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<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="generator" content="Docutils 0.11: http://docutils.sourceforge.net/" />
<title>Session</title>
<meta name="author" content="Arvid Norberg, arvid&#64;rasterbar.com" />
<link rel="stylesheet" type="text/css" href="base.css" />
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<body>
<div class="document" id="session">
<div id="container">
<div id="header">
<div id="orange"></div>
<div id="logo"></div>
</div>
<div id="main">
<h1 class="title">Session</h1>
<table class="docinfo" frame="void" rules="none">
<col class="docinfo-name" />
<col class="docinfo-content" />
<tbody valign="top">
<tr><th class="docinfo-name">Author:</th>
<td>Arvid Norberg, <a class="last reference external" href="mailto:arvid&#64;rasterbar.com">arvid&#64;rasterbar.com</a></td></tr>
<tr><th class="docinfo-name">Version:</th>
<td>1.0.0</td></tr>
</tbody>
</table>
<div class="contents topic" id="table-of-contents">
<p class="topic-title first">Table of contents</p>
<ul class="simple">
<li><a class="reference internal" href="#add-torrent-params" id="id175">add_torrent_params</a></li>
<li><a class="reference internal" href="#cache-status" id="id176">cache_status</a></li>
<li><a class="reference internal" href="#stats-metric" id="id177">stats_metric</a></li>
<li><a class="reference internal" href="#session-proxy" id="id178">session_proxy</a></li>
<li><a class="reference internal" href="#id38" id="id179">session</a></li>
<li><a class="reference internal" href="#dht-lookup" id="id180">dht_lookup</a></li>
<li><a class="reference internal" href="#dht-routing-bucket" id="id181">dht_routing_bucket</a></li>
<li><a class="reference internal" href="#utp-status" id="id182">utp_status</a></li>
<li><a class="reference internal" href="#session-status" id="id183">session_status</a></li>
</ul>
</div>
<a name="add_torrent_params"></a><div class="section" id="add-torrent-params">
<h1>add_torrent_params</h1>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/add_torrent_params.hpp">libtorrent/add_torrent_params.hpp</a>&quot;</p>
<p>The <a class="reference external" href="reference-Session.html#add_torrent_params">add_torrent_params</a> is a parameter pack for adding torrents to a
<a class="reference external" href="reference-Session.html#session">session</a>. The key fields when adding a torrent are:</p>
<ul class="simple">
<li>ti - when you have a .torrent file</li>
<li>url - when you have a magnet link or http URL to the .torrent file</li>
<li>info_hash - when all you have is an info-hash (this is similar to a
magnet link)</li>
</ul>
<p>one of those fields need to be set. Another mandatory field is
<tt class="docutils literal">save_path</tt>. The <a class="reference external" href="reference-Session.html#add_torrent_params">add_torrent_params</a> object is passed into one of the
<tt class="docutils literal"><span class="pre">session::add_torrent()</span></tt> overloads or <tt class="docutils literal"><span class="pre">session::async_add_torrent()</span></tt>.</p>
<p>If you only specify the info-hash, the torrent file will be downloaded
from peers, which requires them to support the metadata extension. For
the metadata extension to work, libtorrent must be built with extensions
enabled (<tt class="docutils literal">TORRENT_DISABLE_EXTENSIONS</tt> must not be defined). It also
takes an optional <tt class="docutils literal">name</tt> argument. This may be left empty in case no
name should be assigned to the torrent. In case it's not, the name is
used for the torrent as long as it doesn't have metadata. See
<tt class="docutils literal"><span class="pre">torrent_handle::name</span></tt>.</p>
<pre class="literal-block">
struct add_torrent_params
{
<strong>add_torrent_params</strong> (storage_constructor_type sc = default_storage_constructor);
enum flags_t
{
flag_seed_mode,
flag_override_resume_data,
flag_upload_mode,
flag_share_mode,
flag_apply_ip_filter,
flag_paused,
flag_auto_managed,
flag_duplicate_is_error,
flag_merge_resume_trackers,
flag_update_subscribe,
flag_super_seeding,
flag_sequential_download,
flag_use_resume_save_path,
flag_pinned,
| flag_auto_managed | flag_paused | flag_apply_ip_filter,
};
int version;
boost::shared_ptr&lt;torrent_info&gt; ti;
std::vector&lt;std::string&gt; trackers;
std::vector&lt;std::string&gt; url_seeds;
std::vector&lt;std::pair&lt;std::string, int&gt; &gt; dht_nodes;
std::string name;
std::string save_path;
std::vector&lt;char&gt; resume_data;
storage_mode_t storage_mode;
storage_constructor_type storage;
void* userdata;
std::vector&lt;boost::uint8_t&gt; file_priorities;
std::string trackerid;
std::string url;
std::string uuid;
std::string source_feed_url;
boost::uint64_t flags;
sha1_hash info_hash;
int max_uploads;
int max_connections;
int upload_limit;
int download_limit;
};
</pre>
<a name="add_torrent_params()"></a><div class="section" id="id5">
<h2>add_torrent_params()</h2>
<pre class="literal-block">
<strong>add_torrent_params</strong> (storage_constructor_type sc = default_storage_constructor);
</pre>
<p>The constructor can be used to initialize the storage constructor,
which determines the storage mechanism for the downloaded or seeding
data for the torrent. For more information, see the <tt class="docutils literal">storage</tt> field.</p>
<a name="flags_t"></a></div>
<div class="section" id="enum-flags-t">
<h2>enum flags_t</h2>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/add_torrent_params.hpp">libtorrent/add_torrent_params.hpp</a>&quot;</p>
<table border="1" class="docutils">
<colgroup>
<col width="42%" />
<col width="5%" />
<col width="53%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">name</th>
<th class="head">value</th>
<th class="head">description</th>
</tr>
</thead>
<tbody valign="top">
<tr><td>flag_seed_mode</td>
<td>1</td>
<td><p class="first">If <tt class="docutils literal">flag_seed_mode</tt> is set, libtorrent will assume that all files
are present for this torrent and that they all match the hashes in
the torrent file. Each time a peer requests to download a block,
the piece is verified against the hash, unless it has been verified
already. If a hash fails, the torrent will automatically leave the
seed mode and recheck all the files. The use case for this mode is
if a torrent is created and seeded, or if the user already know
that the files are complete, this is a way to avoid the initial
file checks, and significantly reduce the startup time.</p>
<p>Setting <tt class="docutils literal">flag_seed_mode</tt> on a torrent without metadata (a
.torrent file) is a no-op and will be ignored.</p>
<p class="last">If resume data is passed in with this torrent, the seed mode saved
in there will override the seed mode you set here.</p>
</td>
</tr>
<tr><td>flag_override_resume_data</td>
<td>2</td>
<td><p class="first">If <tt class="docutils literal">flag_override_resume_data</tt> is set, the <tt class="docutils literal">paused</tt>,
<tt class="docutils literal">auto_managed</tt> and <tt class="docutils literal">save_path</tt> of the torrent are not loaded
from the resume data, but the states requested by the flags in
<tt class="docutils literal">add_torrent_params</tt> will override them.</p>
<p class="last">If you pass in resume data, the paused state of the torrent when
the resume data was saved will override the paused state you pass
in here. You can override this by setting
<tt class="docutils literal">flag_override_resume_data</tt>.</p>
</td>
</tr>
<tr><td>flag_upload_mode</td>
<td>4</td>
<td><p class="first">If <tt class="docutils literal">flag_upload_mode</tt> is set, the torrent will be initialized in
upload-mode, which means it will not make any piece requests. This
state is typically entered on disk I/O errors, and if the torrent
is also auto managed, it will be taken out of this state
periodically. This mode can be used to avoid race conditions when
adjusting priorities of pieces before allowing the torrent to start
downloading.</p>
<p class="last">If the torrent is auto-managed (<tt class="docutils literal">flag_auto_managed</tt>), the torrent
will eventually be taken out of upload-mode, regardless of how it
got there. If it's important to manually control when the torrent
leaves upload mode, don't make it auto managed.</p>
</td>
</tr>
<tr><td>flag_share_mode</td>
<td>8</td>
<td><p class="first">determines if the torrent should be added in <em>share mode</em> or not.
Share mode indicates that we are not interested in downloading the
torrent, but merley want to improve our share ratio (i.e. increase
it). A torrent started in share mode will do its best to never
download more than it uploads to the swarm. If the swarm does not
have enough demand for upload capacity, the torrent will not
download anything. This mode is intended to be safe to add any
number of torrents to, without manual screening, without the risk
of downloading more than is uploaded.</p>
<p>A torrent in share mode sets the priority to all pieces to 0,
except for the pieces that are downloaded, when pieces are decided
to be downloaded. This affects the progress bar, which might be set
to &quot;100% finished&quot; most of the time. Do not change file or piece
priorities for torrents in share mode, it will make it not work.</p>
<p class="last">The share mode has one setting, the share ratio target, see
<tt class="docutils literal"><span class="pre">session_settings::share_mode_target</span></tt> for more info.</p>
</td>
</tr>
<tr><td>flag_apply_ip_filter</td>
<td>16</td>
<td>determines if the IP filter should apply to this torrent or not. By
default all torrents are subject to filtering by the IP filter
(i.e. this flag is set by default). This is useful if certain
torrents needs to be excempt for some reason, being an auto-update
torrent for instance.</td>
</tr>
<tr><td>flag_paused</td>
<td>32</td>
<td>specifies whether or not the torrent is to be started in a paused
state. I.e. it won't connect to the tracker or any of the peers
until it's resumed. This is typically a good way of avoiding race
conditions when setting configuration options on torrents before
starting them.</td>
</tr>
<tr><td>flag_auto_managed</td>
<td>64</td>
<td><p class="first">If the torrent is auto-managed (<tt class="docutils literal">flag_auto_managed</tt>), the torrent
may be resumed at any point, regardless of how it paused. If it's
important to manually control when the torrent is paused and
resumed, don't make it auto managed.</p>
<p>If <tt class="docutils literal">flag_auto_managed</tt> is set, the torrent will be queued,
started and seeded automatically by libtorrent. When this is set,
the torrent should also be started as paused. The default queue
order is the order the torrents were added. They are all downloaded
in that order. For more details, see <a class="reference external" href="manual-ref.html#queuing">queuing</a>.</p>
<p class="last">If you pass in resume data, the auto_managed state of the torrent
when the resume data was saved will override the auto_managed state
you pass in here. You can override this by setting
