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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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172 lines
4.1 KiB
Text
172 lines
4.1 KiB
Text
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1) terms
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--------
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- the managing container (top half). This is the main thread that
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will create and control the main_loop.
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- the main_loop (bottom half), this is the thread that actually does
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the work.
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2) state changes
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================
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NULL->READY
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-----------
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precondition:
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At this point only the top half exists.
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flag GST_THREAD_ACTIVE is unset
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flow: (TH column 1, BH column 2, ! denotes (possible) thread switch)
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get mutex
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pthread create BH
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wait for spin up (release lock) !
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get mutex
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set flag GST_THREAD_ACTIVE
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change state of children to READY (*)
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signal TH
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! wait for commands (release lock)
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(lock reacquired after wait)
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unlock mutex
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(*) marks a spot that could potentially induce another state change.
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READY->NULL
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-----------
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precondition:
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BH is waiting for commands.
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flag GST_THREAD_ACTIVE is set
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flow:
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get mutex
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set command for BH (NULL)
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signal for new command
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wait for ACK (release lock) !
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(lock reacquired after wait for cmd)
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change state of children to NULL (*)
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signal TH
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unset flag GST_THREAD_ACTIVE
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! unlock (release lock)
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! exit
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(lock reacquired after wait)
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join
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unlock (release lock)
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READY->PAUSED
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-------------
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precondition:
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BH is waiting for commands.
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flag GST_THREAD_ACTIVE is set
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flow:
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get mutex
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set command for BH (PAUSED)
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signal for new command
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wait for ACK (release lock) !
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(lock reacquired after wait for cmd)
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change state of children to READY (*)
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signal TH
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! wait for commands (release lock)
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(lock reacquired after wait)
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unlock (release lock)
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PAUSED->PLAYING
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---------------
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precondition:
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BH is waiting for commands.
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flag GST_THREAD_ACTIVE is set
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flow:
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get mutex
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set command for BH (PLAYING)
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signal for new command
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wait for ACK (release lock) !
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(lock reacquired after wait for cmd)
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change state of children to PLAYING (*)
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set flag GST_THREAD_SPINNING
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while (flag SPINNING is set) {
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signal TH
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! unlock mutex
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(lock reacquired after wait) !
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unlock (release lock) !
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! status = iterate() (*)
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lock mutex
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if (!status) // EOS
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unset SPINNING flag
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}
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signal TH
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! wait for commands (release lock)
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PLAYING->PAUSED
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---------------
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precondition:
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1. either:
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BH is spinning
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flag GST_THREAD_ACTIVE is set
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flag GST_THREAD_SPINNING is set
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2. or:
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BH is waiting for commands.
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flag GST_THREAD_ACTIVE is set
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flag GST_THREAD_SPINNING is unset
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flow:
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case 1.
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! while (flag SPINNING is set) {
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! signal TH
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! unlock mutex
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get mutex !
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set command for BH (PAUSED) !
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unset SPINNING flag ! status = iterate ()
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signal for new command !
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wait for ACK (release lock) !
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lock mutex (reacquired after iteration)
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if (!status) // EOS
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unset SPINNING flag
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}
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if (status)
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change state of children to READY (*) (!EOS)
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signal TH
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! wait for commands (release lock)
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(lock reacquired after wait)
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unlock (release lock)
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case 2.
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get mutex
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set command for BH (PAUSED)
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unset SPINNING flag (nop)
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signal for new command
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wait for ACK (release lock) !
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(lock reacquired after wait for cmd)
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change state of children to READY (*)
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signal TH
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! wait for commands (release lock)
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(lock reacquired after wait)
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unlock (release lock)
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PAUSED->READY
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-------------
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similar to READY->PAUSED
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TODO
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|
----
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|
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|
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- review
|
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|
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- figure all all state change scenarios occuring in code marked with (*)
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