The core and the headless tools no longer use mutexes, condition variables,
spinlocks, std::atomic, std::thread or volatile flags. Threads hand off through
libretro-common's retro_atomic and rthreads plus a few small pieces on top of
them in Common/Thread: Thread, MpscQueue, EventCounter, ParkingLot waits and
ReaderGate. Every wait blocks until it's woken; nothing polls on a timer.
State that only one thread touches just loses its lock. The PSP filesystem,
sceIo and the savedata dialog now belong to the emulation thread: async reads
and writes run when they're queued and complete later in emulated time, and
the IO and savedata threads are gone. The friend finder only talks to the
adhoc server and hands what it gets to the emulation thread. GPU init always
runs on the thread that starts the game.
The Vulkan render and compile queues, pipeline and render pass caches, delete
list and SPIR-V cache, the GL render queue, the software renderer's jit caches,
the file loader caches, the web debugger, UPnP, input, savestates, logging and
the GE debugger all hand off through queues and atomics. The IR jit's spinning
profiler thread goes.
A CPU thread with nothing to run now sleeps until work is queued instead of
spinning. Headless with --debugger waits for a client while stopped, and ends
the run once every client that connected has left. Web server shutdown keeps
servicing the CPU queue until the server has finished.
The core no longer sleeps to pace itself: the frontend runs retro_run at
its own rate, so the frame throttle, the idle-vblank delay and the real
clock sync event (and its core option) are gone, and a stepping CPU hands
straight back instead of waiting 2 ms. Waits that polled now park on a
lock-free eventcount through Common/Thread/ParkingLot and are woken by
whoever changes the state: a paused GL emu thread, which also queues a
marker behind its last frame so pausing runs the render queue up to it
instead of polling; async I/O results; the software renderer when its
queue is full; Vulkan pipeline compiles; and debugger requests once
stepping ends. Boot joins the loader thread, cache shutdown joins its
read-ahead thread, and the slow-I/O simulation is removed.
The path browser, the HTTP and WebSocket servers, the Windows console and
the game info cache are left out of the core build. libretro/test gains
lrgltest, which drives the GL backend on a surfaceless EGL context through
every path that pauses or stops the emu thread; run.sh and the image
checks CI job run it on llvmpipe.
System_AudioPushSamples converts straight into the output buffer: the
block loop never advanced the source pointer and copied numSamples*2
int16s out of a 2048-sample stack buffer, a stack OOB read for any push
over 1024 frames. Realloc failure drops samples instead of crashing and
log_cb is NULL-checked. retro_serialize refuses to write a state larger
than the frontend's buffer, retro_get_memory_data/size return nothing
until PSP memory is mapped, deferred unserialize no longer leaks the
previous buffer, and the cheat entry points stop leaking a CWCheatEngine
per call.
The emu thread acknowledges a pause with a CAS so it cannot clobber a
concurrent quit request. EmuThreadStop stops and joins from any live
state, so unloading while paused no longer leaves a thread running over
freed state. EmuThreadPause pumps queued frames until the thread parks,
via a new non-blocking GLRenderManager::HasQueuedThreadWork() check,
instead of draining one frame, which deadlocked when the thread was
blocked on a readback sync in the next frame. retro_run resumes a paused
thread and pauses it before check_variables() rewrites g_Config,
retro_reset stops it before PSP_Shutdown(), and the sleep_ms(4) after
resume is gone.
libretroadmin