mirror of
https://github.com/Mr-Wiseguy/Zelda64Recomp.git
synced 2024-11-05 22:35:06 +01:00
426 lines
12 KiB
C
426 lines
12 KiB
C
|
// Provides an efficient implementation of a semaphore (LightweightSemaphore).
|
||
|
// This is an extension of Jeff Preshing's sempahore implementation (licensed
|
||
|
// under the terms of its separate zlib license) that has been adapted and
|
||
|
// extended by Cameron Desrochers.
|
||
|
|
||
|
#pragma once
|
||
|
|
||
|
#include <cstddef> // For std::size_t
|
||
|
#include <atomic>
|
||
|
#include <type_traits> // For std::make_signed<T>
|
||
|
|
||
|
#if defined(_WIN32)
|
||
|
// Avoid including windows.h in a header; we only need a handful of
|
||
|
// items, so we'll redeclare them here (this is relatively safe since
|
||
|
// the API generally has to remain stable between Windows versions).
|
||
|
// I know this is an ugly hack but it still beats polluting the global
|
||
|
// namespace with thousands of generic names or adding a .cpp for nothing.
|
||
|
extern "C" {
|
||
|
struct _SECURITY_ATTRIBUTES;
|
||
|
__declspec(dllimport) void* __stdcall CreateSemaphoreW(_SECURITY_ATTRIBUTES* lpSemaphoreAttributes, long lInitialCount, long lMaximumCount, const wchar_t* lpName);
|
||
|
__declspec(dllimport) int __stdcall CloseHandle(void* hObject);
|
||
|
__declspec(dllimport) unsigned long __stdcall WaitForSingleObject(void* hHandle, unsigned long dwMilliseconds);
|
||
|
__declspec(dllimport) int __stdcall ReleaseSemaphore(void* hSemaphore, long lReleaseCount, long* lpPreviousCount);
|
||
|
}
|
||
|
#elif defined(__MACH__)
|
||
|
#include <mach/mach.h>
|
||
|
#elif defined(__unix__)
|
||
|
#include <semaphore.h>
|
||
|
|
||
|
#if defined(__GLIBC_PREREQ) && defined(_GNU_SOURCE)
|
||
|
#if __GLIBC_PREREQ(2,30)
|
||
|
#define MOODYCAMEL_LIGHTWEIGHTSEMAPHORE_MONOTONIC
|
||
|
#endif
|
||
|
#endif
|
||
|
#endif
|
||
|
|
||
|
namespace moodycamel
|
||
|
{
|
||
|
namespace details
|
||
|
{
|
||
|
|
||
|
// Code in the mpmc_sema namespace below is an adaptation of Jeff Preshing's
|
||
|
// portable + lightweight semaphore implementations, originally from
|
||
|
// https://github.com/preshing/cpp11-on-multicore/blob/master/common/sema.h
|
||
|
// LICENSE:
|
||
|
// Copyright (c) 2015 Jeff Preshing
|
||
|
//
|
||
|
// This software is provided 'as-is', without any express or implied
|
||
|
// warranty. In no event will the authors be held liable for any damages
|
||
|
// arising from the use of this software.
|
||
|
//
|
||
|
// Permission is granted to anyone to use this software for any purpose,
|
||
|
// including commercial applications, and to alter it and redistribute it
|
||
|
// freely, subject to the following restrictions:
|
||
|
//
|
||
|
// 1. The origin of this software must not be misrepresented; you must not
|
||
|
// claim that you wrote the original software. If you use this software
|
||
|
// in a product, an acknowledgement in the product documentation would be
|
||
|
// appreciated but is not required.
|
||
|
// 2. Altered source versions must be plainly marked as such, and must not be
|
||
|
// misrepresented as being the original software.
|
||
|
// 3. This notice may not be removed or altered from any source distribution.