<tt class="docutils literal">override_resume_data</tt>.</p>
</td>
</tr>
<tr><td>flag_duplicate_is_error</td>
<td>128</td>
<td>&nbsp;</td>
</tr>
<tr><td>flag_merge_resume_trackers</td>
<td>256</td>
<td>defaults to off and specifies whether tracker URLs loaded from
resume data should be added to the trackers in the torrent or
replace the trackers.</td>
</tr>
<tr><td>flag_update_subscribe</td>
<td>512</td>
<td>on by default and means that this torrent will be part of state
updates when calling <a class="reference external" href="reference-Session.html#post_torrent_updates()">post_torrent_updates()</a>.</td>
</tr>
<tr><td>flag_super_seeding</td>
<td>1024</td>
<td>sets the torrent into super seeding mode. If the torrent is not a
seed, this flag has no effect. It has the same effect as calling
<tt class="docutils literal"><span class="pre">torrent_handle::super_seeding(true)</span></tt> on the torrent handle
immediately after adding it.</td>
</tr>
<tr><td>flag_sequential_download</td>
<td>2048</td>
<td>sets the sequential download state for the torrent. It has the same
effect as calling <tt class="docutils literal"><span class="pre">torrent_handle::sequential_download(true)</span></tt> on
the torrent handle immediately after adding it.</td>
</tr>
<tr><td>flag_use_resume_save_path</td>
<td>4096</td>
<td>if this flag is set, the save path from the resume data file, if
present, is honored. This defaults to not being set, in which
case the save_path specified in <a class="reference external" href="reference-Session.html#add_torrent_params">add_torrent_params</a> is always used.</td>
</tr>
<tr><td>flag_pinned</td>
<td>8192</td>
<td>indicates that this torrent should never be unloaded from RAM, even
if unloading torrents are allowed in general. Setting this makes
the torrent exempt from loading/unloading management.</td>
</tr>
<tr><td><div class="first last line-block">
<div class="line">flag_auto_managed | flag_paused | flag_apply_ip_filter</div>
</div>
</td>
<td>8194</td>
<td>&nbsp;</td>
</tr>
</tbody>
</table>
<a name="version"></a><dl class="docutils">
<dt>version</dt>
<dd>filled in by the constructor and should be left untouched. It is used
for forward binary compatibility.</dd>
</dl>
<a name="ti"></a><dl class="docutils">
<dt>ti</dt>
<dd><a class="reference external" href="reference-Core.html#torrent_info">torrent_info</a> object with the torrent to add. Unless the url or
info_hash is set, this is required to be initiazlied.</dd>
</dl>
<a name="trackers"></a><dl class="docutils">
<dt>trackers</dt>
<dd>If the torrent doesn't have a tracker, but relies on the DHT to find
peers, the <tt class="docutils literal">trackers</tt> can specify tracker URLs for the torrent.</dd>
</dl>
<a name="url_seeds"></a><dl class="docutils">
<dt>url_seeds</dt>
<dd>url seeds to be added to the torrent (<a class="reference external" href="http://bittorrent.org/beps/bep_0017.html">BEP 17</a>).</dd>
</dl>
<a name="dht_nodes"></a>
<a name="name"></a><dl class="docutils">
<dt>dht_nodes name</dt>
<dd>a list of hostname and port pairs, representing DHT nodes to be added
to the <a class="reference external" href="reference-Session.html#session">session</a> (if DHT is enabled). The hostname may be an IP address.</dd>
</dl>
<a name="save_path"></a><dl class="docutils">
<dt>save_path</dt>
<dd>the path where the torrent is or will be stored. Note that this may
alos be stored in resume data. If you which the save path saved in
the resume data to be used, you need to set the
flag_use_resume_save_path flag.</dd>
</dl>
<a name="resume_data"></a><dl class="docutils">
<dt>resume_data</dt>
<dd>The optional parameter, <tt class="docutils literal">resume_data</tt> can be given if up to date
fast-resume data is available. The fast-resume data can be acquired
from a running torrent by calling <a class="reference external" href="reference-Core.html#save_resume_data()">save_resume_data()</a> on
<a class="reference external" href="reference-Core.html#torrent_handle">torrent_handle</a>. See <a class="reference external" href="manual-ref.html#fast-resume">fast resume</a>. The <tt class="docutils literal">vector</tt> that is passed in
will be swapped into the running torrent instance with
<tt class="docutils literal"><span class="pre">std::vector::swap()</span></tt>.</dd>
</dl>
<a name="storage_mode"></a><dl class="docutils">
<dt>storage_mode</dt>
<dd>One of the values from <a class="reference external" href="reference-Storage.html#storage_mode_t">storage_mode_t</a>. For more information, see
<a class="reference external" href="manual-ref.html#storage-allocation">storage allocation</a>.</dd>
</dl>
<a name="storage"></a><dl class="docutils">
<dt>storage</dt>
<dd>can be used to customize how the data is stored. The default storage
will simply write the data to the files it belongs to, but it could be
overridden to save everything to a single file at a specific location
or encrypt the content on disk for instance. For more information
about the <a class="reference external" href="reference-Custom_Storage.html#storage_interface">storage_interface</a> that needs to be implemented for a custom
storage, see <a class="reference external" href="reference-Custom_Storage.html#storage_interface">storage_interface</a>.</dd>
</dl>
<a name="userdata"></a><dl class="docutils">
<dt>userdata</dt>
<dd>The <tt class="docutils literal">userdata</tt> parameter is optional and will be passed on to the
extension constructor functions, if any (see <a class="reference internal" href="#add-extension">add_extension()</a>).</dd>
</dl>
<a name="file_priorities"></a><dl class="docutils">
<dt>file_priorities</dt>
<dd>can be set to control the initial file priorities when adding a
torrent. The semantics are the same as for
<tt class="docutils literal"><span class="pre">torrent_handle::prioritize_files()</span></tt>.</dd>
</dl>
<a name="trackerid"></a><dl class="docutils">
<dt>trackerid</dt>
<dd>the default tracker id to be used when announcing to trackers. By
default this is empty, and no tracker ID is used, since this is an
optional argument. If a tracker returns a tracker ID, that ID is used
instead of this.</dd>
</dl>
<a name="url"></a><dl class="docutils">
<dt>url</dt>
<dd><p class="first">If you specify a <tt class="docutils literal">url</tt>, the torrent will be set in
<tt class="docutils literal">downloading_metadata</tt> state until the .torrent file has been
downloaded. If there's any error while downloading, the torrent will
be stopped and the torrent error state (<tt class="docutils literal"><span class="pre">torrent_status::error</span></tt>)
will indicate what went wrong. The <tt class="docutils literal">url</tt> may refer to a magnet link
or a regular http URL.</p>
<p>If it refers to an HTTP URL, the info-hash for the added torrent will
not be the true info-hash of the .torrent. Instead a placeholder,
unique, info-hash is used which is later updated once the .torrent
file has been downloaded.</p>
<p class="last">Once the info-hash change happens, a <a class="reference external" href="reference-Alerts.html#torrent_update_alert">torrent_update_alert</a> is posted.</p>
</dd>
</dl>
<a name="uuid"></a><dl class="docutils">
<dt>uuid</dt>
<dd>if <tt class="docutils literal">uuid</tt> is specified, it is used to find duplicates. If another
torrent is already running with the same UUID as the one being added,
it will be considered a duplicate. This is mainly useful for RSS feed
items which has UUIDs specified.</dd>
</dl>
<a name="source_feed_url"></a><dl class="docutils">
<dt>source_feed_url</dt>
<dd>should point to the URL of the RSS feed this torrent comes from, if it
comes from an RSS feed.</dd>
</dl>
<a name="flags"></a><dl class="docutils">
<dt>flags</dt>
<dd>flags controlling aspects of this torrent and how it's added. See
<a class="reference external" href="reference-Core.html#flags_t">flags_t</a> for details.</dd>
</dl>
<a name="info_hash"></a><dl class="docutils">
<dt>info_hash</dt>
<dd>set this to the info hash of the torrent to add in case the info-hash
is the only known property of the torrent. i.e. you don't have a
.torrent file nor a magnet link.</dd>
</dl>
<a name="max_uploads"></a>
<a name="max_connections"></a>
<a name="upload_limit"></a>
<a name="download_limit"></a><dl class="docutils">
<dt>max_uploads max_connections upload_limit download_limit</dt>
<dd><p class="first"><tt class="docutils literal">max_uploads</tt>, <tt class="docutils literal">max_connections</tt>, <tt class="docutils literal">upload_limit</tt>,
<tt class="docutils literal">download_limit</tt> correspond to the <tt class="docutils literal">set_max_uploads()</tt>,
<tt class="docutils literal">set_max_connections()</tt>, <tt class="docutils literal">set_upload_limit()</tt> and
<tt class="docutils literal">set_download_limit()</tt> functions on <a class="reference external" href="reference-Core.html#torrent_handle">torrent_handle</a>. These values let
you initialize these settings when the torrent is added, instead of
calling these functions immediately following adding it.</p>
<p class="last">-1 means unlimited on these settings just like their counterpart
functions on <a class="reference external" href="reference-Core.html#torrent_handle">torrent_handle</a></p>
</dd>
</dl>
<a name="cache_status"></a></div>
</div>
<div class="section" id="cache-status">
<h1>cache_status</h1>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/disk_io_thread.hpp">libtorrent/disk_io_thread.hpp</a>&quot;</p>
<p>this struct holds a number of statistics counters
relevant for the disk io thread and disk cache.</p>
<pre class="literal-block">
struct cache_status
{
<strong>cache_status</strong> ();
std::vector&lt;cached_piece_info&gt; pieces;
int write_cache_size;
int read_cache_size;
int pinned_blocks;
mutable int total_used_buffers;
int average_read_time;
int average_write_time;
int average_hash_time;
int average_job_time;
int cumulative_job_time;
int cumulative_read_time;
int cumulative_write_time;
int cumulative_hash_time;
int total_read_back;
int read_queue_size;
int blocked_jobs;
int queued_jobs;
int peak_queued;
int pending_jobs;
int num_jobs;
int num_read_jobs;
int num_write_jobs;
int arc_mru_size;
int arc_mru_ghost_size;
int arc_mfu_size;
int arc_mfu_ghost_size;
int arc_write_size;
int arc_volatile_size;
int num_writing_threads;
int num_fence_jobs[disk_io_job::num_job_ids];
};
</pre>
<a name="cache_status()"></a><div class="section" id="id24">
<h2>cache_status()</h2>
<pre class="literal-block">
<strong>cache_status</strong> ();
</pre>
<p>initializes all counters to 0</p>
<a name="write_cache_size"></a><dl class="docutils">
<dt>write_cache_size</dt>
<dd>the number of blocks in the cache used for write cache</dd>
</dl>
<a name="read_cache_size"></a><dl class="docutils">
<dt>read_cache_size</dt>
<dd>the number of 16KiB blocks in the read cache.</dd>
</dl>
<a name="pinned_blocks"></a><dl class="docutils">
<dt>pinned_blocks</dt>
<dd>the number of blocks with a refcount &gt; 0, i.e.
they may not be evicted</dd>
</dl>
<a name="total_used_buffers"></a><dl class="docutils">
<dt>total_used_buffers</dt>
<dd>the total number of buffers currently in use.
