mirror of
https://github.com/kidfromjupiter/nearby.git
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98 lines
2.4 KiB
C++
98 lines
2.4 KiB
C++
// Copyright 2020 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "internal/platform/cancellation_flag.h"
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#include <memory>
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#include "absl/container/flat_hash_set.h"
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#include "absl/synchronization/mutex.h"
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#include "internal/platform/feature_flags.h"
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namespace nearby {
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CancellationFlag::CancellationFlag() {
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mutex_ = std::make_unique<absl::Mutex>();
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}
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CancellationFlag::CancellationFlag(bool cancelled) {
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mutex_ = std::make_unique<absl::Mutex>();
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cancelled_ = cancelled;
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}
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CancellationFlag::~CancellationFlag() {
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absl::MutexLock lock(*mutex_);
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listeners_.clear();
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}
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void CancellationFlag::Cancel() {
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// Return immediately as no-op if feature flag is not enabled.
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if (!FeatureFlags::GetInstance().GetFlags().enable_cancellation_flag) {
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return;
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}
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absl::flat_hash_set<CancelListener *> listeners;
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{
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absl::MutexLock lock(*mutex_);
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if (cancelled_) {
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// Someone already cancelled. Return immediately.
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return;
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}
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cancelled_ = true;
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listeners = listeners_;
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}
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for (auto *listener : listeners) {
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(*listener)();
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}
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}
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void CancellationFlag::Uncancel() {
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// Return immediately as no-op if feature flag is not enabled.
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if (!FeatureFlags::GetInstance().GetFlags().enable_cancellation_flag) {
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return;
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}
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{
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absl::MutexLock lock(*mutex_);
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assert(cancelled_);
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cancelled_ = false;
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}
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}
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bool CancellationFlag::Cancelled() const {
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absl::MutexLock lock(*mutex_);
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// Return false as no-op if feature flag is not enabled.
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if (!FeatureFlags::GetInstance().GetFlags().enable_cancellation_flag) {
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return false;
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}
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return cancelled_;
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}
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void CancellationFlag::RegisterOnCancelListener(CancelListener *listener) {
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absl::MutexLock lock(*mutex_);
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listeners_.emplace(listener);
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}
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void CancellationFlag::UnregisterOnCancelListener(CancelListener *listener) {
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absl::MutexLock lock(*mutex_);
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listeners_.erase(listener);
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}
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} // namespace nearby
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