forked from premiere/premiere-libtorrent
189 lines
9.6 KiB
HTML
189 lines
9.6 KiB
HTML
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<?xml version="1.0" encoding="utf-8" ?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="generator" content="Docutils 0.3.9: http://docutils.sourceforge.net/" />
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<title></title>
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<meta name="author" content="Arvid Norberg, arvid@rasterbar.com" />
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<link rel="stylesheet" href="style.css" type="text/css" />
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</head>
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<body>
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<div class="document">
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<table class="docinfo" frame="void" rules="none">
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<col class="docinfo-name" />
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<col class="docinfo-content" />
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<tbody valign="top">
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<tr><th class="docinfo-name">Author:</th>
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<td>Arvid Norberg, <a class="last reference" href="mailto:arvid@rasterbar.com">arvid@rasterbar.com</a></td></tr>
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</tbody>
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</table>
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<div class="section" id="libtorrent-plugins">
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<h1><a name="libtorrent-plugins">libtorrent plugins</a></h1>
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<div class="contents topic" id="table-of-contents">
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<p class="topic-title first"><a name="contents">Contents</a></p>
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<ul class="simple">
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<li><a class="reference" href="#libtorrent-plugins" id="id1" name="id1">libtorrent plugins</a><ul>
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<li><a class="reference" href="#a-word-of-caution" id="id2" name="id2">a word of caution</a></li>
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</ul>
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</li>
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<li><a class="reference" href="#plugin-interface" id="id3" name="id3">plugin interface</a></li>
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<li><a class="reference" href="#torrent-plugin" id="id4" name="id4">torrent_plugin</a><ul>
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<li><a class="reference" href="#new-connection" id="id5" name="id5">new_connection()</a></li>
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<li><a class="reference" href="#on-piece-pass-on-piece-fail" id="id6" name="id6">on_piece_pass() on_piece_fail()</a></li>
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<li><a class="reference" href="#tick" id="id7" name="id7">tick()</a></li>
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<li><a class="reference" href="#on-pause-on-resume" id="id8" name="id8">on_pause() on_resume()</a></li>
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</ul>
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</li>
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<li><a class="reference" href="#peer-plugin" id="id9" name="id9">peer_plugin</a></li>
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</ul>
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</div>
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<p>libtorrent has a plugin interface for implementing extensions to the protocol.
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These can be general extensions for transferring metadata or peer exchange
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extensions, or it could be used to provide a way to customize the protocol
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to fit a particular (closed) network.</p>
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<p>In short, the plugin interface makes it possible to:</p>
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<ul class="simple">
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<li>register extension messages (sent in the extension handshake), see
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<a class="reference" href="extension_protocol.html">extensions</a>.</li>
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<li>add data and parse data from the extension handshake.</li>
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<li>send extension messages and standard bittorrent messages.</li>
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<li>override or block the handling of standard bittorrent messages.</li>
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</ul>
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<div class="section" id="a-word-of-caution">
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<h2><a name="a-word-of-caution">a word of caution</a></h2>
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<p>Writing your own plugin is a very easy way to introduce serious bugs such as
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dead locks and race conditions. Since a plugin has access to internal
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structures it is also quite easy to sabotage libtorrent's operation.</p>
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<p>All the callbacks in this interface are called with the main libtorrent thread
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mutex locked. And they are always called from the libtorrent main thread. In
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case portions of your plugin are called from other threads, typically the main
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thread, you cannot use any of the member functions on the internal structures
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in libtorrent, since those require the mutex to be locked. Futhermore, you would
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also need to have a mutex on your own shared data within the plugin, to make
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sure it is not accessed at the same time from the libtorrent thread (through a
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callback). See <a class="reference" href="http://www.boost.org/doc/html/mutex.html">boost thread's mutex</a>. If you need to send out a message from
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another thread, use an internal queue, and do the actual sending in <tt class="docutils literal"><span class="pre">tick()</span></tt>.</p>
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</div>
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</div>
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<div class="section" id="plugin-interface">
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<h1><a name="plugin-interface">plugin interface</a></h1>
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<p>The plugin interface consists of two base classes that the plugin may
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implement. These are called <tt class="docutils literal"><span class="pre">torrent_plugin</span></tt> and <tt class="docutils literal"><span class="pre">peer_plugin</span></tt>. They are
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both found in the <tt class="docutils literal"><span class="pre"><libtorrent/extensions.hpp></span></tt> header.</p>
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<p>These plugins are instantiated for each torrent and possibly each peer,
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respectively.</p>
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</div>
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<div class="section" id="torrent-plugin">
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<h1><a name="torrent-plugin">torrent_plugin</a></h1>
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<p>The synopsis for <tt class="docutils literal"><span class="pre">torrent_plugin</span></tt> follows:</p>
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<pre class="literal-block">
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struct torrent_plugin
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{
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virtual ~torrent_plugin();
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virtual boost::shared_ptr<peer_plugin> new_connection(peer_connection*);
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virtual void on_piece_pass(int index);
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virtual void on_piece_failed(int index);
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virtual void tick();
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virtual bool on_pause();
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virtual bool on_resume();
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};
