How to use coroutines to implement high-concurrency swoole_smtp function in Swoole

With the rapid development of the Internet, high concurrency has become a problem we often encounter in our daily development work. Therefore, we need to constantly find and use high-performance solutions to improve the concurrency capabilities of our applications. Swoole is an excellent high-performance network communication framework that provides coroutine technology that can effectively improve the concurrency capabilities of applications. In this article, we will introduce how to use coroutines to implement high-concurrency swoole_smtp function in Swoole.

1. What is the swoole_smtp function

Swoole provides an email sending function named swoole_smtp, which can be used to send emails. The swoole_smtp function is used to encapsulate the SMTP protocol and can send emails to one or more recipients. It makes sending emails more convenient without having to deal with the SMTP protocol manually.

2. Coroutines in Swoole

In Swoole, coroutines are lightweight threads that can execute multiple coroutines in one thread. Each coroutine Switching between is very quick. Coroutines can effectively solve high concurrency problems because they can avoid thread switching overhead and implement functions such as data sharing and collaborative multitasking.

Using coroutines in Swoole is very simple. Just create a coroutine through the swoole_coroutine_create function and perform the tasks that need to be processed in it. During the execution of a coroutine, if it is found that an IO operation will block the current process, it will actively switch and execute other coroutines. After the IO operation is completed, it will switch back and continue to execute the tasks of the current coroutine.

3. How to use coroutine to optimize the swoole_smtp function

Although the swoole_smtp function can easily send emails, its performance is not very ideal. Because it implements the SMTP protocol through blocking, in a high-concurrency environment, it will cause thread blocking and affect the performance of the application.

Using coroutines can solve this problem well. We can create multiple coroutines through the swoole_coroutine_create function and execute multiple email sending tasks simultaneously to improve concurrency. The following is a sample code:

<?php
function send_mail($mail)
{
    $smtp = new SwooleCoroutineClient(SWOOLE_SOCK_TCP);
    if (!$smtp->connect('smtp.exmail.qq.com', 465, true))
    {
        throw new Exception('Connect SMTP server failed!');
    }

    if (!$smtp->recv())
    {
        throw new Exception('SMTP server did not respond!');
    }

    $smtp->send("EHLO swoole
");
    if (!$smtp->recv())
    {
        throw new Exception('SMTP server did not respond!');
    }

    $smtp->send("AUTH LOGIN
");
    if (!$smtp->recv())
    {
        throw new Exception('SMTP server did not respond!');
    }

    $smtp->send(base64_encode('xxxxx') . "
");
    if (!$smtp->recv())
    {
        throw new Exception('SMTP server did not respond!');
    }

    $smtp->send(base64_encode('xxxxx') . "
");
    if (!$smtp->recv())
    {
        throw new Exception('SMTP server did not respond!');
    }

    $smtp->send("MAIL FROM: <noreply@xxxxx.com>
");
    if (!$smtp->recv())
    {
        throw new Exception('SMTP server did not respond!');
    }

    foreach ($mail->getReceivers() as $receiver)
    {
        $smtp->send("RCPT TO: <$receiver>
");
        if (!$smtp->recv())
        {
            throw new Exception('SMTP server did not respond!');
        }
    }

    $smtp->send("DATA
");
    if (!$smtp->recv())
    {
        throw new Exception('SMTP server did not respond!');
    }

    $content = wordwrap($mail->getContent(), 80, "
");
    $smtp->send($content . "
");
    if (!$smtp->recv())
    {
        throw new Exception('SMTP server did not respond!');
    }

    $smtp->send("QUIT
");
    if (!$smtp->recv())
    {
        throw new Exception('SMTP server did not respond!');
    }

    $smtp->close();
}

$smtp = new SwooleCoroutineClient(SWOOLE_SOCK_TCP);

if (!$smtp->connect('smtp.exmail.qq.com', 465, true))
{
    throw new Exception('Connect SMTP server failed!');
}

if (!$smtp->recv())
{
    throw new Exception('SMTP server did not respond!');
}

$smtp->send("EHLO swoole
");
if (!$smtp->recv())
{
    throw new Exception('SMTP server did not respond!');
}

$smtp->send("AUTH LOGIN
");
if (!$smtp->recv())
{
    throw new Exception('SMTP server did not respond!');
}

$smtp->send(base64_encode('xxxxx') . "
");
if (!$smtp->recv())
{
    throw new Exception('SMTP server did not respond!');
}

$smtp->send(base64_encode('xxxxx') . "
");
if (!$smtp->recv())
{
    throw new Exception('SMTP server did not respond!');
}

$smtp->send("MAIL FROM: <noreply@xxxxx.com>
");
if (!$smtp->recv())
{
    throw new Exception('SMTP server did not respond!');
}

$mail_list = array(
    // 邮件内容为$mail1，$mail2，$mail3
    new Mail(),
    new Mail(),
    new Mail()
);

foreach ($mail_list as $mail)
{
    swoole_coroutine_create(function () use ($mail) {
        $smtp = new SwooleCoroutineClient(SWOOLE_SOCK_TCP);
        if (!$smtp->connect('smtp.exmail.qq.com', 465, true))
        {
            throw new Exception('Connect SMTP server failed!');
        }

        if (!$smtp->recv())
        {
            throw new Exception('SMTP server did not respond!');
        }

        $smtp->send("EHLO swoole
");
        if (!$smtp->recv())
        {
            throw new Exception('SMTP server did not respond!');
        }

        $smtp->send("AUTH LOGIN
");
        if (!$smtp->recv())
        {
            throw new Exception('SMTP server did not respond!');
        }

        $smtp->send(base64_encode('xxxxx') . "
");
        if (!$smtp->recv())
        {
            throw new Exception('SMTP server did not respond!');
        }

        $smtp->send(base64_encode('xxxxx') . "
");
        if (!$smtp->recv())
        {
            throw new Exception('SMTP server did not respond!');
        }

        $smtp->send("MAIL FROM: <noreply@xxxxx.com>
");
        if (!$smtp->recv())
        {
            throw new Exception('SMTP server did not respond!');
        }

        foreach ($mail->getReceivers() as $receiver)
        {
            $smtp->send("RCPT TO: <$receiver>
");
            if (!$smtp->recv())
            {
                throw new Exception('SMTP server did not respond!');
            }
        }

        $smtp->send("DATA
");
        if (!$smtp->recv())
        {
            throw new Exception('SMTP server did not respond!');
        }

        $content = wordwrap($mail->getContent(), 80, "
");
        $smtp->send($content . "
");
        if (!$smtp->recv())
        {
            throw new Exception('SMTP server did not respond!');
        }

        $smtp->send("QUIT
");
        if (!$smtp->recv())
        {
            throw new Exception('SMTP server did not respond!');
        }

        $smtp->close();
    });
}

$smtp->close();

In the above sample code, we created three email sending tasks and used the swoole_coroutine_create function to encapsulate them into three coroutines. At the same time, we created an SMTP connection in the program to execute multiple coroutines simultaneously. Procedure. In this way, we can greatly improve the concurrency of email sending tasks, thereby improving the performance of the entire application.

4. Summary

By using coroutine technology, we can easily implement high-concurrency email sending tasks and improve the performance of the entire application. In addition to the swoole_smtp function used in the above example code, we can also use other asynchronous IO functions provided by Swoole to optimize the performance of the application. In short, coroutines are a very good technology that can help us solve problems better when dealing with high concurrency problems.

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