tvl-depot/absl/synchronization/internal/waiter.cc

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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
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//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "absl/synchronization/internal/waiter.h"
#include "absl/base/config.h"
#ifdef _WIN32
#include <windows.h>
#else
#include <pthread.h>
#include <sys/time.h>
#include <unistd.h>
#endif
#ifdef __linux__
#include <linux/futex.h>
#include <sys/syscall.h>
#endif
#ifdef ABSL_HAVE_SEMAPHORE_H
#include <semaphore.h>
#endif
#include <errno.h>
#include <stdio.h>
#include <time.h>
#include <atomic>
#include <cassert>
#include <cstdint>
#include <new>
#include <type_traits>
Export of internal Abseil changes. -- bdce7e57e9e886eff1114d0266781b443f7ec639 by Derek Mauro <dmauro@google.com>: Change {Get|Set}EnvironmentVariable to {Get|Set}EnvironmentVariableA for compatibility with /DUNICODE. PiperOrigin-RevId: 239229514 -- 2276ed502326a044a84060d34eb19d499e3a3be2 by Derek Mauro <dmauro@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 239228622 -- a462efb970ff43b08a362ef2343fb75ac1295a50 by Derek Mauro <dmauro@google.com>: Adding linking of CoreFoundation to CMakeLists in absl/time. Import https://github.com/abseil/abseil-cpp/pull/280. Fix #283 PiperOrigin-RevId: 239220785 -- fc23327b97f940c682aae1956cf7a1bf87f88c06 by Derek Mauro <dmauro@google.com>: Add hermetic test script that uses Docker to build with a very recent version of gcc (8.3.0 today) with libstdc++ and bazel. PiperOrigin-RevId: 239220448 -- 418c08a8f6a53e63b84e39473035774417ca3aa7 by Derek Mauro <dmauro@google.com>: Disable part of the variant exeception safety test on move assignment when using versions of libstd++ that contain a bug. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87431#c7 PiperOrigin-RevId: 239062455 -- 799722217aeda79679577843c91d5be62cbcbb42 by Matt Calabrese <calabrese@google.com>: Add internal-only IsSwappable traits corresponding to std::is_swappable and std::is_nothrow_swappable, which are used with the swap implementations of optional and variant. PiperOrigin-RevId: 239049448 -- aa46a036038a3de5c68ac5e5d3b4bf76f818d2ea by CJ Johnson <johnsoncj@google.com>: Make InlinedVectorStorage constructor explicit PiperOrigin-RevId: 239044361 -- 17949715b3aa21c794701f69f2154e91b6acabc3 by CJ Johnson <johnsoncj@google.com>: Add absl namesapce to internal/inlined_vector.h PiperOrigin-RevId: 239030789 -- 834628325953078cc08ed10d23bb8890e5bec897 by Derek Mauro <dmauro@google.com>: Add test script that uses Docker to build Abseil with gcc-4.8, libstdc++, and cmake. PiperOrigin-RevId: 239028433 -- 80fe24149ed73ed2ced995ad1e372fb060c60427 by CJ Johnson <johnsoncj@google.com>: Factors data members of InlinedVector into an impl type called InlinedVectorStorage so that (in future changes) the contents of a vector can be grouped together with a single pointer. PiperOrigin-RevId: 239021086 -- 585331436d5d4d79f845e45dcf79d918a0dc6169 by Derek Mauro <dmauro@google.com>: Add -Wno-missing-field-initializers to gcc compiler flags. gcc-4.x has spurious missing field initializer warnings. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36750 PiperOrigin-RevId: 239017217 -- 94602fe4e33ee3a552a7f2939c0f57a992f55075 by Abseil Team <absl-team@google.com>: Formatting fixes. PiperOrigin-RevId: 238983038 -- a1c1b63c08505574e0a8c491561840cecb2bb93e by Derek Mauro <dmauro@google.com>: Add hermetic test script that uses Docker to build with a very recent version of clang with libc++ and bazel. PiperOrigin-RevId: 238669118 -- e525f8d20bc2f79a0d69336b902f63858f3bff9d by Derek Mauro <dmauro@google.com>: Disable the test optionalTest.InPlaceTSFINAEBug until libc++ is updated. PiperOrigin-RevId: 238661703 -- f99a2a0b5ec424a059678f7f226600f137b4c74e by Derek Mauro <dmauro@google.com>: Correct the check for the FlatHashMap-Any test bug (list conditions instead of platforms when possible) PiperOrigin-RevId: 238653344 -- 777928035dbcbf39f361eb7d10dc3696822f692f by Jon Cohen <cohenjon@google.com>: Add install rules for Abseil CMake. These are attempted to be limited to in-project installation. This serves two purposes -- first it's morally the same as using Abseil in-source, except you don't have to rebuild us every time. Second, the presence of an install rule makes life massively simpler for package manager maintainers. Currently this doesn't install absl tests or testonly libraries. This can be added in a follow-up patch. Fixes #38, Fixes #80, Closes #182 PiperOrigin-RevId: 238645836 -- ded1c6ce697c191b7a6ff14572b3e6d183117b2c by Derek Mauro <dmauro@google.com>: Add hermetic test script that uses Docker to build with a very recent version of clang with libstdc++ and bazel. PiperOrigin-RevId: 238517815 GitOrigin-RevId: bdce7e57e9e886eff1114d0266781b443f7ec639 Change-Id: I6f745869cb8ef63851891ccac05ae9a7dd241c4f
2019-03-19 19:14:01 +01:00
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#include "absl/base/internal/raw_logging.h"
#include "absl/base/internal/thread_identity.h"
#include "absl/base/optimization.h"
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#include "absl/synchronization/internal/kernel_timeout.h"
namespace absl {
namespace synchronization_internal {
static void MaybeBecomeIdle() {
base_internal::ThreadIdentity *identity =
base_internal::CurrentThreadIdentityIfPresent();
assert(identity != nullptr);
const bool is_idle = identity->is_idle.load(std::memory_order_relaxed);
const int ticker = identity->ticker.load(std::memory_order_relaxed);
const int wait_start = identity->wait_start.load(std::memory_order_relaxed);
if (!is_idle && ticker - wait_start > Waiter::kIdlePeriods) {
identity->is_idle.store(true, std::memory_order_relaxed);
}
}
#if ABSL_WAITER_MODE == ABSL_WAITER_MODE_FUTEX
// Some Android headers are missing these definitions even though they
// support these futex operations.
#ifdef __BIONIC__
#ifndef SYS_futex
#define SYS_futex __NR_futex
#endif
#ifndef FUTEX_WAIT_BITSET
#define FUTEX_WAIT_BITSET 9
#endif
#ifndef FUTEX_PRIVATE_FLAG
#define FUTEX_PRIVATE_FLAG 128
#endif
#ifndef FUTEX_CLOCK_REALTIME
#define FUTEX_CLOCK_REALTIME 256
#endif
#ifndef FUTEX_BITSET_MATCH_ANY
#define FUTEX_BITSET_MATCH_ANY 0xFFFFFFFF
#endif
#endif
Export of internal Abseil changes. -- bdce7e57e9e886eff1114d0266781b443f7ec639 by Derek Mauro <dmauro@google.com>: Change {Get|Set}EnvironmentVariable to {Get|Set}EnvironmentVariableA for compatibility with /DUNICODE. PiperOrigin-RevId: 239229514 -- 2276ed502326a044a84060d34eb19d499e3a3be2 by Derek Mauro <dmauro@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 239228622 -- a462efb970ff43b08a362ef2343fb75ac1295a50 by Derek Mauro <dmauro@google.com>: Adding linking of CoreFoundation to CMakeLists in absl/time. Import https://github.com/abseil/abseil-cpp/pull/280. Fix #283 PiperOrigin-RevId: 239220785 -- fc23327b97f940c682aae1956cf7a1bf87f88c06 by Derek Mauro <dmauro@google.com>: Add hermetic test script that uses Docker to build with a very recent version of gcc (8.3.0 today) with libstdc++ and bazel. PiperOrigin-RevId: 239220448 -- 418c08a8f6a53e63b84e39473035774417ca3aa7 by Derek Mauro <dmauro@google.com>: Disable part of the variant exeception safety test on move assignment when using versions of libstd++ that contain a bug. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87431#c7 PiperOrigin-RevId: 239062455 -- 799722217aeda79679577843c91d5be62cbcbb42 by Matt Calabrese <calabrese@google.com>: Add internal-only IsSwappable traits corresponding to std::is_swappable and std::is_nothrow_swappable, which are used with the swap implementations of optional and variant. PiperOrigin-RevId: 239049448 -- aa46a036038a3de5c68ac5e5d3b4bf76f818d2ea by CJ Johnson <johnsoncj@google.com>: Make InlinedVectorStorage constructor explicit PiperOrigin-RevId: 239044361 -- 17949715b3aa21c794701f69f2154e91b6acabc3 by CJ Johnson <johnsoncj@google.com>: Add absl namesapce to internal/inlined_vector.h PiperOrigin-RevId: 239030789 -- 834628325953078cc08ed10d23bb8890e5bec897 by Derek Mauro <dmauro@google.com>: Add test script that uses Docker to build Abseil with gcc-4.8, libstdc++, and cmake. PiperOrigin-RevId: 239028433 -- 80fe24149ed73ed2ced995ad1e372fb060c60427 by CJ Johnson <johnsoncj@google.com>: Factors data members of InlinedVector into an impl type called InlinedVectorStorage so that (in future changes) the contents of a vector can be grouped together with a single pointer. PiperOrigin-RevId: 239021086 -- 585331436d5d4d79f845e45dcf79d918a0dc6169 by Derek Mauro <dmauro@google.com>: Add -Wno-missing-field-initializers to gcc compiler flags. gcc-4.x has spurious missing field initializer warnings. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36750 PiperOrigin-RevId: 239017217 -- 94602fe4e33ee3a552a7f2939c0f57a992f55075 by Abseil Team <absl-team@google.com>: Formatting fixes. PiperOrigin-RevId: 238983038 -- a1c1b63c08505574e0a8c491561840cecb2bb93e by Derek Mauro <dmauro@google.com>: Add hermetic test script that uses Docker to build with a very recent version of clang with libc++ and bazel. PiperOrigin-RevId: 238669118 -- e525f8d20bc2f79a0d69336b902f63858f3bff9d by Derek Mauro <dmauro@google.com>: Disable the test optionalTest.InPlaceTSFINAEBug until libc++ is updated. PiperOrigin-RevId: 238661703 -- f99a2a0b5ec424a059678f7f226600f137b4c74e by Derek Mauro <dmauro@google.com>: Correct the check for the FlatHashMap-Any test bug (list conditions instead of platforms when possible) PiperOrigin-RevId: 238653344 -- 777928035dbcbf39f361eb7d10dc3696822f692f by Jon Cohen <cohenjon@google.com>: Add install rules for Abseil CMake. These are attempted to be limited to in-project installation. This serves two purposes -- first it's morally the same as using Abseil in-source, except you don't have to rebuild us every time. Second, the presence of an install rule makes life massively simpler for package manager maintainers. Currently this doesn't install absl tests or testonly libraries. This can be added in a follow-up patch. Fixes #38, Fixes #80, Closes #182 PiperOrigin-RevId: 238645836 -- ded1c6ce697c191b7a6ff14572b3e6d183117b2c by Derek Mauro <dmauro@google.com>: Add hermetic test script that uses Docker to build with a very recent version of clang with libstdc++ and bazel. PiperOrigin-RevId: 238517815 GitOrigin-RevId: bdce7e57e9e886eff1114d0266781b443f7ec639 Change-Id: I6f745869cb8ef63851891ccac05ae9a7dd241c4f
2019-03-19 19:14:01 +01:00
class Futex {
public:
static int WaitUntil(std::atomic<int32_t> *v, int32_t val,
KernelTimeout t) {
int err = 0;
if (t.has_timeout()) {
// https://locklessinc.com/articles/futex_cheat_sheet/
// Unlike FUTEX_WAIT, FUTEX_WAIT_BITSET uses absolute time.
struct timespec abs_timeout = t.MakeAbsTimespec();
// Atomically check that the futex value is still 0, and if it
// is, sleep until abs_timeout or until woken by FUTEX_WAKE.
