Practical Guide to Implementing Delayed Message Sending with PHP Queues

Implementing Delayed Message Sending with PHP Queues

In software development, delayed message sending is a common requirement, such as sending SMS verification codes or system notifications. Using PHP queues can effectively achieve delayed sending by placing messages into a queue with a specified delay time, enabling asynchronous processing. This article introduces a solution using Redis as the queue server along with complete PHP example code to help you get started quickly.

Using Redis as the Queue Server

Redis is a high-performance in-memory database that supports various data structures including lists and sorted sets, making it suitable for use as a message queue. First, install Redis and the corresponding PHP extension. On Ubuntu, use the following commands:

sudo apt-get install redis-server
sudo apt-get install php-redis

After installation, the following code demonstrates how to connect to the Redis server:

$redis = new Redis();
$redis->connect('127.0.0.1', 6379);

Implementing Delayed Message Sending

The following example shows how to add messages to the Redis queue with a delay time, and continuously check and send messages that are due:

// Add message to the queue with delay time (seconds)
function addDelayedMessage($message, $delay)
{
    global $redis;

    // Calculate the message sending timestamp
    $delayedTime = time() + $delay;

    // Add message to the sorted set with score as the sending time
    $redis->zAdd('delayed_queue', $delayedTime, $message);
}

// Check and send messages that are due
function checkDelayedMessages()
{
    global $redis;

    while (true) {
        // Get messages with score less than or equal to current time
        $message = $redis->zRangeByScore('delayed_queue', 0, time(), ['limit' => [0, 1]]);

        if (count($message) > 0) {
            // Simulate sending the message by echoing it
            echo "Sending message: " . $message[0] . PHP_EOL;

            // Remove the sent message from the queue
            $redis->zRem('delayed_queue', $message[0]);
        } else {
            // No messages to send, break the loop
            break;
        }
    }
}

// Add sample delayed messages
addDelayedMessage('Message 1', 300); // Send after 5 minutes
addDelayedMessage('Message 2', 600); // Send after 10 minutes

// Perform sending check
checkDelayedMessages();

In the code above, the addDelayedMessage function adds messages to a Redis sorted set, with scores representing future timestamps (delays), thus implementing the delay feature. The checkDelayedMessages function continuously checks for messages whose scheduled time has arrived, simulates sending them, and removes them from the queue to avoid duplicate sends.

Conclusion

Combining PHP with Redis queues provides an efficient way to handle delayed message sending requirements. Redis sorted sets offer a convenient way to manage time-ordered messages, making delay handling straightforward. Mastering this method significantly enhances your system’s asynchronous processing capability and performance.