|
||
|
#if defined(_WIN32)
|
||
|
class Semaphore
|
||
|
{
|
||
|
private:
|
||
|
void* m_hSema;
|
||
|
|
||
|
Semaphore(const Semaphore& other) MOODYCAMEL_DELETE_FUNCTION;
|
||
|
Semaphore& operator=(const Semaphore& other) MOODYCAMEL_DELETE_FUNCTION;
|
||
|
|
||
|
public:
|
||
|
Semaphore(int initialCount = 0)
|
||
|
{
|
||
|
assert(initialCount >= 0);
|
||
|
const long maxLong = 0x7fffffff;
|
||
|
m_hSema = CreateSemaphoreW(nullptr, initialCount, maxLong, nullptr);
|
||
|
assert(m_hSema);
|
||
|
}
|
||
|
|
||
|
~Semaphore()
|
||
|
{
|
||
|
CloseHandle(m_hSema);
|
||
|
}
|
||
|
|
||
|
bool wait()
|
||
|
{
|
||
|
const unsigned long infinite = 0xffffffff;
|
||
|
return WaitForSingleObject(m_hSema, infinite) == 0;
|
||
|
}
|
||
|
|
||
|
bool try_wait()
|
||
|
{
|
||
|
return WaitForSingleObject(m_hSema, 0) == 0;
|
||
|
}
|
||
|
|
||
|
bool timed_wait(std::uint64_t usecs)
|
||
|
{
|
||
|
return WaitForSingleObject(m_hSema, (unsigned long)(usecs / 1000)) == 0;
|
||
|
}
|
||
|
|
||
|
void signal(int count = 1)
|
||
|
{
|
||
|
while (!ReleaseSemaphore(m_hSema, count, nullptr));
|
||
|
}
|
||
|
};
|
||
|
#elif defined(__MACH__)
|
||
|
//---------------------------------------------------------
|
||
|
// Semaphore (Apple iOS and OSX)
|
||
|
// Can't use POSIX semaphores due to http://lists.apple.com/archives/darwin-kernel/2009/Apr/msg00010.html
|
||
|
//---------------------------------------------------------
|
||
|
class Semaphore
|
||
|
{
|
||
|
private:
|
||
|
semaphore_t m_sema;
|
||
|
|
||
|
Semaphore(const Semaphore& other) MOODYCAMEL_DELETE_FUNCTION;
|
||
|
Semaphore& operator=(const Semaphore& other) MOODYCAMEL_DELETE_FUNCTION;
|
||
|
|
||
|
public:
|
||
|
Semaphore(int initialCount = 0)
|
||
|
{
|
||
|
assert(initialCount >= 0);
|
||
|
kern_return_t rc = semaphore_create(mach_task_self(), &m_sema, SYNC_POLICY_FIFO, initialCount);
|
||
|
assert(rc == KERN_SUCCESS);
|
||
|
(void)rc;
|
||
|
}
|
||
|
|
||
|
~Semaphore()
|
||
|
{
|
||
|
semaphore_destroy(mach_task_self(), m_sema);
|
||
|
}
|
||
|
|
||
|
bool wait()
|
||
|
{
|
||
|
return semaphore_wait(m_sema) == KERN_SUCCESS;
|
||
|
}
|
||
|
|
||
|
bool try_wait()
|
||
|
{
|
||
|
return timed_wait(0);
|
||
|
}
|
||
|
|
||
|
bool timed_wait(std::uint64_t timeout_usecs)
|
||
|
{
|
||
|
mach_timespec_t ts;
|
||
|
ts.tv_sec = static_cast<unsigned int>(timeout_usecs / 1000000);
|
||
|
ts.tv_nsec = static_cast<int>((timeout_usecs % 1000000) * 1000);
|
||
|
|
||
|
// added in OSX 10.10: https://developer.apple.com/library/prerelease/mac/documentation/General/Reference/APIDiffsMacOSX10_10SeedDiff/modules/Darwin.html
|
||
|
kern_return_t rc = semaphore_timedwait(m_sema, ts);
|
||
|
return rc == KERN_SUCCESS;
|
||
|
}
|
||
|
|
||
|
void signal()
|
||
|
{
|
||
|
