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// Copyright 2023 The Pigweed Authors
//
// 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.
#pragma once
#include <mutex>
#include "pw_bytes/span.h"
#include "pw_containers/intrusive_list.h"
#include "pw_result/result.h"
#include "pw_span/span.h"
#include "pw_status/status.h"
#include "pw_sync/lock_annotations.h"
#include "pw_sync/mutex.h"
namespace pw::rpc::internal {
// A simple thread-safe FIFO for queueing packets. Used by LocalRpcEgress to
// decouple receiving locally-destined RPC packets from their processing.
template <size_t kMaxPacketSize>
class PacketBufferQueue {
public:
class PacketBuffer : public IntrusiveList<PacketBuffer>::Item {
public:
Status CopyPacket(ConstByteSpan packet) {
if (packet.size() > buffer_.size()) {
return Status::ResourceExhausted();
}
std::copy(packet.begin(), packet.end(), buffer_.begin());
size_ = packet.size();
return OkStatus();
}
Result<ConstByteSpan> GetPacket() {
auto buffer_span = span(buffer_);
return buffer_span.first(size_);
}
protected:
friend PacketBufferQueue;
private:
std::array<std::byte, kMaxPacketSize> buffer_ = {};
size_t size_ = 0;
};
PacketBufferQueue() = default;
explicit PacketBufferQueue(span<PacketBuffer> packets) {
for (auto& packet : packets) {
packet_list_.push_back(packet);
}
}
// Push a packet to the end of the queue.
void Push(PacketBuffer& packet) {
const LockGuard guard(lock_);
packet_list_.push_back(packet);
}
// Pop a packet from the head of the queue.
// Returns a pointer to the packet popped from the queue, or
// ResourceExhausted() if the queue is empty.
Result<PacketBuffer*> Pop() {
const LockGuard lock(lock_);
if (packet_list_.empty()) {
return Status::ResourceExhausted();
}
// Return the first available packet in the list.
PacketBufferQueue::PacketBuffer& front = packet_list_.front();
packet_list_.pop_front();
return &front;
}
private:
using LockGuard = ::std::lock_guard<sync::Mutex>;
sync::Mutex lock_;
IntrusiveList<PacketBuffer> packet_list_ PW_GUARDED_BY(lock_);
};
} // namespace pw::rpc::internal
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