ByteEventTracker.h

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/*
 *  Copyright (c) 2015-present, Facebook, Inc.
 *  All rights reserved.
 *
 *  This source code is licensed under the BSD-style license found in the
 *  LICENSE file in the root directory of this source tree. An additional grant
 *  of patent rights can be found in the PATENTS file in the same directory.
 *
 */
#pragma once

#include <proxygen/lib/http/session/AckLatencyEvent.h>
#include <proxygen/lib/http/session/ByteEvents.h>
#include <proxygen/lib/http/session/HTTPTransaction.h>
#include <proxygen/lib/utils/Time.h>

namespace proxygen {

class TTLBAStats;

class ByteEventTracker {
 public:
  class Callback {
   public:
    virtual ~Callback() {}
    virtual void onPingReplyLatency(int64_t latency) noexcept = 0;
    virtual void onLastByteEvent(HTTPTransaction* txn,
                                 uint64_t offset, bool eomTracked) noexcept = 0;
    virtual void onDeleteAckEvent() noexcept = 0;
  };

  virtual ~ByteEventTracker();
  explicit ByteEventTracker(Callback* callback): callback_(callback) {}

  virtual void absorb(ByteEventTracker&& other);
  void setCallback(Callback* callback) { callback_ = callback; }

  virtual size_t drainByteEvents();

  virtual bool processByteEvents(std::shared_ptr<ByteEventTracker> self,
                                 uint64_t bytesWritten);

  void addPingByteEvent(size_t pingSize,
                        TimePoint timestamp,
                        uint64_t bytesScheduled);

  void addFirstBodyByteEvent(uint64_t offset, HTTPTransaction* txn);

  virtual void addFirstHeaderByteEvent(uint64_t offset, HTTPTransaction* txn);

  virtual void addLastByteEvent(HTTPTransaction* txn,
                                uint64_t byteNo) noexcept;
  virtual void addTrackedByteEvent(HTTPTransaction* txn,
                                   uint64_t byteNo) noexcept;

  virtual void addAckByteEvent(uint64_t /*offset*/, HTTPTransaction* /*txn*/) {}

  virtual uint64_t preSend(bool* /*cork*/, bool* /*eom*/,
                           uint64_t /*bytesWritten*/) {
    return 0;
  }

  virtual void setTTLBAStats(TTLBAStats* /* stats */) {}

 protected:
  // byteEvents_ is in the ascending order of ByteEvent::byteOffset_
  folly::IntrusiveList<ByteEvent, &ByteEvent::listHook> byteEvents_;

  virtual void eomEventProcessed() {}

  Callback* callback_;
};

} // proxygen