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premiere-libtorrent/docs/settings.rst

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.. _user_agent:
.. raw:: html
<a name="user_agent"></a>
+------------+--------+----------------------------------+
| name | type | default |
+============+========+==================================+
| user_agent | string | "libtorrent/" LIBTORRENT_VERSION |
+------------+--------+----------------------------------+
this is the client identification to the tracker.
The recommended format of this string is:
"ClientName/ClientVersion libtorrent/libtorrentVersion".
This name will not only be used when making HTTP requests, but also when
sending extended headers to peers that support that extension.
It may not contain \r or \n
.. _announce_ip:
.. raw:: html
<a name="announce_ip"></a>
+-------------+--------+---------+
| name | type | default |
+=============+========+=========+
| announce_ip | string | 0 |
+-------------+--------+---------+
``announce_ip`` is the ip address passed along to trackers as the ``&ip=`` parameter.
If left as the default, that parameter is omitted.
.. _mmap_cache:
.. raw:: html
<a name="mmap_cache"></a>
+------------+--------+---------+
| name | type | default |
+============+========+=========+
| mmap_cache | string | 0 |
+------------+--------+---------+
``mmap_cache`` may be set to a filename where the disk cache will be mmapped
to. This could be useful, for instance, to map the disk cache from regular
rotating hard drives onto an SSD drive. Doing that effectively introduces
a second layer of caching, allowing the disk cache to be as big as can
fit on an SSD drive (probably about one order of magnitude more than the
available RAM). The intention of this setting is to set it up once at the
start up and not change it while running. The setting may not be changed
as long as there are any disk buffers in use. This default to the empty
string, which means use regular RAM allocations for the disk cache. The file
specified will be created and truncated to the disk cache size (``cache_size``).
Any existing file with the same name will be replaced.
Since this setting sets a hard upper limit on cache usage, it cannot be combined
with ``session_settings::contiguous_recv_buffer``, since that feature treats the
``cache_size`` setting as a soft (but still pretty hard) limit. The result of combining
the two is peers being disconnected after failing to allocate more disk buffers.
This feature requires the ``mmap`` system call, on systems that don't have ``mmap``
this setting is ignored.
.. _handshake_client_version:
.. raw:: html
<a name="handshake_client_version"></a>
+--------------------------+--------+---------+
| name | type | default |
+==========================+========+=========+
| handshake_client_version | string | 0 |
+--------------------------+--------+---------+
this is the client name and version identifier sent to peers in the handshake
message. If this is an empty string, the user_agent is used instead
.. _outgoing_interfaces:
.. raw:: html
<a name="outgoing_interfaces"></a>
+---------------------+--------+---------+
| name | type | default |
+=====================+========+=========+
| outgoing_interfaces | string | "" |
+---------------------+--------+---------+
sets the network interface this session will use when it opens
outgoing connections. By default, it binds outgoing connections to
INADDR_ANY and port 0 (i.e. let the OS decide). Ths parameter must
be a string containing one or more, comma separated, adapter names.
Adapter names on unix systems are of the form "eth0", "eth1", "tun0",
etc. When specifying multiple
interfaces, they will be assigned in round-robin order. This may be
useful for clients that are multi-homed. Binding an outgoing
connection to a local IP does not necessarily make the connection
via the associated NIC/Adapter. Setting this to an empty string
will disable binding of outgoing connections.
.. _listen_interfaces:
.. raw:: html
<a name="listen_interfaces"></a>
+-------------------+--------+----------------+
| name | type | default |
+===================+========+================+
| listen_interfaces | string | "0.0.0.0:6881" |
+-------------------+--------+----------------+
a comma-separated list of (IP or device name, port) pairs. These
are the listen ports that will be opened for accepting incoming uTP
and TCP connections. It is possible to listen on multiple
interfaces and multiple ports. Binding to port 0 will make the
operating system pick the port. The default is "0.0.0.0:0", which
binds to all interfaces on a port the OS picks.
if binding fails, the listen_failed_alert is posted, otherwise the
listen_succeeded_alert.
If the DHT is running, it will also have its socket rebound to the
same port as the main listen port.
The reason why it's a good idea to run the DHT and the bittorrent
socket on the same port is because that is an assumption that may
be used to increase performance. One way to accelerate the
connecting of peers on windows may be to first ping all peers with
a DHT ping packet, and connect to those that responds first. On
windows one can only connect to a few peers at a time because of a
built in limitation (in XP Service pack 2).
.. _proxy_hostname:
.. raw:: html
<a name="proxy_hostname"></a>
+----------------+--------+---------+
| name | type | default |
+================+========+=========+
| proxy_hostname | string | "" |
+----------------+--------+---------+
when using a poxy, this is the hostname where the proxy is running
see proxy_type.
.. _proxy_username:
.. _proxy_password:
.. raw:: html
<a name="proxy_username"></a>
<a name="proxy_password"></a>
+----------------+--------+---------+
| name | type | default |
+================+========+=========+
| proxy_username | string | "" |
+----------------+--------+---------+
| proxy_password | string | "" |
+----------------+--------+---------+
when using a proxy, these are the credentials (if any) to use
whne connecting to it. see proxy_type
.. _i2p_hostname:
.. raw:: html
<a name="i2p_hostname"></a>
+--------------+--------+---------+
| name | type | default |
+==============+========+=========+
| i2p_hostname | string | "" |
+--------------+--------+---------+
sets the i2p_ SAM bridge to connect to. set the port with the
``i2p_port`` setting.
.. _i2p: http://www.i2p2.de
.. _allow_multiple_connections_per_ip:
.. raw:: html
<a name="allow_multiple_connections_per_ip"></a>
+-----------------------------------+------+---------+
| name | type | default |
+===================================+======+=========+
| allow_multiple_connections_per_ip | bool | false |
+-----------------------------------+------+---------+
determines if connections from the same IP address as
existing connections should be rejected or not. Multiple
connections from the same IP address is not allowed by
default, to prevent abusive behavior by peers. It may
be useful to allow such connections in cases where
simulations are run on the same machie, and all peers
in a swarm has the same IP address.
.. _send_redundant_have:
.. raw:: html
<a name="send_redundant_have"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| send_redundant_have | bool | true |
+---------------------+------+---------+
if set to true, upload, download and unchoke limits
are ignored for peers on the local network.
This option is *DEPRECATED*, please use set_peer_class_filter() instead.
``send_redundant_have`` controls if have messages will be sent
to peers that already have the piece. This is typically not necessary,
but it might be necessary for collecting statistics in some cases.
Default is false.
.. _lazy_bitfields:
.. raw:: html
<a name="lazy_bitfields"></a>
+----------------+------+---------+
| name | type | default |
+================+======+=========+
| lazy_bitfields | bool | true |
+----------------+------+---------+
if this is true, outgoing bitfields will never be fuil. If the
client is seed, a few bits will be set to 0, and later filled
in with have messages. This is to prevent certain ISPs
from stopping people from seeding.
.. _use_dht_as_fallback:
.. raw:: html
<a name="use_dht_as_fallback"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| use_dht_as_fallback | bool | false |
+---------------------+------+---------+
``use_dht_as_fallback`` determines how the DHT is used. If this is true,
the DHT will only be used for torrents where all trackers in its tracker
list has failed. Either by an explicit error message or a time out. This
is false by default, which means the DHT is used by default regardless of
.. _upnp_ignore_nonrouters:
.. raw:: html
<a name="upnp_ignore_nonrouters"></a>
+------------------------+------+---------+
| name | type | default |
+========================+======+=========+
| upnp_ignore_nonrouters | bool | false |
+------------------------+------+---------+
``upnp_ignore_nonrouters`` indicates whether or not the UPnP implementation
should ignore any broadcast response from a device whose address is not the
configured router for this machine. i.e. it's a way to not talk to other
people's routers by mistake.
.. _use_parole_mode:
.. raw:: html
<a name="use_parole_mode"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| use_parole_mode | bool | true |
+-----------------+------+---------+
``use_parole_mode`` specifies if parole mode should be used. Parole mode means
that peers that participate in pieces that fail the hash check are put in a mode
where they are only allowed to download whole pieces. If the whole piece a peer
in parole mode fails the hash check, it is banned. If a peer participates in a
piece that passes the hash check, it is taken out of parole mode.
.. _use_read_cache:
.. _use_write_cache:
.. raw:: html
<a name="use_read_cache"></a>
<a name="use_write_cache"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| use_read_cache | bool | true |
+-----------------+------+---------+
| use_write_cache | bool | true |
+-----------------+------+---------+
enable and disable caching of read blocks and
blocks to be written to disk respsectively.
the purpose of the read cache is partly read-ahead of requests
but also to avoid reading blocks back from the disk multiple
times for popular pieces.
the write cache purpose is to hold off writing blocks to disk until
they have been hashed, to avoid having to read them back in again.
.. _dont_flush_write_cache:
.. raw:: html
<a name="dont_flush_write_cache"></a>
+------------------------+------+---------+
| name | type | default |
+========================+======+=========+
| dont_flush_write_cache | bool | false |
+------------------------+------+---------+
this will make the disk cache never flush a write
piece if it would cause is to have to re-read it
once we want to calculate the piece hash
.. _explicit_read_cache:
.. raw:: html
<a name="explicit_read_cache"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| explicit_read_cache | bool | false |
+---------------------+------+---------+
``explicit_read_cache`` defaults to 0. If set to something greater than 0, the
disk read cache will not be evicted by cache misses and will explicitly be
controlled based on the rarity of pieces. Rare pieces are more likely to be
cached. This would typically be used together with ``suggest_mode`` set to
``suggest_read_cache``. The value is the number of pieces to keep in the read
cache. If the actual read cache can't fit as many, it will essentially be clamped.
.. _coalesce_reads:
.. _coalesce_writes:
.. raw:: html
<a name="coalesce_reads"></a>
<a name="coalesce_writes"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| coalesce_reads | bool | false |
+-----------------+------+---------+
| coalesce_writes | bool | false |
+-----------------+------+---------+
allocate separate, contiguous, buffers for read and
write calls. Only used where writev/readv cannot be used
will use more RAM but may improve performance
.. _auto_manage_prefer_seeds:
.. raw:: html
<a name="auto_manage_prefer_seeds"></a>
+--------------------------+------+---------+
| name | type | default |
+==========================+======+=========+
| auto_manage_prefer_seeds | bool | false |
+--------------------------+------+---------+
prefer seeding torrents when determining which torrents to give
active slots to, the default is false which gives preference to
downloading torrents
.. _dont_count_slow_torrents:
.. raw:: html
<a name="dont_count_slow_torrents"></a>
+--------------------------+------+---------+
| name | type | default |
+==========================+======+=========+
| dont_count_slow_torrents | bool | true |
+--------------------------+------+---------+
if ``dont_count_slow_torrents`` is true, torrents without any payload transfers are
not subject to the ``active_seeds`` and ``active_downloads`` limits. This is intended
to make it more likely to utilize all available bandwidth, and avoid having torrents
that don't transfer anything block the active slots.
