How to use coroutines to implement highly concurrent swoole_ftpget function in Swoole

With the development of Internet technology and the gradual expansion of application scenarios, high concurrency has become a core requirement for more and more application systems. In this case, coroutine technology emerged as the times require and has become one of the important means to solve high concurrency. Among them, Swoole is a popular asynchronous coroutine framework in the PHP field. This article will introduce how to use coroutines in Swoole to implement the highly concurrent swoole_ftpget function.

1. Understanding the swoole_ftpget function

Before introducing how to use coroutines to implement the highly concurrent swoole_ftpget function, we must first understand the basic concepts and usage of the swoole_ftpget function. The swoole_ftpget function is a function used to implement the FTP download function in the Swoole framework. The specific usage is as follows:

bool swoole_ftpget(string $filename, string $local_file)

Among them, the $filename parameter is the file name on the FTP server, and the $local_file parameter is the file name to be saved locally. . The swoole_ftpget function will download the specified file on the FTP server to the local computer and return a Boolean value to indicate whether the download is successful.

2. Use coroutines to implement high-concurrency swoole_ftpget function

In Swoole, you can implement high-concurrency swoole_ftpget functions by using coroutines. The specific implementation method is as follows:

(1) Use Swoole's coroutine client to improve download efficiency

When using Swoole to implement the FTP download function, you can use Swoole's coroutine client to achieve concurrent downloads . The specific implementation method is as follows:

$host = '127.0.0.1';
$port = 21;

$ftpClient = new SwooleCoroutineClient(SWOOLE_TCP);

// 连接FTP服务器
if (!$ftpClient->connect($host, $port)) {
    die("connect failed.");
}

// 登录FTP服务器
$ftpClient->recv();
$ftpClient->send("USER username
");
$ftpClient->recv();
$ftpClient->send("PASS password
");
$ftpClient->recv();

// 设置被动模式
$ftpClient->send("PASV
");
$res = $ftpClient->recv();
$pattern = "/([0-9]{1,3}.){3}[0-9]{1,3}:([0-9]{1,5})/";
preg_match($pattern, $res, $match);
$dataHost = $match[0];
$port = (int)substr($match[1], -1) * 256 + (int)substr($match[2], 0, -2);

// 连接数据通道
$dataClient = new SwooleCoroutineClient(SWOOLE_TCP);
if (!$dataClient->connect($dataHost, $port, 30)) {
    die("connect failed.");
}

// 下载文件
$filename = 'test.txt';
$local_file = '/tmp/test.txt';
$ftpClient->send("RETR {$filename}
");
$res = $ftpClient->recv(); 
while ($data = $dataClient->recv()) {
    file_put_contents($local_file, $data, FILE_APPEND);
}

// 关闭连接
$ftpClient->close();
$dataClient->close();

(2) Use Swoole's coroutine to implement concurrent execution of multiple download tasks

In addition to using Swoole's coroutine client to improve download efficiency, You can also implement concurrent execution of multiple download tasks by using coroutines. The specific implementation method is as follows:

$host = '127.0.0.1';
$port = 21;

// 并发下载任务数
$worker_num = 10;
$workers = [];

// 创建协程任务
for ($i = 0; $i < $worker_num; $i++) {
    $workers[$i] = new CoCoroutine(function () use ($host, $port) {
        $ftpClient = new SwooleCoroutineClient(SWOOLE_TCP);

        // 连接FTP服务器
        if (!$ftpClient->connect($host, $port)) {
            die("connect failed.");
        }

        // 登录FTP服务器
        $ftpClient->recv();
        $ftpClient->send("USER username
");
        $ftpClient->recv();
        $ftpClient->send("PASS password
");
        $ftpClient->recv();

        // 设置被动模式
        $ftpClient->send("PASV
");
        $res = $ftpClient->recv();
        $pattern = "/([0-9]{1,3}.){3}[0-9]{1,3}:([0-9]{1,5})/";
        preg_match($pattern, $res, $match);
        $dataHost = $match[0];
        $port = (int)substr($match[1], -1) * 256 + (int)substr($match[2], 0, -2);

        // 连接数据通道
        $dataClient = new SwooleCoroutineClient(SWOOLE_TCP);
        if (!$dataClient->connect($dataHost, $port, 30)) {
            die("connect failed.");
        }

        // 下载文件
        $filename = 'test.txt';
        $local_file = "/tmp/test_{$i}.txt";
        $ftpClient->send("RETR {$filename}
");
        $res = $ftpClient->recv();
        while ($data = $dataClient->recv()) {
            file_put_contents($local_file, $data, FILE_APPEND);
        }

        // 关闭连接
        $ftpClient->close();
        $dataClient->close();
    });
}

// 等待协程任务执行完成
CoWaitGroup::wait();

// 合并下载文件
for ($i = 0; $i < $worker_num; $i++) {
    $local_file = "/tmp/test_{$i}.txt";
    if (file_exists($local_file)) {
        $data = file_get_contents($local_file);
        file_put_contents('/tmp/test.txt', $data, FILE_APPEND);
        unlink($local_file);
    }
}

3. Summary

By using Swoole’s coroutine technology, the highly concurrent swoole_ftpget function can be easily implemented. When using coroutines, you need to pay attention to the maximum number of connections to the FTP server and the number of concurrent download tasks to avoid excessive connections and blocking. At the same time, you need to pay attention to file name conflicts and file read and write permission issues when merging downloaded files. In actual development, it can be adjusted according to specific application scenarios to achieve the best download efficiency and download quality.

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