while (semaphore_signal(m_sema) != KERN_SUCCESS);
|
||
|
}
|
||
|
|
||
|
void signal(int count)
|
||
|
{
|
||
|
while (count-- > 0)
|
||
|
{
|
||
|
while (semaphore_signal(m_sema) != KERN_SUCCESS);
|
||
|
}
|
||
|
}
|
||
|
};
|
||
|
#elif defined(__unix__)
|
||
|
//---------------------------------------------------------
|
||
|
// Semaphore (POSIX, Linux)
|
||
|
//---------------------------------------------------------
|
||
|
class Semaphore
|
||
|
{
|
||
|
private:
|
||
|
sem_t m_sema;
|
||
|
|
||
|
Semaphore(const Semaphore& other) MOODYCAMEL_DELETE_FUNCTION;
|
||
|
Semaphore& operator=(const Semaphore& other) MOODYCAMEL_DELETE_FUNCTION;
|
||
|
|
||
|
public:
|
||
|
Semaphore(int initialCount = 0)
|
||
|
{
|
||
|
assert(initialCount >= 0);
|
||
|
int rc = sem_init(&m_sema, 0, static_cast<unsigned int>(initialCount));
|
||
|
assert(rc == 0);
|
||
|
(void)rc;
|
||
|
}
|
||
|
|
||
|
~Semaphore()
|
||
|
{
|
||
|
sem_destroy(&m_sema);
|
||
|
}
|
||
|
|
||
|
bool wait()
|
||
|
{
|
||
|
// http://stackoverflow.com/questions/2013181/gdb-causes-sem-wait-to-fail-with-eintr-error
|
||
|
int rc;
|
||
|
do {
|
||
|
rc = sem_wait(&m_sema);
|
||
|
} while (rc == -1 && errno == EINTR);
|
||
|
return rc == 0;
|
||
|
}
|
||
|
|
||
|
bool try_wait()
|
||
|
{
|
||
|
int rc;
|
||
|
do {
|
||
|
rc = sem_trywait(&m_sema);
|
||
|
} while (rc == -1 && errno == EINTR);
|
||
|
return rc == 0;
|
||
|
}
|
||
|
|
||
|
bool timed_wait(std::uint64_t usecs)
|
||
|
{
|
||
|
struct timespec ts;
|
||
|
const int usecs_in_1_sec = 1000000;
|
||
|
const int nsecs_in_1_sec = 1000000000;
|
||
|
#ifdef MOODYCAMEL_LIGHTWEIGHTSEMAPHORE_MONOTONIC
|
||
|
clock_gettime(CLOCK_MONOTONIC, &ts);
|
||
|
#else
|
||
|
clock_gettime(CLOCK_REALTIME, &ts);
|
||
|
#endif
|
||
|
ts.tv_sec += (time_t)(usecs / usecs_in_1_sec);
|
||
|
ts.tv_nsec += (long)(usecs % usecs_in_1_sec) * 1000;
|
||
|
// sem_timedwait bombs if you have more than 1e9 in tv_nsec
|
||
|
// so we have to clean things up before passing it in
|
||
|
if (ts.tv_nsec >= nsecs_in_1_sec) {
|
||
|
ts.tv_nsec -= nsecs_in_1_sec;
|
||
|
++ts.tv_sec;
|
||
|
}
|
||
|
|
||
|
int rc;
|
||
|
do {
|
||
|
#ifdef MOODYCAMEL_LIGHTWEIGHTSEMAPHORE_MONOTONIC
|
||
|
rc = sem_clockwait(&m_sema, CLOCK_MONOTONIC, &ts);
|
||
|
#else
|
||
|
rc = sem_timedwait(&m_sema, &ts);
|
||
|
#endif
|
||
|
} while (rc == -1 && errno == EINTR);
|
||
|
return rc == 0;
|
||
|
}
|
||
|
|
||
|
void signal()
|
||
|
{
|
||
|
while (sem_post(&m_sema) == -1);
|
||
|
}
|
||
|
|
||
|
void signal(int count)
|
||
|
{
|
||
|
while (count-- > 0)
|
||
|
{
|
||
|
while (sem_post(&m_sema) == -1);
|
||
|
}
|
||
|
}
|
||
|
};
|
||
|
#else
|
||
|
#error Unsupported platform! (No semaphore wrapper available)
|
||
|
#endif
|
||
|
|
||
|
} // end namespace details
|
||
|
|
||
|
|
||