.. _close_redundant_connections:
.. raw:: html
<a name="close_redundant_connections"></a>
+-----------------------------+------+---------+
| name | type | default |
+=============================+======+=========+
| close_redundant_connections | bool | true |
+-----------------------------+------+---------+
``close_redundant_connections`` specifies whether libtorrent should close
connections where both ends have no utility in keeping the connection open.
For instance if both ends have completed their downloads, there's no point
in keeping it open.
.. _prioritize_partial_pieces:
.. raw:: html
<a name="prioritize_partial_pieces"></a>
+---------------------------+------+---------+
| name | type | default |
+===========================+======+=========+
| prioritize_partial_pieces | bool | false |
+---------------------------+------+---------+
If ``prioritize_partial_pieces`` is true, partial pieces are picked
before pieces that are more rare. If false, rare pieces are always
prioritized, unless the number of partial pieces is growing out of
proportion.
.. _rate_limit_ip_overhead:
.. raw:: html
<a name="rate_limit_ip_overhead"></a>
+------------------------+------+---------+
| name | type | default |
+========================+======+=========+
| rate_limit_ip_overhead | bool | true |
+------------------------+------+---------+
if set to true, the estimated TCP/IP overhead is
drained from the rate limiters, to avoid exceeding
the limits with the total traffic
.. _announce_to_all_tiers:
.. _announce_to_all_trackers:
.. raw:: html
<a name="announce_to_all_tiers"></a>
<a name="announce_to_all_trackers"></a>
+--------------------------+------+---------+
| name | type | default |
+==========================+======+=========+
| announce_to_all_tiers | bool | false |
+--------------------------+------+---------+
| announce_to_all_trackers | bool | false |
+--------------------------+------+---------+
``announce_to_all_trackers`` controls how multi tracker torrents are
treated. If this is set to true, all trackers in the same tier are
announced to in parallel. If all trackers in tier 0 fails, all trackers
in tier 1 are announced as well. If it's set to false, the behavior is as
defined by the multi tracker specification. It defaults to false, which
is the same behavior previous versions of libtorrent has had as well.
``announce_to_all_tiers`` also controls how multi tracker torrents are
treated. When this is set to true, one tracker from each tier is announced
to. This is the uTorrent behavior. This is false by default in order
to comply with the multi-tracker specification.
.. _prefer_udp_trackers:
.. raw:: html
<a name="prefer_udp_trackers"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| prefer_udp_trackers | bool | true |
+---------------------+------+---------+
``prefer_udp_trackers`` is true by default. It means that trackers may
be rearranged in a way that udp trackers are always tried before http
trackers for the same hostname. Setting this to false means that the
trackers' tier is respected and there's no preference of one protocol
over another.
.. _strict_super_seeding:
.. raw:: html
<a name="strict_super_seeding"></a>
+----------------------+------+---------+
| name | type | default |
+======================+======+=========+
| strict_super_seeding | bool | false |
+----------------------+------+---------+
``strict_super_seeding`` when this is set to true, a piece has to
have been forwarded to a third peer before another one is handed out.
This is the traditional definition of super seeding.
.. _lock_disk_cache:
.. raw:: html
<a name="lock_disk_cache"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| lock_disk_cache | bool | false |
+-----------------+------+---------+
if this is set to true, the memory allocated for the
disk cache will be locked in physical RAM, never to
be swapped out. Every time a disk buffer is allocated
and freed, there will be the extra overhead of a system call.
.. _disable_hash_checks:
.. raw:: html
<a name="disable_hash_checks"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| disable_hash_checks | bool | false |
+---------------------+------+---------+
when set to true, all data downloaded from
peers will be assumed to be correct, and not
tested to match the hashes in the torrent
this is only useful for simulation and
testing purposes (typically combined with
disabled_storage)
.. _allow_i2p_mixed:
.. raw:: html
<a name="allow_i2p_mixed"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| allow_i2p_mixed | bool | false |
+-----------------+------+---------+
if this is true, i2p torrents are allowed
to also get peers from other sources than
the tracker, and connect to regular IPs,
not providing any anonymization. This may
be useful if the user is not interested in
the anonymization of i2p, but still wants to
be able to connect to i2p peers.
.. _low_prio_disk:
.. raw:: html
<a name="low_prio_disk"></a>
+---------------+------+---------+
| name | type | default |
+===============+======+=========+
| low_prio_disk | bool | true |
+---------------+------+---------+
``low_prio_disk`` determines if the disk I/O should use a normal
or low priority policy. This defaults to true, which means that
it's low priority by default. Other processes doing disk I/O will
normally take priority in this mode. This is meant to improve the
overall responsiveness of the system while downloading in the
background. For high-performance server setups, this might not
be desirable.
.. _volatile_read_cache:
.. raw:: html
<a name="volatile_read_cache"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| volatile_read_cache | bool | false |
+---------------------+------+---------+
``volatile_read_cache``, if this is set to true, read cache blocks
that are hit by peer read requests are removed from the disk cache
to free up more space. This is useful if you don't expect the disk
cache to create any cache hits from other peers than the one who
triggered the cache line to be read into the cache in the first place.
.. _guided_read_cache:
.. raw:: html
<a name="guided_read_cache"></a>
+-------------------+------+---------+
| name | type | default |
+===================+======+=========+
| guided_read_cache | bool | false |
+-------------------+------+---------+
``guided_read_cache`` enables the disk cache to adjust the size
of a cache line generated by peers to depend on the upload rate
you are sending to that peer. The intention is to optimize the RAM
usage of the cache, to read ahead further for peers that you're
sending faster to.
.. _no_atime_storage:
.. raw:: html
<a name="no_atime_storage"></a>
+------------------+------+---------+
| name | type | default |
+==================+======+=========+
| no_atime_storage | bool | true |
+------------------+------+---------+
``no_atime_storage`` this is a linux-only option and passes in the
``O_NOATIME`` to ``open()`` when opening files. This may lead to
some disk performance improvements.
.. _incoming_starts_queued_torrents:
.. raw:: html
<a name="incoming_starts_queued_torrents"></a>
+---------------------------------+------+---------+
| name | type | default |
+=================================+======+=========+
| incoming_starts_queued_torrents | bool | false |
+---------------------------------+------+---------+
``incoming_starts_queued_torrents`` defaults to false. If a torrent
has been paused by the auto managed feature in libtorrent, i.e.
the torrent is paused and auto managed, this feature affects whether
or not it is automatically started on an incoming connection. The
main reason to queue torrents, is not to make them unavailable, but
to save on the overhead of announcing to the trackers, the DHT and to
avoid spreading one's unchoke slots too thin. If a peer managed to
find us, even though we're no in the torrent anymore, this setting
can make us start the torrent and serve it.
.. _report_true_downloaded:
.. raw:: html
<a name="report_true_downloaded"></a>
+------------------------+------+---------+
| name | type | default |
+========================+======+=========+
| report_true_downloaded | bool | false |
+------------------------+------+---------+
when set to true, the downloaded counter sent to trackers
will include the actual number of payload bytes donwnloaded
including redundant bytes. If set to false, it will not include
any redundany bytes
.. _strict_end_game_mode:
.. raw:: html
<a name="strict_end_game_mode"></a>
+----------------------+------+---------+
| name | type | default |
+======================+======+=========+
| strict_end_game_mode | bool | true |
+----------------------+------+---------+
``strict_end_game_mode`` defaults to true, and controls when a block
may be requested twice. If this is ``true``, a block may only be requested
twice when there's ay least one request to every piece that's left to
download in the torrent. This may slow down progress on some pieces
sometimes, but it may also avoid downloading a lot of redundant bytes.
If this is ``false``, libtorrent attempts to use each peer connection
to its max, by always requesting something, even if it means requesting
something that has been requested from another peer already.
.. _broadcast_lsd:
.. raw:: html
<a name="broadcast_lsd"></a>
+---------------+------+---------+
| name | type | default |
+===============+======+=========+
| broadcast_lsd | bool | true |
+---------------+------+---------+
if ``broadcast_lsd`` is set to true, the local peer discovery
(or Local Service Discovery) will not only use IP multicast, but also
broadcast its messages. This can be useful when running on networks
that don't support multicast. Since broadcast messages might be
expensive and disruptive on networks, only every 8th announce uses
broadcast.
.. _enable_outgoing_utp:
.. _enable_incoming_utp:
.. _enable_outgoing_tcp:
.. _enable_incoming_tcp:
.. raw:: html
<a name="enable_outgoing_utp"></a>
<a name="enable_incoming_utp"></a>
<a name="enable_outgoing_tcp"></a>
<a name="enable_incoming_tcp"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| enable_outgoing_utp | bool | true |
+---------------------+------+---------+
| enable_incoming_utp | bool | true |
+---------------------+------+---------+
| enable_outgoing_tcp | bool | true |
+---------------------+------+---------+
| enable_incoming_tcp | bool | true |
+---------------------+------+---------+
when set to true, libtorrent will try to make outgoing utp connections
controls whether libtorrent will accept incoming connections or make
outgoing connections of specific type.
.. _ignore_resume_timestamps:
.. raw:: html
<a name="ignore_resume_timestamps"></a>
+--------------------------+------+---------+
| name | type | default |
+==========================+======+=========+
| ignore_resume_timestamps | bool | false |
+--------------------------+------+---------+
``ignore_resume_timestamps`` determines if the storage, when loading
resume data files, should verify that the file modification time
with the timestamps in the resume data. This defaults to false, which
means timestamps are taken into account, and resume data is less likely
to accepted (torrents are more likely to be fully checked when loaded).
It might be useful to set this to true if your network is faster than your
disk, and it would be faster to redownload potentially missed pieces than
to go through the whole storage to look for them.
.. _no_recheck_incomplete_resume:
.. raw:: html
<a name="no_recheck_incomplete_resume"></a>
+------------------------------+------+---------+
| name | type | default |
+==============================+======+=========+
| no_recheck_incomplete_resume | bool | false |
+------------------------------+------+---------+
``no_recheck_incomplete_resume`` determines if the storage should check
the whole files when resume data is incomplete or missing or whether
it should simply assume we don't have any of the data. By default, this
is determined by the existance of any of the files. By setting this setting
to true, the files won't be checked, but will go straight to download
mode.
.. _anonymous_mode:
.. raw:: html
<a name="anonymous_mode"></a>
+----------------+------+---------+
| name | type | default |
+================+======+=========+
| anonymous_mode | bool | true |
+----------------+------+---------+
``anonymous_mode`` defaults to false. When set to true, the client tries
to hide its identity to a certain degree. The peer-ID will no longer
include the client's fingerprint. The user-agent will be reset to an
empty string. Trackers will only be used if they are using a proxy
server. The listen sockets are closed, and incoming connections will
only be accepted through a SOCKS5 or I2P proxy (if a peer proxy is set up and
is run on the same machine as the tracker proxy). Since no incoming connections
are accepted, NAT-PMP, UPnP, DHT and local peer discovery are all turned off
when this setting is enabled.
If you're using I2P, it might make sense to enable anonymous mode as well.
