Examples

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# Examples

Example #1 Simple timers

    <?php
    // Create and start timer firing after 2 seconds
    $w1 = new EvTimer(2, 0, function () {
        echo "2 seconds elapsed\n";
    });

    // Create and launch timer firing after 2 seconds repeating each second
    // until we manually stop it
    $w2 = new EvTimer(2, 1, function ($w) {
        echo "is called every second, is launched after 2 seconds\n";
        echo "iteration = ", Ev::iteration(), PHP_EOL;

        // Stop the watcher after 5 iterations
        Ev::iteration() == 5 and $w->stop();
        // Stop the watcher if further calls cause more than 10 iterations
        Ev::iteration() >= 10 and $w->stop();
    });

    // Create stopped timer. It will be inactive until we start it ourselves
    $w_stopped = EvTimer::createStopped(10, 5, function($w) {
        echo "Callback of a timer created as stopped\n";

        // Stop the watcher after 2 iterations
        Ev::iteration() >= 2 and $w->stop();
    });

    // Loop until Ev::stop() is called or all of watchers stop
    Ev::run();

    // Start and look if it works
    $w_stopped->start();
    echo "Run single iteration\n";
    Ev::run(Ev::RUN_ONCE);

    echo "Restart the second watcher and try to handle the same events, but don't block\n";
    $w2->again();
    Ev::run(Ev::RUN_NOWAIT);

    $w = new EvTimer(10, 0, function() {});
    echo "Running a blocking loop\n";
    Ev::run();
    echo "END\n";
    ?>

The above example will output something similar to:

    2 seconds elapsed
    is called every second, is launched after 2 seconds
    iteration = 1
    is called every second, is launched after 2 seconds
    iteration = 2
    is called every second, is launched after 2 seconds
    iteration = 3
    is called every second, is launched after 2 seconds
    iteration = 4
    is called every second, is launched after 2 seconds
    iteration = 5
    Run single iteration
    Callback of a timer created as stopped
    Restart the second watcher and try to handle the same events, but don't block
    Running a blocking loop
    is called every second, is launched after 2 seconds
    iteration = 8
    is called every second, is launched after 2 seconds
    iteration = 9
    is called every second, is launched after 2 seconds
    iteration = 10
    END

Example #2 Periodic timer. Tick each 10.5 seconds

    <?php
    $w = new EvPeriodic(0., 10.5, NULL, function ($w, $revents) {
        echo time(), PHP_EOL;
    });

    Ev::run();
    ?>

Example #3 Periodic timer. Use reschedule callback

    <?php
    // Tick each 10.5 seconds

    function reschedule_cb ($watcher, $now) {
        return $now + (10.5. - fmod($now, 10.5));
    }

    $w = new EvPeriodic(0., 0., "reschedule_cb", function ($w, $revents) {
        echo time(), PHP_EOL;
    });

    Ev::run();
    ?>

Example #4 Periodic timer. Tick every 10.5 seconds starting at now

    <?php
    // Tick every 10.5 seconds starting at now
    $w = new EvPeriodic(fmod(Ev::now(), 10.5), 10.5, NULL, function ($w, $revents) {
        echo time(), PHP_EOL;
    });

    Ev::run();
    ?>

Example #5 Wait until STDIN is readable

    <?php
    // Wait until STDIN is readable
    $w = new EvIo(STDIN, Ev::READ, function ($watcher, $revents) {
        echo "STDIN is readable\n";
    });

    Ev::run(Ev::RUN_ONCE);
    ?>

Example #6 Use some async I/O to access a socket

    <?php
    /* Use some async I/O to access a socket */

    // `sockets' extension still logs warnings
    // for EINPROGRESS, EAGAIN/EWOULDBLOCK etc.
    error_reporting(E_ERROR);

    $e_nonblocking = array (/*EAGAIN or EWOULDBLOCK*/11, /*EINPROGRESS*/115);

    // Get the port for the WWW service
    $service_port = getservbyname('www', 'tcp');

    // Get the IP address for the target host
    $address = gethostbyname('google.co.uk');

    // Create a TCP/IP socket
    $socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
    if ($socket === FALSE) {
        echo "socket_create() failed: reason: "
            .socket_strerror(socket_last_error()) . "\n";
    }

    // Set O_NONBLOCK flag
    socket_set_nonblock($socket);

    // Abort on timeout
    $timeout_watcher = new EvTimer(10.0, 0., function () use ($socket) {
        socket_close($socket);
        Ev::stop(Ev::BREAK_ALL);
    });

    // Make HEAD request when the socket is writable
    $write_watcher = new EvIo($socket, Ev::WRITE, function ($w)
        use ($socket, $timeout_watcher, $e_nonblocking)
    {
        // Stop timeout watcher
        $timeout_watcher->stop();
        // Stop write watcher
        $w->stop();

        $in = "HEAD / HTTP/1.1\r\n";
        $in .= "Host: google.co.uk\r\n";
        $in .= "Connection: Close\r\n\r\n";

        if (!socket_write($socket, $in, strlen($in))) {
            trigger_error("Failed writing $in to socket", E_USER_ERROR);
        }

