frame.h

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// Copyright 2026 The Symbian SDK Authors.
// Licensed under the Apache License, Version 2.0.
 
#ifndef SYMBIAN_AGENT_FRAME_H_
#define SYMBIAN_AGENT_FRAME_H_
 
#include <cstddef>
#include <cstdint>
#include <deque>
#include <optional>
#include <span>
#include <string>
 
#include "absl/status/statusor.h"
 
namespace symbian::agent {
 
inline constexpr std::size_t kMaximumFrameBytes = 64 * 1024;
 
inline constexpr std::size_t kMaximumQueuedBytes = 256 * 1024;
 
inline constexpr std::size_t kMaximumQueuedFrames = 4;
 
struct Frame {
  std::string payload;
};
 
absl::StatusOr<std::size_t> DecodeFrameLength(
    std::span<const std::uint8_t> prefix,
    std::size_t maximum_frame_bytes = kMaximumFrameBytes);
 
class FrameDecoder {
 public:
  explicit FrameDecoder(std::size_t maximum_frame_bytes = kMaximumFrameBytes);
 
  std::size_t buffered_bytes() const { return payload_.size(); }
 
  void Reset();
 
  absl::StatusOr<std::size_t> Consume(std::span<const std::uint8_t> bytes,
                                      std::optional<Frame>* completed);
 
 private:
  std::size_t maximum_frame_bytes_;
  std::uint8_t prefix_[4] = {};
  std::size_t prefix_size_ = 0;
  std::size_t expected_size_ = 0;
  std::string payload_;
  bool failed_ = false;
};
 
absl::StatusOr<std::string> EncodeFrame(
    std::span<const std::uint8_t> payload,
    std::size_t maximum_frame_bytes = kMaximumFrameBytes);
 
class InboundQueue {
 public:
  absl::Status Push(Frame frame);
 
  std::optional<Frame> Pop();
 
  std::size_t queued_bytes() const { return queued_bytes_; }
 
  std::size_t size() const { return frames_.size(); }
 
  void Clear();
 
 private:
  std::deque<Frame> frames_;
  std::size_t queued_bytes_ = 0;
};
 
}  // namespace symbian::agent
 
#endif  // SYMBIAN_AGENT_FRAME_H_