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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 <unistd.h>
#include <functional>
#include <mutex>
#include <queue>
#include "common/bind.h"
#include "common/callback.h"
#include "os/handler.h"
#ifdef OS_LINUX_GENERIC
#include "os/linux_generic/reactive_semaphore.h"
#endif
#include "os/log.h"
namespace bluetooth {
namespace os {
// See documentation for |Queue|
template <typename T>
class IQueueEnqueue {
public:
using EnqueueCallback = common::Callback<std::unique_ptr<T>()>;
virtual ~IQueueEnqueue() = default;
virtual void RegisterEnqueue(Handler* handler, EnqueueCallback callback) = 0;
virtual void UnregisterEnqueue() = 0;
};
// See documentation for |Queue|
template <typename T>
class IQueueDequeue {
public:
using DequeueCallback = common::Callback<void()>;
virtual ~IQueueDequeue() = default;
virtual void RegisterDequeue(Handler* handler, DequeueCallback callback) = 0;
virtual void UnregisterDequeue() = 0;
virtual std::unique_ptr<T> TryDequeue() = 0;
};
template <typename T>
class Queue : public IQueueEnqueue<T>, public IQueueDequeue<T> {
public:
// A function moving data from enqueue end buffer to queue, it will be continually be invoked until queue
// is full. Enqueue end should make sure buffer isn't empty and UnregisterEnqueue when buffer become empty.
using EnqueueCallback = common::Callback<std::unique_ptr<T>()>;
// A function moving data form queue to dequeue end buffer, it will be continually be invoked until queue
// is empty. TryDequeue should be use in this function to get data from queue.
using DequeueCallback = common::Callback<void()>;
// Create a queue with |capacity| is the maximum number of messages a queue can contain
explicit Queue(size_t capacity);
~Queue();
// Register |callback| that will be called on |handler| when the queue is able to enqueue one piece of data.
// This will cause a crash if handler or callback has already been registered before.
void RegisterEnqueue(Handler* handler, EnqueueCallback callback) override;
// Unregister current EnqueueCallback from this queue, this will cause a crash if not registered yet.
void UnregisterEnqueue() override;
// Register |callback| that will be called on |handler| when the queue has at least one piece of data ready
// for dequeue. This will cause a crash if handler or callback has already been registered before.
void RegisterDequeue(Handler* handler, DequeueCallback callback) override;
// Unregister current DequeueCallback from this queue, this will cause a crash if not registered yet.
void UnregisterDequeue() override;
// Try to dequeue an item from this queue. Return nullptr when there is nothing in the queue.
std::unique_ptr<T> TryDequeue() override;
private:
void EnqueueCallbackInternal(EnqueueCallback callback);
// An internal queue that holds at most |capacity| pieces of data
std::queue<std::unique_ptr<T>> queue_;
// A mutex that guards data in this queue
std::mutex mutex_;
class QueueEndpoint {
public:
#ifdef OS_LINUX_GENERIC
explicit QueueEndpoint(unsigned int initial_value)
: reactive_semaphore_(initial_value), handler_(nullptr), reactable_(nullptr) {}
ReactiveSemaphore reactive_semaphore_;
#endif
Handler* handler_;
Reactor::Reactable* reactable_;
};
QueueEndpoint enqueue_;
QueueEndpoint dequeue_;
};
template <typename T>
class EnqueueBuffer {
public:
EnqueueBuffer(IQueueEnqueue<T>* queue) : queue_(queue) {}
~EnqueueBuffer() {
if (enqueue_registered_.exchange(false)) {
queue_->UnregisterEnqueue();
}
}
void Enqueue(std::unique_ptr<T> t, os::Handler* handler) {
std::lock_guard<std::mutex> lock(mutex_);
buffer_.push(std::move(t));
if (!enqueue_registered_.exchange(true)) {
queue_->RegisterEnqueue(handler, common::Bind(&EnqueueBuffer<T>::enqueue_callback, common::Unretained(this)));
}
}
void Clear() {
std::lock_guard<std::mutex> lock(mutex_);
if (enqueue_registered_.exchange(false)) {
queue_->UnregisterEnqueue();
std::queue<std::unique_ptr<T>> empty;
std::swap(buffer_, empty);
}
}
auto Size() const {
return buffer_.size();
}
void NotifyOnEmpty(common::OnceClosure callback) {
std::lock_guard<std::mutex> lock(mutex_);
ASSERT(callback_on_empty_.is_null());
callback_on_empty_ = std::move(callback);
}
private:
std::unique_ptr<T> enqueue_callback() {
std::lock_guard<std::mutex> lock(mutex_);
std::unique_ptr<T> enqueued_t = std::move(buffer_.front());
buffer_.pop();
if (buffer_.empty() && enqueue_registered_.exchange(false)) {
queue_->UnregisterEnqueue();
if (!callback_on_empty_.is_null()) {
std::move(callback_on_empty_).Run();
}
}
return enqueued_t;
}
mutable std::mutex mutex_;
IQueueEnqueue<T>* queue_;
std::atomic_bool enqueue_registered_ = false;
std::queue<std::unique_ptr<T>> buffer_;
common::OnceClosure callback_on_empty_;
};
#ifdef OS_LINUX_GENERIC
#include "os/linux_generic/queue.tpp"
#endif
} // namespace os
} // namespace bluetooth
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