<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision: 318955 $ -->

<book xml:id="book.eio" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <title>Eio</title>
 <titleabbrev>Eio</titleabbrev>
<!--{{{ preface -->
 <preface xml:id="intro.eio">
  &reftitle.intro;
  <para>
   This extension provides asyncronous POSIX I/O by means of <link
   xlink:href="&url.eio.libeio;">libeio</link> C
   library written by Marc Lehmann.
  </para>

  &note.no-windows.extension;

  <para>

  <warning>
  <simpara>
  It is important to 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.
  </simpara>
  </warning>

  <example>
  <title>Incorrect requests</title>
  <programlisting role="php"><![CDATA[
<?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();
?>
]]>
   </programlisting>
   </example>

   In the example above <function>eio_rename</function> request may finish
   before <function>eio_symlink</function>. To fix it you might call <function>eio_rename</function>
   in the callback of <function>eio_symlink</function>:
  <example>
   <title>Calling request from a request callback</title>
   <programlisting role="php"><![CDATA[
<?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();
?>
   ]]>
   </programlisting>
  </example>

  Alternatively, you might want to create a request group:

  <example>
   <title>Calling request from a request callback</title>
   <programlisting role="php"><![CDATA[
<?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();
?>
]]></programlisting>
  </example>

  Group is a special kind of request that could accumulate a set of regular
  <emphasis>eio</emphasis> requests. This could be used to create a complex
  request that opens, reads and closes a file.
  </para>
  <para>
  Since version 0.3.0 alpha, a variable used in communications with libeio
  internally, could be retrieved with
  <function>eio_get_event_stream</function>. 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>
   <title>Using eio with libevent</title>
   <programlisting role="php"><![CDATA[
<?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 */
?>
]]></programlisting>
  </example>

  </para>
 </preface>
<!--}}}-->
 &reference.eio.setup;
 &reference.eio.constants;
 &reference.eio.examples;
 &reference.eio.reference;

</book>

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