        $read_watcher = new EvIo($socket, Ev::READ, function ($w, $re)
            use ($socket, $e_nonblocking)
        {
            // Socket is readable. recv() 20 bytes using non-blocking mode
            $ret = socket_recv($socket, $out, 20, MSG_DONTWAIT);

            if ($ret) {
                echo $out;
            } elseif ($ret === 0) {
                // All read
                $w->stop();
                socket_close($socket);
                return;
            }

            // Caught EINPROGRESS, EAGAIN, or EWOULDBLOCK
            if (in_array(socket_last_error(), $e_nonblocking)) {
                return;
            }

            $w->stop();
            socket_close($socket);
        });

        Ev::run();
    });

    $result = socket_connect($socket, $address, $service_port);

    Ev::run();
    ?>

The above example will output something similar to:

    HTTP/1.1 301 Moved Permanently
    Location: http://www.google.co.uk/
    Content-Type: text/html; charset=UTF-8
    Date: Sun, 23 Dec 2012 16:08:27 GMT
    Expires: Tue, 22 Jan 2013 16:08:27 GMT
    Cache-Control: public, max-age=2592000
    Server: gws
    Content-Length: 221
    X-XSS-Protection: 1; mode=block
    X-Frame-Options: SAMEORIGIN
    Connection: close

Example #7 Embedding one loop into another

    <?php
    /*
    * Try to get an embeddable event loop and embed it into the default event loop.
    * If it is impossible, use the default
    * loop. The default loop is stored in $loop_hi, while the embeddable loop is
    * stored in $loop_lo(which is $loop_hi in the case no embeddable loop can be
    * used).
    *
    * Sample translated to PHP
    * http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#Examples_CONTENT-9
    */
    $loop_hi = EvLoop::defaultLoop();
    $loop_lo = NULL;
    $embed   = NULL;

    /*
    * See if there is a chance of getting one that works
    * (flags' value of 0 means autodetection)
    */
    $loop_lo = Ev::embeddableBackends() & Ev::recommendedBackends()
        ? new EvLoop(Ev::embeddableBackends() & Ev::recommendedBackends())
        : 0;

    if ($loop_lo) {
        $embed = new EvEmbed($loop_lo, function () {});
    } else {
        $loop_lo = $loop_hi;
    }
    ?>

Example #8 Embedding loop created with kqueue backend into the default loop

    <?php
    /*
    * Check if kqueue is available but not recommended and create a kqueue backend
    * for use with sockets (which usually work with any kqueue implementation).
    * Store the kqueue/socket-only event loop in loop_socket. (One might optionally
    * use EVFLAG_NOENV, too)
    *
    * Example borrowed from
    * http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#Examples_CONTENT-9
    */
    $loop        = EvLoop::defaultLoop();
    $socket_loop = NULL;
    $embed       = NULL;

    if (Ev::supportedBackends() & ~Ev::recommendedBackends() & Ev::BACKEND_KQUEUE) {
        if (($socket_loop = new EvLoop(Ev::BACKEND_KQUEUE))) {
            $embed = new EvEmbed($loop);
        }
    }

    if (!$socket_loop) {
        $socket_loop = $loop;
    }

    // Now use $socket_loop for all sockets, and $loop for anything else
    ?>

Example #9 Handle SIGTERM signal

    <?php
    $w = new EvSignal(SIGTERM, function ($watcher) {
        echo "SIGTERM received\n";
        $watcher->stop();
    });

    Ev::run();
    ?>

Example #10 Monitor changes of /var/log/messages

    <?php
    // Use 10 second update interval.
    $w = new EvStat("/var/log/messages", 8, function ($w) {
        echo "/var/log/messages changed\n";

        $attr = $w->attr();

        if ($attr['nlink']) {
            printf("Current size: %ld\n", $attr['size']);
            printf("Current atime: %ld\n", $attr['atime']);
            printf("Current mtime: %ld\n", $attr['mtime']);
        } else {
            fprintf(STDERR, "`messages` file is not there!");
            $w->stop();
        }
    });

    Ev::run();
    ?>

Example #11 Monotor changes of /var/log/messages. Avoid missing updates by means of one second delay

    <?php
    $timer = EvTimer::createStopped(0., 1.02, function ($w) {
        $w->stop();

        $stat = $w->data;

        // 1 second after the most recent change of the file
        printf("Current size: %ld\n", $stat->attr()['size']);
    });

    $stat = new EvStat("/var/log/messages", 0., function () use ($timer) {
        // Reset timer watcher
        $timer->again();
    });

    $timer->data = $stat;

    Ev::run();
    ?>

Example #12 Process status changes

    <?php
    $pid = pcntl_fork();

    if ($pid == -1) {
        fprintf(STDERR, "pcntl_fork failed\n");
    } elseif ($pid) {
        $w = new EvChild($pid, FALSE, function ($w, $revents) {
            $w->stop();

            printf("Process %d exited with status %d\n", $w->rpid, $w->rstatus);
        });

        Ev::run();

        // Protect against Zombies
        pcntl_wait($status);
    } else {
        //Forked child
        exit(2);
    }
    ?>