This includes the read/write disk cache as well as send and receive buffers
used in peer connections.</dd>
</dl>
<a name="average_read_time"></a><dl class="docutils">
<dt>average_read_time</dt>
<dd>the time read jobs takes on average to complete
(not including the time in the queue), in microseconds. This only measures
read cache misses.</dd>
</dl>
<a name="average_write_time"></a><dl class="docutils">
<dt>average_write_time</dt>
<dd>the time write jobs takes to complete, on average,
in microseconds. This does not include the time the job sits in the disk job
queue or in the write cache, only blocks that are flushed to disk.</dd>
</dl>
<a name="average_hash_time"></a>
<a name="average_job_time"></a><dl class="docutils">
<dt>average_hash_time average_job_time</dt>
<dd>the time hash jobs takes to complete on average, in
microseconds. Hash jobs include running SHA-1 on the data (which for the most
part is done incrementally) and sometimes reading back parts of the piece. It
also includes checking files without valid resume data.</dd>
</dl>
<a name="cumulative_job_time"></a>
<a name="cumulative_read_time"></a>
<a name="cumulative_write_time"></a>
<a name="cumulative_hash_time"></a><dl class="docutils">
<dt>cumulative_job_time cumulative_read_time cumulative_write_time cumulative_hash_time</dt>
<dd>the number of milliseconds spent in all disk jobs, and specific ones
since the start of the <a class="reference external" href="reference-Session.html#session">session</a>. Times are specified in milliseconds</dd>
</dl>
<a name="total_read_back"></a><dl class="docutils">
<dt>total_read_back</dt>
<dd>the number of blocks that had to be read back from disk because
they were flushed before the SHA-1 hash got to hash them. If this
is large, a larger cache could significantly improve performance</dd>
</dl>
<a name="read_queue_size"></a><dl class="docutils">
<dt>read_queue_size</dt>
<dd>number of read jobs in the disk job queue</dd>
</dl>
<a name="blocked_jobs"></a><dl class="docutils">
<dt>blocked_jobs</dt>
<dd>number of jobs blocked because of a fence</dd>
</dl>
<a name="queued_jobs"></a><dl class="docutils">
<dt>queued_jobs</dt>
<dd>number of jobs waiting to be issued (m_to_issue)
average over 30 seconds</dd>
</dl>
<a name="peak_queued"></a><dl class="docutils">
<dt>peak_queued</dt>
<dd>largest ever seen number of queued jobs</dd>
</dl>
<a name="pending_jobs"></a><dl class="docutils">
<dt>pending_jobs</dt>
<dd>number of jobs waiting to complete (m_pending)
average over 30 seconds</dd>
</dl>
<a name="num_jobs"></a><dl class="docutils">
<dt>num_jobs</dt>
<dd>total number of disk job objects allocated right now</dd>
</dl>
<a name="num_read_jobs"></a><dl class="docutils">
<dt>num_read_jobs</dt>
<dd>total number of disk read job objects allocated right now</dd>
</dl>
<a name="num_write_jobs"></a><dl class="docutils">
<dt>num_write_jobs</dt>
<dd>total number of disk write job objects allocated right now</dd>
</dl>
<a name="arc_mru_size"></a>
<a name="arc_mru_ghost_size"></a>
<a name="arc_mfu_size"></a>
<a name="arc_mfu_ghost_size"></a>
<a name="arc_write_size"></a>
<a name="arc_volatile_size"></a><dl class="docutils">
<dt>arc_mru_size arc_mru_ghost_size arc_mfu_size arc_mfu_ghost_size arc_write_size arc_volatile_size</dt>
<dd>ARC cache stats. All of these counters are in number of pieces
not blocks. A piece does not necessarily correspond to a certain
number of blocks. The pieces in the ghost list never have any
blocks in them</dd>
</dl>
<a name="num_writing_threads"></a><dl class="docutils">
<dt>num_writing_threads</dt>
<dd>the number of threads currently writing to disk</dd>
</dl>
<a name="num_fence_jobs[disk_io_job"></a><dl class="docutils">
<dt>num_fence_jobs[disk_io_job</dt>
<dd>counts only fence jobs that are currently blocking jobs
not fences that are themself blocked</dd>
</dl>
<a name="stats_metric"></a></div>
</div>
<div class="section" id="stats-metric">
<h1>stats_metric</h1>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session.hpp">libtorrent/session.hpp</a>&quot;</p>
<p>describes one statistics metric from the <a class="reference external" href="reference-Session.html#session">session</a>. For more information,
see the <a class="reference external" href="manual-ref.html#session-statistics">session statistics</a> section.</p>
<pre class="literal-block">
struct stats_metric
{
char const* name;
int value_index;
int type;
};
</pre>
<a name="session_proxy"></a></div>
<div class="section" id="session-proxy">
<h1>session_proxy</h1>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session.hpp">libtorrent/session.hpp</a>&quot;</p>
<p>this is a holder for the internal <a class="reference external" href="reference-Session.html#session">session</a> implementation object. Once the
<a class="reference external" href="reference-Session.html#session">session</a> destruction is explicitly initiated, this holder is used to
synchronize the completion of the shutdown. The lifetime of this object
may outlive <a class="reference external" href="reference-Session.html#session">session</a>, causing the <a class="reference external" href="reference-Session.html#session">session</a> destructor to not block. The
<a class="reference external" href="reference-Session.html#session_proxy">session_proxy</a> destructor will block however, until the underlying <a class="reference external" href="reference-Session.html#session">session</a>
is done shutting down.</p>
<pre class="literal-block">
class session_proxy
{
<strong>session_proxy</strong> ();
};
</pre>
<a name="session_proxy()"></a><div class="section" id="id36">
<h2>session_proxy()</h2>
<pre class="literal-block">
<strong>session_proxy</strong> ();
</pre>
<p>default constructor, does not refer to any <a class="reference external" href="reference-Session.html#session">session</a>
implementation object.</p>
<a name="session"></a></div>
</div>
<div class="section" id="id38">
<h1>session</h1>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session.hpp">libtorrent/session.hpp</a>&quot;</p>
<p>The <a class="reference external" href="reference-Session.html#session">session</a> holds all state that spans multiple torrents. Among other
things it runs the network loop and manages all torrents. Once it's
created, the <a class="reference external" href="reference-Session.html#session">session</a> object will spawn the main thread that will do all
the work. The main thread will be idle as long it doesn't have any
torrents to participate in.</p>
<p>You have some control over <a class="reference external" href="reference-Session.html#session">session</a> configuration through the
<tt class="docutils literal"><span class="pre">session::apply_settings()</span></tt> member function. To change one or more
configuration options, create a <a class="reference external" href="reference-Settings.html#settings_pack">settings_pack</a>. object and fill it with
the settings to be set and pass it in to <tt class="docutils literal"><span class="pre">session::apply_settings()</span></tt>.</p>
<p>see <a class="reference external" href="reference-Session.html#apply_settings()">apply_settings()</a>.</p>
<pre class="literal-block">
class session: public boost::noncopyable
{
<strong>session</strong> (fingerprint const&amp; print = fingerprint(&quot;LT&quot;
, LIBTORRENT_VERSION_MAJOR, LIBTORRENT_VERSION_MINOR, 0, 0)
, int flags = start_default_features | add_default_plugins
, boost::uint32_t alert_mask = alert::error_notification
TORRENT_LOGPATH_ARG_DEFAULT);
<strong>session</strong> (settings_pack const&amp; pack
, fingerprint const&amp; print = fingerprint(&quot;LT&quot;
, LIBTORRENT_VERSION_MAJOR, LIBTORRENT_VERSION_MINOR, 0, 0)
, int flags = start_default_features | add_default_plugins);
<strong>session</strong> (fingerprint const&amp; print
, std::pair&lt;int, int&gt; listen_port_range
, char const* listen_interface = &quot;0.0.0.0&quot;
, int flags = start_default_features | add_default_plugins
, int alert_mask = alert::error_notification
TORRENT_LOGPATH_ARG_DEFAULT);
<strong>~session</strong> ();
void <strong>load_state</strong> (lazy_entry const&amp; e);
void <strong>save_state</strong> (entry&amp; e, boost::uint32_t flags = 0xffffffff) const;
void <strong>refresh_torrent_status</strong> (std::vector&lt;torrent_status&gt;* ret
, boost::uint32_t flags = 0) const;
void <strong>get_torrent_status</strong> (std::vector&lt;torrent_status&gt;* ret
, boost::function&lt;bool(torrent_status const&amp;)&gt; const&amp; pred
, boost::uint32_t flags = 0) const;
void <strong>post_torrent_updates</strong> ();
void <strong>post_session_stats</strong> ();
torrent_handle <strong>find_torrent</strong> (sha1_hash const&amp; info_hash) const;
std::vector&lt;torrent_handle&gt; <strong>get_torrents</strong> () const;
void <strong>async_add_torrent</strong> (add_torrent_params const&amp; params);
torrent_handle <strong>add_torrent</strong> (add_torrent_params const&amp; params, error_code&amp; ec);
torrent_handle <strong>add_torrent</strong> (add_torrent_params const&amp; params);
session_proxy <strong>abort</strong> ();
void <strong>resume</strong> ();
void <strong>pause</strong> ();
bool <strong>is_paused</strong> () const;
void <strong>set_load_function</strong> (user_load_function_t fun);
session_status <strong>status</strong> () const;
void <strong>get_cache_info</strong> (cache_status* ret, torrent_handle h = torrent_handle(), int flags = 0) const;
feed_handle <strong>add_feed</strong> (feed_settings const&amp; feed);
void <strong>remove_feed</strong> (feed_handle h);
void <strong>get_feeds</strong> (std::vector&lt;feed_handle&gt;&amp; f) const;
bool <strong>is_dht_running</strong> () const;
void <strong>set_dht_settings</strong> (dht_settings const&amp; settings);
void <strong>add_dht_router</strong> (std::pair&lt;std::string, int&gt; const&amp; node);
void <strong>add_dht_node</strong> (std::pair&lt;std::string, int&gt; const&amp; node);
void <strong>dht_get_item</strong> (sha1_hash const&amp; target);
void <strong>dht_get_item</strong> (boost::array&lt;char, 32&gt; key
, std::string salt = std::string());
sha1_hash <strong>dht_put_item</strong> (entry data);
void <strong>dht_put_item</strong> (boost::array&lt;char, 32&gt; key
, boost::function&lt;void(entry&amp;, boost::array&lt;char,64&gt;&amp;
, boost::uint64_t&amp;, std::string const&amp;)&gt; cb
, std::string salt = std::string());
void <strong>add_extension</strong> (boost::function&lt;boost::shared_ptr&lt;torrent_plugin&gt;(
torrent*, void*)&gt; ext);
void <strong>add_extension</strong> (boost::shared_ptr&lt;plugin&gt; ext);
void <strong>load_country_db</strong> (char const* file);
void <strong>load_asnum_db</strong> (char const* file);
int <strong>as_for_ip</strong> (address const&amp; addr);
ip_filter <strong>get_ip_filter</strong> () const;
void <strong>set_ip_filter</strong> (ip_filter const&amp; f);
void <strong>set_port_filter</strong> (port_filter const&amp; f);
peer_id <strong>id</strong> () const;
void <strong>set_peer_id</strong> (peer_id const&amp; pid);
void <strong>set_key</strong> (int key);
bool <strong>is_listening</strong> () const;
unsigned short <strong>listen_port</strong> () const;
unsigned short <strong>ssl_listen_port</strong> () const;
void <strong>set_peer_class_filter</strong> (ip_filter const&amp; f);
void <strong>set_peer_class_type_filter</strong> (peer_class_type_filter const&amp; f);
int <strong>create_peer_class</strong> (char const* name);
void <strong>delete_peer_class</strong> (int cid);
peer_class_info <strong>get_peer_class</strong> (int cid);
void <strong>set_peer_class</strong> (int cid, peer_class_info const&amp; pci);
void <strong>remove_torrent</strong> (const torrent_handle&amp; h, int options = 0);
aux::session_settings <strong>get_settings</strong> () const;
void <strong>apply_settings</strong> (settings_pack const&amp; s);
void <strong>pop_alerts</strong> (std::deque&lt;alert*&gt;* alerts);
std::auto_ptr&lt;alert&gt; <strong>pop_alert</strong> ();
alert const* <strong>wait_for_alert</strong> (time_duration max_wait);
void <strong>set_alert_dispatch</strong> (boost::function&lt;void(std::auto_ptr&lt;alert&gt;)&gt; const&amp; fun);
void <strong>delete_port_mapping</strong> (int handle);
int <strong>add_port_mapping</strong> (protocol_type t, int external_port, int local_port);
enum save_state_flags_t
{
save_settings,
save_dht_settings,
save_dht_state,
save_encryption_settings,
save_feeds,
};
enum options_t
{
delete_files,
};
enum session_flags_t
{
add_default_plugins,
start_default_features,
};
enum protocol_type
{
udp,
tcp,
};
};
</pre>
<a name="session()"></a><div class="section" id="id45">
<h2>session()</h2>
<pre class="literal-block">
<strong>session</strong> (fingerprint const&amp; print = fingerprint(&quot;LT&quot;
, LIBTORRENT_VERSION_MAJOR, LIBTORRENT_VERSION_MINOR, 0, 0)
, int flags = start_default_features | add_default_plugins
, boost::uint32_t alert_mask = alert::error_notification
TORRENT_LOGPATH_ARG_DEFAULT);
<strong>session</strong> (settings_pack const&amp; pack
, fingerprint const&amp; print = fingerprint(&quot;LT&quot;
, LIBTORRENT_VERSION_MAJOR, LIBTORRENT_VERSION_MINOR, 0, 0)
, int flags = start_default_features | add_default_plugins);
<strong>session</strong> (fingerprint const&amp; print
, std::pair&lt;int, int&gt; listen_port_range
, char const* listen_interface = &quot;0.0.0.0&quot;
, int flags = start_default_features | add_default_plugins
, int alert_mask = alert::error_notification
TORRENT_LOGPATH_ARG_DEFAULT);
</pre>
<p>TODO: 3 could the fingerprint be a setting as well? And should the
<a class="reference external" href="reference-Settings.html#settings_pack">settings_pack</a> be optional?</p>
<a name="~session()"></a></div>
<div class="section" id="id47">
<h2>~session()</h2>
<pre class="literal-block">
<strong>~session</strong> ();
</pre>
<p>The destructor of <a class="reference external" href="reference-Session.html#session">session</a> will notify all trackers that our torrents
have been shut down. If some trackers are down, they will time out.