.. _report_web_seed_downloads:
.. raw:: html
<a name="report_web_seed_downloads"></a>
+---------------------------+------+---------+
| name | type | default |
+===========================+======+=========+
| report_web_seed_downloads | bool | true |
+---------------------------+------+---------+
specifies whether downloads from web seeds is reported to the
tracker or not. Defaults to on
.. _utp_dynamic_sock_buf:
.. raw:: html
<a name="utp_dynamic_sock_buf"></a>
+----------------------+------+---------+
| name | type | default |
+======================+======+=========+
| utp_dynamic_sock_buf | bool | true |
+----------------------+------+---------+
controls if the uTP socket manager is allowed to increase
the socket buffer if a network interface with a large MTU is used (such as loopback
or ethernet jumbo frames). This defaults to true and might improve uTP throughput.
For RAM constrained systems, disabling this typically saves around 30kB in user space
and probably around 400kB in kernel socket buffers (it adjusts the send and receive
buffer size on the kernel socket, both for IPv4 and IPv6).
.. _announce_double_nat:
.. raw:: html
<a name="announce_double_nat"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| announce_double_nat | bool | false |
+---------------------+------+---------+
set to true if uTP connections should be rate limited
This option is *DEPRECATED*, please use set_peer_class_filter() instead.
if this is true, the ``&ip=`` argument in tracker requests
(unless otherwise specified) will be set to the intermediate
IP address if the user is double NATed. If ther user is not
double NATed, this option does not have an affect
.. _seeding_outgoing_connections:
.. raw:: html
<a name="seeding_outgoing_connections"></a>
+------------------------------+------+---------+
| name | type | default |
+==============================+======+=========+
| seeding_outgoing_connections | bool | true |
+------------------------------+------+---------+
``seeding_outgoing_connections`` determines if seeding (and finished) torrents
should attempt to make outgoing connections or not. By default this is true. It
may be set to false in very specific applications where the cost of making
outgoing connections is high, and there are no or small benefits of doing so.
For instance, if no nodes are behind a firewall or a NAT, seeds don't need to
make outgoing connections.
.. _no_connect_privileged_ports:
.. raw:: html
<a name="no_connect_privileged_ports"></a>
+-----------------------------+------+---------+
| name | type | default |
+=============================+======+=========+
| no_connect_privileged_ports | bool | false |
+-----------------------------+------+---------+
when this is true, libtorrent will not attempt to make outgoing
connections to peers whose port is < 1024. This is a safety
precaution to avoid being part of a DDoS attack
.. _smooth_connects:
.. raw:: html
<a name="smooth_connects"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| smooth_connects | bool | true |
+-----------------+------+---------+
``smooth_connects`` is true by default, which means the number of connection
attempts per second may be limited to below the ``connection_speed``, in case
we're close to bump up against the limit of number of connections. The intention
of this setting is to more evenly distribute our connection attempts over time,
instead of attempting to connectin in batches, and timing them out in batches.
.. _always_send_user_agent:
.. raw:: html
<a name="always_send_user_agent"></a>
+------------------------+------+---------+
| name | type | default |
+========================+======+=========+
| always_send_user_agent | bool | false |
+------------------------+------+---------+
always send user-agent in every web seed request. If false, only
the first request per http connection will include the user agent
.. _apply_ip_filter_to_trackers:
.. raw:: html
<a name="apply_ip_filter_to_trackers"></a>
+-----------------------------+------+---------+
| name | type | default |
+=============================+======+=========+
| apply_ip_filter_to_trackers | bool | true |
+-----------------------------+------+---------+
``apply_ip_filter_to_trackers`` defaults to true. It determines whether the
IP filter applies to trackers as well as peers. If this is set to false,
trackers are exempt from the IP filter (if there is one). If no IP filter
is set, this setting is irrelevant.
.. _use_disk_read_ahead:
.. raw:: html
<a name="use_disk_read_ahead"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| use_disk_read_ahead | bool | true |
+---------------------+------+---------+
``use_disk_read_ahead`` defaults to true and will attempt to optimize disk reads
by giving the operating system heads up of disk read requests as they are queued
in the disk job queue.
.. _lock_files:
.. raw:: html
<a name="lock_files"></a>
+------------+------+---------+
| name | type | default |
+============+======+=========+
| lock_files | bool | false |
+------------+------+---------+
``lock_files`` determines whether or not to lock files which libtorrent is downloading
to or seeding from. This is implemented using ``fcntl(F_SETLK)`` on unix systems and
by not passing in ``SHARE_READ`` and ``SHARE_WRITE`` on windows. This might prevent
3rd party processes from corrupting the files under libtorrent's feet.
.. _contiguous_recv_buffer:
.. raw:: html
<a name="contiguous_recv_buffer"></a>
+------------------------+------+---------+
| name | type | default |
+========================+======+=========+
| contiguous_recv_buffer | bool | true |
+------------------------+------+---------+
``contiguous_recv_buffer`` determines whether or not libtorrent should receive
data from peers into a contiguous intermediate buffer, to then copy blocks into
disk buffers from, or to make many smaller calls to ``read()``, each time passing
in the specific buffer the data belongs in. When downloading at high rates, the latter
may save some time copying data. When seeding at high rates, all incoming traffic
consists of a very large number of tiny packets, and enabling ``contiguous_recv_buffer``
will provide higher performance. When this is enabled, it will only be used when
seeding to peers, since that's when it provides performance improvements.
.. _ban_web_seeds:
.. raw:: html
<a name="ban_web_seeds"></a>
+---------------+------+---------+
| name | type | default |
+===============+======+=========+
| ban_web_seeds | bool | true |
+---------------+------+---------+
when true, web seeds sending bad data will be banned
.. _allow_partial_disk_writes:
.. raw:: html
<a name="allow_partial_disk_writes"></a>
+---------------------------+------+---------+
| name | type | default |
+===========================+======+=========+
| allow_partial_disk_writes | bool | true |
+---------------------------+------+---------+
when set to false, the ``write_cache_line_size`` will apply across piece boundaries.
this is a bad idea unless the piece picker also is configured to have an affinity
to pick pieces belonging to the same write cache line as is configured in the
disk cache.
.. _force_proxy:
.. raw:: html
<a name="force_proxy"></a>
+-------------+------+---------+
| name | type | default |
+=============+======+=========+
| force_proxy | bool | false |
+-------------+------+---------+
If true, disables any communication that's not going over a proxy.
Enabling this requires a proxy to be configured as well, see ``set_proxy_settings``.
The listen sockets are closed, and incoming connections will
only be accepted through a SOCKS5 or I2P proxy (if a peer proxy is set up and
is run on the same machine as the tracker proxy). This setting also
disabled peer country lookups, since those are done via DNS lookups that
aren't supported by proxies.
.. _support_share_mode:
.. raw:: html
<a name="support_share_mode"></a>
+--------------------+------+---------+
| name | type | default |
+====================+======+=========+
| support_share_mode | bool | true |
+--------------------+------+---------+
if false, prevents libtorrent to advertise share-mode support
.. _support_merkle_torrents:
.. raw:: html
<a name="support_merkle_torrents"></a>
+-------------------------+------+---------+
| name | type | default |
+=========================+======+=========+
| support_merkle_torrents | bool | true |
+-------------------------+------+---------+
if this is false, don't advertise support for
the Tribler merkle tree piece message
.. _report_redundant_bytes:
.. raw:: html
<a name="report_redundant_bytes"></a>
+------------------------+------+---------+
| name | type | default |
+========================+======+=========+
| report_redundant_bytes | bool | true |
+------------------------+------+---------+
if this is true, the number of redundant bytes
is sent to the tracker
.. _listen_system_port_fallback:
.. raw:: html
<a name="listen_system_port_fallback"></a>
+-----------------------------+------+---------+
| name | type | default |
+=============================+======+=========+
| listen_system_port_fallback | bool | true |
+-----------------------------+------+---------+
if this is true, libtorrent will fall back to listening on a port chosen
by the operating system (i.e. binding to port 0). If a failure is preferred,
set this to false.
.. _use_disk_cache_pool:
.. raw:: html
<a name="use_disk_cache_pool"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| use_disk_cache_pool | bool | false |
+---------------------+------+---------+
``use_disk_cache_pool`` enables using a pool allocator for disk cache blocks.
Enabling it makes the cache perform better at high throughput.
It also makes the cache less likely and slower at returning memory back to the system,
once allocated.
.. _announce_crypto_support:
.. raw:: html
<a name="announce_crypto_support"></a>
+-------------------------+------+---------+
| name | type | default |
+=========================+======+=========+
| announce_crypto_support | bool | true |
+-------------------------+------+---------+
when this is true, and incoming encrypted connections are enabled, &supportcrypt=1
is included in http tracker announces
.. _enable_upnp:
.. raw:: html
<a name="enable_upnp"></a>
+-------------+------+---------+
| name | type | default |
+=============+======+=========+
| enable_upnp | bool | true |
+-------------+------+---------+
Starts and stops the UPnP service. When started, the listen port and the DHT
port are attempted to be forwarded on local UPnP router devices.
The upnp object returned by ``start_upnp()`` can be used to add and remove
arbitrary port mappings. Mapping status is returned through the
portmap_alert and the portmap_error_alert. The object will be valid until
``stop_upnp()`` is called. See upnp-and-nat-pmp_.
.. _enable_natpmp:
.. raw:: html
<a name="enable_natpmp"></a>
+---------------+------+---------+
| name | type | default |
+===============+======+=========+
| enable_natpmp | bool | true |
+---------------+------+---------+
Starts and stops the NAT-PMP service. When started, the listen port and the DHT
port are attempted to be forwarded on the router through NAT-PMP.
The natpmp object returned by ``start_natpmp()`` can be used to add and remove
arbitrary port mappings. Mapping status is returned through the
portmap_alert and the portmap_error_alert. The object will be valid until
``stop_natpmp()`` is called. See upnp-and-nat-pmp_.
.. _enable_lsd:
.. raw:: html
<a name="enable_lsd"></a>
+------------+------+---------+
| name | type | default |
+============+======+=========+
| enable_lsd | bool | true |
+------------+------+---------+
Starts and stops Local Service Discovery. This service will broadcast
the infohashes of all the non-private torrents on the local network to
look for peers on the same swarm within multicast reach.
.. _enable_dht:
.. raw:: html
<a name="enable_dht"></a>
+------------+------+---------+
| name | type | default |
+============+======+=========+
| enable_dht | bool | true |
+------------+------+---------+
starts the dht node and makes the trackerless service
available to torrents.
.. _prefer_rc4:
.. raw:: html
<a name="prefer_rc4"></a>
+------------+------+---------+
| name | type | default |
+============+======+=========+
| prefer_rc4 | bool | false |
+------------+------+---------+
if the allowed encryption level is both, setting this to
true will prefer rc4 if both methods are offered, plaintext
otherwise
.. _proxy_hostnames:
.. raw:: html
<a name="proxy_hostnames"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| proxy_hostnames | bool | true |
+-----------------+------+---------+
if true, hostname lookups are done via the configured proxy (if
any). This is only supported by SOCKS5 and HTTP.
