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Diffstat (limited to 'src/common/atomic_helpers.h')
| -rw-r--r-- | src/common/atomic_helpers.h | 772 |
1 files changed, 772 insertions, 0 deletions
diff --git a/src/common/atomic_helpers.h b/src/common/atomic_helpers.h new file mode 100644 index 000000000..6d912b52e --- /dev/null +++ b/src/common/atomic_helpers.h @@ -0,0 +1,772 @@ +// ©2013-2016 Cameron Desrochers. +// Distributed under the simplified BSD license (see the license file that +// should have come with this header). +// Uses Jeff Preshing's semaphore implementation (under the terms of its +// separate zlib license, embedded below). + +#pragma once + +// Provides portable (VC++2010+, Intel ICC 13, GCC 4.7+, and anything C++11 compliant) +// implementation of low-level memory barriers, plus a few semi-portable utility macros (for +// inlining and alignment). Also has a basic atomic type (limited to hardware-supported atomics with +// no memory ordering guarantees). Uses the AE_* prefix for macros (historical reasons), and the +// "moodycamel" namespace for symbols. + +#include <cassert> +#include <cerrno> +#include <cstdint> +#include <ctime> +#include <type_traits> + +// Platform detection +#if defined(__INTEL_COMPILER) +#define AE_ICC +#elif defined(_MSC_VER) +#define AE_VCPP +#elif defined(__GNUC__) +#define AE_GCC +#endif + +#if defined(_M_IA64) || defined(__ia64__) +#define AE_ARCH_IA64 +#elif defined(_WIN64) || defined(__amd64__) || defined(_M_X64) || defined(__x86_64__) +#define AE_ARCH_X64 +#elif defined(_M_IX86) || defined(__i386__) +#define AE_ARCH_X86 +#elif defined(_M_PPC) || defined(__powerpc__) +#define AE_ARCH_PPC +#else +#define AE_ARCH_UNKNOWN +#endif + +// AE_UNUSED +#define AE_UNUSED(x) ((void)x) + +// AE_NO_TSAN/AE_TSAN_ANNOTATE_* +#if defined(__has_feature) +#if __has_feature(thread_sanitizer) +#if __cplusplus >= 201703L // inline variables require C++17 +namespace Common { +inline int ae_tsan_global; +} +#define AE_TSAN_ANNOTATE_RELEASE() \ + AnnotateHappensBefore(__FILE__, __LINE__, (void*)(&::moodycamel::ae_tsan_global)) +#define AE_TSAN_ANNOTATE_ACQUIRE() \ + AnnotateHappensAfter(__FILE__, __LINE__, (void*)(&::moodycamel::ae_tsan_global)) +extern "C" void AnnotateHappensBefore(const char*, int, void*); +extern "C" void AnnotateHappensAfter(const char*, int, void*); +#else // when we can't work with tsan, attempt to disable its warnings +#define AE_NO_TSAN __attribute__((no_sanitize("thread"))) +#endif +#endif +#endif +#ifndef AE_NO_TSAN +#define AE_NO_TSAN +#endif +#ifndef AE_TSAN_ANNOTATE_RELEASE +#define AE_TSAN_ANNOTATE_RELEASE() +#define AE_TSAN_ANNOTATE_ACQUIRE() +#endif + +// AE_FORCEINLINE +#if defined(AE_VCPP) || defined(AE_ICC) +#define AE_FORCEINLINE __forceinline +#elif defined(AE_GCC) +//#define AE_FORCEINLINE __attribute__((always_inline)) +#define AE_FORCEINLINE inline +#else +#define AE_FORCEINLINE inline +#endif + +// AE_ALIGN +#if defined(AE_VCPP) || defined(AE_ICC) +#define AE_ALIGN(x) __declspec(align(x)) +#elif defined(AE_GCC) +#define AE_ALIGN(x) __attribute__((aligned(x))) +#else +// Assume GCC compliant syntax... +#define AE_ALIGN(x) __attribute__((aligned(x))) +#endif + +// Portable atomic fences implemented below: + +namespace Common { + +enum memory_order { + memory_order_relaxed, + memory_order_acquire, + memory_order_release, + memory_order_acq_rel, + memory_order_seq_cst, + + // memory_order_sync: Forces a full sync: + // #LoadLoad, #LoadStore, #StoreStore, and most significantly, #StoreLoad + memory_order_sync = memory_order_seq_cst +}; + +} // namespace Common + +#if (defined(AE_VCPP) && (_MSC_VER < 1700 || defined(__cplusplus_cli))) || \ + (defined(AE_ICC) && __INTEL_COMPILER < 