eden-miror/src/common/thread.cpp

// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
// SPDX-License-Identifier: GPL-3.0-or-later
// SPDX-FileCopyrightText: 2013 Dolphin Emulator Project
// SPDX-FileCopyrightText: 2014 Citra Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#include <chrono>
#include <limits>
#include <string>
#include <thread>

#include "common/error.h"
#include "common/logging.h"
#include "common/assert.h"
#include "common/thread.h"
#ifdef __APPLE__
#include <mach/mach.h>
#elif defined(__HAIKU__)
#include <kernel/OS.h>
#elif defined(_WIN32)
#include <windows.h>
#include "common/string_util.h"
#include "common/windows/timer_resolution.h"
#else
#if defined(__FreeBSD__)
#include <sys/cpuset.h>
#include <sys/_cpuset.h>
#include <pthread_np.h>
// Compatibility with CPUset
#define cpu_set_t cpuset_t
#elif defined(__DragonFly__) || defined(__OpenBSD__) || defined(__Bitrig__)
#include <pthread_np.h>
#endif
#include <pthread.h>
#include <sched.h>
#endif

#ifndef _WIN32
#include <unistd.h>
#endif

#include "common/cpu_features.h"
#ifdef ARCHITECTURE_x86_64
#ifdef _MSC_VER
#include <intrin.h>
#else
#include <x86intrin.h>
#endif
#include "common/x64/rdtsc.h"
#endif
#include "core/core_timing.h"

namespace Common {

void SetCurrentThreadPriority(ThreadPriority new_priority) {
#ifdef _WIN32
    int windows_priority = [&]() {
        switch (new_priority) {
        case ThreadPriority::Low: return THREAD_PRIORITY_BELOW_NORMAL;
        case ThreadPriority::Normal: return THREAD_PRIORITY_NORMAL;
        case ThreadPriority::High: return THREAD_PRIORITY_ABOVE_NORMAL;
        case ThreadPriority::VeryHigh: return THREAD_PRIORITY_HIGHEST;
        case ThreadPriority::Critical: return THREAD_PRIORITY_TIME_CRITICAL;
        default: return THREAD_PRIORITY_NORMAL;
        }
    }();
    SetThreadPriority(GetCurrentThread(), windows_priority);
#elif defined(__HAIKU__)
    // TODO: We have priorities for 3D rendering applications - may help lavapipe?
    int priority = [&]() {
        switch (new_priority) {
        case ThreadPriority::Low: return B_LOW_PRIORITY;
        case ThreadPriority::Normal: return B_NORMAL_PRIORITY;
        case ThreadPriority::High: return B_DISPLAY_PRIORITY;
        case ThreadPriority::VeryHigh: return B_URGENT_DISPLAY_PRIORITY;
        case ThreadPriority::Critical: return B_URGENT_PRIORITY;
        default: return B_NORMAL_PRIORITY;
        }
    }();
    set_thread_priority(find_thread(NULL), priority);
#else
    pthread_t this_thread = pthread_self();
    const auto scheduling_type = SCHED_OTHER;
    s32 max_prio = sched_get_priority_max(scheduling_type);
    s32 min_prio = sched_get_priority_min(scheduling_type);
    u32 level = (std::max)(u32(new_priority) + 1, 4U);

    struct sched_param params;
    if (max_prio > min_prio) {
        params.sched_priority = min_prio + ((max_prio - min_prio) * level) / 4;
    } else {
        params.sched_priority = min_prio - ((min_prio - max_prio) * level) / 4;
    }

    pthread_setschedparam(this_thread, scheduling_type, &params);
#endif
}

void SetCurrentThreadName(const char* name) {
#ifdef _MSC_VER
    // Sets the debugger-visible name of the current thread.
    if (auto pf = (decltype(&SetThreadDescription))(void*)GetProcAddress(GetModuleHandle(TEXT("KernelBase.dll")), "SetThreadDescription"); pf)
        pf(GetCurrentThread(), UTF8ToUTF16W(name).data()); // Windows 10+
    else
        ; // No-op
#elif  defined(__APPLE__)
    pthread_setname_np(name);
#elif defined(__HAIKU__)
    rename_thread(find_thread(NULL), name);
#elif defined(__Bitrig__) || defined(__DragonFly__) || defined(__FreeBSD__) || defined(__OpenBSD__)
    pthread_set_name_np(pthread_self(), name);
#elif defined(__NetBSD__)
    pthread_setname_np(pthread_self(), "%s", (void*)name);
#elif defined(__linux__) || defined(__CYGWIN__) || defined(__sun__) || defined(__glibc__) || defined(__managarm__)
    int ret = pthread_setname_np(pthread_self(), name);
    if (ret == ERANGE) {
        // Linux limits thread names to 15 characters and will outright reject any
        // attempt to set a longer name with ERANGE.
        char buf[16];
        size_t const len = std::min<size_t>(std::strlen(name), sizeof(buf) - 1);
        std::memcpy(buf, name, len);
        buf[len] = '\0';
        pthread_setname_np(pthread_self(), buf);
    }
#elif defined(_WIN32)
    // MinGW with the POSIX threading model does not support pthread_setname_np
    // See for reference
    // https://gitlab.freedesktop.org/mesa/mesa/-/blame/main/src/util/u_thread.c?ref_type=heads#L75
    (void)name;
#else
    pthread_setname_np(pthread_self(), name);
#endif
}