.. _proxy_peer_connections:
.. raw:: html
<a name="proxy_peer_connections"></a>
+------------------------+------+---------+
| name | type | default |
+========================+======+=========+
| proxy_peer_connections | bool | true |
+------------------------+------+---------+
if true, peer connections are made (and accepted) over the
configured proxy, if any.
.. _tracker_completion_timeout:
.. raw:: html
<a name="tracker_completion_timeout"></a>
+----------------------------+------+---------+
| name | type | default |
+============================+======+=========+
| tracker_completion_timeout | int | 60 |
+----------------------------+------+---------+
``tracker_completion_timeout`` is the number of seconds the tracker
connection will wait from when it sent the request until it considers the
tracker to have timed-out. Default value is 60 seconds.
.. _tracker_receive_timeout:
.. raw:: html
<a name="tracker_receive_timeout"></a>
+-------------------------+------+---------+
| name | type | default |
+=========================+======+=========+
| tracker_receive_timeout | int | 40 |
+-------------------------+------+---------+
``tracker_receive_timeout`` is the number of seconds to wait to receive
any data from the tracker. If no data is received for this number of
seconds, the tracker will be considered as having timed out. If a tracker
is down, this is the kind of timeout that will occur.
.. _stop_tracker_timeout:
.. raw:: html
<a name="stop_tracker_timeout"></a>
+----------------------+------+---------+
| name | type | default |
+======================+======+=========+
| stop_tracker_timeout | int | 5 |
+----------------------+------+---------+
the time to wait when sending a stopped message
before considering a tracker to have timed out.
this is usually shorter, to make the client quit
faster
.. _tracker_maximum_response_length:
.. raw:: html
<a name="tracker_maximum_response_length"></a>
+---------------------------------+------+-----------+
| name | type | default |
+=================================+======+===========+
| tracker_maximum_response_length | int | 1024*1024 |
+---------------------------------+------+-----------+
this is the maximum number of bytes in a tracker
response. If a response size passes this number
of bytes it will be rejected and the connection
will be closed. On gzipped responses this size is
measured on the uncompressed data. So, if you get
20 bytes of gzip response that'll expand to 2 megabytes,
it will be interrupted before the entire response
has been uncompressed (assuming the limit is lower
than 2 megs).
.. _piece_timeout:
.. raw:: html
<a name="piece_timeout"></a>
+---------------+------+---------+
| name | type | default |
+===============+======+=========+
| piece_timeout | int | 20 |
+---------------+------+---------+
the number of seconds from a request is sent until
it times out if no piece response is returned.
.. _request_timeout:
.. raw:: html
<a name="request_timeout"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| request_timeout | int | 50 |
+-----------------+------+---------+
the number of seconds one block (16kB) is expected
to be received within. If it's not, the block is
requested from a different peer
.. _request_queue_time:
.. raw:: html
<a name="request_queue_time"></a>
+--------------------+------+---------+
| name | type | default |
+====================+======+=========+
| request_queue_time | int | 3 |
+--------------------+------+---------+
the length of the request queue given in the number
of seconds it should take for the other end to send
all the pieces. i.e. the actual number of requests
depends on the download rate and this number.
.. _max_allowed_in_request_queue:
.. raw:: html
<a name="max_allowed_in_request_queue"></a>
+------------------------------+------+---------+
| name | type | default |
+==============================+======+=========+
| max_allowed_in_request_queue | int | 500 |
+------------------------------+------+---------+
the number of outstanding block requests a peer is
allowed to queue up in the client. If a peer sends
more requests than this (before the first one has
been sent) the last request will be dropped.
the higher this is, the faster upload speeds the
client can get to a single peer.
.. _max_out_request_queue:
.. raw:: html
<a name="max_out_request_queue"></a>
+-----------------------+------+---------+
| name | type | default |
+=======================+======+=========+
| max_out_request_queue | int | 500 |
+-----------------------+------+---------+
``max_out_request_queue`` is the maximum number of outstanding requests to
send to a peer. This limit takes precedence over ``request_queue_time``. i.e.
no matter the download speed, the number of outstanding requests will never
exceed this limit.
.. _whole_pieces_threshold:
.. raw:: html
<a name="whole_pieces_threshold"></a>
+------------------------+------+---------+
| name | type | default |
+========================+======+=========+
| whole_pieces_threshold | int | 20 |
+------------------------+------+---------+
if a whole piece can be downloaded in this number
of seconds, or less, the peer_connection will prefer
to request whole pieces at a time from this peer.
The benefit of this is to better utilize disk caches by
doing localized accesses and also to make it easier
to identify bad peers if a piece fails the hash check.
.. _peer_timeout:
.. raw:: html
<a name="peer_timeout"></a>
+--------------+------+---------+
| name | type | default |
+==============+======+=========+
| peer_timeout | int | 120 |
+--------------+------+---------+
``peer_timeout`` is the number of seconds the peer connection should
wait (for any activity on the peer connection) before closing it due
to time out. This defaults to 120 seconds, since that's what's specified
in the protocol specification. After half the time out, a keep alive message
is sent.
.. _urlseed_timeout:
.. raw:: html
<a name="urlseed_timeout"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| urlseed_timeout | int | 20 |
+-----------------+------+---------+
same as peer_timeout, but only applies to url-seeds.
this is usually set lower, because web servers are
expected to be more reliable.
.. _urlseed_pipeline_size:
.. raw:: html
<a name="urlseed_pipeline_size"></a>
+-----------------------+------+---------+
| name | type | default |
+=======================+======+=========+
| urlseed_pipeline_size | int | 5 |
+-----------------------+------+---------+
controls the pipelining size of url-seeds. i.e. the number
of HTTP request to keep outstanding before waiting for
the first one to complete. It's common for web servers
to limit this to a relatively low number, like 5
.. _urlseed_wait_retry:
.. raw:: html
<a name="urlseed_wait_retry"></a>
+--------------------+------+---------+
| name | type | default |
+====================+======+=========+
| urlseed_wait_retry | int | 30 |
+--------------------+------+---------+
time to wait until a new retry of a web seed takes place
.. _file_pool_size:
.. raw:: html
<a name="file_pool_size"></a>
+----------------+------+---------+
| name | type | default |
+================+======+=========+
| file_pool_size | int | 40 |
+----------------+------+---------+
sets the upper limit on the total number of files this
session will keep open. The reason why files are
left open at all is that some anti virus software
hooks on every file close, and scans the file for
viruses. deferring the closing of the files will
be the difference between a usable system and
a completely hogged down system. Most operating
systems also has a limit on the total number of
file descriptors a process may have open. It is
usually a good idea to find this limit and set the
number of connections and the number of files
limits so their sum is slightly below it.
.. _max_failcount:
.. raw:: html
<a name="max_failcount"></a>
+---------------+------+---------+
| name | type | default |
+===============+======+=========+
| max_failcount | int | 3 |
+---------------+------+---------+
``max_failcount`` is the maximum times we try to connect to a peer before
stop connecting again. If a peer succeeds, the failcounter is reset. If
a peer is retrieved from a peer source (other than DHT) the failcount is
decremented by one, allowing another try.
.. _min_reconnect_time:
.. raw:: html
<a name="min_reconnect_time"></a>
+--------------------+------+---------+
| name | type | default |
+====================+======+=========+
| min_reconnect_time | int | 60 |
+--------------------+------+---------+
the number of seconds to wait to reconnect to a peer.
this time is multiplied with the failcount.
.. _peer_connect_timeout:
.. raw:: html
<a name="peer_connect_timeout"></a>
+----------------------+------+---------+
| name | type | default |
+======================+======+=========+
| peer_connect_timeout | int | 15 |
+----------------------+------+---------+
``peer_connect_timeout`` the number of seconds to wait after a connection
attempt is initiated to a peer until it is considered as having timed out.
This setting is especially important in case the number of half-open
connections are limited, since stale half-open
connection may delay the connection of other peers considerably.
.. _connection_speed:
.. raw:: html
<a name="connection_speed"></a>
+------------------+------+---------+
| name | type | default |
+==================+======+=========+
| connection_speed | int | 6 |
+------------------+------+---------+
``connection_speed`` is the number of connection attempts that
are made per second. If a number < 0 is specified, it will default to
200 connections per second. If 0 is specified, it means don't make
outgoing connections at all.
.. _inactivity_timeout:
.. raw:: html
<a name="inactivity_timeout"></a>
+--------------------+------+---------+
| name | type | default |
+====================+======+=========+
| inactivity_timeout | int | 600 |
+--------------------+------+---------+
if a peer is uninteresting and uninterested for longer
than this number of seconds, it will be disconnected.
default is 10 minutes
.. _unchoke_interval:
.. raw:: html
<a name="unchoke_interval"></a>
+------------------+------+---------+
| name | type | default |
+==================+======+=========+
| unchoke_interval | int | 15 |
+------------------+------+---------+
``unchoke_interval`` is the number of seconds between chokes/unchokes.
On this interval, peers are re-evaluated for being choked/unchoked. This
is defined as 30 seconds in the protocol, and it should be significantly
longer than what it takes for TCP to ramp up to it's max rate.
.. _optimistic_unchoke_interval:
.. raw:: html
<a name="optimistic_unchoke_interval"></a>
+-----------------------------+------+---------+
| name | type | default |
+=============================+======+=========+
| optimistic_unchoke_interval | int | 30 |
+-----------------------------+------+---------+
``optimistic_unchoke_interval`` is the number of seconds between
each *optimistic* unchoke. On this timer, the currently optimistically
unchoked peer will change.
.. _num_want:
.. raw:: html
<a name="num_want"></a>
+----------+------+---------+
| name | type | default |
+==========+======+=========+
| num_want | int | 200 |
+----------+------+---------+
``num_want`` is the number of peers we want from each tracker request. It defines
what is sent as the ``&num_want=`` parameter to the tracker.
.. _initial_picker_threshold:
.. raw:: html
<a name="initial_picker_threshold"></a>
+--------------------------+------+---------+
| name | type | default |
+==========================+======+=========+
| initial_picker_threshold | int | 4 |
+--------------------------+------+---------+
``initial_picker_threshold`` specifies the number of pieces we need before we
switch to rarest first picking. This defaults to 4, which means the 4 first
pieces in any torrent are picked at random, the following pieces are picked
in rarest first order.
.. _allowed_fast_set_size:
.. raw:: html
<a name="allowed_fast_set_size"></a>
+-----------------------+------+---------+
| name | type | default |
+=======================+======+=========+
| allowed_fast_set_size | int | 10 |
+-----------------------+------+---------+
the number of allowed pieces to send to peers
that supports the fast extensions
.. _suggest_mode:
.. raw:: html
<a name="suggest_mode"></a>
+--------------+------+-------------------------------------+
| name | type | default |
+==============+======+=====================================+
| suggest_mode | int | settings_pack::no_piece_suggestions |
+--------------+------+-------------------------------------+
``suggest_mode`` controls whether or not libtorrent will send out suggest
messages to create a bias of its peers to request certain pieces. The modes
are:
* ``no_piece_suggestsions`` which is the default and will not send out suggest
messages.
