chromium/third_party/grpc/src/src/core/lib/iomgr/buffer_list.h

//
//
// Copyright 2018 gRPC 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 GRPC_SRC_CORE_LIB_IOMGR_BUFFER_LIST_H
#define GRPC_SRC_CORE_LIB_IOMGR_BUFFER_LIST_H

#include <grpc/support/port_platform.h>

#include "absl/types/optional.h"

#include <grpc/grpc.h>
#include <grpc/support/time.h>

#include "src/core/lib/gprpp/sync.h"
#include "src/core/lib/iomgr/error.h"
#include "src/core/lib/iomgr/internal_errqueue.h"
#include "src/core/lib/iomgr/port.h"

namespace grpc_core {

struct ConnectionMetrics { … };

struct BufferTimestamp { … };

struct Timestamps { … };

// TracedBuffer is a class to keep track of timestamps for a specific buffer in
// the TCP layer. We are only tracking timestamps for Linux kernels and hence
// this class would only be used by Linux platforms. For all other platforms,
// TracedBuffer would be an empty class.
// The timestamps collected are according to Timestamps declared above A
// TracedBuffer list is kept track of using the head element of the list. If
// *the head element of the list is nullptr, then the list is empty.
#ifdef GRPC_LINUX_ERRQUEUE

class TracedBufferList { … };

#else   // GRPC_LINUX_ERRQUEUE
// TracedBufferList implementation is a no-op for this platform.
class TracedBufferList {
 public:
  void AddNewEntry(int32_t /*seq_no*/, int /*fd*/, void* /*arg*/) {}
  void ProcessTimestamp(struct sock_extended_err* /*serr*/,
                        struct cmsghdr* /*opt_stats*/,
                        struct scm_timestamping* /*tss*/) {}
  int Size() { return 0; }
  void Shutdown(void* /*remaining*/, absl::Status /*shutdown_err*/) {}
};
#endif  // GRPC_LINUX_ERRQUEUE

/// Sets the callback function to call when timestamps for a write are
/// collected. The callback does not own a reference to error.
void grpc_tcp_set_write_timestamps_callback(
    void (*fn)(void*, Timestamps*, grpc_error_handle error));

}  // namespace grpc_core

#endif  // GRPC_SRC_CORE_LIB_IOMGR_BUFFER_LIST_H