All this before the destructor of <a class="reference external" href="reference-Session.html#session">session</a> returns. So, it's advised
that any kind of interface (such as windows) are closed before
destructing the <a class="reference external" href="reference-Session.html#session">session</a> object. Because it can take a few second for
it to finish. The timeout can be set with <a class="reference external" href="reference-Session.html#apply_settings()">apply_settings()</a>.</p>
<a name="load_state()"></a>
<a name="save_state()"></a></div>
<div class="section" id="load-state-save-state">
<h2>load_state() save_state()</h2>
<pre class="literal-block">
void <strong>load_state</strong> (lazy_entry const&amp; e);
void <strong>save_state</strong> (entry&amp; e, boost::uint32_t flags = 0xffffffff) const;
</pre>
<p>loads and saves all <a class="reference external" href="reference-Session.html#session">session</a> settings, including <a class="reference external" href="reference-Settings.html#dht_settings">dht_settings</a>,
encryption settings and proxy settings. <tt class="docutils literal">save_state</tt> writes all keys
to the <tt class="docutils literal">entry</tt> that's passed in, which needs to either not be
initialized, or initialized as a dictionary.</p>
<p><tt class="docutils literal">load_state</tt> expects a <a class="reference external" href="reference-Bencoding.html#lazy_entry">lazy_entry</a> which can be built from a bencoded
buffer with <a class="reference external" href="reference-Bencoding.html#lazy_bdecode()">lazy_bdecode()</a>.</p>
<p>The <tt class="docutils literal">flags</tt> arguments passed in to <tt class="docutils literal">save_state</tt> can be used to
filter which parts of the <a class="reference external" href="reference-Session.html#session">session</a> state to save. By default, all state
is saved (except for the individual torrents). see <a class="reference external" href="reference-Session.html#save_state_flags_t">save_state_flags_t</a></p>
<a name="get_torrent_status()"></a>
<a name="refresh_torrent_status()"></a></div>
<div class="section" id="get-torrent-status-refresh-torrent-status">
<h2>get_torrent_status() refresh_torrent_status()</h2>
<pre class="literal-block">
void <strong>refresh_torrent_status</strong> (std::vector&lt;torrent_status&gt;* ret
, boost::uint32_t flags = 0) const;
void <strong>get_torrent_status</strong> (std::vector&lt;torrent_status&gt;* ret
, boost::function&lt;bool(torrent_status const&amp;)&gt; const&amp; pred
, boost::uint32_t flags = 0) const;
</pre>
<div class="note">
<p class="first admonition-title">Note</p>
<p class="last">these calls are potentially expensive and won't scale well with
lots of torrents. If you're concerned about performance, consider
using <tt class="docutils literal">post_torrent_updates()</tt> instead.</p>
</div>
<p><tt class="docutils literal">get_torrent_status</tt> returns a vector of the <a class="reference external" href="reference-Core.html#torrent_status">torrent_status</a> for
every torrent which satisfies <tt class="docutils literal">pred</tt>, which is a predicate function
which determines if a torrent should be included in the returned set
or not. Returning true means it should be included and false means
excluded. The <tt class="docutils literal">flags</tt> argument is the same as to
<tt class="docutils literal"><span class="pre">torrent_handle::status()</span></tt>. Since <tt class="docutils literal">pred</tt> is guaranteed to be
called for every torrent, it may be used to count the number of
torrents of different categories as well.</p>
<p><tt class="docutils literal">refresh_torrent_status</tt> takes a vector of <a class="reference external" href="reference-Core.html#torrent_status">torrent_status</a> structs
(for instance the same vector that was returned by
<a class="reference external" href="reference-Session.html#get_torrent_status()">get_torrent_status()</a> ) and refreshes the status based on the
<tt class="docutils literal">handle</tt> member. It is possible to use this function by first
setting up a vector of default constructed <tt class="docutils literal">torrent_status</tt> objects,
only initializing the <tt class="docutils literal">handle</tt> member, in order to request the
torrent status for multiple torrents in a single call. This can save a
significant amount of time if you have a lot of torrents.</p>
<p>Any <a class="reference external" href="reference-Core.html#torrent_status">torrent_status</a> object whose <tt class="docutils literal">handle</tt> member is not referring to
a valid torrent are ignored.</p>
<a name="post_torrent_updates()"></a></div>
<div class="section" id="post-torrent-updates">
<h2>post_torrent_updates()</h2>
<pre class="literal-block">
void <strong>post_torrent_updates</strong> ();
</pre>
<p>This functions instructs the <a class="reference external" href="reference-Session.html#session">session</a> to post the <a class="reference external" href="reference-Alerts.html#state_update_alert">state_update_alert</a>,
containing the status of all torrents whose state changed since the
last time this function was called.</p>
<p>Only torrents who has the state subscription flag set will be
included. This flag is on by default. See <a class="reference external" href="reference-Session.html#add_torrent_params">add_torrent_params</a>.</p>
<a name="post_session_stats()"></a></div>
<div class="section" id="post-session-stats">
<h2>post_session_stats()</h2>
<pre class="literal-block">
void <strong>post_session_stats</strong> ();
</pre>
<p>This function will post a <a class="reference external" href="reference-Alerts.html#session_stats_alert">session_stats_alert</a> object, containing a
snapshot of the performance counters from the internals of libtorrent.
To interpret these counters, query the <a class="reference external" href="reference-Session.html#session">session</a> via
<a class="reference external" href="reference-Session.html#session_stats_metrics()">session_stats_metrics()</a>.</p>
<p>For more information, see the <a class="reference external" href="manual-ref.html#session-statistics">session statistics</a> section.</p>
<a name="find_torrent()"></a>
<a name="get_torrents()"></a></div>
<div class="section" id="find-torrent-get-torrents">
<h2>find_torrent() get_torrents()</h2>
<pre class="literal-block">
torrent_handle <strong>find_torrent</strong> (sha1_hash const&amp; info_hash) const;
std::vector&lt;torrent_handle&gt; <strong>get_torrents</strong> () const;
</pre>
<p><tt class="docutils literal">find_torrent()</tt> looks for a torrent with the given info-hash. In
case there is such a torrent in the <a class="reference external" href="reference-Session.html#session">session</a>, a <a class="reference external" href="reference-Core.html#torrent_handle">torrent_handle</a> to that
torrent is returned. In case the torrent cannot be found, an invalid
<a class="reference external" href="reference-Core.html#torrent_handle">torrent_handle</a> is returned.</p>
<p>See <tt class="docutils literal"><span class="pre">torrent_handle::is_valid()</span></tt> to know if the torrent was found or
not.</p>
<p><tt class="docutils literal">get_torrents()</tt> returns a vector of torrent_handles to all the
torrents currently in the <a class="reference external" href="reference-Session.html#session">session</a>.</p>
<a name="add_torrent()"></a>
<a name="async_add_torrent()"></a></div>
<div class="section" id="add-torrent-async-add-torrent">
<h2>add_torrent() async_add_torrent()</h2>
<pre class="literal-block">
void <strong>async_add_torrent</strong> (add_torrent_params const&amp; params);
torrent_handle <strong>add_torrent</strong> (add_torrent_params const&amp; params, error_code&amp; ec);
torrent_handle <strong>add_torrent</strong> (add_torrent_params const&amp; params);
</pre>
<p>You add torrents through the <a class="reference external" href="reference-Session.html#add_torrent()">add_torrent()</a> function where you give an
object with all the parameters. The <a class="reference external" href="reference-Session.html#add_torrent()">add_torrent()</a> overloads will block
until the torrent has been added (or failed to be added) and returns
an error code and a <a class="reference external" href="reference-Core.html#torrent_handle">torrent_handle</a>. In order to add torrents more
efficiently, consider using <a class="reference external" href="reference-Session.html#async_add_torrent()">async_add_torrent()</a> which returns
immediately, without waiting for the torrent to add. Notification of
the torrent being added is sent as <a class="reference external" href="reference-Alerts.html#add_torrent_alert">add_torrent_alert</a>.</p>
<p>The overload that does not take an error_code throws an exception on
error and is not available when building without exception support.
The <a class="reference external" href="reference-Core.html#torrent_handle">torrent_handle</a> returned by <a class="reference external" href="reference-Session.html#add_torrent()">add_torrent()</a> can be used to retrieve
information about the torrent's progress, its peers etc. It is also
used to abort a torrent.</p>
<p>If the torrent you are trying to add already exists in the <a class="reference external" href="reference-Session.html#session">session</a> (is
either queued for checking, being checked or downloading)
<tt class="docutils literal">add_torrent()</tt> will throw <a class="reference external" href="reference-Error_Codes.html#libtorrent_exception">libtorrent_exception</a> which derives from
<tt class="docutils literal"><span class="pre">std::exception</span></tt> unless duplicate_is_error is set to false. In that
case, <a class="reference external" href="reference-Session.html#add_torrent()">add_torrent()</a> will return the handle to the existing torrent.</p>
<p>all torrent_handles must be destructed before the <a class="reference external" href="reference-Session.html#session">session</a> is destructed!</p>
<a name="abort()"></a></div>
<div class="section" id="abort">
<h2>abort()</h2>
<pre class="literal-block">
session_proxy <strong>abort</strong> ();
</pre>
<p>In case you want to destruct the <a class="reference external" href="reference-Session.html#session">session</a> asynchrounously, you can
request a <a class="reference external" href="reference-Session.html#session">session</a> destruction proxy. If you don't do this, the
destructor of the <a class="reference external" href="reference-Session.html#session">session</a> object will block while the trackers are
contacted. If you keep one <tt class="docutils literal">session_proxy</tt> to the <a class="reference external" href="reference-Session.html#session">session</a> when
destructing it, the destructor will not block, but start to close down
the <a class="reference external" href="reference-Session.html#session">session</a>, the destructor of the proxy will then synchronize the
threads. So, the destruction of the <a class="reference external" href="reference-Session.html#session">session</a> is performed from the
<tt class="docutils literal">session</tt> destructor call until the <tt class="docutils literal">session_proxy</tt> destructor
call. The <tt class="docutils literal">session_proxy</tt> does not have any operations on it (since
the <a class="reference external" href="reference-Session.html#session">session</a> is being closed down, no operations are allowed on it).
The only valid operation is calling the destructor:</p>
<pre class="literal-block">
class session_proxy
{
public:
session_proxy();
~session_proxy()
};
</pre>
<a name="pause()"></a>
<a name="resume()"></a>
<a name="is_paused()"></a></div>
<div class="section" id="pause-resume-is-paused">
<h2>pause() resume() is_paused()</h2>
<pre class="literal-block">
void <strong>resume</strong> ();
void <strong>pause</strong> ();
bool <strong>is_paused</strong> () const;
</pre>
<p>Pausing the <a class="reference external" href="reference-Session.html#session">session</a> has the same effect as pausing every torrent in
it, except that torrents will not be resumed by the auto-manage
mechanism. Resuming will restore the torrents to their previous paused
state. i.e. the <a class="reference external" href="reference-Session.html#session">session</a> pause state is separate from the torrent pause
state. A torrent is inactive if it is paused or if the <a class="reference external" href="reference-Session.html#session">session</a> is
paused.</p>
<a name="set_load_function()"></a></div>
<div class="section" id="set-load-function">
<h2>set_load_function()</h2>
<pre class="literal-block">
void <strong>set_load_function</strong> (user_load_function_t fun);
</pre>
<p>This function enables <a class="reference external" href="manual-ref.html#dynamic-loading-of-torrent-files">dynamic loading of torrent files</a>. When a
torrent is unloaded but needs to be availabe in memory, this function
is called <strong>from within the libtorrent network thread</strong>. From within
this thread, you can <strong>not</strong> use any of the public APIs of libtorrent
itself. The the info-hash of the torrent is passed in to the function
and it is expected to fill in the passed in <tt class="docutils literal">vector&lt;char&gt;</tt> with the
.torrent file corresponding to it.</p>
<p>If there is an error loading the torrent file, the <tt class="docutils literal">error_code</tt>
(<tt class="docutils literal">ec</tt>) should be set to reflect the error. In such case, the torrent
itself is stopped and set to an error state with the corresponding
error code.</p>
<p>Given that the function is called from the internal network thread of
libtorrent, it's important to not stall. libtorrent will not be able
to send nor receive any data until the function call returns.</p>
<p>The signature of the function to pass in is:</p>
<pre class="literal-block">
void fun(sha1_hash const&amp; info_hash, std::vector&lt;char&gt;&amp; buf, error_code&amp; ec);
</pre>
<a name="status()"></a></div>
<div class="section" id="status">
<h2>status()</h2>
<pre class="literal-block">
session_status <strong>status</strong> () const;
</pre>
<p>returns <a class="reference external" href="reference-Session.html#session">session</a> wide-statistics and status. For more information, see
the <tt class="docutils literal">session_status</tt> struct.</p>
<a name="get_cache_info()"></a></div>
<div class="section" id="get-cache-info">
<h2>get_cache_info()</h2>
<pre class="literal-block">
void <strong>get_cache_info</strong> (cache_status* ret, torrent_handle h = torrent_handle(), int flags = 0) const;
</pre>
<p>Fills in the <a class="reference external" href="reference-Session.html#cache_status">cache_status</a> struct with information about the given torrent.
