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libev extension for php_PHP tutorial
- WBOYOriginal
- 2016-07-14 10:07:541548browse
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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