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</pre>
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<p>This is the base class for a torrent_plugin. Your derived class is (if added
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as an extension) instantiated for each torrent in the session. The callback
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hook functions are defined as follows.</p>
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<div class="section" id="new-connection">
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<h2><a name="new-connection">new_connection()</a></h2>
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<pre class="literal-block">
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boost::shared_ptr<peer_plugin> new_connection(peer_connection*);
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</pre>
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<p>This function is called each time a new peer is connected to the torrent. You
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may choose to ignore this by just returning a default constructed
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<tt class="docutils literal"><span class="pre">shared_ptr</span></tt> (in which case you don't need to override this member
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function).</p>
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<p>If you need an extension to the peer connection (which most plugins do) you
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are supposed to return an instance of your <tt class="docutils literal"><span class="pre">peer_plugin</span></tt> class. Which in
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turn will have its hook functions called on event specific to that peer.</p>
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<p>The <tt class="docutils literal"><span class="pre">peer_connection</span></tt> will be valid as long as the <tt class="docutils literal"><span class="pre">shared_ptr</span></tt> is being
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held by the torrent object. So, it is generally a good idea to not keep a
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<tt class="docutils literal"><span class="pre">shared_ptr</span></tt> to your own peer_plugin. If you want to keep references to it,
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use <tt class="docutils literal"><span class="pre">weak_ptr</span></tt>.</p>
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<p>If this function throws an exception, the connection will be closed.</p>
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</div>
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<div class="section" id="on-piece-pass-on-piece-fail">
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<h2><a name="on-piece-pass-on-piece-fail">on_piece_pass() on_piece_fail()</a></h2>
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<pre class="literal-block">
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void on_piece_pass(int index);
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void on_piece_failed(int index);
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</pre>
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<p>These hooks are called when a piece passes the hash check or fails the hash
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check, respectively. The <tt class="docutils literal"><span class="pre">index</span></tt> is the piece index that was downloaded.
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It is possible to access the list of peers that participated in sending the
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piece through the <tt class="docutils literal"><span class="pre">torrent</span></tt> and the <tt class="docutils literal"><span class="pre">piece_picker</span></tt>.</p>
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</div>
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<div class="section" id="tick">
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<h2><a name="tick">tick()</a></h2>
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<pre class="literal-block">
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void tick();
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</pre>
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<p>This hook is called approximately once per second. It is a way of making it
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easy for plugins to do timed events, for sending messages or whatever.</p>
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</div>
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<div class="section" id="on-pause-on-resume">
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<h2><a name="on-pause-on-resume">on_pause() on_resume()</a></h2>
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<pre class="literal-block">
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bool on_pause();
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bool on_resume();
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</pre>
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<p>These hooks are called when the torrent is paused and unpaused respectively.
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The return value indicates if the event was handled. A return value of
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<tt class="docutils literal"><span class="pre">true</span></tt> indicates that it was handled, and no other plugin after this one
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will have this hook function called, and the standard handler will also not be
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invoked. So, returning true effectively overrides the standard behavior of
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pause or unpause.</p>
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<p>Note that if you call <tt class="docutils literal"><span class="pre">pause()</span></tt> or <tt class="docutils literal"><span class="pre">resume()</span></tt> on the torrent from your
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handler it will recurse back into your handler, so in order to invoke the
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standard handler, you have to keep your own state on whether you want standard
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behavior or overridden behavior.</p>
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</div>
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</div>
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<div class="section" id="peer-plugin">
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<h1><a name="peer-plugin">peer_plugin</a></h1>
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<pre class="literal-block">
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struct peer_plugin
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{
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virtual ~peer_plugin();
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virtual void add_handshake(entry&);
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virtual bool on_handshake();
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virtual bool on_extension_handshake(entry const& h);
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virtual bool on_choke();
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virtual bool on_unchoke();
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virtual bool on_interested();
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virtual bool on_not_interested();
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virtual bool on_have(int index);
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virtual bool on_bitfield(std::vector<bool> const& bitfield);
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virtual bool on_request(peer_request const& req);
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virtual bool on_piece(peer_request const& piece, char const* data);
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virtual bool on_cancel(peer_request const& req);
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virtual bool on_extended(int length
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, int msg, buffer::const_interval body);
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virtual bool on_unknown_message(int length, int msg
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, buffer::const_interval body);
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virtual void on_piece_pass(int index);
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virtual void on_piece_failed(int index);
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virtual void tick();
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virtual bool write_request(peer_request const& r);
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};
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</pre>
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</div>
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</div>
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</body>
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</html>
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