# 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);
}
?>`