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/*
* Copyright 2019 The Android Open Source Project
*
* 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
*
* http://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.
*/
#pragma once
#include <grpc++/grpc++.h>
#include <atomic>
#include <chrono>
#include <utility>
#include "blueberry/facade/common.pb.h"
#include "common/blocking_queue.h"
#include "os/log.h"
namespace bluetooth {
namespace grpc {
template <typename T>
class GrpcEventQueue {
public:
/**
* Create a GrpcEventQueue that can be used to shuffle event from one thread to another
* @param log_name
*/
explicit GrpcEventQueue(std::string log_name) : log_name_(std::move(log_name)){};
/**
* Run the event loop and blocks until client cancels the stream request
* Event queue will be cleared before entering the loop. Hence, only events occurred after gRPC request will be
* delivered to the user. Hence user is advised to run the loop before generating pending events.
*
* @param context client context
* @param writer output writer
* @return gRPC status
*/
::grpc::Status RunLoop(::grpc::ServerContext* context, ::grpc::ServerWriter<T>* writer) {
using namespace std::chrono_literals;
LOG_INFO("%s: Entering Loop", log_name_.c_str());
while (!context->IsCancelled()) {
// Wait for 100 ms so that cancellation can be caught in amortized 50 ms latency
if (pending_events_.wait_to_take(100ms)) {
LOG_INFO("%s: Got event from queue", log_name_.c_str());
writer->Write(pending_events_.take());
}
}
running_ = false;
LOG_INFO("%s: Exited Loop", log_name_.c_str());
return ::grpc::Status::OK;
}
/**
* Called when there is an incoming event
* @param event incoming event
*/
void OnIncomingEvent(T event) {
if (!running_) {
LOG_INFO("%s: Discarding an event while not running the loop", log_name_.c_str());
return;
}
LOG_INFO("%s: Got event, enqueuing", log_name_.c_str());
pending_events_.push(std::move(event));
}
private:
std::string log_name_;
std::atomic<bool> running_{true};
common::BlockingQueue<T> pending_events_;
};
} // namespace grpc
} // namespace bluetooth
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