api/test/network_emulation/leaky_bucket_network_queue.h

/*
 *  Copyright 2025 The WebRTC Project Authors. All rights reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#ifndef API_TEST_NETWORK_EMULATION_LEAKY_BUCKET_NETWORK_QUEUE_H_
#define API_TEST_NETWORK_EMULATION_LEAKY_BUCKET_NETWORK_QUEUE_H_

#include <cstddef>
#include <memory>
#include <optional>
#include <queue>
#include <vector>

#include "api/test/network_emulation/network_queue.h"
#include "api/test/simulated_network.h"
#include "api/units/timestamp.h"

namespace webrtc {

// A network queue that uses a leaky bucket to limit the number of packets that
// can be queued.
class LeakyBucketNetworkQueue : public NetworkQueue {
 public:
  LeakyBucketNetworkQueue() = default;
  // If `max_capacity` is larger than current queue length, existing packets are
  // not dropped. But the queue will not accept new packets until queue length
  // is below `max_capacity`,
  void SetMaxPacketCapacity(size_t max_capactiy) override;

  bool EnqueuePacket(const PacketInFlightInfo& packet_info) override;
  std::optional<PacketInFlightInfo> PeekNextPacket() const override;
  std::optional<PacketInFlightInfo> DequeuePacket(Timestamp time_now) override;
  std::vector<PacketInFlightInfo> DequeueDroppedPackets() override;
  bool empty() const override;

  void DropOldestPacket();

 private:
  size_t max_packet_capacity_ = kMaxPacketCapacity;

  std::queue<PacketInFlightInfo> queue_;
  std::vector<PacketInFlightInfo> dropped_packets_;
};

class LeakyBucketNetworkQueueFactory : public NetworkQueueFactory {
 public:
  std::unique_ptr<NetworkQueue> CreateQueue() override {
    return std::make_unique<LeakyBucketNetworkQueue>();
  }
};
}  // namespace webrtc

#endif  // API_TEST_NETWORK_EMULATION_LEAKY_BUCKET_NETWORK_QUEUE_H_