|
//---------------------------------------------------------
|
||
|
// LightweightSemaphore
|
||
|
//---------------------------------------------------------
|
||
|
class LightweightSemaphore
|
||
|
{
|
||
|
public:
|
||
|
typedef std::make_signed<std::size_t>::type ssize_t;
|
||
|
|
||
|
private:
|
||
|
std::atomic<ssize_t> m_count;
|
||
|
details::Semaphore m_sema;
|
||
|
int m_maxSpins;
|
||
|
|
||
|
bool waitWithPartialSpinning(std::int64_t timeout_usecs = -1)
|
||
|
{
|
||
|
ssize_t oldCount;
|
||
|
int spin = m_maxSpins;
|
||
|
while (--spin >= 0)
|
||
|
{
|
||
|
oldCount = m_count.load(std::memory_order_relaxed);
|
||
|
if ((oldCount > 0) && m_count.compare_exchange_strong(oldCount, oldCount - 1, std::memory_order_acquire, std::memory_order_relaxed))
|
||
|
return true;
|
||
|
std::atomic_signal_fence(std::memory_order_acquire); // Prevent the compiler from collapsing the loop.
|
||
|
}
|
||
|
oldCount = m_count.fetch_sub(1, std::memory_order_acquire);
|
||
|
if (oldCount > 0)
|
||
|
return true;
|
||
|
if (timeout_usecs < 0)
|
||
|
{
|
||
|
if (m_sema.wait())
|
||
|
return true;
|
||
|
}
|
||
|
if (timeout_usecs > 0 && m_sema.timed_wait((std::uint64_t)timeout_usecs))
|
||
|
return true;
|
||
|
// At this point, we've timed out waiting for the semaphore, but the
|
||
|
// count is still decremented indicating we may still be waiting on
|
||
|
// it. So we have to re-adjust the count, but only if the semaphore
|
||
|
// wasn't signaled enough times for us too since then. If it was, we
|
||
|
// need to release the semaphore too.
|
||
|
while (true)
|
||
|
{
|
||
|
oldCount = m_count.load(std::memory_order_acquire);
|
||
|
if (oldCount >= 0 && m_sema.try_wait())
|
||
|
return true;
|
||
|
if (oldCount < 0 && m_count.compare_exchange_strong(oldCount, oldCount + 1, std::memory_order_relaxed, std::memory_order_relaxed))
|
||
|
return false;
|
||
|
}
|
||
|
}
|
||
|
|
||
|
ssize_t waitManyWithPartialSpinning(ssize_t max, std::int64_t timeout_usecs = -1)
|
||
|
{
|
||
|
assert(max > 0);
|
||
|
ssize_t oldCount;
|
||
|
int spin = m_maxSpins;
|
||
|
while (--spin >= 0)
|
||
|
{
|
||
|
oldCount = m_count.load(std::memory_order_relaxed);
|
||
|
if (oldCount > 0)
|
||
|
{
|
||
|
ssize_t newCount = oldCount > max ? oldCount - max : 0;
|
||
|
if (m_count.compare_exchange_strong(oldCount, newCount, std::memory_order_acquire, std::memory_order_relaxed))
|
||
|
return oldCount - newCount;
|
||
|
}
|
||
|
std::atomic_signal_fence(std::memory_order_acquire);
|
||
|
}
|
||
|
oldCount = m_count.fetch_sub(1, std::memory_order_acquire);
|
||
|
if (oldCount <= 0)
|
||
|
{
|
||
|
if ((timeout_usecs == 0) || (timeout_usecs < 0 && !m_sema.wait()) || (timeout_usecs > 0 && !m_sema.timed_wait((std::uint64_t)timeout_usecs)))
|
||
|
{
|
||
