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 $w->stop();});// Loop until Ev::stop() is called or all of watchers stopEv::run();// Start and look if it works$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 secondsfunction 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 ($socket === FALSE) {    echo "socket_create() failed: reason: "        .socket_strerror(socket_last_error()) . "\n";}// Set O_NONBLOCK flagsocket_set_nonblock($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);}?>