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The RabbitMQ Java client library allows Java applications to interface with RabbitMQ.
// The contents of this file are subject to the Mozilla Public License
// Version 1.1 (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.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS"
// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
// the License for the specific language governing rights and
// limitations under the License.
//
// The Original Code is RabbitMQ.
//
// The Initial Developer of the Original Code is GoPivotal, Inc.
// Copyright (c) 2007-2014 GoPivotal, Inc. All rights reserved.
//
package com.rabbitmq.client;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.IOException;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.TimeoutException;
import com.rabbitmq.client.impl.MethodArgumentReader;
import com.rabbitmq.client.impl.MethodArgumentWriter;
import com.rabbitmq.client.impl.ValueReader;
import com.rabbitmq.client.impl.ValueWriter;
import com.rabbitmq.utility.BlockingCell;
/**
* Convenience class which manages simple RPC-style communication.
* The class is agnostic about the format of RPC arguments / return values.
* It simply provides a mechanism for sending a message to an exchange with a given routing key,
* and waiting for a response.
*/
public class RpcClient {
/** Channel we are communicating on */
private final Channel _channel;
/** Exchange to send requests to */
private final String _exchange;
/** Routing key to use for requests */
private final String _routingKey;
/** timeout to use on call responses */
private final int _timeout;
/** NO_TIMEOUT value must match convention on {@link BlockingCell#uninterruptibleGet(int)} */
protected final static int NO_TIMEOUT = -1;
/** Map from request correlation ID to continuation BlockingCell */
private final Map> _continuationMap = new HashMap>();
/** Contains the most recently-used request correlation ID */
private int _correlationId;
/** Consumer attached to our reply queue */
private DefaultConsumer _consumer;
/**
* Construct a new RpcClient that will communicate on the given channel, sending
* requests to the given exchange with the given routing key.
*
* Causes the creation of a temporary private autodelete queue.
* @param channel the channel to use for communication
* @param exchange the exchange to connect to
* @param routingKey the routing key
* @param timeout milliseconds before timing out on wait for response
* @throws IOException if an error is encountered
*/
public RpcClient(Channel channel, String exchange, String routingKey, int timeout) throws IOException {
_channel = channel;
_exchange = exchange;
_routingKey = routingKey;
if (timeout < NO_TIMEOUT) throw new IllegalArgumentException("Timeout arguument must be NO_TIMEOUT(-1) or non-negative.");
_timeout = timeout;
_correlationId = 0;
_consumer = setupConsumer();
}
/**
* Construct a new RpcClient that will communicate on the given channel, sending
* requests to the given exchange with the given routing key.
*
* Causes the creation of a temporary private autodelete queue.
*
* Waits forever for responses (that is, no timeout).
* @param channel the channel to use for communication
* @param exchange the exchange to connect to
* @param routingKey the routing key
* @throws IOException if an error is encountered
*/
public RpcClient(Channel channel, String exchange, String routingKey) throws IOException {
this(channel, exchange, routingKey, NO_TIMEOUT);
}
/**
* Private API - ensures the RpcClient is correctly open.
* @throws IOException if an error is encountered
*/
public void checkConsumer() throws IOException {
if (_consumer == null) {
throw new EOFException("RpcClient is closed");
}
}
/**
* Public API - cancels the consumer, thus deleting the temporary queue, and marks the RpcClient as closed.
* @throws IOException if an error is encountered
*/
public void close() throws IOException {
if (_consumer != null) {
_channel.basicCancel(_consumer.getConsumerTag());
_consumer = null;
}
}
/**
* Registers a consumer on the reply queue.
* @throws IOException if an error is encountered
* @return the newly created and registered consumer
*/
protected DefaultConsumer setupConsumer() throws IOException {
DefaultConsumer consumer = new DefaultConsumer(_channel) {
@Override
public void handleShutdownSignal(String consumerTag,
ShutdownSignalException signal) {
synchronized (_continuationMap) {
for (Entry> entry : _continuationMap.entrySet()) {
entry.getValue().set(signal);
}
_consumer = null;
}
}
@Override
public void handleDelivery(String consumerTag,
Envelope envelope,
AMQP.BasicProperties properties,
byte[] body)
throws IOException {
synchronized (_continuationMap) {
String replyId = properties.getCorrelationId();
BlockingCell