err = syscall(
SYS_futex, reinterpret_cast<int32_t *>(v),
FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME, val,
&abs_timeout, nullptr, FUTEX_BITSET_MATCH_ANY);
} else {
// Atomically check that the futex value is still 0, and if it
// is, sleep until woken by FUTEX_WAKE.
err = syscall(SYS_futex, reinterpret_cast<int32_t *>(v),
FUTEX_WAIT | FUTEX_PRIVATE_FLAG, val, nullptr);
}
if (err != 0) {
err = -errno;
}
return err;
}
static int Wake(std::atomic<int32_t> *v, int32_t count) {
int err = syscall(SYS_futex, reinterpret_cast<int32_t *>(v),
FUTEX_WAKE | FUTEX_PRIVATE_FLAG, count);
if (ABSL_PREDICT_FALSE(err < 0)) {
err = -errno;
}
return err;
}
};
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void Waiter::Init() {
futex_.store(0, std::memory_order_relaxed);
}
bool Waiter::Wait(KernelTimeout t) {
// Loop until we can atomically decrement futex from a positive
// value, waiting on a futex while we believe it is zero.
while (true) {
int32_t x = futex_.load(std::memory_order_relaxed);
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if (x != 0) {
if (!futex_.compare_exchange_weak(x, x - 1,
std::memory_order_acquire,
std::memory_order_relaxed)) {
continue; // Raced with someone, retry.
}
return true; // Consumed a wakeup, we are done.
}
const int err = Futex::WaitUntil(&futex_, 0, t);
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if (err != 0) {
if (err == -EINTR || err == -EWOULDBLOCK) {
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// Do nothing, the loop will retry.
} else if (err == -ETIMEDOUT) {
return false;
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} else {
ABSL_RAW_LOG(FATAL, "Futex operation failed with error %d\n", err);
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}
}
MaybeBecomeIdle();
}
}
void Waiter::Post() {
if (futex_.fetch_add(1, std::memory_order_release) == 0) {
// We incremented from 0, need to wake a potential waker.
Poke();
}
}
void Waiter::Poke() {
// Wake one thread waiting on the futex.
const int err = Futex::Wake(&futex_, 1);
if (ABSL_PREDICT_FALSE(err < 0)) {
ABSL_RAW_LOG(FATAL, "Futex operation failed with error %d\n", err);
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}
}
#elif ABSL_WAITER_MODE == ABSL_WAITER_MODE_CONDVAR
class PthreadMutexHolder {
public:
explicit PthreadMutexHolder(pthread_mutex_t *mu) : mu_(mu) {
const int err = pthread_mutex_lock(mu_);
if (err != 0) {
ABSL_RAW_LOG(FATAL, "pthread_mutex_lock failed: %d", err);
}
}
PthreadMutexHolder(const PthreadMutexHolder &rhs) = delete;
PthreadMutexHolder &operator=(const PthreadMutexHolder &rhs) = delete;
~PthreadMutexHolder() {
const int err = pthread_mutex_unlock(mu_);
if (err != 0) {
ABSL_RAW_LOG(FATAL, "pthread_mutex_unlock failed: %d", err);
}
}
private:
pthread_mutex_t *mu_;
};
void Waiter::Init() {
const int err = pthread_mutex_init(&mu_, 0);
if (err != 0) {
ABSL_RAW_LOG(FATAL, "pthread_mutex_init failed: %d", err);
}
const int err2 = pthread_cond_init(&cv_, 0);
if (err2 != 0) {
ABSL_RAW_LOG(FATAL, "pthread_cond_init failed: %d", err2);
}
waiter_count_.store(0, std::memory_order_relaxed);
wakeup_count_.store(0, std::memory_order_relaxed);
}
bool Waiter::Wait(KernelTimeout t) {
struct timespec abs_timeout;
if (t.has_timeout()) {
abs_timeout = t.MakeAbsTimespec();
}
PthreadMutexHolder h(&mu_);
waiter_count_.fetch_add(1, std::memory_order_relaxed);
// Loop until we find a wakeup to consume or timeout.
while (true) {
int x = wakeup_count_.load(std::memory_order_relaxed);
if (x != 0) {
if (!wakeup_count_.compare_exchange_weak(x, x - 1,
std::memory_order_acquire,
std::memory_order_relaxed)) {
continue; // Raced with someone, retry.
