mirror of
https://github.com/hrydgard/ppsspp.git
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libretroadmin
f1208a7a5a
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.
96 lines
2.1 KiB
C++
96 lines
2.1 KiB
C++
#include <cstdio>
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#include <retro_atomic.h>
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#include "Common/File/FileUtil.h"
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#include "Common/File/PositionalFile.h"
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namespace {
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// Ids are never reused, so a handle cached for a file that has since gone away
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// can't be mistaken for one of a newer file.
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retro_atomic_int_t g_nextId;
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struct Handle {
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uint32_t id;
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FILE *file;
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int64_t pos; // where file is; -1 when unknown
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uint32_t lastUse;
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};
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// This thread's handles: a few files at once, least recently used goes first.
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struct HandleCache {
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enum { SLOTS = 8 };
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Handle slots[SLOTS]{};
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uint32_t clock = 0;
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~HandleCache() {
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for (Handle &h : slots) {
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if (h.file)
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fclose(h.file);
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}
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}
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Handle *Get(uint32_t id, const Path &path) {
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Handle *victim = &slots[0];
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for (Handle &h : slots) {
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if (h.file && h.id == id) {
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h.lastUse = ++clock;
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return &h;
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}
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if (!h.file || h.lastUse < victim->lastUse)
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victim = &h;
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}
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FILE *file = File::OpenCFile(path, "rb");
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if (!file)
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return nullptr;
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if (victim->file)
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fclose(victim->file);
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*victim = Handle{ id, file, 0, ++clock };
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return victim;
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}
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void Forget(uint32_t id) {
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for (Handle &h : slots) {
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if (h.file && h.id == id) {
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fclose(h.file);
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h = Handle{};
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}
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}
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}
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};
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thread_local HandleCache t_handles;
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} // namespace
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PositionalFile::PositionalFile(const Path &path) : path_(path) {
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id_ = (uint32_t)retro_atomic_fetch_add_int(&g_nextId, 1) + 1;
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Handle *h = t_handles.Get(id_, path_);
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if (h)
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size_ = File::GetFileSize(h->file);
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}
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PositionalFile::~PositionalFile() {
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// Other threads' handles for this file close when they're evicted or the thread ends.
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t_handles.Forget(id_);
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}
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size_t PositionalFile::ReadAt(uint64_t offset, void *dst, size_t len) {
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if (len == 0 || size_ < 0)
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return 0;
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Handle *h = t_handles.Get(id_, path_);
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if (!h)
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return 0;
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if (h->pos != (int64_t)offset) {
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if (File::Fseek(h->file, (int64_t)offset, SEEK_SET) != 0) {
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h->pos = -1;
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return 0;
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}
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h->pos = (int64_t)offset;
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}
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const size_t got = fread(dst, 1, len, h->file);
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h->pos = got == len ? h->pos + (int64_t)got : -1;
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return got;
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}
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