If <tt class="docutils literal">flags</tt> is <tt class="docutils literal"><span class="pre">session::disk_cache_no_pieces</span></tt> the <tt class="docutils literal"><span class="pre">cache_status::pieces</span></tt> field
will not be set. This may significantly reduce the cost of this call.</p>
<a name="add_feed()"></a></div>
<div class="section" id="add-feed">
<h2>add_feed()</h2>
<pre class="literal-block">
feed_handle <strong>add_feed</strong> (feed_settings const&amp; feed);
</pre>
<p>This adds an RSS feed to the <a class="reference external" href="reference-Session.html#session">session</a>. The feed will be refreshed
regularly and optionally add all torrents from the feed, as they
appear.</p>
<p>Before adding the feed, you must set the <tt class="docutils literal">url</tt> field to the feed's
url. It may point to an RSS or an atom feed. The returned <a class="reference external" href="reference-RSS.html#feed_handle">feed_handle</a>
is a handle which is used to interact with the feed, things like
forcing a refresh or querying for information about the items in the
feed. For more information, see <a class="reference external" href="reference-RSS.html#feed_handle">feed_handle</a>.</p>
<a name="remove_feed()"></a></div>
<div class="section" id="remove-feed">
<h2>remove_feed()</h2>
<pre class="literal-block">
void <strong>remove_feed</strong> (feed_handle h);
</pre>
<p>Removes a feed from being watched by the <a class="reference external" href="reference-Session.html#session">session</a>. When this
call returns, the feed handle is invalid and won't refer
to any feed.</p>
<a name="get_feeds()"></a></div>
<div class="section" id="get-feeds">
<h2>get_feeds()</h2>
<pre class="literal-block">
void <strong>get_feeds</strong> (std::vector&lt;feed_handle&gt;&amp; f) const;
</pre>
<p>Returns a list of all RSS feeds that are being watched by the <a class="reference external" href="reference-Session.html#session">session</a>.</p>
<a name="is_dht_running()"></a>
<a name="set_dht_settings()"></a></div>
<div class="section" id="is-dht-running-set-dht-settings">
<h2>is_dht_running() set_dht_settings()</h2>
<pre class="literal-block">
bool <strong>is_dht_running</strong> () const;
void <strong>set_dht_settings</strong> (dht_settings const&amp; settings);
</pre>
<p><tt class="docutils literal">set_dht_settings</tt> sets some parameters availavle to the dht node.
See <a class="reference external" href="reference-Settings.html#dht_settings">dht_settings</a> for more information.</p>
<p><tt class="docutils literal">is_dht_running()</tt> returns true if the DHT support has been started
and false
otherwise.</p>
<a name="add_dht_router()"></a>
<a name="add_dht_node()"></a></div>
<div class="section" id="add-dht-router-add-dht-node">
<h2>add_dht_router() add_dht_node()</h2>
<pre class="literal-block">
void <strong>add_dht_router</strong> (std::pair&lt;std::string, int&gt; const&amp; node);
void <strong>add_dht_node</strong> (std::pair&lt;std::string, int&gt; const&amp; node);
</pre>
<p><tt class="docutils literal">add_dht_node</tt> takes a host name and port pair. That endpoint will be
pinged, and if a valid DHT reply is received, the node will be added to
the routing table.</p>
<p><tt class="docutils literal">add_dht_router</tt> adds the given endpoint to a list of DHT router
nodes. If a search is ever made while the routing table is empty,
those nodes will be used as backups. Nodes in the router node list
will also never be added to the regular routing table, which
effectively means they are only used for bootstrapping, to keep the
load off them.</p>
<p>An example routing node that you could typically add is
<tt class="docutils literal">router.bittorrent.com</tt>.</p>
<a name="dht_get_item()"></a></div>
<div class="section" id="dht-get-item">
<h2>dht_get_item()</h2>
<pre class="literal-block">
void <strong>dht_get_item</strong> (sha1_hash const&amp; target);
</pre>
<p>query the DHT for an immutable item at the <tt class="docutils literal">target</tt> hash.
the result is posted as a <a class="reference external" href="reference-Alerts.html#dht_immutable_item_alert">dht_immutable_item_alert</a>.</p>
<a name="dht_get_item()"></a></div>
<div class="section" id="id104">
<h2>dht_get_item()</h2>
<pre class="literal-block">
void <strong>dht_get_item</strong> (boost::array&lt;char, 32&gt; key
, std::string salt = std::string());
</pre>
<p>query the DHT for a mutable item under the public key <tt class="docutils literal">key</tt>.
this is an ed25519 key. <tt class="docutils literal">salt</tt> is optional and may be left
as an empty string if no salt is to be used.
if the item is found in the DHT, a <a class="reference external" href="reference-Alerts.html#dht_mutable_item_alert">dht_mutable_item_alert</a> is
posted.</p>
<a name="dht_put_item()"></a></div>
<div class="section" id="dht-put-item">
<h2>dht_put_item()</h2>
<pre class="literal-block">
sha1_hash <strong>dht_put_item</strong> (entry data);
</pre>
<p>store the given bencoded data as an immutable item in the DHT.
the returned hash is the key that is to be used to look the item
up agan. It's just the sha-1 hash of the bencoded form of the
structure.</p>
<a name="dht_put_item()"></a></div>
<div class="section" id="id106">
<h2>dht_put_item()</h2>
<pre class="literal-block">
void <strong>dht_put_item</strong> (boost::array&lt;char, 32&gt; key
, boost::function&lt;void(entry&amp;, boost::array&lt;char,64&gt;&amp;
, boost::uint64_t&amp;, std::string const&amp;)&gt; cb
, std::string salt = std::string());
</pre>
<p>store an immutable item. The <tt class="docutils literal">key</tt> is the public key the blob is
to be stored under. The optional <tt class="docutils literal">salt</tt> argument is a string that
is to be mixed in with the key when determining where in the DHT
the value is to be stored. The callback function is called from within
the libtorrent network thread once we've found where to store the blob,
possibly with the current value stored under the key.
The values passed to the callback functions are:</p>
<dl class="docutils">
<dt>entry&amp; value</dt>
<dd>the current value stored under the key (may be empty). Also expected
to be set to the value to be stored by the function.</dd>
<dt>boost::array&lt;char,64&gt;&amp; signature</dt>
<dd>the signature authenticating the current value. This may be zeroes
if there is currently no value stored. The functon is expected to
fill in this buffer with the signature of the new value to store.
To generate the signature, you may want to use the
<tt class="docutils literal">sign_mutable_item</tt> function.</dd>
<dt>boost::uint64_t&amp; seq</dt>
<dd>current sequence number. May be zero if there is no current value.
The function is expected to set this to the new sequence number of
the value that is to be stored. Sequence numbers must be monotonically
increasing. Attempting to overwrite a value with a lower or equal
sequence number will fail, even if the signature is correct.</dd>
<dt>std::string const&amp; salt</dt>
<dd>this is the salt that was used for this put call.</dd>
</dl>
<p>Since the callback function <tt class="docutils literal">cb</tt> is called from within libtorrent,
it is critical to not perform any blocking operations. Ideally not
even locking a mutex. Pass any data required for this function along
with the function object's context and make the function entirely
self-contained. The only reason data blobs' values are computed
via a function instead of just passing in the new value is to avoid
race conditions. If you want to <em>update</em> the value in the DHT, you
must first retrieve it, then modify it, then write it back. The way
the DHT works, it is natural to always do a lookup before storing and
calling the callback in between is convenient.</p>
<a name="add_extension()"></a></div>
<div class="section" id="add-extension">
<h2>add_extension()</h2>
<pre class="literal-block">
void <strong>add_extension</strong> (boost::function&lt;boost::shared_ptr&lt;torrent_plugin&gt;(
torrent*, void*)&gt; ext);
void <strong>add_extension</strong> (boost::shared_ptr&lt;plugin&gt; ext);
</pre>
<p>This function adds an extension to this <a class="reference external" href="reference-Session.html#session">session</a>. The argument is a
function object that is called with a <tt class="docutils literal">torrent*</tt> and which should
return a <tt class="docutils literal"><span class="pre">boost::shared_ptr&lt;torrent_plugin&gt;</span></tt>. To write custom
plugins, see <a class="reference external" href="libtorrent_plugins.html">libtorrent plugins</a>. For the typical bittorrent client
all of these extensions should be added. The main plugins implemented
in libtorrent are:</p>
<dl class="docutils">
<dt>metadata extension</dt>
<dd>Allows peers to download the metadata (.torren files) from the swarm
directly. Makes it possible to join a swarm with just a tracker and
info-hash.</dd>
</dl>
<pre class="literal-block">
#include &lt;libtorrent/extensions/metadata_transfer.hpp&gt;
ses.add_extension(&amp;libtorrent::create_metadata_plugin);
</pre>
<dl class="docutils">
<dt>uTorrent metadata</dt>
<dd>Same as <tt class="docutils literal">metadata extension</tt> but compatible with uTorrent.</dd>
</dl>
<pre class="literal-block">
#include &lt;libtorrent/extensions/ut_metadata.hpp&gt;
ses.add_extension(&amp;libtorrent::create_ut_metadata_plugin);
</pre>
<dl class="docutils">
<dt>uTorrent peer exchange</dt>
<dd>Exchanges peers between clients.</dd>
</dl>
<pre class="literal-block">
#include &lt;libtorrent/extensions/ut_pex.hpp&gt;
ses.add_extension(&amp;libtorrent::create_ut_pex_plugin);
</pre>
<dl class="docutils">
<dt>smart ban <a class="reference external" href="reference-Plugins.html#plugin">plugin</a></dt>
<dd>A <a class="reference external" href="reference-Plugins.html#plugin">plugin</a> that, with a small overhead, can ban peers
that sends bad data with very high accuracy. Should
eliminate most problems on poisoned torrents.</dd>
</dl>
<pre class="literal-block">
#include &lt;libtorrent/extensions/smart_ban.hpp&gt;
ses.add_extension(&amp;libtorrent::create_smart_ban_plugin);
</pre>
<a name="load_asnum_db()"></a>
<a name="load_country_db()"></a>
<a name="as_for_ip()"></a></div>
<div class="section" id="load-asnum-db-load-country-db-as-for-ip">
<h2>load_asnum_db() load_country_db() as_for_ip()</h2>
<pre class="literal-block">
void <strong>load_country_db</strong> (char const* file);
void <strong>load_asnum_db</strong> (char const* file);
int <strong>as_for_ip</strong> (address const&amp; addr);
</pre>
<p>These functions are not available if <tt class="docutils literal">TORRENT_DISABLE_GEO_IP</tt> is
defined. They expects a path to the <a class="reference external" href="http://www.maxmind.com/app/asnum">MaxMind ASN database</a> and
<a class="reference external" href="http://www.maxmind.com/app/geolitecountry">MaxMind GeoIP database</a> respectively. This will be used to look up
which AS and country peers belong to.</p>
<p><tt class="docutils literal">as_for_ip</tt> returns the AS number for the IP address specified. If
the IP is not in the database or the ASN database is not loaded, 0 is
returned.</p>
<a name="get_ip_filter()"></a>
<a name="set_ip_filter()"></a></div>
<div class="section" id="get-ip-filter-set-ip-filter">
<h2>get_ip_filter() set_ip_filter()</h2>
<pre class="literal-block">
ip_filter <strong>get_ip_filter</strong> () const;
void <strong>set_ip_filter</strong> (ip_filter const&amp; f);
</pre>
<p>Sets a filter that will be used to reject and accept incoming as well
as outgoing connections based on their originating ip address. The
default filter will allow connections to any ip address. To build a
set of rules for which addresses are accepted and not, see <a class="reference external" href="reference-Filter.html#ip_filter">ip_filter</a>.</p>
<p>Each time a peer is blocked because of the IP filter, a
<a class="reference external" href="reference-Alerts.html#peer_blocked_alert">peer_blocked_alert</a> is generated. <tt class="docutils literal">get_ip_filter()</tt> Returns the
<a class="reference external" href="reference-Filter.html#ip_filter">ip_filter</a> currently in the <a class="reference external" href="reference-Session.html#session">session</a>. See <a class="reference external" href="reference-Filter.html#ip_filter">ip_filter</a>.</p>
<a name="set_port_filter()"></a></div>
<div class="section" id="set-port-filter">
<h2>set_port_filter()</h2>
<pre class="literal-block">
void <strong>set_port_filter</strong> (port_filter const&amp; f);
</pre>
<p>apply <a class="reference external" href="reference-Filter.html#port_filter">port_filter</a> <tt class="docutils literal">f</tt> to incoming and outgoing peers. a port filter
will reject making outgoing peer connections to certain remote ports.