}
// Successfully consumed a wakeup, we're done.
waiter_count_.fetch_sub(1, std::memory_order_relaxed);
return true;
}
// No wakeups available, time to wait.
if (!t.has_timeout()) {
const int err = pthread_cond_wait(&cv_, &mu_);
if (err != 0) {
ABSL_RAW_LOG(FATAL, "pthread_cond_wait failed: %d", err);
}
} else {
const int err = pthread_cond_timedwait(&cv_, &mu_, &abs_timeout);
if (err == ETIMEDOUT) {
waiter_count_.fetch_sub(1, std::memory_order_relaxed);
return false;
}
if (err != 0) {
ABSL_RAW_LOG(FATAL, "pthread_cond_wait failed: %d", err);
}
}
MaybeBecomeIdle();
}
}
void Waiter::Post() {
wakeup_count_.fetch_add(1, std::memory_order_release);
Poke();
}
void Waiter::Poke() {
if (waiter_count_.load(std::memory_order_relaxed) == 0) {
return;
}
// Potentially a waker. Take the lock and check again.
PthreadMutexHolder h(&mu_);
if (waiter_count_.load(std::memory_order_relaxed) == 0) {
return;
}
const int err = pthread_cond_signal(&cv_);
if (err != 0) {
ABSL_RAW_LOG(FATAL, "pthread_cond_signal failed: %d", err);
}
}
#elif ABSL_WAITER_MODE == ABSL_WAITER_MODE_SEM
void Waiter::Init() {
if (sem_init(&sem_, 0, 0) != 0) {
ABSL_RAW_LOG(FATAL, "sem_init failed with errno %d\n", errno);
}
wakeups_.store(0, std::memory_order_relaxed);
}
bool Waiter::Wait(KernelTimeout t) {
struct timespec abs_timeout;
if (t.has_timeout()) {
abs_timeout = t.MakeAbsTimespec();
}
// Loop until we timeout or consume a wakeup.
while (true) {
int x = wakeups_.load(std::memory_order_relaxed);
if (x != 0) {
if (!wakeups_.compare_exchange_weak(x, x - 1,
std::memory_order_acquire,
std::memory_order_relaxed)) {
continue; // Raced with someone, retry.
}
// Successfully consumed a wakeup, we're done.
return true;
}
// Nothing to consume, wait (looping on EINTR).
while (true) {
if (!t.has_timeout()) {
if (sem_wait(&sem_) == 0) break;
if (errno == EINTR) continue;
ABSL_RAW_LOG(FATAL, "sem_wait failed: %d", errno);
} else {
if (sem_timedwait(&sem_, &abs_timeout) == 0) break;
if (errno == EINTR) continue;
if (errno == ETIMEDOUT) return false;
ABSL_RAW_LOG(FATAL, "sem_timedwait failed: %d", errno);
}
}
MaybeBecomeIdle();
}
}
void Waiter::Post() {
wakeups_.fetch_add(1, std::memory_order_release); // Post a wakeup.
Poke();
}
void Waiter::Poke() {
if (sem_post(&sem_) != 0) { // Wake any semaphore waiter.
ABSL_RAW_LOG(FATAL, "sem_post failed with errno %d\n", errno);
}
}
#elif ABSL_WAITER_MODE == ABSL_WAITER_MODE_WIN32
class Waiter::WinHelper {
public:
static SRWLOCK *GetLock(Waiter *w) {
return reinterpret_cast<SRWLOCK *>(&w->mu_storage_);
}
static CONDITION_VARIABLE *GetCond(Waiter *w) {
return reinterpret_cast<CONDITION_VARIABLE *>(&w->cv_storage_);
}
static_assert(sizeof(SRWLOCK) == sizeof(Waiter::SRWLockStorage),
"SRWLockStorage does not have the same size as SRWLOCK");
static_assert(
alignof(SRWLOCK) == alignof(Waiter::SRWLockStorage),
"SRWLockStorage does not have the same alignment as SRWLOCK");
static_assert(sizeof(CONDITION_VARIABLE) ==
sizeof(Waiter::ConditionVariableStorage),
"ABSL_CONDITION_VARIABLE_STORAGE does not have the same size "
"as CONDITION_VARIABLE");
static_assert(alignof(CONDITION_VARIABLE) ==
alignof(Waiter::ConditionVariableStorage),
"ConditionVariableStorage does not have the same "
"alignment as CONDITION_VARIABLE");
// The SRWLOCK and CONDITION_VARIABLE types must be trivially constuctible
// and destructible because we never call their constructors or destructors.
