Eio

Introduction

This extension provides asyncronous POSIX I/O by means of » libeio C library written by Marc Lehmann.

Note: This extension is not available on Windows platforms.

Warning

It is important to be aware that each request is executed in a thread, and the order of execution of continuously queued requests basically is unpredictable. For instance, the following piece of code is incorrect.

Example #1 Incorrect requests

<?php
// Request to create symlink of $filename to $link
eio_symlink($filename, $link);

// Request to move $filename to $new_filename
eio_rename($filename, $new_filename);

// Process requests
eio_event_loop();
?>
In the example above eio_rename() request may finish before eio_symlink(). To fix it you might call eio_rename() in the callback of eio_symlink():

Example #2 Calling request from a request callback

<?php
function my_symlink_done($filename, $result) {
// Request to move $filename to $new_filename
eio_rename($filename, "/path/to/new-name");

// Process requests
eio_event_loop();
}

// Request to create symlink of $filename to $link
eio_symlink($filename, $link, EIO_PRI_DEFAULT, "my_symlink_done", $filename);

// Process requests
eio_event_loop();
?>
Alternatively, you might want to create a request group:

Example #3 Calling request from a request callback

<?php
/* Is called when the group requests are done */
function my_grp_done($data, $result) {
// ...
}

function my_symlink_done($filename, $result) {
// Create eio_rename request and add it to the group
$req = eio_rename($filename, "/path/to/new-name");
eio_grp_add($grp, $req);
// You might want to add more requests...
}

// Create a request group
$grp = eio_grp("my_grp_done", "my_grp_data");

// Create eio_symlink request and add it to the group
// Pass $filename to the callback
$req = eio_symlink($filename, $link,
EIO_PRI_DEFAULT, "my_symlink_done", $filename);
eio_grp_add($grp, $req);

// Process requests
eio_event_loop();
?>
Group is a special kind of request that could accumulate a set of regular eio requests. This could be used to create a complex request that opens, reads and closes a file.

Since version 0.3.0 alpha, a variable used in communications with libeio internally, could be retrieved with eio_get_event_stream(). The variable could be used to bind to an event loop supported by some other extension. You might organize a simple event loop where eio and libevent work together:

Example #4 Using eio with libevent

<?php
function my_eio_poll($fd, $events, $arg) {
/* Some libevent regulation might go here .. */
if (eio_nreqs()) {
eio_poll();
}
/* .. and here */
}

function my_res_cb($d, $r) {
var_dump($r); var_dump($d);
}

$base = event_base_new();
$event = event_new();

// This stream is used to bind with libevent
$fd = eio_get_event_stream();

eio_nop(EIO_PRI_DEFAULT, "my_res_cb", "nop data");
eio_mkdir("/tmp/abc-eio-temp", 0750, EIO_PRI_DEFAULT, "my_res_cb", "mkdir data");
/* some other eio_* calls here ... */


// set event flags
event_set($event, $fd, EV_READ /*| EV_PERSIST*/, "my_eio_poll", array($event, $base));

// set event base
event_base_set($event, $base);

// enable event
event_add($event);

// start event loop
event_base_loop($base);

/* The same will be available via buffered libevent interface */
?>