The main intention is to be able to avoid triggering certain
anti-virus software by connecting to SMTP, FTP ports.</p>
<a name="set_peer_id()"></a>
<a name="id()"></a></div>
<div class="section" id="set-peer-id-id">
<h2>set_peer_id() id()</h2>
<pre class="literal-block">
peer_id <strong>id</strong> () const;
void <strong>set_peer_id</strong> (peer_id const&amp; pid);
</pre>
<p>sets and gets the raw peer ID used by libtorrent. When anonymous
mode is set the peer ID is randomized per peer anyway.</p>
<a name="set_key()"></a></div>
<div class="section" id="set-key">
<h2>set_key()</h2>
<pre class="literal-block">
void <strong>set_key</strong> (int key);
</pre>
<p>sets the key sent to trackers. If it's not set, it is initialized
by libtorrent. The key may be used by the tracker to identify the
peer potentially across you changing your IP.</p>
<a name="listen_port()"></a>
<a name="ssl_listen_port()"></a>
<a name="is_listening()"></a></div>
<div class="section" id="listen-port-ssl-listen-port-is-listening">
<h2>listen_port() ssl_listen_port() is_listening()</h2>
<pre class="literal-block">
bool <strong>is_listening</strong> () const;
unsigned short <strong>listen_port</strong> () const;
unsigned short <strong>ssl_listen_port</strong> () const;
</pre>
<p><tt class="docutils literal">is_listening()</tt> will tell you whether or not the <a class="reference external" href="reference-Session.html#session">session</a> has
successfully opened a listening port. If it hasn't, this function will
return false, and then you can set a new
<a class="reference external" href="reference-Settings.html#listen_interfaces">settings_pack::listen_interfaces</a> to try another interface and port to
bind to.</p>
<p><tt class="docutils literal">listen_port()</tt> returns the port we ended up listening on. If the
port specified in <a class="reference external" href="reference-Settings.html#listen_interfaces">settings_pack::listen_interfaces</a> failed, libtorrent
will try to bind to the next port, and so on. If it fails
<a class="reference external" href="reference-Settings.html#max_retry_port_bind">settings_pack::max_retry_port_bind</a> times, it will bind to port 0
(meaning the OS picks the port). The only way to know which port it
ended up binding to is to ask for it by calling <tt class="docutils literal">listen_port()</tt>.</p>
<p>If all ports in the specified range fails to be opened for listening,
libtorrent will try to use port 0 (which tells the operating system to
pick a port that's free). If that still fails you may see a
<a class="reference external" href="reference-Alerts.html#listen_failed_alert">listen_failed_alert</a> with port 0 even if you didn't ask to listen on
it.</p>
<p>It is possible to prevent libtorrent from binding to port 0 by passing
in the flag <tt class="docutils literal"><span class="pre">session::no_system_port</span></tt> in the <tt class="docutils literal">flags</tt> argument.</p>
<p>The interface parameter can also be a hostname that will resolve to
the device you want to listen on. If you don't specify an interface,
libtorrent may attempt to listen on multiple interfaces (typically
0.0.0.0 and ::). This means that if your IPv6 interface doesn't work,
you may still see a <a class="reference external" href="reference-Alerts.html#listen_failed_alert">listen_failed_alert</a>, even though the IPv4 port
succeeded.</p>
<p>The <tt class="docutils literal">flags</tt> parameter can either be 0 or
<tt class="docutils literal"><span class="pre">session::listen_reuse_address</span></tt>, which will set the reuse address
socket option on the listen socket(s). By default, the listen socket
does not use reuse address. If you're running a service that needs to
run on a specific port no matter if it's in use, set this flag.</p>
<a name="set_peer_class_filter()"></a></div>
<div class="section" id="set-peer-class-filter">
<h2>set_peer_class_filter()</h2>
<pre class="literal-block">
void <strong>set_peer_class_filter</strong> (ip_filter const&amp; f);
</pre>
<p>Sets the peer class filter for this <a class="reference external" href="reference-Session.html#session">session</a>. All new peer connections
will take this into account and be added to the peer classes specified
by this filter, based on the peer's IP address.</p>
<p>The ip-filter essentially maps an IP -&gt; uint32. Each bit in that 32
bit integer represents a peer class. The least significant bit
represents class 0, the next bit class 1 and so on.</p>
<p>For more info, see <a class="reference external" href="reference-Filter.html#ip_filter">ip_filter</a>.</p>
<p>For example, to make all peers in the range 200.1.1.0 - 200.1.255.255
belong to their own peer class, apply the following filter:</p>
<pre class="literal-block">
ip_filter f;
int my_class = ses.create_peer_class(&quot;200.1.x.x IP range&quot;);
f.add_rule(address_v4::from_string(&quot;200.1.1.0&quot;)
, address_v4::from_string(&quot;200.1.255.255&quot;)
, 1 &lt;&lt; my_class);
ses.set_peer_class_filter(f);
</pre>
<p>This setting only applies to new connections, it won't affect existing
peer connections.</p>
<p>This function is limited to only peer class 0-31, since there are only
32 bits in the IP range mapping. Only the set bits matter; no peer
class will be removed from a peer as a result of this call, peer
classes are only added.</p>
<p>The <tt class="docutils literal">peer_class</tt> argument cannot be greater than 31. The bitmasks
representing peer classes in the <tt class="docutils literal">peer_class_filter</tt> are 32 bits.</p>
<p>For more information, see <a class="reference external" href="manual-ref.html#peer-classes">peer classes</a>.</p>
<a name="set_peer_class_type_filter()"></a></div>
<div class="section" id="set-peer-class-type-filter">
<h2>set_peer_class_type_filter()</h2>
<pre class="literal-block">
void <strong>set_peer_class_type_filter</strong> (peer_class_type_filter const&amp; f);
</pre>
<p>Sets and gets the <em>peer class type filter</em>. This is controls automatic
peer class assignments to peers based on what kind of socket it is.</p>
<p>It does not only support assigning peer classes, it also supports
removing peer classes based on socket type.</p>
<p>The order of these rules being applied are:</p>
<ol class="arabic simple">
<li>peer-class IP filter</li>
<li>peer-class type filter, removing classes</li>
<li>peer-class type filter, adding classes</li>
</ol>
<p>For more information, see <a class="reference external" href="manual-ref.html#peer-classes">peer classes</a>.
TODO: add get_peer_class_type_filter() as well</p>
<a name="create_peer_class()"></a></div>
<div class="section" id="create-peer-class">
<h2>create_peer_class()</h2>
<pre class="literal-block">
int <strong>create_peer_class</strong> (char const* name);
</pre>
<p>Creates a new peer class (see <a class="reference external" href="manual-ref.html#peer-classes">peer classes</a>) with the given name. The
returned integer is the new peer class' identifier. Peer classes may
have the same name, so each invocation of this function creates a new
class and returns a unique identifier.</p>
<p>Identifiers are assigned from low numbers to higher. So if you plan on
using certain peer classes in a call to <a class="reference internal" href="#set-peer-class-filter">set_peer_class_filter()</a>,
make sure to create those early on, to get low identifiers.</p>
<p>For more information on peer classes, see <a class="reference external" href="manual-ref.html#peer-classes">peer classes</a>.</p>
<a name="delete_peer_class()"></a></div>
<div class="section" id="delete-peer-class">
<h2>delete_peer_class()</h2>
<pre class="literal-block">
void <strong>delete_peer_class</strong> (int cid);
</pre>
<p>This call dereferences the reference count of the specified peer
class. When creating a peer class it's automatically referenced by 1.
If you want to recycle a peer class, you may call this function. You
may only call this function <strong>once</strong> per peer class you create.
Calling it more than once for the same class will lead to memory
corruption.</p>
<p>Since peer classes are reference counted, this function will not
remove the peer class if it's still assigned to torrents or peers. It
will however remove it once the last peer and torrent drops their
references to it.</p>
<p>There is no need to call this function for custom peer classes. All
peer classes will be properly destructed when the <a class="reference external" href="reference-Session.html#session">session</a> object
destructs.</p>
<p>For more information on peer classes, see <a class="reference external" href="manual-ref.html#peer-classes">peer classes</a>.</p>
<a name="get_peer_class()"></a>
<a name="set_peer_class()"></a></div>
<div class="section" id="get-peer-class-set-peer-class">
<h2>get_peer_class() set_peer_class()</h2>
<pre class="literal-block">
peer_class_info <strong>get_peer_class</strong> (int cid);
void <strong>set_peer_class</strong> (int cid, peer_class_info const&amp; pci);
</pre>
<p>These functions queries information from a peer class and updates the
configuration of a peer class, respectively.</p>
<p><tt class="docutils literal">cid</tt> must refer to an existing peer class. If it does not, the
return value of <tt class="docutils literal">get_peer_class()</tt> is undefined.</p>
<p><tt class="docutils literal">set_peer_class()</tt> sets all the information in the
<tt class="docutils literal">peer_class_info</tt> object in the specified peer class. There is no
option to only update a single property.</p>
<p>A peer or torrent balonging to more than one class, the highest
priority among any of its classes is the one that is taken into
account.</p>
<p>For more information, see <a class="reference external" href="manual-ref.html#peer-classes">peer classes</a>.</p>
<a name="remove_torrent()"></a></div>
<div class="section" id="remove-torrent">
<h2>remove_torrent()</h2>
<pre class="literal-block">
void <strong>remove_torrent</strong> (const torrent_handle&amp; h, int options = 0);
</pre>
<p><tt class="docutils literal">remove_torrent()</tt> will close all peer connections associated with
the torrent and tell the tracker that we've stopped participating in
the swarm. This operation cannot fail. When it completes, you will
receive a <a class="reference external" href="reference-Alerts.html#torrent_removed_alert">torrent_removed_alert</a>.</p>
<p>The optional second argument <tt class="docutils literal">options</tt> can be used to delete all the
files downloaded by this torrent. To do so, pass in the value
<tt class="docutils literal"><span class="pre">session::delete_files</span></tt>. The removal of the torrent is asyncronous,
there is no guarantee that adding the same torrent immediately after
it was removed will not throw a <a class="reference external" href="reference-Error_Codes.html#libtorrent_exception">libtorrent_exception</a> exception. Once
the torrent is deleted, a <a class="reference external" href="reference-Alerts.html#torrent_deleted_alert">torrent_deleted_alert</a> is posted.</p>
<a name="get_settings()"></a>
<a name="apply_settings()"></a></div>
<div class="section" id="get-settings-apply-settings">
<h2>get_settings() apply_settings()</h2>
<pre class="literal-block">
aux::session_settings <strong>get_settings</strong> () const;
void <strong>apply_settings</strong> (settings_pack const&amp; s);
</pre>
<p>Applies the settings specified by the <a class="reference external" href="reference-Settings.html#settings_pack">settings_pack</a> <tt class="docutils literal">s</tt>. This is an
asynchronous operation that will return immediately and actually apply
the settings to the main thread of libtorrent some time later.</p>
<a name="pop_alert()"></a>
<a name="pop_alerts()"></a>
<a name="wait_for_alert()"></a></div>
<div class="section" id="pop-alert-pop-alerts-wait-for-alert">
<h2>pop_alert() pop_alerts() wait_for_alert()</h2>
<pre class="literal-block">
void <strong>pop_alerts</strong> (std::deque&lt;alert*&gt;* alerts);
std::auto_ptr&lt;alert&gt; <strong>pop_alert</strong> ();
alert const* <strong>wait_for_alert</strong> (time_duration max_wait);
</pre>
<p><tt class="docutils literal">pop_alert()</tt> is used to ask the <a class="reference external" href="reference-Session.html#session">session</a> if any errors or events has
occurred. With <a class="reference external" href="reference-Settings.html#alert_mask">settings_pack::alert_mask</a> you can filter which alerts
to receive through <tt class="docutils literal">pop_alert()</tt>. For information about the <a class="reference external" href="reference-Alerts.html#alert">alert</a>
categories, see <a class="reference external" href="manual-ref.html#alerts">alerts</a>.</p>
<p><tt class="docutils literal">pop_alerts()</tt> pops all pending alerts in a single call. In high
performance environments with a very high <a class="reference external" href="reference-Alerts.html#alert">alert</a> churn rate, this can
save significant amount of time compared to popping alerts one at a
time. Each call requires one round-trip to the network thread. If
alerts are produced in a higher rate than they can be popped (when
popped one at a time) it's easy to get stuck in an infinite loop,
trying to drain the <a class="reference external" href="reference-Alerts.html#alert">alert</a> queue. Popping the entire queue at once
avoids this problem.</p>
<p>However, the <tt class="docutils literal">pop_alerts</tt> function comes with significantly more
responsibility. You pass in an <em>empty</em> <tt class="docutils literal"><span class="pre">std::dequeue&lt;alert*&gt;</span></tt> to it.