1600) +// VS2010 and ICC13 don't support std::atomic_*_fence, implement our own fences + +#include <intrin.h> + +#if defined(AE_ARCH_X64) || defined(AE_ARCH_X86) +#define AeFullSync _mm_mfence +#define AeLiteSync _mm_mfence +#elif defined(AE_ARCH_IA64) +#define AeFullSync __mf +#define AeLiteSync __mf +#elif defined(AE_ARCH_PPC) +#include <ppcintrinsics.h> +#define AeFullSync __sync +#define AeLiteSync __lwsync +#endif + +#ifdef AE_VCPP +#pragma warning(push) +#pragma warning(disable : 4365) // Disable erroneous 'conversion from long to unsigned int, + // signed/unsigned mismatch' error when using `assert` +#ifdef __cplusplus_cli +#pragma managed(push, off) +#endif +#endif + +namespace Common { + +AE_FORCEINLINE void compiler_fence(memory_order order) AE_NO_TSAN { + switch (order) { + case memory_order_relaxed: + break; + case memory_order_acquire: + _ReadBarrier(); + break; + case memory_order_release: + _WriteBarrier(); + break; + case memory_order_acq_rel: + _ReadWriteBarrier(); + break; + case memory_order_seq_cst: + _ReadWriteBarrier(); + break; + default: + assert(false); + } +} + +// x86/x64 have a strong memory model -- all loads and stores have +// acquire and release semantics automatically (so only need compiler +// barriers for those). +#if defined(AE_ARCH_X86) || defined(AE_ARCH_X64) +AE_FORCEINLINE void fence(memory_order order) AE_NO_TSAN { + switch (order) { + case memory_order_relaxed: + break; + case memory_order_acquire: + _ReadBarrier(); + break; + case memory_order_release: + _WriteBarrier(); + break; + case memory_order_acq_rel: + _ReadWriteBarrier(); + break; + case memory_order_seq_cst: + _ReadWriteBarrier(); + AeFullSync(); + _ReadWriteBarrier(); + break; + default: + assert(false); + } +} +#else +AE_FORCEINLINE void fence(memory_order order) AE_NO_TSAN { + // Non-specialized arch, use heavier memory barriers everywhere just in case :-( + switch (order) { + case memory_order_relaxed: + break; + case memory_order_acquire: + _ReadBarrier(); + AeLiteSync(); + _ReadBarrier(); + break; + case memory_order_release: + _WriteBarrier(); + AeLiteSync(); + _WriteBarrier(); + break; + case memory_order_acq_rel: + _ReadWriteBarrier(); + AeLiteSync(); + _ReadWriteBarrier(); + break; + case memory_order_seq_cst: + _ReadWriteBarrier(); + AeFullSync(); + _ReadWriteBarrier(); + break; + default: + assert(false); + } +} +#endif +} // namespace Common +#else +// Use standard library of atomics +#include <atomic> + +namespace Common { + +AE_FORCEINLINE void compiler_fence(memory_order order) AE_NO_TSAN { + switch (order) { + case memory_order_relaxed: + break; + case memory_order_acquire: + std::atomic_signal_fence(std::memory_order_acquire); + break; + case memory_order_release: + std::atomic_signal_fence(std::memory_order_release); + break; + case memory_order_acq_rel: + std::atomic_signal_fence(std::memory_order_acq_rel); + break; + case memory_order_seq_cst: + std::atomic_signal_fence(std::memory_order_seq_cst); + break; + default: + assert(false); + } +} + +AE_FORCEINLINE void fence(memory_order order) AE_NO_TSAN { + switch (order) { + case memory_order_relaxed: + break; + case memory_order_acquire: + AE_TSAN_ANNOTATE_ACQUIRE(); + std::atomic_thread_fence(std::memory_order_acquire); + break; + case memory_order_release: + AE_TSAN_ANNOTATE_RELEASE(); + std::atomic_thread_fence(std::memory_order_release); + break; + case memory_order_acq_rel: + AE_TSAN_ANNOTATE_ACQUIRE(); + AE_TSAN_ANNOTATE_RELEASE(); + std::atomic_thread_fence(std::memory_order_acq_rel); + break; + case memory_order_seq_cst: + AE_TSAN_ANNOTATE_ACQUIRE(); + AE_TSAN_ANNOTATE_RELEASE(); + std::atomic_thread_fence(std::memory_order_seq_cst); + break; + default: + assert(false); + } +} + +} // namespace Common + +#endif + +#if !defined(AE_VCPP) || (_MSC_VER >= 1700 && !defined(__cplusplus_cli)) +#define AE_USE_STD_ATOMIC_FOR_WEAK_ATOMIC +#endif + +#ifdef AE_USE_STD_ATOMIC_FOR_WEAK_ATOMIC +#include <atomic> +#endif +#include <utility> + +// WARNING: *NOT* A REPLACEMENT FOR std::atomic. READ CAREFULLY: +// Provides basic support for atomic variables -- no memory ordering guarantees are provided. +// The guarantee of atomicity is only made for types that already have atomic load and store +// guarantees at the hardware level -- on most platforms this generally means aligned pointers and +// integers (only). +namespace Common { +template <typename T> +class weak_atomic { +public: + AE_NO_TSAN weak_atomic() : value() {} +#ifdef AE_VCPP +#pragma warning(push) +#pragma warning(disable : 4100) // Get rid of (erroneous) 'unreferenced formal parameter' warning +#endif + template <typename U> + AE_NO_TSAN weak_atomic(U&& x) : value(std::forward<U>(x)) {} +#ifdef __cplusplus_cli + // Work around bug with universal reference/nullptr combination that only appears when /clr is + // on + AE_NO_TSAN weak_atomic(nullptr_t) : value(nullptr) {} +#endif + AE_NO_TSAN weak_atomic(weak_atomic const& other) : value(other.load()) {} + AE_NO_TSAN weak_atomic(weak_atomic&& other) : value(std::move(other.load())) {} +#ifdef AE_VCPP +#pragma warning(pop) +#endif + + AE_FORCEINLINE operator T() const AE_NO_TSAN { + return load(); + } + +#ifndef AE_USE_STD_ATOMIC_FOR_WEAK_ATOMIC + template <typename U> + AE_FORCEINLINE weak_atomic const& operator=(U&& x) AE_NO_TSAN { + value = std::forward<U>(x); + return *this; + } + AE_FORCEINLINE weak_atomic const& operator=(weak_atomic const& other) AE_NO_TSAN { + value = other.value; + return *this; + } + + AE_FORCEINLINE T load() const AE_NO_TSAN { + return value; + } + + AE_FORCEINLINE T fetch_add_acquire(T increment) AE_NO_TSAN { +#if defined(AE_ARCH_X64) || defined(AE_ARCH_X86) + if (sizeof(T) == 4) + return _InterlockedExchangeAdd((long volatile*)&value, (long)increment); +#if defined(_M_AMD64) + else if (sizeof(T) == 8) + return _InterlockedExchangeAdd64((long long volatile*)&value, (long long)increment); +#endif +#else +#error Unsupported platform +#endif + assert(false && "T must be either a 32 or 64 bit type"); + return value; + } + + AE_FORCEINLINE T fetch_add_release(T increment) AE_NO_TSAN { +#if defined(AE_ARCH_X64) || defined(AE_ARCH_X86) + if (sizeof(T) == 4) + return _InterlockedExchangeAdd((long volatile*)&value, (long)increment); +#if defined(_M_AMD64) + else if (sizeof(T) == 8) + return _InterlockedExchangeAdd64((long long volatile*)&value, (long long)increment); +#endif +#else +#error Unsupported platform +#endif + assert(false && "T must be either a 32 or 64 bit type"); + return value; + } +#else + template <typename U> + AE_FORCEINLINE weak_atomic const& operator=(U&& x) AE_NO_TSAN { + value.store(std::forward<U>(x), std::memory_order_relaxed); + return *this; + } + + AE_FORCEINLINE weak_atomic const& operator=(weak_atomic const& other) AE_NO_TSAN { + value.store(other.value.load(std::memory_order_relaxed), std::memory_order_relaxed); + return *this; + } + + AE_FORCEINLINE T load() const AE_NO_TSAN { + return value.load(std::memory_order_relaxed); + } + + AE_FORCEINLINE T fetch_add_acquire(T increment) AE_NO_TSAN { + return value.fetch_add(increment, std::memory_order_acquire); + } + + AE_FORCEINLINE T fetch_add_release(T increment) AE_NO_TSAN { + return value.fetch_add(increment, std::memory_order_release); + } +#endif + +private: +#ifndef AE_USE_STD_ATOMIC_FOR_WEAK_ATOMIC + // No std::atomic support, but still need to circumvent compiler optimizations. + // `volatile` will make memory access