* ``suggest_read_cache`` which will send out suggest messages for the most
recent pieces that are in the read cache.
.. _max_queued_disk_bytes:
.. raw:: html
<a name="max_queued_disk_bytes"></a>
+-----------------------+------+-------------+
| name | type | default |
+=======================+======+=============+
| max_queued_disk_bytes | int | 1024 * 1024 |
+-----------------------+------+-------------+
``max_queued_disk_bytes`` is the number maximum number of bytes, to be
written to disk, that can wait in the disk I/O thread queue. This queue
is only for waiting for the disk I/O thread to receive the job and either
write it to disk or insert it in the write cache. When this limit is reached,
the peer connections will stop reading data from their sockets, until the disk
thread catches up. Setting this too low will severly limit your download rate.
.. _handshake_timeout:
.. raw:: html
<a name="handshake_timeout"></a>
+-------------------+------+---------+
| name | type | default |
+===================+======+=========+
| handshake_timeout | int | 10 |
+-------------------+------+---------+
the number of seconds to wait for a handshake
response from a peer. If no response is received
within this time, the peer is disconnected.
.. _send_buffer_low_watermark:
.. _send_buffer_watermark:
.. _send_buffer_watermark_factor:
.. raw:: html
<a name="send_buffer_low_watermark"></a>
<a name="send_buffer_watermark"></a>
<a name="send_buffer_watermark_factor"></a>
+------------------------------+------+------------+
| name | type | default |
+==============================+======+============+
| send_buffer_low_watermark | int | 512 |
+------------------------------+------+------------+
| send_buffer_watermark | int | 500 * 1024 |
+------------------------------+------+------------+
| send_buffer_watermark_factor | int | 50 |
+------------------------------+------+------------+
``send_buffer_low_watermark`` the minimum send buffer target
size (send buffer includes bytes pending being read from disk).
For good and snappy seeding performance, set this fairly high, to
at least fit a few blocks. This is essentially the initial
window size which will determine how fast we can ramp up
the send rate
if the send buffer has fewer bytes than ``send_buffer_watermark``,
we'll read another 16kB block onto it. If set too small,
upload rate capacity will suffer. If set too high,
memory will be wasted.
The actual watermark may be lower than this in case
the upload rate is low, this is the upper limit.
the current upload rate to a peer is multiplied by
this factor to get the send buffer watermark. The
factor is specified as a percentage. i.e. 50 -> 0.5
This product is clamped to the ``send_buffer_watermark``
setting to not exceed the max. For high speed
upload, this should be set to a greater value than
100. For high capacity connections, setting this
higher can improve upload performance and disk throughput. Setting it too
high may waste RAM and create a bias towards read jobs over write jobs.
.. _choking_algorithm:
.. _seed_choking_algorithm:
.. raw:: html
<a name="choking_algorithm"></a>
<a name="seed_choking_algorithm"></a>
+------------------------+------+-----------------------------------+
| name | type | default |
+========================+======+===================================+
| choking_algorithm | int | settings_pack::fixed_slots_choker |
+------------------------+------+-----------------------------------+
| seed_choking_algorithm | int | settings_pack::round_robin |
+------------------------+------+-----------------------------------+
``choking_algorithm`` specifies which algorithm to use to determine which peers
to unchoke.
The options for choking algorithms are:
* ``fixed_slots_choker`` is the traditional choker with a fixed number of unchoke
slots (as specified by ``session::set_max_uploads()``).
* ``auto_expand_choker`` opens at least the number of slots as specified by
``session::set_max_uploads()`` but opens up more slots if the upload capacity
is not saturated. This unchoker will work just like the ``fixed_slots_choker``
if there's no global upload rate limit set.
* ``rate_based_choker`` opens up unchoke slots based on the upload rate
achieved to peers. The more slots that are opened, the marginal upload
rate required to open up another slot increases.
* ``bittyrant_choker`` attempts to optimize download rate by finding the
reciprocation rate of each peer individually and prefers peers that gives
the highest *return on investment*. It still allocates all upload capacity,
but shuffles it around to the best peers first. For this choker to be
efficient, you need to set a global upload rate limit
(``session::set_upload_rate_limit()``). For more information about this
choker, see the paper_. This choker is not fully implemented nor tested.
.. _paper: http://bittyrant.cs.washington.edu/#papers
``seed_choking_algorithm`` controls the seeding unchoke behavior. The available
options are:
* ``round_robin`` which round-robins the peers that are unchoked when seeding. This
distributes the upload bandwidht uniformly and fairly. It minimizes the ability
for a peer to download everything without redistributing it.
* ``fastest_upload`` unchokes the peers we can send to the fastest. This might be
a bit more reliable in utilizing all available capacity.
* ``anti_leech`` prioritizes peers who have just started or are just about to finish
the download. The intention is to force peers in the middle of the download to
trade with each other.
.. _cache_size:
.. _cache_buffer_chunk_size:
.. _cache_expiry:
.. raw:: html
<a name="cache_size"></a>
<a name="cache_buffer_chunk_size"></a>
<a name="cache_expiry"></a>
+-------------------------+------+---------+
| name | type | default |
+=========================+======+=========+
| cache_size | int | 1024 |
+-------------------------+------+---------+
| cache_buffer_chunk_size | int | 0 |
+-------------------------+------+---------+
| cache_expiry | int | 300 |
+-------------------------+------+---------+
``cache_size`` is the disk write and read cache. It is specified
in units of 16 KiB blocks. Buffers that are part of a peer's send
or receive buffer also count against this limit. Send and receive
buffers will never be denied to be allocated, but they will cause
the actual cached blocks to be flushed or evicted. If this is set
to -1, the cache size is automatically set to the amount of
physical RAM available in the machine divided by 8. If the amount
of physical RAM cannot be determined, it's set to 1024 (= 16 MiB).
Disk buffers are allocated using a pool allocator, the number of
blocks that are allocated at a time when the pool needs to grow can
be specified in ``cache_buffer_chunk_size``. Lower numbers saves
memory at the expense of more heap allocations. If it is set to 0,
the effective chunk size is proportional to the total cache size,
attempting to strike a good balance between performance and memory
usage. It defaults to 0. ``cache_expiry`` is the number of seconds
from the last cached write to a piece in the write cache, to when
it's forcefully flushed to disk. Default is 60 second.
.. _explicit_cache_interval:
.. raw:: html
<a name="explicit_cache_interval"></a>
+-------------------------+------+---------+
| name | type | default |
+=========================+======+=========+
| explicit_cache_interval | int | 30 |
+-------------------------+------+---------+
``explicit_cache_interval`` is the number of seconds in between
each refresh of a part of the explicit read cache. Torrents take
turns in refreshing and this is the time in between each torrent
refresh. Refreshing a torrent's explicit read cache means scanning
all pieces and picking a random set of the rarest ones. There is an
affinity to pick pieces that are already in the cache, so that
subsequent refreshes only swaps in pieces that are rarer than
whatever is in
the cache at the time.
.. _disk_io_write_mode:
.. _disk_io_read_mode:
.. raw:: html
<a name="disk_io_write_mode"></a>
<a name="disk_io_read_mode"></a>
+--------------------+------+--------------------------------+
| name | type | default |
+====================+======+================================+
| disk_io_write_mode | int | settings_pack::enable_os_cache |
+--------------------+------+--------------------------------+
| disk_io_read_mode | int | settings_pack::enable_os_cache |
+--------------------+------+--------------------------------+
determines how files are opened when they're in read only mode versus
read and write mode. The options are:
* enable_os_cache
This is the default and files are opened normally, with the OS caching
reads and writes.
* disable_os_cache
This opens all files in no-cache mode. This corresponds to the
OS not letting blocks for the files linger in the cache. This
makes sense in order to avoid the bittorrent client to
potentially evict all other processes' cache by simply handling
high throughput and large files. If libtorrent's read cache is
disabled, enabling this may reduce performance.
One reason to disable caching is that it may help the operating
system from growing its file cache indefinitely. Since some OSes
only allow aligned files to be opened in unbuffered mode, It is
recommended to make the largest file in a torrent the first file
(with offset 0) or use pad files to align all files to piece
boundries.
.. _outgoing_port:
.. _num_outgoing_ports:
.. raw:: html
<a name="outgoing_port"></a>
<a name="num_outgoing_ports"></a>
+--------------------+------+---------+
| name | type | default |
+====================+======+=========+
| outgoing_port | int | 0 |
+--------------------+------+---------+
| num_outgoing_ports | int | 0 |
+--------------------+------+---------+
this is the first port to use for binding
outgoing connections to. This is useful
for users that have routers that
allow QoS settings based on local port.
when binding outgoing connections to specific
ports, ``num_outgoing_ports`` is the size of
the range. It should be more than a few
.. warning:: setting outgoing ports will limit the ability to keep multiple
connections to the same client, even for different torrents. It is not
recommended to change this setting. Its main purpose is to use as an
escape hatch for cheap routers with QoS capability but can only classify
flows based on port numbers.
It is a range instead of a single port because of the problems with
failing to reconnect to peers if a previous socket to that peer and
port is in ``TIME_WAIT`` state.
.. _peer_tos:
.. raw:: html
<a name="peer_tos"></a>
+----------+------+---------+
| name | type | default |
+==========+======+=========+
| peer_tos | int | 0 |
+----------+------+---------+
``peer_tos`` determines the TOS byte set in the IP header of every packet
sent to peers (including web seeds). The default value for this is ``0x0``
(no marking). One potentially useful TOS mark is ``0x20``, this represents
the *QBone scavenger service*. For more details, see QBSS_.
.. _`QBSS`: http://qbone.internet2.edu/qbss/
.. _active_downloads:
.. _active_seeds:
.. _active_dht_limit:
.. _active_tracker_limit:
.. _active_lsd_limit:
.. _active_limit:
.. _active_loaded_limit:
.. raw:: html
<a name="active_downloads"></a>
<a name="active_seeds"></a>
<a name="active_dht_limit"></a>
<a name="active_tracker_limit"></a>
<a name="active_lsd_limit"></a>
<a name="active_limit"></a>
<a name="active_loaded_limit"></a>
+----------------------+------+---------+
| name | type | default |
+======================+======+=========+
| active_downloads | int | 3 |
+----------------------+------+---------+
| active_seeds | int | 5 |
+----------------------+------+---------+
| active_dht_limit | int | 88 |
+----------------------+------+---------+
| active_tracker_limit | int | 1600 |
+----------------------+------+---------+
| active_lsd_limit | int | 60 |
+----------------------+------+---------+
| active_limit | int | 15 |
+----------------------+------+---------+
| active_loaded_limit | int | 100 |
+----------------------+------+---------+
for auto managed torrents, these are the limits
they are subject to. If there are too many torrents
some of the auto managed ones will be paused until
some slots free up.
``active_downloads`` and ``active_seeds`` controls how many active seeding and
downloading torrents the queuing mechanism allows. The target number of active
torrents is ``min(active_downloads + active_seeds, active_limit)``.
