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gstreamer/docs/random/wtay/threads_hilevel

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pseudo code describing a GstThread synchronisation proposal. pretty similar to what there is now but with some subtle... Original commit message from CVS: pseudo code describing a GstThread synchronisation proposal. pretty similar to what there is now but with some subtle differences.
2001-11-27 22:01:12 +00:00
1) terms
--------
- the managing container (top half). This is the main thread that
will create and control the main_loop.
- the main_loop (bottom half), this is the thread that actually does
the work.
2) state changes
================
NULL->READY
-----------
precondition:
At this point only the top half exists.
flag GST_THREAD_ACTIVE is unset
flow: (TH column 1, BH column 2, ! denotes (possible) thread switch)
get mutex
pthread create BH
wait for spin up (release lock) !
get mutex
set flag GST_THREAD_ACTIVE
change state of children to READY (*)
signal TH
! wait for commands (release lock)
(lock reacquired after wait)
unlock mutex
(*) marks a spot that could potentially induce another state change.
READY->NULL
-----------
precondition:
BH is waiting for commands.
flag GST_THREAD_ACTIVE is set
flow:
get mutex
set command for BH (NULL)
signal for new command
wait for ACK (release lock) !
(lock reacquired after wait for cmd)
change state of children to NULL (*)
signal TH
unset flag GST_THREAD_ACTIVE
! unlock (release lock)
! exit
(lock reacquired after wait)
join
unlock (release lock)
READY->PAUSED
-------------
precondition:
BH is waiting for commands.
flag GST_THREAD_ACTIVE is set
flow:
get mutex
set command for BH (PAUSED)
signal for new command
wait for ACK (release lock) !
(lock reacquired after wait for cmd)
change state of children to READY (*)
signal TH
! wait for commands (release lock)
(lock reacquired after wait)
unlock (release lock)
PAUSED->PLAYING
---------------
precondition:
BH is waiting for commands.
flag GST_THREAD_ACTIVE is set
flow:
get mutex
set command for BH (PLAYING)
signal for new command
wait for ACK (release lock) !
(lock reacquired after wait for cmd)
change state of children to PLAYING (*)
set flag GST_THREAD_SPINNING
while (flag SPINNING is set) {
signal TH
! unlock mutex
(lock reacquired after wait) !
unlock (release lock) !
! status = iterate() (*)
lock mutex
- some fixes to int2float making automake 1.5 happy (gst now requires automake1.5). It's still not perfect but it bui... Original commit message from CVS: - added playondemand plugin by Leif Morgan Johnson <lmjohns3@eos.ncsu.edu> - some fixes to int2float - aplied a patch from wrobell <wrobell@ite.pl> that is a first attempt at making automake 1.5 happy (gst now requires automake1.5). It's still not perfect but it builds. - Made the schedulers plugable. The default scheduler now lives inside a plugin. - Added a new mpeg1/2 parser/demuxer. - Fixed some compiler warnings in the core libs. - substantial work to GstThread (hopefully less race conditions). simplified the code in GstThread a bit. A state change can now also happen in the thread context. - reworked the state semantics of a bin. it'll now automatically get the highest state of its children. - the autoplugger now nests the threads so that a state change failure of one thread doesn't make its upstream thread lock. - GstQueue refuses to go to PLAYING if the sinkpad is not connected. This way the queue will not wedge in the _get lock. - GstQueue unlocks its mutexes when going to PAUSED. - make sure that when all elements in a bin/thread go to PAUSED, the bin is set to PAUSED too. - make a parent bin wait for its children to PAUSE before ending the iteration with FALSE (EOS) - Some changes to GstPlay to deal with EOS. - aplied the latest patch from Zeenix to gstrtp. end result: GstPlay doesn't crash on EOS and the pipeline is now shut down properly.
2001-12-04 22:12:50 +00:00
signal TH
pseudo code describing a GstThread synchronisation proposal. pretty similar to what there is now but with some subtle... Original commit message from CVS: pseudo code describing a GstThread synchronisation proposal. pretty similar to what there is now but with some subtle differences.
2001-11-27 22:01:12 +00:00
if (!status) // EOS
unset SPINNING flag
}
signal TH
! wait for commands (release lock)
PLAYING->PAUSED
---------------
precondition:
1. either:
BH is spinning
flag GST_THREAD_ACTIVE is set
flag GST_THREAD_SPINNING is set
2. or:
BH is waiting for commands.
flag GST_THREAD_ACTIVE is set
flag GST_THREAD_SPINNING is unset
flow:
case 1.
! while (flag SPINNING is set) {
! signal TH
! unlock mutex
get mutex !
set command for BH (PAUSED) !
unset SPINNING flag ! status = iterate ()
signal for new command !
wait for ACK (release lock) !
lock mutex (reacquired after iteration)
if (!status) // EOS
unset SPINNING flag
}
if (status)
change state of children to READY (*) (!EOS)
signal TH
! wait for commands (release lock)
(lock reacquired after wait)
unlock (release lock)
case 2.
get mutex
set command for BH (PAUSED)
unset SPINNING flag (nop)
signal for new command
wait for ACK (release lock) !
(lock reacquired after wait for cmd)
change state of children to READY (*)
signal TH
! wait for commands (release lock)
(lock reacquired after wait)
unlock (release lock)
PAUSED->READY
-------------
similar to READY->PAUSED
TODO
----
- review
Fix typos in comments and docs Found via `codespell` https://bugzilla.gnome.org/show_bug.cgi?id=795610
2018-04-27 16:40:31 +00:00
- figure all state change scenarios occurring in code marked with (*)
pseudo code describing a GstThread synchronisation proposal. pretty similar to what there is now but with some subtle... Original commit message from CVS: pseudo code describing a GstThread synchronisation proposal. pretty similar to what there is now but with some subtle differences.
2001-11-27 22:01:12 +00:00
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