com.continuuity.weave.internal.ZKMessages.java Source code

Introduction

Here is the source code for com.continuuity.weave.internal.ZKMessages.java

Source

/**
 * Copyright 2012-2013 Continuuity,Inc. All Rights Reserved.
 *
 * Licensed 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.
 */
package com.continuuity.weave.internal;

import com.continuuity.weave.internal.state.Message;
import com.continuuity.weave.internal.state.MessageCodec;
import com.continuuity.weave.zookeeper.ZKClient;
import com.continuuity.weave.zookeeper.ZKOperations;
import com.google.common.base.Function;
import com.google.common.util.concurrent.AsyncFunction;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import org.apache.zookeeper.CreateMode;

/**
 *
 */
public final class ZKMessages {

    /**
     * Creates a message node in zookeeper. The message node created is a PERSISTENT_SEQUENTIAL node.
     *
     * @param zkClient The ZooKeeper client for interacting with ZooKeeper.
     * @param messagePathPrefix ZooKeeper path prefix for the message node.
     * @param message The {@link Message} object for the content of the message node.
     * @param completionResult Object to set to the result future when the message is processed.
     * @param <V> Type of the completion result.
     * @return A {@link ListenableFuture} that will be completed when the message is consumed, which indicated
     *         by deletion of the node. If there is exception during the process, it will be reflected
     *         to the future returned.
     */
    public static <V> ListenableFuture<V> sendMessage(final ZKClient zkClient, String messagePathPrefix,
            final Message message, final V completionResult) {
        return Futures.transform(
                zkClient.create(messagePathPrefix, MessageCodec.encode(message), CreateMode.PERSISTENT_SEQUENTIAL),
                new AsyncFunction<String, V>() {
                    @Override
                    public ListenableFuture<V> apply(String path) throws Exception {
                        return Futures.transform(ZKOperations.watchDeleted(zkClient, path),
                                new Function<String, V>() {
                                    @Override
                                    public V apply(String path) {
                                        return completionResult;
                                    }
                                });
                    }
                });
    }

    private ZKMessages() {
    }
}