``active_downloads`` and ``active_seeds`` are upper limits on the number of
downloading torrents and seeding torrents respectively. Setting the value to
-1 means unlimited.
For example if there are 10 seeding torrents and 10 downloading torrents, and
``active_downloads`` is 4 and ``active_seeds`` is 4, there will be 4 seeds
active and 4 downloading torrents. If the settings are ``active_downloads`` = 2
and ``active_seeds`` = 4, then there will be 2 downloading torrents and 4 seeding
torrents active. Torrents that are not auto managed are not counted against these
limits.
``active_limit`` is a hard limit on the number of active torrents. This applies even to
slow torrents.
``active_dht_limit`` is the max number of torrents to announce to the DHT. By default
this is set to 88, which is no more than one DHT announce every 10 seconds.
``active_tracker_limit`` is the max number of torrents to announce to their trackers.
By default this is 360, which is no more than one announce every 5 seconds.
``active_lsd_limit`` is the max number of torrents to announce to the local network
over the local service discovery protocol. By default this is 80, which is no more
than one announce every 5 seconds (assuming the default announce interval of 5 minutes).
You can have more torrents *active*, even though they are not announced to the DHT,
lsd or their tracker. If some peer knows about you for any reason and tries to connect,
it will still be accepted, unless the torrent is paused, which means it won't accept
any connections.
``active_loaded_limit`` is the number of torrents that are allowed to be *loaded*
at any given time. Note that a torrent can be active even though it's not loaded.
if an unloaded torrents finds a peer that wants to access it, the torrent will be
loaded on demand, using a user-supplied callback function. If the feature of unloading
torrents is not enabled, this setting have no effect. If this limit is set to 0, it
means unlimited. For more information, see dynamic-loading-of-torrent-files_.
.. _auto_manage_interval:
.. raw:: html
<a name="auto_manage_interval"></a>
+----------------------+------+---------+
| name | type | default |
+======================+======+=========+
| auto_manage_interval | int | 30 |
+----------------------+------+---------+
``auto_manage_interval`` is the number of seconds between the torrent queue
is updated, and rotated.
.. _seed_time_limit:
.. raw:: html
<a name="seed_time_limit"></a>
+-----------------+------+--------------+
| name | type | default |
+=================+======+==============+
| seed_time_limit | int | 24 * 60 * 60 |
+-----------------+------+--------------+
this is the limit on the time a torrent has been an active seed
(specified in seconds) before it is considered having met the seed limit criteria.
See queuing_.
.. _auto_scrape_interval:
.. _auto_scrape_min_interval:
.. raw:: html
<a name="auto_scrape_interval"></a>
<a name="auto_scrape_min_interval"></a>
+--------------------------+------+---------+
| name | type | default |
+==========================+======+=========+
| auto_scrape_interval | int | 1800 |
+--------------------------+------+---------+
| auto_scrape_min_interval | int | 300 |
+--------------------------+------+---------+
``auto_scrape_interval`` is the number of seconds between scrapes of
queued torrents (auto managed and paused torrents). Auto managed
torrents that are paused, are scraped regularly in order to keep
track of their downloader/seed ratio. This ratio is used to determine
which torrents to seed and which to pause.
``auto_scrape_min_interval`` is the minimum number of seconds between any
automatic scrape (regardless of torrent). In case there are a large number
of paused auto managed torrents, this puts a limit on how often a scrape
request is sent.
.. _max_peerlist_size:
.. _max_paused_peerlist_size:
.. raw:: html
<a name="max_peerlist_size"></a>
<a name="max_paused_peerlist_size"></a>
+--------------------------+------+---------+
| name | type | default |
+==========================+======+=========+
| max_peerlist_size | int | 3000 |
+--------------------------+------+---------+
| max_paused_peerlist_size | int | 1000 |
+--------------------------+------+---------+
``max_peerlist_size`` is the maximum number of peers in the list of
known peers. These peers are not necessarily connected, so this number
should be much greater than the maximum number of connected peers.
Peers are evicted from the cache when the list grows passed 90% of
this limit, and once the size hits the limit, peers are no longer
added to the list. If this limit is set to 0, there is no limit on
how many peers we'll keep in the peer list.
``max_paused_peerlist_size`` is the max peer list size used for torrents
that are paused. This default to the same as ``max_peerlist_size``, but
can be used to save memory for paused torrents, since it's not as
important for them to keep a large peer list.
.. _min_announce_interval:
.. raw:: html
<a name="min_announce_interval"></a>
+-----------------------+------+---------+
| name | type | default |
+=======================+======+=========+
| min_announce_interval | int | 5 * 60 |
+-----------------------+------+---------+
this is the minimum allowed announce interval for a tracker. This
is specified in seconds and is used as a sanity check on what is
returned from a tracker. It mitigates hammering misconfigured trackers.
.. _auto_manage_startup:
.. raw:: html
<a name="auto_manage_startup"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| auto_manage_startup | int | 60 |
+---------------------+------+---------+
this is the number of seconds a torrent is considered
active after it was started, regardless of upload and download speed. This
is so that newly started torrents are not considered inactive until they
have a fair chance to start downloading.
.. _seeding_piece_quota:
.. raw:: html
<a name="seeding_piece_quota"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| seeding_piece_quota | int | 20 |
+---------------------+------+---------+
``seeding_piece_quota`` is the number of pieces to send to a peer,
when seeding, before rotating in another peer to the unchoke set.
It defaults to 3 pieces, which means that when seeding, any peer we've
sent more than this number of pieces to will be unchoked in favour of
a choked peer.
.. _max_sparse_regions:
.. raw:: html
<a name="max_sparse_regions"></a>
+--------------------+------+---------+
| name | type | default |
+====================+======+=========+
| max_sparse_regions | int | 0 |
+--------------------+------+---------+
``max_sparse_regions`` is a limit of the number of *sparse regions* in
a torrent. A sparse region is defined as a hole of pieces we have not
yet downloaded, in between pieces that have been downloaded. This is
used as a hack for windows vista which has a bug where you cannot
write files with more than a certain number of sparse regions. This
limit is not hard, it will be exceeded. Once it's exceeded, pieces
that will maintain or decrease the number of sparse regions are
prioritized. To disable this functionality, set this to 0. It defaults
to 0 on all platforms except windows.
.. _max_rejects:
.. raw:: html
<a name="max_rejects"></a>
+-------------+------+---------+
| name | type | default |
+=============+======+=========+
| max_rejects | int | 50 |
+-------------+------+---------+
TODO: deprecate this
``max_rejects`` is the number of piece requests we will reject in a row
while a peer is choked before the peer is considered abusive and is
disconnected.
.. _recv_socket_buffer_size:
.. _send_socket_buffer_size:
.. raw:: html
<a name="recv_socket_buffer_size"></a>
<a name="send_socket_buffer_size"></a>
+-------------------------+------+---------+
| name | type | default |
+=========================+======+=========+
| recv_socket_buffer_size | int | 0 |
+-------------------------+------+---------+
| send_socket_buffer_size | int | 0 |
+-------------------------+------+---------+
``recv_socket_buffer_size`` and ``send_socket_buffer_size`` specifies
the buffer sizes set on peer sockets. 0 (which is the default) means
the OS default (i.e. don't change the buffer sizes). The socket buffer
sizes are changed using setsockopt() with SOL_SOCKET/SO_RCVBUF and
SO_SNDBUFFER.
.. _file_checks_delay_per_block:
.. raw:: html
<a name="file_checks_delay_per_block"></a>
+-----------------------------+------+---------+
| name | type | default |
+=============================+======+=========+
| file_checks_delay_per_block | int | 0 |
+-----------------------------+------+---------+
``file_checks_delay_per_block`` is the number of milliseconds to sleep
in between disk read operations when checking torrents. This defaults
to 0, but can be set to higher numbers to slow down the rate at which
data is read from the disk while checking. This may be useful for
background tasks that doesn't matter if they take a bit longer, as long
as they leave disk I/O time for other processes.
.. _read_cache_line_size:
.. _write_cache_line_size:
.. raw:: html
<a name="read_cache_line_size"></a>
<a name="write_cache_line_size"></a>
+-----------------------+------+---------+
| name | type | default |
+=======================+======+=========+
| read_cache_line_size | int | 32 |
+-----------------------+------+---------+
| write_cache_line_size | int | 16 |
+-----------------------+------+---------+
``read_cache_line_size`` is the number of blocks to read into the read
cache when a read cache miss occurs. Setting this to 0 is essentially
the same thing as disabling read cache. The number of blocks read
into the read cache is always capped by the piece boundry.
When a piece in the write cache has ``write_cache_line_size`` contiguous
blocks in it, they will be flushed. Setting this to 1 effectively
disables the write cache.
.. _optimistic_disk_retry:
.. raw:: html
<a name="optimistic_disk_retry"></a>
+-----------------------+------+---------+
| name | type | default |
+=======================+======+=========+
| optimistic_disk_retry | int | 10 * 60 |
+-----------------------+------+---------+
``optimistic_disk_retry`` is the number of seconds from a disk write
errors occur on a torrent until libtorrent will take it out of the
upload mode, to test if the error condition has been fixed.
libtorrent will only do this automatically for auto managed torrents.
You can explicitly take a torrent out of upload only mode using
set_upload_mode().
.. _max_suggest_pieces:
.. raw:: html
<a name="max_suggest_pieces"></a>
+--------------------+------+---------+
| name | type | default |
+====================+======+=========+
| max_suggest_pieces | int | 10 |
+--------------------+------+---------+
``max_suggest_pieces`` is the max number of suggested piece indices received
from a peer that's remembered. If a peer floods suggest messages, this limit
prevents libtorrent from using too much RAM. It defaults to 10.
.. _local_service_announce_interval:
.. raw:: html
<a name="local_service_announce_interval"></a>
+---------------------------------+------+---------+
| name | type | default |
+=================================+======+=========+
| local_service_announce_interval | int | 5 * 60 |
+---------------------------------+------+---------+
``local_service_announce_interval`` is the time between local
network announces for a torrent. By default, when local service
discovery is enabled a torrent announces itself every 5 minutes.
This interval is specified in seconds.
.. _dht_announce_interval:
.. raw:: html
<a name="dht_announce_interval"></a>
+-----------------------+------+---------+
| name | type | default |
+=======================+======+=========+
| dht_announce_interval | int | 15 * 60 |
+-----------------------+------+---------+
``dht_announce_interval`` is the number of seconds between announcing
torrents to the distributed hash table (DHT).
.. _udp_tracker_token_expiry:
.. raw:: html
<a name="udp_tracker_token_expiry"></a>
+--------------------------+------+---------+
| name | type | default |
+==========================+======+=========+
| udp_tracker_token_expiry | int | 60 |
+--------------------------+------+---------+
``udp_tracker_token_expiry`` is the number of seconds libtorrent
will keep UDP tracker connection tokens around for. This is specified
to be 60 seconds, and defaults to that. The higher this value is, the
fewer packets have to be sent to the UDP tracker. In order for higher
values to work, the tracker needs to be configured to match the
expiration time for tokens.
