channel_wire_stream.h

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/*
 * Copyright 2026 The A11 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
 *
 *     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.
 */
 
#ifndef A11_NET_CHANNEL_WIRE_STREAM_H_
#define A11_NET_CHANNEL_WIRE_STREAM_H_
 
#include <cstddef>
#include <functional>
#include <memory>
#include <optional>
#include <string>
 
#include <absl/base/nullability.h>
#include <absl/status/status.h>
#include <absl/status/statusor.h>
#include <absl/time/time.h>
 
#include "a11/concurrency/future.h"
#include "a11/data/types.h"
#include "a11/net/byte_chunking.h"
#include "a11/net/wire_stream.h"
 
namespace a11::net {
 
namespace internal {
class BinaryChannel;
}  // namespace internal
 
enum class ChannelEndpointRole { kClient, kServer, kEither };
 
struct ChannelFramingOptions {
  // Serialized byte packets never exceed split_size. Complete messages carry
  // a small suffix; larger messages use length-suffixed first chunks followed
  // by ordinary chunks in A11's byte-chunking protocol.
  size_t split_size = 64 * 1024;     
  size_t max_pending_messages = 64;  
  size_t max_pending_bytes = 64 * 1024 * 1024;  
 
  absl::Status Validate() const;
};
 
class ChannelWireStream
    : public WireStream,
      public std::enable_shared_from_this<ChannelWireStream> {
 public:
  using OpenOperation = std::function<absl::Status()>;
 
  using WireStream::HalfClose;
  using WireStream::SetDeadline;
 
  ~ChannelWireStream() override;
 
  absl::Status Send(data::WireMessage message) override;
  a11::Task Start(OnMessage on_message, OnDone on_done) override;
  a11::Task Accept(OnMessage on_message, OnDone on_done) override;
  absl::Status HalfClose(data::ByteMap trailers) override;
  a11::Task DrainOutgoingMessages() override;
  absl::Status Abort(absl::Status status) override;
  absl::Status SetDeadline(absl::Time deadline) override;
 
  [[nodiscard]] absl::Time deadline() const override;
  [[nodiscard]] absl::Status GetStatus() const override;
  [[nodiscard]] std::optional<data::ByteMap> GetTrailers() const override;
  [[nodiscard]] std::string GetId() const override;
  [[nodiscard]] void* absl_nullable GetImpl() const override;
 
 protected:
  struct State;
 
  explicit ChannelWireStream(std::shared_ptr<State> state)
      : state_(std::move(state)) {}
 
  static absl::StatusOr<std::shared_ptr<State>> MakeState(
      std::shared_ptr<internal::BinaryChannel> channel, std::string id,
      ChannelEndpointRole role, OpenOperation open_operation,
      WireStreamOptions options, ChannelFramingOptions framing = {});
 
 private:
  a11::Task StartEndpoint(bool accept, OnMessage on_message, OnDone on_done);
  static void Sender(const std::shared_ptr<State>& state);
  static void DeliverClaimed(const std::shared_ptr<State>& state,
                             const data::WireMessage& message,
                             std::uint64_t message_id);
  static void Receiver(const std::shared_ptr<State>& state);
  static void WatchTiming(const std::shared_ptr<State>& state);
  static void MarkActivity(const std::shared_ptr<State>& state);
  static void ForceAbort(const std::shared_ptr<State>& state,
                         absl::Status status, bool can_communicate = true);
  static void MaybeFinish(const std::shared_ptr<State>& state);
  static void Finish(const std::shared_ptr<State>& state,
                     std::optional<absl::Status> terminal_error = std::nullopt);
  static void Notify(const std::shared_ptr<State>& state);
 
  std::shared_ptr<State> state_;
};
 
}  // namespace a11::net
 
#endif  // A11_NET_CHANNEL_WIRE_STREAM_H_