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pseudo code describing a GstThread synchronisation proposal. pretty similar to what there is now but with some subtle...

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Original commit message from CVS:
pseudo code describing a GstThread synchronisation proposal. pretty
similar to what there is now but with some subtle differences.
This commit is contained in:
Wim Taymans 2001-11-27 22:01:12 +00:00
parent ac66719205
commit fbc4cff87c
1 changed files with 171 additions and 0 deletions
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docs/random/wtay/threads_hilevel Normal file
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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
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
- figure all all state change scenarios occuring in code marked with (*)