.. _default_cache_min_age:
.. raw:: html
<a name="default_cache_min_age"></a>
+-----------------------+------+---------+
| name | type | default |
+=======================+======+=========+
| default_cache_min_age | int | 1 |
+-----------------------+------+---------+
``default_cache_min_age`` is the minimum number of seconds any read
cache line is kept in the cache. This defaults to one second but
may be greater if ``guided_read_cache`` is enabled. Having a lower
bound on the time a cache line stays in the cache is an attempt
to avoid swapping the same pieces in and out of the cache in case
there is a shortage of spare cache space.
.. _num_optimistic_unchoke_slots:
.. raw:: html
<a name="num_optimistic_unchoke_slots"></a>
+------------------------------+------+---------+
| name | type | default |
+==============================+======+=========+
| num_optimistic_unchoke_slots | int | 0 |
+------------------------------+------+---------+
``num_optimistic_unchoke_slots`` is the number of optimistic unchoke
slots to use. It defaults to 0, which means automatic. Having a higher
number of optimistic unchoke slots mean you will find the good peers
faster but with the trade-off to use up more bandwidth. When this is
set to 0, libtorrent opens up 20% of your allowed upload slots as
optimistic unchoke slots.
.. _default_est_reciprocation_rate:
.. _increase_est_reciprocation_rate:
.. _decrease_est_reciprocation_rate:
.. raw:: html
<a name="default_est_reciprocation_rate"></a>
<a name="increase_est_reciprocation_rate"></a>
<a name="decrease_est_reciprocation_rate"></a>
+---------------------------------+------+---------+
| name | type | default |
+=================================+======+=========+
| default_est_reciprocation_rate | int | 16000 |
+---------------------------------+------+---------+
| increase_est_reciprocation_rate | int | 20 |
+---------------------------------+------+---------+
| decrease_est_reciprocation_rate | int | 3 |
+---------------------------------+------+---------+
``default_est_reciprocation_rate`` is the assumed reciprocation rate
from peers when using the BitTyrant choker. This defaults to 14 kiB/s.
If set too high, you will over-estimate your peers and be more altruistic
while finding the true reciprocation rate, if it's set too low, you'll
be too stingy and waste finding the true reciprocation rate.
``increase_est_reciprocation_rate`` specifies how many percent the
extimated reciprocation rate should be increased by each unchoke
interval a peer is still choking us back. This defaults to 20%.
This only applies to the BitTyrant choker.
``decrease_est_reciprocation_rate`` specifies how many percent the
estimated reciprocation rate should be decreased by each unchoke
interval a peer unchokes us. This default to 3%.
This only applies to the BitTyrant choker.
.. _max_pex_peers:
.. raw:: html
<a name="max_pex_peers"></a>
+---------------+------+---------+
| name | type | default |
+===============+======+=========+
| max_pex_peers | int | 50 |
+---------------+------+---------+
the max number of peers we accept from pex messages from a single peer.
this limits the number of concurrent peers any of our peers claims to
be connected to. If they clain to be connected to more than this, we'll
ignore any peer that exceeds this limit
.. _tick_interval:
.. raw:: html
<a name="tick_interval"></a>
+---------------+------+---------+
| name | type | default |
+===============+======+=========+
| tick_interval | int | 500 |
+---------------+------+---------+
``tick_interval`` specifies the number of milliseconds between internal
ticks. This is the frequency with which bandwidth quota is distributed to
peers. It should not be more than one second (i.e. 1000 ms). Setting this
to a low value (around 100) means higher resolution bandwidth quota distribution,
setting it to a higher value saves CPU cycles.
.. _share_mode_target:
.. raw:: html
<a name="share_mode_target"></a>
+-------------------+------+---------+
| name | type | default |
+===================+======+=========+
| share_mode_target | int | 3 |
+-------------------+------+---------+
``share_mode_target`` specifies the target share ratio for share mode torrents.
This defaults to 3, meaning we'll try to upload 3 times as much as we download.
Setting this very high, will make it very conservative and you might end up
not downloading anything ever (and not affecting your share ratio). It does
not make any sense to set this any lower than 2. For instance, if only 3 peers
need to download the rarest piece, it's impossible to download a single piece
and upload it more than 3 times. If the share_mode_target is set to more than 3,
nothing is downloaded.
.. _upload_rate_limit:
.. _download_rate_limit:
.. raw:: html
<a name="upload_rate_limit"></a>
<a name="download_rate_limit"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| upload_rate_limit | int | 0 |
+---------------------+------+---------+
| download_rate_limit | int | 0 |
+---------------------+------+---------+
``upload_rate_limit``, ``download_rate_limit``, ``local_upload_rate_limit``
and ``local_download_rate_limit`` sets the session-global limits of upload
and download rate limits, in bytes per second. The local rates refer to peers
on the local network. By default peers on the local network are not rate limited.
These rate limits are only used for local peers (peers within the same subnet as
the client itself) and it is only used when ``ignore_limits_on_local_network``
is set to true (which it is by default). These rate limits default to unthrottled,
but can be useful in case you want to treat local peers preferentially, but not
quite unthrottled.
A value of 0 means unlimited.
.. _dht_upload_rate_limit:
.. raw:: html
<a name="dht_upload_rate_limit"></a>
+-----------------------+------+---------+
| name | type | default |
+=======================+======+=========+
| dht_upload_rate_limit | int | 4000 |
+-----------------------+------+---------+
``dht_upload_rate_limit`` sets the rate limit on the DHT. This is specified in
bytes per second and defaults to 4000. For busy boxes with lots of torrents
that requires more DHT traffic, this should be raised.
.. _unchoke_slots_limit:
.. raw:: html
<a name="unchoke_slots_limit"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| unchoke_slots_limit | int | 8 |
+---------------------+------+---------+
``unchoke_slots_limit`` is the max number of unchoked peers in the session.
The number of unchoke slots may be ignored depending on what
``choking_algorithm`` is set to.
.. _half_open_limit:
.. raw:: html
<a name="half_open_limit"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| half_open_limit | int | 0 |
+-----------------+------+---------+
``half_open_limit`` sets the maximum number of half-open connections
libtorrent will have when connecting to peers. A half-open connection is one
where connect() has been called, but the connection still hasn't been established
(nor failed). Windows XP Service Pack 2 sets a default, system wide, limit of
the number of half-open connections to 10. So, this limit can be used to work
nicer together with other network applications on that system. The default is
to have no limit, and passing -1 as the limit, means to have no limit. When
limiting the number of simultaneous connection attempts, peers will be put in
a queue waiting for their turn to get connected.
.. _connections_limit:
.. raw:: html
<a name="connections_limit"></a>
+-------------------+------+---------+
| name | type | default |
+===================+======+=========+
| connections_limit | int | 200 |
+-------------------+------+---------+
``connections_limit`` sets a global limit on the number of connections
opened. The number of connections is set to a hard minimum of at least two per
torrent, so if you set a too low connections limit, and open too many torrents,
the limit will not be met.
.. _connections_slack:
.. raw:: html
<a name="connections_slack"></a>
+-------------------+------+---------+
| name | type | default |
+===================+======+=========+
| connections_slack | int | 10 |
+-------------------+------+---------+
``connections_slack`` is the the number of incoming connections exceeding the
connection limit to accept in order to potentially replace existing ones.
.. _utp_target_delay:
.. _utp_gain_factor:
.. _utp_min_timeout:
.. _utp_syn_resends:
.. _utp_fin_resends:
.. _utp_num_resends:
.. _utp_connect_timeout:
.. _utp_loss_multiplier:
.. raw:: html
<a name="utp_target_delay"></a>
<a name="utp_gain_factor"></a>
<a name="utp_min_timeout"></a>
<a name="utp_syn_resends"></a>
<a name="utp_fin_resends"></a>
<a name="utp_num_resends"></a>
<a name="utp_connect_timeout"></a>
<a name="utp_loss_multiplier"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| utp_target_delay | int | 100 |
+---------------------+------+---------+
| utp_gain_factor | int | 1500 |
+---------------------+------+---------+
| utp_min_timeout | int | 500 |
+---------------------+------+---------+
| utp_syn_resends | int | 2 |
+---------------------+------+---------+
| utp_fin_resends | int | 2 |
+---------------------+------+---------+
| utp_num_resends | int | 6 |
+---------------------+------+---------+
| utp_connect_timeout | int | 3000 |
+---------------------+------+---------+
| utp_loss_multiplier | int | 50 |
+---------------------+------+---------+
``utp_target_delay`` is the target delay for uTP sockets in milliseconds. A high
value will make uTP connections more aggressive and cause longer queues in the upload
bottleneck. It cannot be too low, since the noise in the measurements would cause
it to send too slow. The default is 50 milliseconds.
``utp_gain_factor`` is the number of bytes the uTP congestion window can increase
at the most in one RTT. This defaults to 300 bytes. If this is set too high,
the congestion controller reacts too hard to noise and will not be stable, if it's
set too low, it will react slow to congestion and not back off as fast.
``utp_min_timeout`` is the shortest allowed uTP socket timeout, specified in milliseconds.
This defaults to 500 milliseconds. The timeout depends on the RTT of the connection, but
is never smaller than this value. A connection times out when every packet in a window
is lost, or when a packet is lost twice in a row (i.e. the resent packet is lost as well).
The shorter the timeout is, the faster the connection will recover from this situation,
assuming the RTT is low enough.
``utp_syn_resends`` is the number of SYN packets that are sent (and timed out) before
giving up and closing the socket.
``utp_num_resends`` is the number of times a packet is sent (and lossed or timed out)
before giving up and closing the connection.
``utp_connect_timeout`` is the number of milliseconds of timeout for the initial SYN
packet for uTP connections. For each timed out packet (in a row), the timeout is doubled.
``utp_loss_multiplier`` controls how the congestion window is changed when a packet
loss is experienced. It's specified as a percentage multiplier for ``cwnd``. By default
it's set to 50 (i.e. cut in half). Do not change this value unless you know what
you're doing. Never set it higher than 100.
.. _mixed_mode_algorithm:
.. raw:: html
<a name="mixed_mode_algorithm"></a>
+----------------------+------+----------------------------------+
| name | type | default |
+======================+======+==================================+
| mixed_mode_algorithm | int | settings_pack::peer_proportional |
+----------------------+------+----------------------------------+
The ``mixed_mode_algorithm`` determines how to treat TCP connections when there are
uTP connections. Since uTP is designed to yield to TCP, there's an inherent problem
when using swarms that have both TCP and uTP connections. If nothing is done, uTP
connections would often be starved out for bandwidth by the TCP connections. This mode
is ``prefer_tcp``. The ``peer_proportional`` mode simply looks at the current throughput
and rate limits all TCP connections to their proportional share based on how many of
the connections are TCP. This works best if uTP connections are not rate limited by
the global rate limiter (which they aren't by default).
.. _listen_queue_size:
.. raw:: html
<a name="listen_queue_size"></a>
+-------------------+------+---------+
| name | type | default |
+===================+======+=========+
| listen_queue_size | int | 5 |
+-------------------+------+---------+
``listen_queue_size`` is the value passed in to listen() for the listen socket.
