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Export of internal Abseil changes

Browse source 
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90ecacd2a3db96ee64ef23af37a80fad404e2b32 by Gennadiy Rozental <rogeeff@google.com>:

Fixes MSVC regression by making MSVC version of class Flag into an aggregate type.

PiperOrigin-RevId: 277767054

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018f3b040df51d91a988fa146fee163721e605e9 by Abseil Team <absl-team@google.com>:

Change libstdc++ lacking std::unique_ptr check from a gcc version check to based on feature macros.

PiperOrigin-RevId: 277736042

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475844775ae343e2414318f08549ee3fa6676a8d by CJ Johnson <johnsoncj@google.com>:

Pass allocator_type through allocator_traits before extracting the typedefs

PiperOrigin-RevId: 277730393

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d843bc4bc30bf5b11af76db8beda8634b6111a62 by Abseil Team <absl-team@google.com>:

Convert the Waiter::Init() method to the default constructor and define
a destructor for the Waiter class.

Use placement new and delete with Waiter objects.

PiperOrigin-RevId: 277728823

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1ba6edf421dd2dfe13c55970a03c99592cb6677d by Derek Mauro <dmauro@google.com>:

Use lowercase spelling for include of dbghelp.h
When cross-compiling under MinGW this is important

PiperOrigin-RevId: 277629783

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cfc662a6fa357a84ddda8037156c7f26cee40c36 by Abseil Team <absl-team@google.com>:

Don't use atomic ops on waiter and wakeup counts in WIN32 waiter mode.

Port the new CONDVAR waiter mode code in CL 277366017 to the WIN32
waiter mode.

PiperOrigin-RevId: 277603611

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833106542e61fa0832900adf3c1b2afc6890b94b by Abseil Team <absl-team@google.com>:

Add the PerThreadSem::Destroy() method.

For ABSL_WAITER_MODE_CONDVAR or ABSL_WAITER_MODE_SEM,
PerThreadSem::Destroy() is used to destroy the pthread mutex and
condition variable or the POSIX semaphore.
PiperOrigin-RevId: 277586675

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7814da4a59106cf1e0e4db1a31b9592ebbd2094b by Samuel Benzaquen <sbenza@google.com>:

Enable the assertion in the iterator's operator* and operator->

PiperOrigin-RevId: 277563401
GitOrigin-RevId: 90ecacd2a3db96ee64ef23af37a80fad404e2b32
Change-Id: Ib19be3680da74f0b94055c9039115ec6bcaea7b0
This commit is contained in:
Abseil Team 2019-10-31 11:37:35 -07:00 • committed by vslashg
parent 83880e3d8c
commit 846e5dbeda
13 changed files with 238 additions and 143 deletions
Download patch file Download diff file Expand all files Collapse all files

77
absl/synchronization/internal/waiter.cc
View file

@ -122,10 +122,12 @@ class Futex {
}
};
void Waiter::Init() {
Waiter::Waiter() {
futex_.store(0, std::memory_order_relaxed);
}
Waiter::~Waiter() = default;
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.
@ -199,7 +201,7 @@ class PthreadMutexHolder {
pthread_mutex_t *mu_;
};
void Waiter::Init() {
Waiter::Waiter() {
const int err = pthread_mutex_init(&mu_, 0);
if (err != 0) {
ABSL_RAW_LOG(FATAL, "pthread_mutex_init failed: %d", err);
@ -214,6 +216,18 @@ void Waiter::Init() {
wakeup_count_ = 0;
}
Waiter::~Waiter() {
const int err = pthread_mutex_destroy(&mu_);
if (err != 0) {
ABSL_RAW_LOG(FATAL, "pthread_mutex_destroy failed: %d", err);
}
const int err2 = pthread_cond_destroy(&cv_);
if (err2 != 0) {
ABSL_RAW_LOG(FATAL, "pthread_cond_destroy failed: %d", err2);
}
}
bool Waiter::Wait(KernelTimeout t) {
struct timespec abs_timeout;
if (t.has_timeout()) {
@ -274,13 +288,19 @@ void Waiter::InternalCondVarPoke() {
#elif ABSL_WAITER_MODE == ABSL_WAITER_MODE_SEM
void Waiter::Init() {
Waiter::Waiter() {
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);
}
Waiter::~Waiter() {
if (sem_destroy(&sem_) != 0) {
ABSL_RAW_LOG(FATAL, "sem_destroy failed with errno %d\n", errno);
}
}
bool Waiter::Wait(KernelTimeout t) {
struct timespec abs_timeout;
if (t.has_timeout()) {
@ -388,39 +408,32 @@ class LockHolder {
SRWLOCK* mu_;
};
void Waiter::Init() {
Waiter::Waiter() {
auto *mu = ::new (static_cast<void *>(&mu_storage_)) SRWLOCK;
auto *cv = ::new (static_cast<void *>(&cv_storage_)) CONDITION_VARIABLE;
InitializeSRWLock(mu);
InitializeConditionVariable(cv);
waiter_count_.store(0, std::memory_order_relaxed);
wakeup_count_.store(0, std::memory_order_relaxed);
waiter_count_ = 0;
wakeup_count_ = 0;
}
// SRW locks and condition variables do not need to be explicitly destroyed.
// https://docs.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-initializesrwlock
// https://stackoverflow.com/questions/28975958/why-does-windows-have-no-deleteconditionvariable-function-to-go-together-with
Waiter::~Waiter() = default;
bool Waiter::Wait(KernelTimeout t) {
SRWLOCK *mu = WinHelper::GetLock(this);
CONDITION_VARIABLE *cv = WinHelper::GetCond(this);
LockHolder h(mu);
waiter_count_.fetch_add(1, std::memory_order_relaxed);
++waiter_count_;
// Loop until we find a wakeup to consume or timeout.
// Note that, since the thread ticker is just reset, we don't need to check
// whether the thread is idle on the very first pass of the loop.
bool first_pass = true;
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;
}
while (wakeup_count_ == 0) {
if (!first_pass) MaybeBecomeIdle();
// No wakeups available, time to wait.
if (!SleepConditionVariableSRW(cv, mu, t.InMillisecondsFromNow(), 0)) {
@ -429,7 +442,7 @@ bool Waiter::Wait(KernelTimeout t) {
// 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);
--waiter_count_;
return false;
} else {
ABSL_RAW_LOG(FATAL, "SleepConditionVariableSRW failed: %lu", err);
@ -437,23 +450,27 @@ bool Waiter::Wait(KernelTimeout t) {
}
first_pass = false;
}
// Consume a wakeup and we're done.
--wakeup_count_;
--waiter_count_;
return true;
}
void Waiter::Post() {
wakeup_count_.fetch_add(1, std::memory_order_release);
Poke();
LockHolder h(WinHelper::GetLock(this));
++wakeup_count_;
InternalCondVarPoke();
}
void Waiter::Poke() {
if (waiter_count_.load(std::memory_order_relaxed) == 0) {
return;
}
// Potentially a waiter. Take the lock and check again.
LockHolder h(WinHelper::GetLock(this));
if (waiter_count_.load(std::memory_order_relaxed) == 0) {
return;
InternalCondVarPoke();
}
void Waiter::InternalCondVarPoke() {
if (waiter_count_ != 0) {
WakeConditionVariable(WinHelper::GetCond(this));
}
WakeConditionVariable(WinHelper::GetCond(this));
}
#else