If it's not empty, all elements in it will be deleted and then
cleared. All currently pending alerts are returned by being swapped
into the passed in container. The responsibility of deleting the
alerts is transferred to the caller. This means you need to call
delete for each item in the returned dequeue. It's probably a good
idea to delete the alerts as you handle them, to save one extra pass
over the dequeue.</p>
<p>Alternatively, you can pass in the same container the next time you
call <tt class="docutils literal">pop_alerts</tt>.</p>
<p><tt class="docutils literal">wait_for_alert</tt> blocks until an <a class="reference external" href="reference-Alerts.html#alert">alert</a> is available, or for no more
than <tt class="docutils literal">max_wait</tt> time. If <tt class="docutils literal">wait_for_alert</tt> returns because of the
time-out, and no alerts are available, it returns 0. If at least one
<a class="reference external" href="reference-Alerts.html#alert">alert</a> was generated, a pointer to that <a class="reference external" href="reference-Alerts.html#alert">alert</a> is returned. The <a class="reference external" href="reference-Alerts.html#alert">alert</a> is
not popped, any subsequent calls to <tt class="docutils literal">wait_for_alert</tt> will return the
same pointer until the <a class="reference external" href="reference-Alerts.html#alert">alert</a> is popped by calling <tt class="docutils literal">pop_alert</tt>. This
is useful for leaving any <a class="reference external" href="reference-Alerts.html#alert">alert</a> dispatching mechanism independent of
this blocking call, the dispatcher can be called and it can pop the
<a class="reference external" href="reference-Alerts.html#alert">alert</a> independently.</p>
<div class="note">
<p class="first admonition-title">Note</p>
<p class="last">Although these functions are all thread-safe, popping alerts from
multiple separate threads may introduce race conditions in that
the thread issuing an asynchronous operation may not be the one
receiving the alert with the result.</p>
</div>
<p>In the python binding, <tt class="docutils literal">wait_for_alert</tt> takes the number of
milliseconds to wait as an integer.</p>
<p>To control the max number of alerts that's queued by the <a class="reference external" href="reference-Session.html#session">session</a>, see
<tt class="docutils literal"><span class="pre">session_settings::alert_queue_size</span></tt>.</p>
<p><a class="reference external" href="reference-Alerts.html#save_resume_data_alert">save_resume_data_alert</a> and <a class="reference external" href="reference-Alerts.html#save_resume_data_failed_alert">save_resume_data_failed_alert</a> are always
posted, regardelss of the <a class="reference external" href="reference-Alerts.html#alert">alert</a> mask.</p>
<a name="set_alert_dispatch()"></a></div>
<div class="section" id="set-alert-dispatch">
<h2>set_alert_dispatch()</h2>
<pre class="literal-block">
void <strong>set_alert_dispatch</strong> (boost::function&lt;void(std::auto_ptr&lt;alert&gt;)&gt; const&amp; fun);
</pre>
<p>This sets a function to be called (from within libtorrent's netowrk
thread) every time an <a class="reference external" href="reference-Alerts.html#alert">alert</a> is posted. Since the function (<tt class="docutils literal">fun</tt>) is
run in libtorrent's internal thread, it may not call any of
libtorrent's external API functions. Doing so results in a dead lock.</p>
<p>The main intention with this function is to support integration with
platform-dependent message queues or signalling systems. For instance,
on windows, one could post a message to an HNWD or on linux, write to
a pipe or an eventfd.</p>
<a name="add_port_mapping()"></a>
<a name="delete_port_mapping()"></a></div>
<div class="section" id="add-port-mapping-delete-port-mapping">
<h2>add_port_mapping() delete_port_mapping()</h2>
<pre class="literal-block">
void <strong>delete_port_mapping</strong> (int handle);
int <strong>add_port_mapping</strong> (protocol_type t, int external_port, int local_port);
</pre>
<p>add_port_mapping adds a port forwarding on UPnP and/or NAT-PMP,
whichever is enabled. The return value is a handle referring to the
port mapping that was just created. Pass it to <a class="reference external" href="reference-Session.html#delete_port_mapping()">delete_port_mapping()</a>
to remove it.</p>
<a name="save_state_flags_t"></a></div>
<div class="section" id="enum-save-state-flags-t">
<h2>enum save_state_flags_t</h2>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session.hpp">libtorrent/session.hpp</a>&quot;</p>
<table border="1" class="docutils">
<colgroup>
<col width="26%" />
<col width="7%" />
<col width="67%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">name</th>
<th class="head">value</th>
<th class="head">description</th>
</tr>
</thead>
<tbody valign="top">
<tr><td>save_settings</td>
<td>1</td>
<td>saves settings (i.e. the session_settings)</td>
</tr>
<tr><td>save_dht_settings</td>
<td>2</td>
<td>saves <a class="reference external" href="reference-Settings.html#dht_settings">dht_settings</a></td>
</tr>
<tr><td>save_dht_state</td>
<td>4</td>
<td>saves dht state such as nodes and node-id, possibly accelerating
joining the DHT if provided at next <a class="reference external" href="reference-Session.html#session">session</a> startup.</td>
</tr>
<tr><td>save_encryption_settings</td>
<td>32</td>
<td>save pe_settings</td>
</tr>
<tr><td>save_feeds</td>
<td>128</td>
<td>saves RSS feeds</td>
</tr>
</tbody>
</table>
<a name="options_t"></a></div>
<div class="section" id="enum-options-t">
<h2>enum options_t</h2>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session.hpp">libtorrent/session.hpp</a>&quot;</p>
<table border="1" class="docutils">
<colgroup>
<col width="19%" />
<col width="9%" />
<col width="72%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">name</th>
<th class="head">value</th>
<th class="head">description</th>
</tr>
</thead>
<tbody valign="top">
<tr><td>delete_files</td>
<td>1</td>
<td>delete the files belonging to the torrent from disk.</td>
</tr>
</tbody>
</table>
<a name="session_flags_t"></a></div>
<div class="section" id="enum-session-flags-t">
<h2>enum session_flags_t</h2>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session.hpp">libtorrent/session.hpp</a>&quot;</p>
<table border="1" class="docutils">
<colgroup>
<col width="25%" />
<col width="7%" />
<col width="68%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">name</th>
<th class="head">value</th>
<th class="head">description</th>
</tr>
</thead>
<tbody valign="top">
<tr><td>add_default_plugins</td>
<td>1</td>
<td>this will add common extensions like ut_pex, ut_metadata, lt_tex
smart_ban and possibly others.</td>
</tr>
<tr><td>start_default_features</td>
<td>2</td>
<td>this will start features like DHT, local service discovery, UPnP
and NAT-PMP.</td>
</tr>
</tbody>
</table>
<a name="protocol_type"></a></div>
<div class="section" id="enum-protocol-type">
<h2>enum protocol_type</h2>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session.hpp">libtorrent/session.hpp</a>&quot;</p>
<table border="1" class="docutils">
<colgroup>
<col width="23%" />
<col width="27%" />
<col width="50%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">name</th>
<th class="head">value</th>
<th class="head">description</th>
</tr>
</thead>
<tbody valign="top">
<tr><td>udp</td>
<td>1</td>
<td>&nbsp;</td>
</tr>
<tr><td>tcp</td>
<td>2</td>
<td>&nbsp;</td>
</tr>
</tbody>
</table>
<a name="dht_lookup"></a></div>
</div>
<div class="section" id="dht-lookup">
<h1>dht_lookup</h1>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session_status.hpp">libtorrent/session_status.hpp</a>&quot;</p>
<p>holds statistics about a current <a class="reference external" href="reference-Session.html#dht_lookup">dht_lookup</a> operation.
a DHT lookup is the travesal of nodes, looking up a
set of target nodes in the DHT for retrieving and possibly
storing information in the DHT</p>
<pre class="literal-block">
struct dht_lookup
{
char const* type;
int outstanding_requests;
int timeouts;
int responses;
int branch_factor;
int nodes_left;
int last_sent;
int first_timeout;
};
</pre>
<a name="type"></a><dl class="docutils">
<dt>type</dt>
<dd>string literal indicating which kind of lookup this is</dd>
</dl>
<a name="outstanding_requests"></a><dl class="docutils">
<dt>outstanding_requests</dt>
<dd>the number of outstanding request to individual nodes
this lookup has right now</dd>
</dl>
<a name="timeouts"></a><dl class="docutils">
<dt>timeouts</dt>
<dd>the total number of requests that have timed out so far
for this lookup</dd>
</dl>
<a name="responses"></a><dl class="docutils">
<dt>responses</dt>
<dd>the total number of responses we have received for this
lookup so far for this lookup</dd>
</dl>
<a name="branch_factor"></a><dl class="docutils">
<dt>branch_factor</dt>
<dd>the branch factor for this lookup. This is the number of
nodes we keep outstanding requests to in parallel by default.
