videolan/vlc - vlc - Gitea: Git with a cup of tea

Rémi Denis-Courmont 2d099490ee input: add per-thread sleep interruption framework For the sake of simplicity and for historical reasons, access and demux modules perform I/O in blocking mode. If no data is available (or more generally no I/O events), the blocking I/O calls will sleep and hold the whole input thread. This can lead to long time-outs or even complete deadlocks, e.g. notably in case of network error. Originally, a volatile flag (b_die) was checked at frequent interval to ascertain whether to abort. This violated the threaded memory model, and was incompatible with race-to-idle power management. In 2007, the VLC object thread signaling functions were introduced (vlc_object_wait, vlc_object_signal, ...) in an attempt to solve this. They proved inflexible and were not compatible with poll/select-style I/O events multiplexing. Those functions were ultimately removed a little over a year later. In the mean time, the "wait pipe" had been introduced. It was focused on network/socket data reception. While it continues to be used, it suffers several limitations: - it affects other threads using the same VLC object, and indistinctly disrupts all I/O after the "kill", - it incorrectly assumes that the same VLC object is used everywhere (leading to race conditions and live loops), - the convenience wrappers around the wait pipe can only wait on one single I/O event direction on a single file descriptor at a time, - it is currently tied to the VLC input thread. Also at about the same time, thread cancellation was reintroduced. Thread cancellation has proven helpful for simple thread main loops. But it ranges from impractical to unusable when sleeping deep within layers of code, such as in access and stream modules. Generally the problem of interrupting I/O is an intractable halting problem. And in practice a given reading operations inside a demuxer cannot be interrupted without breaking the state machine of the demuxer - in many or most cases. This changes set is only an attempt to complement thread cancellation, This does overcome most limitations of the existing "wait pipe" system and of former VLC object signals: - It is triggered by a function call specifying a target context. The context is tied to the thread that needs to be woken up from sleep. This works quite well because the problem essentially relates to the call flow of the sleeping thread. On the trigger side, this is similar to thread cancellation. - It leaves some flexibility w.r.t. choice of sleeping primitives. This initial change uses semaphores. Low-level file I/O will be introduced later. - The wake-up mechanism is edge-triggered and can be fired multiple times. Thus it does not irreversibly prevent all I/O and sleeping operations once fired. It only interrupts the ongoing or next sleep. In principles non-fatal interruptions could be handled that way, for instance input thread seek (rather than forceful stop) although that is not part of the changes set. - It is not tied to any specific event. The initial use case is stopping the input thread and checking vlc_object_alive() but it can be used for other purposes.		11 years ago
autotools	Update gettext to version 19.2	12 years ago
bin	bin: build a vlc-osx-static similar to vlc-static, to fix tests	11 years ago
compat	Add replacement for GNU ffsll()	11 years ago
contrib	contrib/darwin: don't hard link against lc++	11 years ago
doc	latex: batchmode and hyperlinks	11 years ago
extras	ios: compile for iOS 7 instead of 6.1	11 years ago
include	input: add per-thread sleep interruption framework	11 years ago
lib	Revert "libvlc_media_player: create the aout when first setting audio options"	11 years ago
m4	configure: test and enable C11 where available	11 years ago
modules	avcodec: document the unmapped codecs	11 years ago
po	Add VideoToolbox based decoder	11 years ago
share	Lua.cli: improve lua 5.3 compatibility	11 years ago
src	input: add per-thread sleep interruption framework	11 years ago
test	Remove time variable type	11 years ago
.gitattributes	Supports $ rewrite via .gitattributes	18 years ago
.gitignore	Ignore trs files from test suite	12 years ago
.mailmap	mailmap: remove one former address of mine	11 years ago
AUTHORS	Adding translator	11 years ago
COPYING	COPYING.*: Use full versions of licenses.	14 years ago
COPYING.LIB	COPYING.*: Use full versions of licenses.	14 years ago
INSTALL	Remove reference to old RPM and ipkg support	13 years ago
Makefile.am	bin: build a vlc-osx-static similar to vlc-static, to fix tests	11 years ago
NEWS	Add VideoToolbox based decoder	11 years ago
README	Update README	13 years ago
THANKS	Update THANKS for dvdread/dvdnav	11 years ago
bootstrap	stream_out: remove Makefile recursion	11 years ago
configure.ac	configure: really print an error if the compiler cannot be found	11 years ago
make-alias	Take program prefix and suffix into account in the make-alias script.	18 years ago

README

README for the VLC media player
===============================

VLC is a popular libre and open source media player and multimedia engine,
used by a large number of individuals, professionals, companies and
institutions. Using open source technologies and libraries, VLC has been
ported to most computing platforms, including GNU/Linux, Windows, Mac OS X,
BSD, iOS and Android.
VLC can play most multimedia files, discs, streams, allows playback from
devices, and is able to convert to or stream in various formats.
The VideoLAN project was started at the university École Centrale Paris who
relicensed VLC under the GPLv2 license in February 2001. Since then, VLC has
been downloaded close to one billion times.

Links:
======

The VLC web site  . . . . . http://www.videolan.org/
Support . . . . . . . . . . http://www.videolan.org/support/
Forums  . . . . . . . . . . http://forum.videolan.org/
Wiki  . . . . . . . . . . . http://wiki.videolan.org/
The Developers site . . . . http://wiki.videolan.org/Developers_Corner
VLC hacking guide . . . . . http://wiki.videolan.org/Hacker_Guide
Bugtracker  . . . . . . . . http://trac.videolan.org/vlc/
The VideoLAN web site . . . http://www.videolan.org/

Source Code Content:
===================
ABOUT-NLS          - Notes on the Free Translation Project.
AUTHORS            - VLC authors.
COPYING            - The GPL license.
COPYING.LIB        - The LGPL license.
INSTALL            - Installation and building instructions.
NEWS               - Important modifications between the releases.
README             - This file.
THANKS             - VLC contributors.

bin/               - VLC binaries.
bindings/          - libVLC bindings to other languages.
compat/            - compatibility library for operating systems missing
                     essential functionalities.
contrib/           - Facilities for retrieving external libraries and building
                     them for systems that don't have the right versions.
doc/               - Miscellaneous documentation.
extras/analyser    - Code analyser and editor specific files.
extras/buildsystem - different buildsystems specific files.
extras/misc        - Files that don't fit in the other extras/ categories.
extras/package     - VLC packaging specific files such as spec files.
extras/tools/      - Facilities for retrieving external building tools needed
                     for systems that don't have the right versions.
include/           - Header files.
lib/               - libVLC source code.
modules/           - VLC plugins and modules. Most of the code is here.
po/                - VLC translations.
share/             - Common Resources files.
src/               - libvlccore source code.
test/              - testing system.