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项目开发中，如果有定时任务的业务需求，可以选择使用Linux的crontab工具来处理。但需要注意的是，crontab的最小粒度是分钟级别，对于需要秒级或毫秒级定时任务来说，它就不足以满足需求。幸运的是，Swoole提供了强大的毫秒定时器功能，可以更灵活地满足各种定时任务的需求。

应用场景举例

在实际项目中，我们可能会遇到以下几种定时任务的场景：

Swoole毫秒定时器

Swoole提供了多种异步毫秒定时器函数，支持以毫秒级精度执行定时任务：

• swoole_timer_tick(int $msec, callable $callback)

  设置一个间隔$msec$毫秒的定时器，每隔$msec$毫秒执行一次$callback$，类似于JavaScript的setInterval()。

• swoole_timer_after(int $after_time_ms, mixed $callback_function)

  在指定的时间$after_time_ms$后执行$callback_function$，类似于JavaScript的setTimeout()。

• swoole_timer_clear(int $timer_id)

  删除指定id的定时器，类似于JavaScript的clearInterval()。

解决方案

场景一：

swoole_timer_tick(30000, function($timer) use ($task_id) {
    $memPercent = $this->getMemoryUsage();
    echo date('Y-m-d H:i:s') . '当前内存使用率：' . $memPercent . "\n";
});

场景二：

swoole_timer_after(120000, function() use ($str) {
    $this->sendReport();
    echo "send report, $str\n";
});

场景三：

swoole_timer_tick(5 * 60 * 1000, function($timer) use ($url) {
    $rs = $this->postUrl($url);
    if ($rs) {
        // 业务代码...
        swoole_timer_clear($timer); // 停止定时器
        echo date('Y-m-d H:i:s') . "请求接口任务执行成功\n";
    } else {
        echo date('Y-m-d H:i:s') . "请求接口失败，5分钟后再次尝试\n";
    }
});

示例代码

文件：src/App/Task.php

namespace Helloweba\Swoole;
use swoole_server;
class Task {
    protected $serv;
    protected $host = '127.0.0.1';
    protected $port = 9506;
    protected $taskName = 'swooleTask';
    protected $pidPath = '/run/swooletask.pid';
    protected $options = [
        'worker_num' => 4,
        'daemonize' => true,
        'log_file' => '/data/log/swoole-task.log',
        'log_level' => 0,
        'dispatch_mode' => 1,
        'task_worker_num' => 4,
        'task_ipc_mode' => 3,
    ];
    public function __construct($options = []) {
        date_default_timezone_set('PRC');
        $this->serv = new swoole_server($this->host, $this->port);
        if (!empty($options)) {
            $this->options = array_merge($this->options, $options);
        }
        $this->serv->set($this->options);
        $this->serv->on('Start', [$this, 'onStart']);
        $this->serv->on('Connect', [$this, 'onConnect']);
        $this->serv->on('Receive', [$this, 'onReceive']);
        $this->serv->on('Task', [$this, 'onTask']);
        $this->serv->on('Finish', [$this, 'onFinish']);
        $this->serv->on('Close', [$this, 'onClose']);
    }
    public function start() {
        $this->serv->start();
    }
    public function onStart($serv) {
        cli_set_process_title($this->taskName);
        $pid = "{$serv->master_pid}\n{$serv->manager_pid}";
        file_put_contents($this->pidPath, $pid);
    }
    public function onConnect($serv, $fd, $from_id) {
        $serv->send($fd, "Hello {$fd}!");
    }
    public function onReceive(swoole_server $serv, $fd, $from_id, $data) {
        echo "Get Message From Client {$fd}:{$data}\n";
        $res['result'] = 'success';
        $serv->send($fd, json_encode($res));
        $serv->task($data);
    }
    public function onTask(swoole_server $serv, $task_id, $from_id, $data) {
        swoole_timer_tick(30000, function($timer) use ($task_id) {
            $memPercent = $this->getMemoryUsage();
            echo date('Y-m-d H:i:s') . '当前内存使用率：' . $memPercent . "\n";
        });
    }
    public function onFinish(swoole_server $serv, $task_id, $data) {
        // ...
    }
    public function onClose($serv, $fd, $from_id) {
        echo "Client {$fd} close connection\n";
    }
    public function stop() {
        $this->serv->stop();
    }
    private function getMemoryUsage() {
        if (false === ($str = @file("/proc/meminfo"))) return false;
        $str = implode("", $str);
        preg_match_all("/MemTotal\s{0,}\:+\s{0,}([\d\.]+).+?MemFree\s{0,}\:+\s{0,}([\d\.]+).+?Cached\s{0,}\:+\s{0,}([\d\.]+).+?SwapTotal\s{0,}\:+\s{0,}([\d\.]+).+?SwapFree\s{0,}\:+\s{0,}([\d\.]+)/s", $str, $buf);
        $memTotal = round($buf[1][0]/1024, 2);
        $memFree = round($buf[2][0]/1024, 2);
        $memUsed = $memTotal - $memFree;
        $memPercent = (floatval($memTotal) != 0) ? round($memUsed/$memTotal*100, 2) : 0;
        return $memPercent;
    }
}

文件：src/App/TaskServer.php

    false,
];
$ser = new Task($opt);
$ser->start();

文件：src/App/TaskClient.php

   client = new swoole_client(SWOOLE_SOCK_TCP);
    }
    public function connect() {
        if (!$this->client->connect("127.0.0.1", 9506, 1)) {
            echo "Error: {$this->client->errMsg}[{$this->client->errCode}]\n";
        }
        fwrite(STDOUT, "请输入消息 Please input msg：");
        $msg = trim(fgets(STDIN));
        $this->client->send($msg);
        $message = $this->client->recv();
        echo "Get Message From Server:{$message}\n";
    }
}
$client = new Client();
$client->connect();

验证效果

php taskServer.php

php taskClient.php

Get Message From Server: {"result":"success"}

通过以上步骤，可以验证Swoole毫秒定时器的功能是否正常工作。

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