It is the number of outstanding incoming connections to queue up while we're not
actively waiting for a connection to be accepted. The default is 5 which should
be sufficient for any normal client. If this is a high performance server which
expects to receive a lot of connections, or used in a simulator or test, it
might make sense to raise this number. It will not take affect until listen_on()
is called again (or for the first time).
.. _torrent_connect_boost:
.. raw:: html
<a name="torrent_connect_boost"></a>
+-----------------------+------+---------+
| name | type | default |
+=======================+======+=========+
| torrent_connect_boost | int | 10 |
+-----------------------+------+---------+
``torrent_connect_boost`` is the number of peers to try to connect to immediately
when the first tracker response is received for a torrent. This is a boost to
given to new torrents to accelerate them starting up. The normal connect scheduler
is run once every second, this allows peers to be connected immediately instead
of waiting for the session tick to trigger connections.
.. _alert_queue_size:
.. raw:: html
<a name="alert_queue_size"></a>
+------------------+------+---------+
| name | type | default |
+==================+======+=========+
| alert_queue_size | int | 1000 |
+------------------+------+---------+
``alert_queue_size`` is the maximum number of alerts queued up internally. If
alerts are not popped, the queue will eventually fill up to this level.
.. _max_metadata_size:
.. raw:: html
<a name="max_metadata_size"></a>
+-------------------+------+------------------+
| name | type | default |
+===================+======+==================+
| max_metadata_size | int | 3 * 1024 * 10240 |
+-------------------+------+------------------+
``max_metadata_size`` is the maximum allowed size (in bytes) to be received
by the metadata extension, i.e. magnet links. It defaults to 1 MiB.
.. _hashing_threads:
.. raw:: html
<a name="hashing_threads"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| hashing_threads | int | 1 |
+-----------------+------+---------+
``hashing_threads`` is the number of threads to use for piece hash verification. It
defaults to 1. For very high download rates, on machines with multiple cores, this
could be incremented. Setting it higher than the number of CPU cores would presumably
not provide any benefit of setting it to the number of cores. If it's set to 0,
hashing is done in the disk thread.
.. _checking_mem_usage:
.. raw:: html
<a name="checking_mem_usage"></a>
+--------------------+------+---------+
| name | type | default |
+====================+======+=========+
| checking_mem_usage | int | 256 |
+--------------------+------+---------+
the number of blocks to keep outstanding at any given time when
checking torrents. Higher numbers give faster re-checks but uses
more memory. Specified in number of 16 kiB blocks
.. _predictive_piece_announce:
.. raw:: html
<a name="predictive_piece_announce"></a>
+---------------------------+------+---------+
| name | type | default |
+===========================+======+=========+
| predictive_piece_announce | int | 0 |
+---------------------------+------+---------+
if set to > 0, pieces will be announced to other peers before they
are fully downloaded (and before they are hash checked). The intention
is to gain 1.5 potential round trip times per downloaded piece. When
non-zero, this indicates how many milliseconds in advance pieces
should be announced, before they are expected to be completed.
.. _aio_threads:
.. _aio_max:
.. raw:: html
<a name="aio_threads"></a>
<a name="aio_max"></a>
+-------------+------+---------+
| name | type | default |
+=============+======+=========+
| aio_threads | int | 4 |
+-------------+------+---------+
| aio_max | int | 300 |
+-------------+------+---------+
for some aio back-ends, ``aio_threads`` specifies the number of
io-threads to use, and ``aio_max`` the max number of outstanding jobs.
.. _network_threads:
.. raw:: html
<a name="network_threads"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| network_threads | int | 0 |
+-----------------+------+---------+
``network_threads`` is the number of threads to use to call ``async_write_some``
(i.e. send) on peer connection sockets. When seeding at extremely high rates,
this may become a bottleneck, and setting this to 2 or more may parallelize
that cost. When using SSL torrents, all encryption for outgoing traffic is
done withint the socket send functions, and this will help parallelizing the
cost of SSL encryption as well.
.. _ssl_listen:
.. raw:: html
<a name="ssl_listen"></a>
+------------+------+---------+
| name | type | default |
+============+======+=========+
| ssl_listen | int | 4433 |
+------------+------+---------+
``ssl_listen`` sets the listen port for SSL connections. If this is set to 0,
no SSL listen port is opened. Otherwise a socket is opened on this port. This
setting is only taken into account when opening the regular listen port, and
won't re-open the listen socket simply by changing this setting.
.. _tracker_backoff:
.. raw:: html
<a name="tracker_backoff"></a>
+-----------------+------+---------+
| name | type | default |
+=================+======+=========+
| tracker_backoff | int | 250 |
+-----------------+------+---------+
``tracker_backoff`` determines how aggressively to back off from retrying
failing trackers. This value determines *x* in the following formula, determining
the number of seconds to wait until the next retry:
delay = 5 + 5 * x / 100 * fails^2
This setting may be useful to make libtorrent more or less aggressive in hitting
trackers.
.. _share_ratio_limit:
.. _seed_time_ratio_limit:
.. raw:: html
<a name="share_ratio_limit"></a>
<a name="seed_time_ratio_limit"></a>
+-----------------------+------+---------+
| name | type | default |
+=======================+======+=========+
| share_ratio_limit | int | 200 |
+-----------------------+------+---------+
| seed_time_ratio_limit | int | 700 |
+-----------------------+------+---------+
when a seeding torrent reaches eaither the share ratio
(bytes up / bytes down) or the seed time ratio
(seconds as seed / seconds as downloader) or the seed
time limit (seconds as seed) it is considered
done, and it will leave room for other torrents
these are specified as percentages
.. _peer_turnover:
.. _peer_turnover_cutoff:
.. _peer_turnover_interval:
.. raw:: html
<a name="peer_turnover"></a>
<a name="peer_turnover_cutoff"></a>
<a name="peer_turnover_interval"></a>
+------------------------+------+---------+
| name | type | default |
+========================+======+=========+
| peer_turnover | int | 4 |
+------------------------+------+---------+
| peer_turnover_cutoff | int | 90 |
+------------------------+------+---------+
| peer_turnover_interval | int | 300 |
+------------------------+------+---------+
peer_turnover is the percentage of peers to disconnect
every turnover peer_turnover_interval (if we're at
the peer limit), this is specified in percent
when we are connected to more than
limit * peer_turnover_cutoff peers
disconnect peer_turnover fraction
of the peers. It is specified in percent
peer_turnover_interval is the interval (in seconds)
between optimistic disconnects
if the disconnects happen and how many peers are disconnected
is controlled by peer_turnover and peer_turnover_cutoff
.. _connect_seed_every_n_download:
.. raw:: html
<a name="connect_seed_every_n_download"></a>
+-------------------------------+------+---------+
| name | type | default |
+===============================+======+=========+
| connect_seed_every_n_download | int | 10 |
+-------------------------------+------+---------+
this setting controls the priority of downloading torrents
over seeding or finished torrents when it comes to making
peer connections. Peer connections are throttled by the
connection_speed and the half-open connection limit. This
makes peer connections a limited resource. Torrents that
still have pieces to download are prioritized by default,
to avoid having many seeding torrents use most of the connection
attempts and only give one peer every now and then to the
downloading torrent. libtorrent will loop over the downloading
torrents to connect a peer each, and every n:th connection
attempt, a finished torrent is picked to be allowed to connect
to a peer. This setting controls n.
.. _max_http_recv_buffer_size:
.. raw:: html
<a name="max_http_recv_buffer_size"></a>
+---------------------------+------+------------+
| name | type | default |
+===========================+======+============+
| max_http_recv_buffer_size | int | 4*1024*204 |
+---------------------------+------+------------+
the max number of bytes to allow an HTTP response to be when
announcing to trackers or downloading .torrent files via
the ``url`` provided in ``add_torrent_params``.
.. _max_retry_port_bind:
.. raw:: html
<a name="max_retry_port_bind"></a>
+---------------------+------+---------+
| name | type | default |
+=====================+======+=========+
| max_retry_port_bind | int | 10 |
+---------------------+------+---------+
if binding to a specific port fails, should the port be incremented
by one and tried again? This setting specifies how many times to
retry a failed port bind
.. _alert_mask:
.. raw:: html
<a name="alert_mask"></a>
+------------+------+---------------------------+
| name | type | default |
+============+======+===========================+
| alert_mask | int | alert::error_notification |
+------------+------+---------------------------+
a bitmask combining flags from alert::category_t defining
which kinds of alerts to receive
.. _out_enc_policy:
.. _in_enc_policy:
.. raw:: html
<a name="out_enc_policy"></a>
<a name="in_enc_policy"></a>
+----------------+------+---------------------------+
| name | type | default |
+================+======+===========================+
| out_enc_policy | int | settings_pack::pe_enabled |
+----------------+------+---------------------------+
| in_enc_policy | int | settings_pack::pe_enabled |
+----------------+------+---------------------------+
control the settings for incoming
and outgoing connections respectively.
see enc_policy enum for the available options.
.. _allowed_enc_level:
.. raw:: html
<a name="allowed_enc_level"></a>
+-------------------+------+------------------------+
| name | type | default |
+===================+======+========================+
| allowed_enc_level | int | settings_pack::pe_both |
+-------------------+------+------------------------+
determines the encryption level of the
connections. This setting will adjust which encryption scheme is
offered to the other peer, as well as which encryption scheme is
selected by the client. See enc_level enum for options.
.. _inactive_down_rate:
.. _inactive_up_rate:
.. raw:: html
<a name="inactive_down_rate"></a>
<a name="inactive_up_rate"></a>
+--------------------+------+---------+
| name | type | default |
+====================+======+=========+
| inactive_down_rate | int | 2048 |
+--------------------+------+---------+
| inactive_up_rate | int | 2048 |
+--------------------+------+---------+
the download and upload rate limits for a torrent to be considered
active by the queuing mechanism. A torrent whose download rate is less
than ``inactive_down_rate`` and whose upload rate is less than
``inactive_up_rate`` for ``auto_manage_startup`` seconds, is
considered inactive, and another queued torrent may be startert.
This logic is disabled if ``dont_count_slow_torrents`` is false.
.. _proxy_type:
.. raw:: html
<a name="proxy_type"></a>
+------------+------+---------------------+
| name | type | default |
+============+======+=====================+
| proxy_type | int | settings_pack::none |
+------------+------+---------------------+
proxy to use, defaults to none. see proxy_type_t.
.. _proxy_port:
.. raw:: html
<a name="proxy_port"></a>
+------------+------+---------+
| name | type | default |
+============+======+=========+
| proxy_port | int | 0 |
+------------+------+---------+
the port of the proxy server
.. _i2p_port:
.. raw:: html
<a name="i2p_port"></a>
+----------+------+---------+
| name | type | default |
+==========+======+=========+
| i2p_port | int | 0 |
+----------+------+---------+
sets the i2p_ SAM bridge port to connect to. set the hostname with
the ``i2p_hostname`` setting.
.. _i2p: http://www.i2p2.de
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