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https://github.com/flutter/flutter.git
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e356dbca2c
When flutter/synchronization was first authored, we did not own fml (it was called fxl then). Now we do, so use a single spot for such utilities. The pipeline was meant to be a general purpose utility that was only ever used by the animator (it even has animator specific tracing), so move that to shell instead (where the animator resides).
166 lines
3.0 KiB
C++
166 lines
3.0 KiB
C++
// Copyright 2013 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "flutter/fml/synchronization/semaphore.h"
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#include "flutter/fml/build_config.h"
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#include "flutter/fml/logging.h"
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#if OS_MACOSX
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#include <dispatch/dispatch.h>
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namespace fml {
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class PlatformSemaphore {
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public:
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explicit PlatformSemaphore(uint32_t count)
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: _sem(dispatch_semaphore_create(count)), _initial(count) {}
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~PlatformSemaphore() {
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for (uint32_t i = 0; i < _initial; ++i) {
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Signal();
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}
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if (_sem != nullptr) {
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dispatch_release(reinterpret_cast<dispatch_object_t>(_sem));
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_sem = nullptr;
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}
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}
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bool IsValid() const { return _sem != nullptr; }
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bool TryWait() {
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if (_sem == nullptr) {
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return false;
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}
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return dispatch_semaphore_wait(_sem, DISPATCH_TIME_NOW) == 0;
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}
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void Signal() {
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if (_sem != nullptr) {
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dispatch_semaphore_signal(_sem);
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}
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}
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private:
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dispatch_semaphore_t _sem;
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const uint32_t _initial;
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FML_DISALLOW_COPY_AND_ASSIGN(PlatformSemaphore);
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};
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} // namespace fml
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#elif OS_WIN
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#include <windows.h>
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namespace fml {
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class PlatformSemaphore {
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public:
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explicit PlatformSemaphore(uint32_t count)
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: _sem(CreateSemaphore(NULL, count, LONG_MAX, NULL)) {}
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~PlatformSemaphore() {
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if (_sem != nullptr) {
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CloseHandle(_sem);
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_sem = nullptr;
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}
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}
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bool IsValid() const { return _sem != nullptr; }
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bool TryWait() {
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if (_sem == nullptr) {
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return false;
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}
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return WaitForSingleObject(_sem, 0) == WAIT_OBJECT_0;
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}
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void Signal() {
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if (_sem != nullptr) {
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ReleaseSemaphore(_sem, 1, NULL);
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}
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}
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private:
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HANDLE _sem;
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FML_DISALLOW_COPY_AND_ASSIGN(PlatformSemaphore);
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};
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} // namespace fml
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#else
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#include <semaphore.h>
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#include "flutter/fml/eintr_wrapper.h"
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namespace fml {
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class PlatformSemaphore {
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public:
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explicit PlatformSemaphore(uint32_t count)
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: valid_(::sem_init(&sem_, 0 /* not shared */, count) == 0) {}
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~PlatformSemaphore() {
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if (valid_) {
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int result = ::sem_destroy(&sem_);
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// Can only be EINVAL which should not be possible since we checked for
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// validity.
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FML_DCHECK(result == 0);
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}
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}
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bool IsValid() const { return valid_; }
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bool TryWait() {
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if (!valid_) {
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return false;
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}
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return FML_HANDLE_EINTR(::sem_trywait(&sem_)) == 0;
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}
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void Signal() {
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if (!valid_) {
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return;
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}
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::sem_post(&sem_);
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return;
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}
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private:
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bool valid_;
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sem_t sem_;
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FML_DISALLOW_COPY_AND_ASSIGN(PlatformSemaphore);
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};
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} // namespace fml
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#endif
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namespace fml {
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Semaphore::Semaphore(uint32_t count) : _impl(new PlatformSemaphore(count)) {}
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Semaphore::~Semaphore() = default;
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bool Semaphore::IsValid() const {
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return _impl->IsValid();
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}
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bool Semaphore::TryWait() {
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return _impl->TryWait();
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}
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void Semaphore::Signal() {
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return _impl->Signal();
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}
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} // namespace fml
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