void PinCurrentThreadToPerformanceCore(size_t core_id) {
    ASSERT(core_id < 4);
    // If we set a flag for a CPU that doesn't exist, the thread may not be allowed to
    // run in ANY processor!
    auto const total_cores = std::thread::hardware_concurrency();
    if (core_id < total_cores) {
#if defined(__ANDROID__)
        cpu_set_t set;
        CPU_ZERO(&set);
        CPU_SET(core_id, &set);
        sched_setaffinity(pthread_self(), sizeof(set), &set);
#elif defined(__linux__) || defined(__FreeBSD__)
        cpu_set_t set;
        CPU_ZERO(&set);
        CPU_SET(core_id, &set);
        pthread_setaffinity_np(pthread_self(), sizeof(set), &set);
#elif defined(_WIN32)
        DWORD set = 1UL << core_id;
        SetThreadAffinityMask(GetCurrentThread(), set);
#else
        // No pin functionality implemented
#endif
    }
}

#ifdef ARCHITECTURE_x86_64
// On Linux and UNIX systems, a futex would nominally be used to cover the costs
// the idea is that it's intuitivelly cheaper to use a direct instruction as opposed to a full futex call
// the underlying libc++ implementation uses pthread_cond_timedwait which MAY invoke a futex
// Let's pretend the OS is too expensive to jump into, and avoid ANY context switches
// this should *IN THEORY* lower CPU usage while just waiting for stuff effectively
// For windows the minimal quanta resolution is about 500us, and normal CRT cond var is 1.5ms(?)
// so may as well avoid that too
// Let's just give ALL platforms the same mechanisms (almost) for when they have umonitor OR waitpkg
#ifdef __clang__
__attribute__((target("waitpkg,mwaitx")))
#elif defined(__GNUC__)
#pragma GCC target("waitpkg")
#pragma GCC target("mwaitx")
#endif
bool Event::WaitFor(const std::chrono::nanoseconds time) {
#ifdef _WIN32
    auto const start = Common::X64::FencedRDTSC();
    auto const& caps = Common::g_cpu_caps;
    [[maybe_unused]] auto const end = start + Common::g_wall_clock.NsToTicks(time);
    if (caps.monitorx) {
        while (true) {
            // Armed monitor, as per manual, MWAITX must be conditional if the condition isn't satisfied
            // to prevent a race condition.
            _mm_monitorx(reinterpret_cast<u64*>(std::addressof(is_set)), 0, 0);
            if (!is_set.load()) {
                // RDTSC may be fenced here due to atomic load
                auto const now = _rdtsc();
                if (end > now) {
                    u32 const cycles = std::min<u32>((std::numeric_limits<u32>::max)(), s64(end) - s64(now));
                    // See here: https://github.com/torvalds/linux/blob/948a64995aca6820abefd17f1a4258f5835c5ad9/arch/x86/lib/delay.c#L93
                    // MWAITX accepts a 32-bit input timer which determines the total number of cycles to wait for
                    // NOT THE TOTAL ABSOLUTE TSC VALUE, it's just a delta
                    // BIT[1] = use a timer
                    // Hint = 0: Use C1 state when sleepy (means slower wakeup but better savings)
                    _mm_mwaitx(1 << 1, 0u, cycles);
                    if (!is_set.load())
                        return false;
                } else
                    return false; //timeout
            }
            bool expected = true;
            if (is_set.compare_exchange_weak(expected, false, std::memory_order_release))
                return true;
        }
    } else if (caps.waitpkg) {
        // #UD If CPUID.7.0:ECX.WAITPKG[bit 5]=0.
        while (true) {
            _umonitor(std::addressof(is_set));
            if (!is_set.load() && !_umwait(0, end)) //umwait is absolute time!!!
                return false;
            bool expected = true;
            if (is_set.compare_exchange_weak(expected, false, std::memory_order_release))
                return true;
        }
    } else {
        while (!is_set.load() && end > _rdtsc())
            Common::Windows::SleepForOneTick();
        if (is_set.load())
            Reset();
        return true;
    }
#else
    std::unique_lock lk{mutex};
    if (!condvar.wait_for(lk, time, [this] { return is_set.load(); }))
        return false;
    is_set = false;
    return true;
#endif
}
#else
bool Event::WaitFor(const std::chrono::nanoseconds time) {
#ifdef _WIN32
    auto const end = Common::g_wall_clock.GetTimeNS() + time;
    while (!is_set.load() && end > Common::g_wall_clock.GetTimeNS())
        Common::Windows::SleepForOneTick();
    if (is_set.load())
        Reset();
    return true;
#else
    std::unique_lock lk{mutex};
    if (!condvar.wait_for(lk, time, [this] { return is_set.load(); }))
        return false;
    is_set = false;
    return true;
#endif
}
#endif

} // namespace Common