slow, but is guaranteed to be reliable. + volatile T value; +#else + std::atomic<T> value; +#endif +}; + +} // namespace Common + +// Portable single-producer, single-consumer semaphore below: + +#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> +#elif defined(FREERTOS) +#include <FreeRTOS.h> +#include <semphr.h> +#include <task.h> +#endif + +namespace Common { +// Code in the spsc_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. +namespace spsc_sema { +#if defined(_WIN32) +class Semaphore { +private: + void* m_hSema; + + Semaphore(const Semaphore& other); + Semaphore& operator=(const Semaphore& other); + +public: + AE_NO_TSAN Semaphore(int initialCount = 0) : m_hSema() { + assert(initialCount >= 0); + const long maxLong = 0x7fffffff; + m_hSema = CreateSemaphoreW(nullptr, initialCount, maxLong, nullptr); + assert(m_hSema); + } + + AE_NO_TSAN ~Semaphore() { + CloseHandle(m_hSema); + } + + bool wait() AE_NO_TSAN { + const unsigned long infinite = 0xffffffff; + return WaitForSingleObject(m_hSema, infinite) == 0; + } + + bool try_wait() AE_NO_TSAN { + return WaitForSingleObject(m_hSema, 0) == 0; + } + + bool timed_wait(std::uint64_t usecs) AE_NO_TSAN { + return WaitForSingleObject(m_hSema, (unsigned long)(usecs / 1000)) == 0; + } + + void signal(int count = 1) AE_NO_TSAN { + 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); + Semaphore& operator=(const Semaphore& other); + +public: + AE_NO_TSAN Semaphore(int initialCount = 0) : m_sema() { + assert(initialCount >= 0); + kern_return_t rc = + semaphore_create(mach_task_self(), &m_sema, SYNC_POLICY_FIFO, initialCount); + assert(rc == KERN_SUCCESS); + AE_UNUSED(rc); + } + + AE_NO_TSAN ~Semaphore() { + semaphore_destroy(mach_task_self(), m_sema); + } + + bool wait() AE_NO_TSAN { + return semaphore_wait(m_sema) == KERN_SUCCESS; + } + + bool try_wait() AE_NO_TSAN { + return timed_wait(0); + } + + bool timed_wait(std::uint64_t timeout_usecs) AE_NO_TSAN { + 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() AE_NO_TSAN { + while (semaphore_signal(m_sema) != KERN_SUCCESS) + ; + } + + void signal(int count) AE_NO_TSAN { + 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); + Semaphore& operator=(const Semaphore& other); + +public: + AE_NO_TSAN Semaphore(int initialCount = 0) : m_sema() { + assert(initialCount >= 0); + int rc = sem_init(&m_sema, 0, static_cast<unsigned int>(initialCount)); + assert(rc == 0); + AE_UNUSED(rc); + } + + AE_NO_TSAN ~Semaphore() { + sem_destroy(&m_sema); + } + + bool wait() AE_NO_TSAN { + // 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() AE_NO_TSAN { + int rc; + do { + rc = sem_trywait(&m_sema); + } while (rc == -1 && errno == EINTR); + return rc == 0; + } + + bool timed_wait(std::uint64_t usecs) AE_NO_TSAN { + struct timespec ts; + const int usecs_in_1_sec = 1000000; + const int nsecs_in_1_sec = 1000000000; + clock_gettime(CLOCK_REALTIME, &ts); + ts.tv_sec += static_cast<time_t>(usecs / usecs_in_1_sec); + ts.tv_nsec += static_cast<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 { + rc = sem_timedwait(&m_sema, &ts); + } while (rc == -1 && errno == EINTR); + return rc == 0; + } + + void signal() AE_NO_TSAN { + while (sem_post(&m_sema) == -1) + ; + } + + void signal(int count) AE_NO_TSAN { + while (count-- > 0) { + while (sem_post(&m_sema) == -1) + ; + } + } +}; +#elif defined(FREERTOS) +//--------------------------------------------------------- +// Semaphore (FreeRTOS) +//--------------------------------------------------------- +class Semaphore { +private: + SemaphoreHandle_t m_sema; + + Semaphore(const Semaphore& other); + Semaphore& operator=(const Semaphore& other); + +public: + AE_NO_TSAN Semaphore(int initialCount = 0) : m_sema() { + assert(initialCount >= 0); + m_sema = xSemaphoreCreateCounting(static_cast<UBaseType_t>(~0ull), + static_cast<UBaseType_t>(initialCount)); + assert(m_sema); + } + + AE_NO_TSAN ~Semaphore() { + vSemaphoreDelete(m_sema); + } + + bool wait() AE_NO_TSAN { + return xSemaphoreTake(m_sema, portMAX_DELAY) == pdTRUE; + } + + bool try_wait() AE_NO_TSAN { + // Note: In an ISR context, if this causes a task to unblock, + // the caller won't know about it + if (xPortIsInsideInterrupt()) + return xSemaphoreTakeFromISR(m_sema, NULL) == pdTRUE; + return xSemaphoreTake(m_sema, 0) == pdTRUE; + } + + bool timed_wait(std::uint64_t usecs) AE_NO_TSAN { + std::uint64_t msecs = usecs / 1000; + TickType_t ticks = static_cast<TickType_t>(msecs / portTICK_PERIOD_MS); + if (ticks == 0) + return try_wait(); + return xSemaphoreTake(m_sema, ticks) == pdTRUE; + } + + void signal() AE_NO_TSAN { + // Note: In an ISR context, if this causes a task to unblock, + // the caller won't know about it + BaseType_t rc; + if (xPortIsInsideInterrupt()) + rc = xSemaphoreGiveFromISR(m_sema, NULL); + else + rc = xSemaphoreGive(m_sema); + assert(rc == pdTRUE); + AE_UNUSED(rc); + } + + void signal(int count) AE_NO_TSAN { + while (count-- > 0) + signal(); + } +}; +#else +#error Unsupported platform! (No semaphore wrapper available) +#endif + +//--------------------------------------------------------- +// LightweightSemaphore +//--------------------------------------------------------- +class LightweightSemaphore { +public: + typedef std::make_signed<std::size_t>::type ssize_t; + +private: + weak_atomic<ssize_t> m_count; + Semaphore m_sema; + + bool waitWithPartialSpinning(std::int64_t timeout_usecs = -1) AE_NO_TSAN { + ssize_t oldCount; + // Is there a better way to set the initial spin count? + // If we lower it to 1000, testBenaphore becomes 15x slower on my Core i7-5930K Windows PC, + // as threads start hitting the kernel semaphore. + int spin = 1024; + while (--spin >= 0) { + if (m_count.load() > 0) { + m_count.fetch_add_acquire(-1); + return true; + } + compiler_fence(memory_order_acquire); // Prevent the compiler from collapsing the loop. + } + oldCount = m_count.fetch_add_acquire(-1); + if (oldCount > 0) + return true; + if (timeout_usecs < 0) { + if (m_sema.wait()) + return true; + } + if (timeout_usecs > 0 && m_sema.timed_wait(static_cast<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.fetch_add_release(1); + if (oldCount < 0) + return false; // successfully restored things to the way they were + // Oh, the producer thread just signaled the semaphore after all. Try again: + oldCount = m_count.fetch_add_acquire(-1); + if (oldCount > 0 && m_sema.try_wait()) + return true; + } + } + +public: + AE_NO_TSAN LightweightSemaphore(ssize_t initialCount = 0) : m_count(initialCount), m_sema() { + assert(initialCount >= 0); + } + + bool tryWait() AE_NO_TSAN { + if (m_count.load() > 0) { + m_count.fetch_add_acquire(-1); + return true; + } + return false; + } + + bool wait() AE_NO_TSAN { + return tryWait() || waitWithPartialSpinning(); + } + + bool wait(std::int64_t timeout_usecs) AE_NO_TSAN { + return tryWait() || waitWithPartialSpinning(timeout_usecs); + } + + void signal(ssize_t count = 1) AE_NO_TSAN { + assert(count >= 0); + ssize_t oldCount = m_count.fetch_add_release(count); + assert(oldCount >= -1); + if (oldCount < 0) { + m_sema.signal(1); + } + } + + std::size_t availableApprox() const AE_NO_TSAN { + ssize_t count = m_count.load(); + return count > 0 ? static_cast<std::size_t>(count) : 0; + } +}; +} // namespace spsc_sema +} // namespace Common + +#if defined(AE_VCPP) && (_MSC_VER < 1700 || defined(__cplusplus_cli)) +#pragma warning(pop) +#ifdef __cplusplus_cli +#pragma managed(pop) +#endif +#endif |