ceph/src/rocksdb/include/rocksdb/trace_reader_writer.h

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5
   6 #pragma once
   7
   8 #include "rocksdb/env.h"
   9
  10 namespace ROCKSDB_NAMESPACE {
  11
  12 // Allow custom implementations of TraceWriter and TraceReader.
  13 // By default, RocksDB provides a way to capture the traces to a file using the
  14 // factory NewFileTraceWriter(). But users could also choose to export traces to
  15 // any other system by providing custom implementations of TraceWriter and
  16 // TraceReader.
  17
  18 // TraceWriter allows exporting RocksDB traces to any system, one operation at
  19 // a time.
  20 class TraceWriter {
  21  public:
  22   virtual ~TraceWriter() = default;
  23
  24   virtual Status Write(const Slice& data) = 0;
  25   virtual Status Close() = 0;
  26   virtual uint64_t GetFileSize() = 0;
  27 };
  28
  29 // TraceReader allows reading RocksDB traces from any system, one operation at
  30 // a time. A RocksDB Replayer could depend on this to replay operations.
  31 class TraceReader {
  32  public:
  33   virtual ~TraceReader() = default;
  34
  35   virtual Status Read(std::string* data) = 0;
  36   virtual Status Close() = 0;
  37
  38   // Seek back to the trace header. Replayer can call this method to restart
  39   // replaying. Note this method may fail if the reader is already closed.
  40   virtual Status Reset() = 0;
  41 };
  42
  43 // Factory methods to write/read traces to/from a file.
  44 // The implementations may not be thread-safe.
  45 Status NewFileTraceWriter(Env* env, const EnvOptions& env_options,
  46                           const std::string& trace_filename,
  47                           std::unique_ptr<TraceWriter>* trace_writer);
  48 Status NewFileTraceReader(Env* env, const EnvOptions& env_options,
  49                           const std::string& trace_filename,
  50                           std::unique_ptr<TraceReader>* trace_reader);
  51
  52 }  // namespace ROCKSDB_NAMESPACE