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 libretro core is the frontend, and the headless tools are the test and
debugging hosts. The Windows, UWP, Android, iOS, macOS and SDL apps, the UI
framework and imgui go, along with what only they used: the Win32 debugger
hooks (g_frameMutex, the shutdown lock), JNI thread attachment, the Android
text drawer, RAIntegration, Discord, recent files, game installs, tilt input,
the audio resamplers, the control mapper, memstick moving and the remote ISO
and upload server modes. The web server keeps the debugger. The MSVC, Gradle
and ndk-build projects go too.
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.
since 7e6405291 only full 64 KB reads get cached, so any read touching the
shorter last block of a file came back short. count blocks with
blocks_.size() too, so failed reads can't inflate the count until
MakeCacheSpaceFor loops forever. also stop read-ahead from asking the
backend for blocks past the end of the file.
SaveIntoCache() discarded backend_->ReadAt()'s return value entirely
and unconditionally marked the requested block(s) as cached. A short
or failed read from the backend (e.g. a Remote ISO connection dropping
mid-file, now that LocalFileLoader/RetryingFileLoader correctly report
failures as 0 rather than a huge count) would still get stored as a
"valid" cached block, permanently serving its uninitialized tail as if
it were real file data on every later read, with no retry.
Only insert a block once we've confirmed the backend actually
delivered the full BLOCK_SIZE for it.
Turns out these were needed after all. For some reason, on Windows and
Mac, <algorithm> gets auto-included by something else so I don't notice
when it's missing, and MSVC's include dependency tracker doesn't see it
either.
sleep_ms() should generally be avoided when possible. This can be used to try
to track down unnecessary sleeps by adding some logging.
This commit on its own doesn't actually add any logging.
Since the majority of the code is using ReadAt API already, map this to
a `readp` "syscall" which does not mutate any state about the file
descriptor therefore making it fairly safe multi-threading wise.
This allows to get rid of read-time mutexes in RamCachedFileLoader and
therefore fixes#9803
libretroadmin