| // Copyright 2020 Google LLC |
| // |
| // 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 |
| // |
| // 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. |
| |
| #ifndef LOCATION_NEARBY_CPP_PLATFORM_PUBLIC_SETTABLE_FUTURE_H_ |
| #define LOCATION_NEARBY_CPP_PLATFORM_PUBLIC_SETTABLE_FUTURE_H_ |
| |
| #include <utility> |
| |
| #include "platform/public/condition_variable.h" |
| #include "platform/public/mutex.h" |
| #include "platform/public/mutex_lock.h" |
| #include "platform/public/system_clock.h" |
| |
| namespace location { |
| namespace nearby { |
| |
| template <typename T> |
| class SettableFuture : public api::SettableFuture<T> { |
| public: |
| SettableFuture() = default; |
| ~SettableFuture() override = default; |
| |
| bool Set(T value) override { |
| MutexLock lock(&mutex_); |
| if (!done_) { |
| value_ = std::move(value); |
| done_ = true; |
| exception_ = {Exception::kSuccess}; |
| completed_.Notify(); |
| InvokeAllLocked(); |
| return true; |
| } |
| return false; |
| } |
| |
| void AddListener(Runnable runnable, api::Executor* executor) override { |
| MutexLock lock(&mutex_); |
| if (done_) { |
| executor->Execute(std::move(runnable)); |
| } else { |
| listeners_.emplace_back(std::make_pair(executor, std::move(runnable))); |
| } |
| } |
| |
| bool IsSet() const { |
| MutexLock lock(&mutex_); |
| return done_; |
| } |
| |
| bool SetException(Exception exception) override { |
| MutexLock lock(&mutex_); |
| return SetExceptionLocked(exception); |
| } |
| |
| ExceptionOr<T> Get() override { |
| MutexLock lock(&mutex_); |
| while (!done_) { |
| completed_.Wait(); |
| } |
| return exception_.value != Exception::kSuccess |
| ? ExceptionOr<T>{exception_.value} |
| : ExceptionOr<T>{value_}; |
| } |
| |
| ExceptionOr<T> Get(absl::Duration timeout) override { |
| MutexLock lock(&mutex_); |
| while (!done_) { |
| absl::Time start_time = SystemClock::ElapsedRealtime(); |
| if (completed_.Wait(timeout).Raised(Exception::kInterrupted)) { |
| SetExceptionLocked({Exception::kInterrupted}); |
| break; |
| } |
| absl::Duration spent = SystemClock::ElapsedRealtime() - start_time; |
| if (spent < timeout) { |
| timeout -= spent; |
| } else if (!done_) { |
| SetExceptionLocked({Exception::kTimeout}); |
| break; |
| } |
| } |
| return exception_.value != Exception::kSuccess |
| ? ExceptionOr<T>{exception_.value} |
| : ExceptionOr<T>{value_}; |
| } |
| |
| private: |
| bool SetExceptionLocked(Exception exception) { |
| if (!done_) { |
| exception_ = exception.value != Exception::kSuccess |
| ? exception |
| : Exception{Exception::kFailed}; |
| done_ = true; |
| completed_.Notify(); |
| InvokeAllLocked(); |
| } |
| return true; |
| } |
| |
| void InvokeAllLocked() { |
| for (auto& item : listeners_) { |
| item.first->Execute(std::move(item.second)); |
| } |
| listeners_.clear(); |
| } |
| |
| mutable Mutex mutex_; |
| ConditionVariable completed_{&mutex_}; |
| std::vector<std::pair<api::Executor*, std::function<void()>>> listeners_; |
| bool done_{false}; |
| T value_; |
| Exception exception_{Exception::kFailed}; |
| }; |
| |
| } // namespace nearby |
| } // namespace location |
| |
| #endif // LOCATION_NEARBY_CPP_PLATFORM_PUBLIC_SETTABLE_FUTURE_H_ |