static_assert(std::is_trivially_constructible<SRWLOCK>::value,
"The SRWLOCK type must be trivially constructible");
static_assert(std::is_trivially_constructible<CONDITION_VARIABLE>::value,
"The CONDITION_VARIABLE type must be trivially constructible");
static_assert(std::is_trivially_destructible<SRWLOCK>::value,
"The SRWLOCK type must be trivially destructible");
static_assert(std::is_trivially_destructible<CONDITION_VARIABLE>::value,
"The CONDITION_VARIABLE type must be trivially destructible");
};
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class LockHolder {
public:
explicit LockHolder(SRWLOCK* mu) : mu_(mu) {
AcquireSRWLockExclusive(mu_);
}
LockHolder(const LockHolder&) = delete;
LockHolder& operator=(const LockHolder&) = delete;
~LockHolder() {
ReleaseSRWLockExclusive(mu_);
}
private:
SRWLOCK* mu_;
};
void Waiter::Init() {
auto *mu = ::new (static_cast<void *>(&mu_storage_)) SRWLOCK;
auto *cv = ::new (static_cast<void *>(&cv_storage_)) CONDITION_VARIABLE;
InitializeSRWLock(mu);
InitializeConditionVariable(cv);
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waiter_count_.store(0, std::memory_order_relaxed);
wakeup_count_.store(0, std::memory_order_relaxed);
}
bool Waiter::Wait(KernelTimeout t) {
SRWLOCK *mu = WinHelper::GetLock(this);
CONDITION_VARIABLE *cv = WinHelper::GetCond(this);
LockHolder h(mu);
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waiter_count_.fetch_add(1, std::memory_order_relaxed);
// Loop until we find a wakeup to consume or timeout.
while (true) {
int x = wakeup_count_.load(std::memory_order_relaxed);
if (x != 0) {
if (!wakeup_count_.compare_exchange_weak(x, x - 1,
std::memory_order_acquire,
std::memory_order_relaxed)) {
continue; // Raced with someone, retry.
}
// Successfully consumed a wakeup, we're done.
waiter_count_.fetch_sub(1, std::memory_order_relaxed);
return true;
}
// No wakeups available, time to wait.
if (!SleepConditionVariableSRW(cv, mu, t.InMillisecondsFromNow(), 0)) {
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// GetLastError() returns a Win32 DWORD, but we assign to
// unsigned long to simplify the ABSL_RAW_LOG case below. The uniform
// initialization guarantees this is not a narrowing conversion.
const unsigned long err{GetLastError()}; // NOLINT(runtime/int)
if (err == ERROR_TIMEOUT) {
waiter_count_.fetch_sub(1, std::memory_order_relaxed);
return false;
} else {
ABSL_RAW_LOG(FATAL, "SleepConditionVariableSRW failed: %lu", err);
}
}
MaybeBecomeIdle();
}
}
void Waiter::Post() {
wakeup_count_.fetch_add(1, std::memory_order_release);
Poke();
}
void Waiter::Poke() {
if (waiter_count_.load(std::memory_order_relaxed) == 0) {
return;
}
// Potentially a waker. Take the lock and check again.
LockHolder h(WinHelper::GetLock(this));
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if (waiter_count_.load(std::memory_order_relaxed) == 0) {
return;
}
WakeConditionVariable(WinHelper::GetCond(this));
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}
#else
#error Unknown ABSL_WAITER_MODE
#endif
} // namespace synchronization_internal
} // namespace absl