RabbitMq初探——消息持久化

消息持久化

前言

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通过上一节，我们知道，有消息确认机制，保证了当消费者进程挂掉后，消息的不丢失。

但是如果rabbitmq挂掉呢？它的队列和消息都会丢失的。为了保证消息在rabbitmq挂掉重启后不丢失，

我们需要用到rabbitmq的持久化机制。

开启持久化功能

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1. 首先保证queue的持久化，在publisher和consumer声明queue时，开启持久化功能。本章例子可以通过下面代码开启

//函数第三个参数置为true，代表开启队列的持久化
$channel->queue_declare('durable_queue', false, true, false, false);

2. 其次保证message的持久化，在publisher传递消息前开启消息的持久化功能。

$msg = new AMQPMessage($data, array('delivery_mode' => AMQPMessage::DELIVERY_MODE_PERSISTENT));

代码

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sender.php

<?php
/**
 * sender.php
 * Created by PhpStorm.
 * User: wangdaxi
 * Date: 2017/10/18
 * Time: 14:26
 */
require_once __DIR__ . '/vendor/autoload.php';
use PhpAmqpLib\Connection\AMQPStreamConnection;
use PhpAmqpLib\Message\AMQPMessage;

$connection = new AMQPStreamConnection('127.0.0.1', 5672, 'guest', 'guest');
$channel = $connection->channel();

$channel->queue_declare('durable_queue', false, true, false, false);

$data = implode(" ", array_slice($argv, 1));
empty($data) && $data = "Hello World!";

$msg = new AMQPMessage($data, array('delivery_mode' => AMQPMessage::DELIVERY_MODE_PERSISTENT));

$channel->basic_publish($msg, '', 'durable_queue');

echo " [x] Sent '$data'\n";

//close the channel and connection;
$channel->close();
$connection->close();

receive.php

<?php
/**
 * receive.php
 * Created by PhpStorm.
 * User: wangdaxi
 * Date: 2017/10/18
 * Time: 14:34
 */
require_once __DIR__ . '/vendor/autoload.php';
use PhpAmqpLib\Connection\AMQPStreamConnection;

$connection = new AMQPStreamConnection('127.0.0.1', 5672, 'guest', 'guest');
$channel = $connection->channel();

$channel->queue_declare('durable_queue', false, true, false, false);
echo ' [*] Waiting for messages. To exit press CTRL+C', "\n";

$callback = function($msg) {
    echo "[x] Received ", $msg->body, "\n";
    sleep(substr_count($msg->body, '.'));
    echo "[x] Done\n";
    //消息确认
    $msg->delivery_info['channel']->basic_ack($msg->delivery_info['delivery_tag']);
};
$channel->basic_consume('durable_queue', '', false, false, false, false, $callback);

while(count($channel->callbacks)) {
    $channel->wait();
}

测试

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1. php sender.php 这里开启了队列，并且发送了一条消息‘hello world’

2. sudo rabbitmqctl stop_app 关闭服务

3. sudo rabbitmqctl start_app 开启服务

4. php receive.php 开启消费者进程，发现能从队列【durable_queue】接收到消息。

以上。