte[] getData(final String path, final Watcher watcher, final Stat stat) throws KeeperException, InterruptedException { return execute(new ZKExecutor<byte[]>("getData") { @Override byte[] execute() throws KeeperException, InterruptedException { LOG.debug("ZK Call - getData [{0}] [{1}] [{2}]", path, watcher, stat); return ZooKeeperClient.super.getData(path, watcher, stat); } }); } @Override public byte[] getData(final String path, final boolean watch, final Stat stat) throws KeeperException, InterruptedException { return execute(new ZKExecutor<byte[]>("getData") { @Override byte[] execute() throws KeeperException, InterruptedException { LOG.debug("ZK Call - getData [{0}] [{1}] [{2}]", path, watch, stat); return ZooKeeperClient.super.getData(path, watch, stat); } }); } @Override public Stat setData(final String path, final byte[] data, final int version) throws KeeperException, InterruptedException { return execute(new ZKExecutor<Stat>("setData") { @Override Stat execute() throws KeeperException, InterruptedException { LOG.debug("ZK Call - setData [{0}] [{1}] [{2}]", path, data, version); return ZooKeeperClient.super.setData(path, data, version); } }); } @Override public List<ACL> getACL(final String path, final Stat stat) throws KeeperException, InterruptedException { return execute(new ZKExecutor<List<ACL>>("getACL") { @Override List<ACL> execute() throws KeeperException, InterruptedException { return ZooKeeperClient.super.getACL(path, stat); } }); } @Override public Stat setACL(final String path, final List<ACL> acl, final int version) throws KeeperException, InterruptedException { return execute(new ZKExecutor<Stat>("setACL") { @Override Stat execute() throws KeeperException, InterruptedException { return ZooKeeperClient.super.setACL(path, acl, version); } }); } @Override public List<String> getChildren(final String path, final Watcher watcher) throws KeeperException, InterruptedException { return execute(new ZKExecutor<List<String>>("getChildren") { @Override List<String> execute() throws KeeperException, InterruptedException { LOG.debug("ZK Call - getChildren [{0}] [{1}]", path, watcher); return ZooKeeperClient.super.getChildren(path, watcher); } @Override public String toString() { return "path=" + path + " watcher=" + watcher; } }); } @Override public List<String> getChildren(final String path, final boolean watch) throws KeeperException, InterruptedException { return execute(new ZKExecutor<List<String>>("getChildren") { @Override List<String> execute() throws KeeperException, InterruptedException { LOG.debug("ZK Call - getChildren [{0}] [{1}]", path, watch); return ZooKeeperClient.super.getChildren(path, watch); } @Override public String toString() { return "path=" + path + " watch=" + watch; } }); } @Override public List<String> getChildren(final String path, final Watcher watcher, final Stat stat) throws KeeperException, InterruptedException { return execute(new ZKExecutor<List<String>>("getChildren") { @Override List<String> execute() throws KeeperException, InterruptedException { LOG.debug("ZK Call - getChildren [{0}] [{1}] [{2}]", path, watcher, stat); return ZooKeeperClient.super.getChildren(path, watcher, stat); } }); } @Override public List<String> getChildren(final String path, final boolean watch, final Stat stat) throws KeeperException, InterruptedException { return execute(new ZKExecutor<List<String>>("getChildren") { @Override List<String> execute() throws KeeperException, InterruptedException { LOG.debug("ZK Call - getChildren [{0}] [{1}] [{2}]", path, watch, stat); return ZooKeeperClient.super.getChildren(path, watch, stat); } }); } }