libev extension for php_PHP tutorial

ev is a PECL extension providing inteface to libev library – high performance full-featured event loop written in C.

ABOUT LIBEV

Libev is an event loop: you register interest in certain events (such as a file descriptor being readable or a timeout occurring), and it will manage these event sources and provide your program with events.

So what is libev? Here’s an excerpt from the Internet:

libev is a high-performance event loop/event model networking library and includes a lot of new features.

It is a new set of network libraries after lievent and Event perl module. The goals it pursues: faster speed, fewer bugs, more features, and smaller size. www.2cto.com

It is very similar to libevent. According to the author's introduction, it can be used as a replacement for libevent and can provide higher performance. No complicated configuration is required.

It seems to be closely related to the previously mentioned libevent, but the author of this extension is obviously more active, submitting 3 versions within a week.

Code Example

Usage of timer

// Create a timer and trigger it after 2 seconds

$w1 = new EvTimer(2, 0, function () {

echo "2 seconds elapsedn";

});

// Create a timer and trigger it after 2 seconds, repeating every second

// Until we stop manually

$w2 = new EvTimer(2, 1, function ($w) {

echo "is called every second, is launched after 2 secondsn";

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 a stopped timer, manual start is only valid

$w_stopped = EvTimer::createStopped(10, 5, function($w) {

echo "Callback of a timer created as stoppedn";

// 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";

Ev::run(Ev::RUN_ONCE);

echo "Restart the second watcher and try to handle the same events, but don't blockn";

$w2->again();

Ev::run(Ev::RUN_NOWAIT);

$w = new EvTimer(10, 0, function() {});

echo "Running a blocking loopn";

Ev::run();

echo "ENDn";

?>

Output content

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

I/O events

Example 1

// Wait until STDIN is readable

$w = new EvIo(STDIN, Ev::READ, function ($watcher, $revents) {

echo "STDIN is readablen";

});

Ev::run(Ev::RUN_ONCE);

?>

Example 2

/* 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/1.1rn";

    $in .= "Host: google.co.ukrn";

    $in .= "Connection: Closernrn";

 

    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();

?>

输出

 

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

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