|
while (true)
|
||
|
{
|
||
|
oldCount = m_count.load(std::memory_order_acquire);
|
||
|
if (oldCount >= 0 && m_sema.try_wait())
|
||
|
break;
|
||
|
if (oldCount < 0 && m_count.compare_exchange_strong(oldCount, oldCount + 1, std::memory_order_relaxed, std::memory_order_relaxed))
|
||
|
return 0;
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
if (max > 1)
|
||
|
return 1 + tryWaitMany(max - 1);
|
||
|
return 1;
|
||
|
}
|
||
|
|
||
|
public:
|
||
|
LightweightSemaphore(ssize_t initialCount = 0, int maxSpins = 10000) : m_count(initialCount), m_maxSpins(maxSpins)
|
||
|
{
|
||
|
assert(initialCount >= 0);
|
||
|
assert(maxSpins >= 0);
|
||
|
}
|
||
|
|
||
|
bool tryWait()
|
||
|
{
|
||
|
ssize_t oldCount = m_count.load(std::memory_order_relaxed);
|
||
|
while (oldCount > 0)
|
||
|
{
|
||
|
if (m_count.compare_exchange_weak(oldCount, oldCount - 1, std::memory_order_acquire, std::memory_order_relaxed))
|
||
|
return true;
|
||
|
}
|
||
|
return false;
|
||
|
}
|
||
|
|
||
|
bool wait()
|
||
|
{
|
||
|
return tryWait() || waitWithPartialSpinning();
|
||
|
}
|
||
|
|
||
|
bool wait(std::int64_t timeout_usecs)
|
||
|
{
|
||
|
return tryWait() || waitWithPartialSpinning(timeout_usecs);
|
||
|
}
|
||
|
|
||
|
// Acquires between 0 and (greedily) max, inclusive
|
||
|
ssize_t tryWaitMany(ssize_t max)
|
||
|
{
|
||
|
assert(max >= 0);
|
||
|
ssize_t oldCount = m_count.load(std::memory_order_relaxed);
|
||
|
while (oldCount > 0)
|
||
|
{
|
||
|
ssize_t newCount = oldCount > max ? oldCount - max : 0;
|
||
|
if (m_count.compare_exchange_weak(oldCount, newCount, std::memory_order_acquire, std::memory_order_relaxed))
|
||
|
return oldCount - newCount;
|
||
|
}
|
||
|
return 0;
|
||
|
}
|
||
|
|
||
|
// Acquires at least one, and (greedily) at most max
|
||
|
ssize_t waitMany(ssize_t max, std::int64_t timeout_usecs)
|
||
|
{
|
||
|
assert(max >= 0);
|
||
|
ssize_t result = tryWaitMany(max);
|
||
|
if (result == 0 && max > 0)
|
||
|
result = waitManyWithPartialSpinning(max, timeout_usecs);
|
||
|
return result;
|
||
|
}
|
||
|
|
||
|
ssize_t waitMany(ssize_t max)
|
||
|
{
|
||
|
ssize_t result = waitMany(max, -1);
|
||
|
assert(result > 0);
|
||
|
return result;
|
||
|
}
|
||
|
|
||
|
void signal(ssize_t count = 1)
|
||
|
{
|
||
|
assert(count >= 0);
|
||
|
ssize_t oldCount = m_count.fetch_add(count, std::memory_order_release);
|
||
|
ssize_t toRelease = -oldCount < count ? -oldCount : count;
|
||
|
if (toRelease > 0)
|
||
|
{
|
||
|
m_sema.signal((int)toRelease);
|
||
|
}
|
||
|
}
|
||
|
|
||
|
std::size_t availableApprox() const
|
||
|
{
|
||
|
ssize_t count = m_count.load(std::memory_order_relaxed);
|
||
|
return count > 0 ? static_cast<std::size_t>(count) : 0;
|
||
|
}
|
||
|
};
|
||
|
|
||
|
} // end namespace moodycamel
|