when nodes time out we may increase this.</dd>
</dl>
<a name="nodes_left"></a><dl class="docutils">
<dt>nodes_left</dt>
<dd>the number of nodes left that could be queries for this
lookup. Many of these are likely to be part of the trail
while performing the lookup and would never end up actually
being queried.</dd>
</dl>
<a name="last_sent"></a><dl class="docutils">
<dt>last_sent</dt>
<dd>the number of seconds ago the
last message was sent that's still
outstanding</dd>
</dl>
<a name="first_timeout"></a><dl class="docutils">
<dt>first_timeout</dt>
<dd>the number of outstanding requests
that have exceeded the short timeout
and are considered timed out in the
sense that they increased the branch
factor</dd>
</dl>
<a name="dht_routing_bucket"></a></div>
<div class="section" id="dht-routing-bucket">
<h1>dht_routing_bucket</h1>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session_status.hpp">libtorrent/session_status.hpp</a>&quot;</p>
<p>holds dht routing table stats</p>
<pre class="literal-block">
struct dht_routing_bucket
{
int num_nodes;
int num_replacements;
int last_active;
};
</pre>
<a name="num_nodes"></a>
<a name="num_replacements"></a><dl class="docutils">
<dt>num_nodes num_replacements</dt>
<dd>the total number of nodes and replacement nodes
in the routing table</dd>
</dl>
<a name="last_active"></a><dl class="docutils">
<dt>last_active</dt>
<dd>number of seconds since last activity</dd>
</dl>
<a name="utp_status"></a></div>
<div class="section" id="utp-status">
<h1>utp_status</h1>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session_status.hpp">libtorrent/session_status.hpp</a>&quot;</p>
<p>holds counters and gauges for the uTP sockets</p>
<pre class="literal-block">
struct utp_status
{
int num_idle;
int num_syn_sent;
int num_connected;
int num_fin_sent;
int num_close_wait;
};
</pre>
<a name="num_idle"></a>
<a name="num_syn_sent"></a>
<a name="num_connected"></a>
<a name="num_fin_sent"></a>
<a name="num_close_wait"></a><dl class="docutils">
<dt>num_idle num_syn_sent num_connected num_fin_sent num_close_wait</dt>
<dd>gauges. These are snapshots of the number of
uTP sockets in each respective state</dd>
</dl>
<a name="session_status"></a></div>
<div class="section" id="session-status">
<h1>session_status</h1>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session_status.hpp">libtorrent/session_status.hpp</a>&quot;</p>
<p>contains <a class="reference external" href="reference-Session.html#session">session</a> wide state and counters</p>
<pre class="literal-block">
struct session_status
{
bool has_incoming_connections;
int upload_rate;
int download_rate;
size_type total_download;
size_type total_upload;
int payload_upload_rate;
int payload_download_rate;
size_type total_payload_download;
size_type total_payload_upload;
int ip_overhead_upload_rate;
int ip_overhead_download_rate;
size_type total_ip_overhead_download;
size_type total_ip_overhead_upload;
int dht_upload_rate;
int dht_download_rate;
size_type total_dht_download;
size_type total_dht_upload;
int tracker_upload_rate;
int tracker_download_rate;
size_type total_tracker_download;
size_type total_tracker_upload;
size_type total_redundant_bytes;
size_type total_failed_bytes;
int num_peers;
int num_dead_peers;
int num_unchoked;
int allowed_upload_slots;
int up_bandwidth_queue;
int down_bandwidth_queue;
int up_bandwidth_bytes_queue;
int down_bandwidth_bytes_queue;
int optimistic_unchoke_counter;
int unchoke_counter;
int disk_write_queue;
int disk_read_queue;
int dht_nodes;
int dht_node_cache;
int dht_torrents;
size_type dht_global_nodes;
std::vector&lt;dht_lookup&gt; active_requests;
std::vector&lt;dht_routing_bucket&gt; dht_routing_table;
int dht_total_allocations;
utp_status utp_stats;
int peerlist_size;
int num_torrents;
int num_paused_torrents;
};
</pre>
<a name="has_incoming_connections"></a><dl class="docutils">
<dt>has_incoming_connections</dt>
<dd>false as long as no incoming connections have been
established on the listening socket. Every time you change the listen port, this will
be reset to false.</dd>
</dl>
<a name="upload_rate"></a>
<a name="download_rate"></a><dl class="docutils">
<dt>upload_rate download_rate</dt>
<dd>the total download and upload rates accumulated
from all torrents. This includes bittorrent protocol, DHT and an estimated TCP/IP
protocol overhead.</dd>
</dl>
<a name="total_download"></a>
<a name="total_upload"></a><dl class="docutils">
<dt>total_download total_upload</dt>
<dd>the total number of bytes downloaded and
uploaded to and from all torrents. This also includes all the protocol overhead.</dd>
</dl>
<a name="payload_upload_rate"></a>
<a name="payload_download_rate"></a><dl class="docutils">
<dt>payload_upload_rate payload_download_rate</dt>
<dd>the rate of the payload
down- and upload only.</dd>
</dl>
<a name="total_payload_download"></a>
<a name="total_payload_upload"></a><dl class="docutils">
<dt>total_payload_download total_payload_upload</dt>
<dd>the total transfers of payload
only. The payload does not include the bittorrent protocol overhead, but only parts of the
actual files to be downloaded.</dd>
</dl>
<a name="ip_overhead_upload_rate"></a>
<a name="ip_overhead_download_rate"></a>
<a name="total_ip_overhead_download"></a>
<a name="total_ip_overhead_upload"></a><dl class="docutils">
<dt>ip_overhead_upload_rate ip_overhead_download_rate total_ip_overhead_download total_ip_overhead_upload</dt>
<dd>the estimated TCP/IP overhead in each direction.</dd>
</dl>
<a name="dht_upload_rate"></a>
<a name="dht_download_rate"></a>
<a name="total_dht_download"></a>
<a name="total_dht_upload"></a><dl class="docutils">
<dt>dht_upload_rate dht_download_rate total_dht_download total_dht_upload</dt>
<dd>the upload and download rate used by DHT traffic. Also the total number
of bytes sent and received to and from the DHT.</dd>
</dl>
<a name="tracker_upload_rate"></a>
<a name="tracker_download_rate"></a>
<a name="total_tracker_download"></a>
<a name="total_tracker_upload"></a><dl class="docutils">
<dt>tracker_upload_rate tracker_download_rate total_tracker_download total_tracker_upload</dt>
<dd>the upload and download rate used by tracker traffic. Also the total number
of bytes sent and received to and from trackers.</dd>
</dl>
<a name="total_redundant_bytes"></a><dl class="docutils">
<dt>total_redundant_bytes</dt>
<dd>the number of bytes that has been received more than once.
This can happen if a request from a peer times out and is requested from a different
peer, and then received again from the first one. To make this lower, increase the
<tt class="docutils literal">request_timeout</tt> and the <tt class="docutils literal">piece_timeout</tt> in the <a class="reference external" href="reference-Session.html#session">session</a> settings.</dd>
</dl>
<a name="total_failed_bytes"></a><dl class="docutils">
<dt>total_failed_bytes</dt>
<dd>the number of bytes that was downloaded which later failed
the hash-check.</dd>
</dl>
<a name="num_peers"></a><dl class="docutils">
<dt>num_peers</dt>
<dd>the total number of peer connections this <a class="reference external" href="reference-Session.html#session">session</a> has. This includes
incoming connections that still hasn't sent their handshake or outgoing connections
that still hasn't completed the TCP connection. This number may be slightly higher
than the sum of all peers of all torrents because the incoming connections may not
be assigned a torrent yet.</dd>
</dl>
<a name="num_unchoked"></a><dl class="docutils">
<dt>num_unchoked</dt>
<dd>the current number of unchoked peers.</dd>
</dl>
<a name="allowed_upload_slots"></a><dl class="docutils">
<dt>allowed_upload_slots</dt>
<dd>the current allowed number of unchoked peers.</dd>
</dl>
<a name="up_bandwidth_queue"></a>
<a name="down_bandwidth_queue"></a><dl class="docutils">
<dt>up_bandwidth_queue down_bandwidth_queue</dt>
<dd>the number of peers that are
waiting for more bandwidth quota from the torrent rate limiter.</dd>
</dl>
<a name="up_bandwidth_bytes_queue"></a>
<a name="down_bandwidth_bytes_queue"></a><dl class="docutils">
<dt>up_bandwidth_bytes_queue down_bandwidth_bytes_queue</dt>
<dd>count the number of
bytes the connections are waiting for to be able to send and receive.</dd>
</dl>
<a name="optimistic_unchoke_counter"></a>
<a name="unchoke_counter"></a><dl class="docutils">
<dt>optimistic_unchoke_counter unchoke_counter</dt>
<dd>tells the number of
seconds until the next optimistic unchoke change and the start of the next
unchoke interval. These numbers may be reset prematurely if a peer that is
unchoked disconnects or becomes notinterested.</dd>
</dl>
<a name="disk_write_queue"></a>
<a name="disk_read_queue"></a><dl class="docutils">
<dt>disk_write_queue disk_read_queue</dt>
<dd>the number of peers currently
waiting on a disk write or disk read to complete before it receives or sends
any more data on the socket. It'a a metric of how disk bound you are.</dd>
</dl>
<a name="dht_nodes"></a>
<a name="dht_node_cache"></a><dl class="docutils">
<dt>dht_nodes dht_node_cache</dt>
<dd>only available when
built with DHT support. They are all set to 0 if the DHT isn't running. When
the DHT is running, <tt class="docutils literal">dht_nodes</tt> is set to the number of nodes in the routing
table. This number only includes <em>active</em> nodes, not cache nodes. The
<tt class="docutils literal">dht_node_cache</tt> is set to the number of nodes in the node cache. These nodes
are used to replace the regular nodes in the routing table in case any of them
becomes unresponsive.</dd>
</dl>
<a name="dht_torrents"></a><dl class="docutils">
<dt>dht_torrents</dt>
<dd>the number of torrents tracked by the DHT at the moment.</dd>
</dl>
<a name="dht_global_nodes"></a><dl class="docutils">
<dt>dht_global_nodes</dt>
<dd>an estimation of the total number of nodes in the DHT
network.</dd>
</dl>
<a name="active_requests"></a><dl class="docutils">
<dt>active_requests</dt>
<dd>a vector of the currently running DHT lookups.</dd>
</dl>
<a name="dht_routing_table"></a><dl class="docutils">
<dt>dht_routing_table</dt>
<dd>contains information about every bucket in the DHT routing
table.</dd>
</dl>
<a name="dht_total_allocations"></a><dl class="docutils">
<dt>dht_total_allocations</dt>
<dd>the number of nodes allocated dynamically for a
particular DHT lookup. This represents roughly the amount of memory used
by the DHT.</dd>
</dl>
<a name="utp_stats"></a><dl class="docutils">
<dt>utp_stats</dt>
<dd>statistics on the uTP sockets.</dd>
</dl>
<a name="peerlist_size"></a><dl class="docutils">
<dt>peerlist_size</dt>
<dd>the number of known peers across all torrents. These are not necessarily
connected peers, just peers we know of.</dd>
</dl>
<a name="num_torrents"></a>
<a name="num_paused_torrents"></a><dl class="docutils">
<dt>num_torrents num_paused_torrents</dt>
<dd>the number of torrents in the
<a class="reference external" href="reference-Session.html#session">session</a> and the number of them that are currently paused, respectively.</dd>
</dl>
<a name="find_metric_idx()"></a><div class="section" id="find-metric-idx">
<h2>find_metric_idx()</h2>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session.hpp">libtorrent/session.hpp</a>&quot;</p>
<pre class="literal-block">
int <strong>find_metric_idx</strong> (char const* name);
</pre>
<p>given a name of a metric, this function returns the counter index of it,
or -1 if it could not be found. The counter index is the index into the
values array returned by <a class="reference external" href="reference-Alerts.html#session_stats_alert">session_stats_alert</a>.</p>
<a name="session_stats_metrics()"></a></div>
<div class="section" id="session-stats-metrics">
<h2>session_stats_metrics()</h2>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/session.hpp">libtorrent/session.hpp</a>&quot;</p>
<pre class="literal-block">
std::vector&lt;stats_metric&gt; <strong>session_stats_metrics</strong> ();
</pre>
<p>This free function returns the list of available metrics exposed by
libtorrent's statistics API. Each metric has a name and a <em>value index</em>.
The value index is the index into the array in <a class="reference external" href="reference-Alerts.html#session_stats_alert">session_stats_alert</a> where
this metric's value can be found when the <a class="reference external" href="reference-Session.html#session">session</a> stats is sampled (by
calling <a class="reference external" href="reference-Session.html#post_session_stats()">post_session_stats()</a>).</p>
</div>
</div>
</div>
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