ceph/src/rocksdb/db/blob/blob_log_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 #pragma once
   6
   7 #include <cstdint>
   8 #include <memory>
   9 #include <string>
  10
  11 #include "db/blob/blob_log_format.h"
  12 #include "rocksdb/env.h"
  13 #include "rocksdb/slice.h"
  14 #include "rocksdb/statistics.h"
  15 #include "rocksdb/status.h"
  16 #include "rocksdb/types.h"
  17
  18 namespace ROCKSDB_NAMESPACE {
  19
  20 class WritableFileWriter;
  21
  22 /**
  23  * BlobLogWriter is the blob log stream writer. It provides an append-only
  24  * abstraction for writing blob data.
  25  *
  26  *
  27  * Look at blob_db_format.h to see the details of the record formats.
  28  */
  29
  30 class BlobLogWriter {
  31  public:
  32   // Create a writer that will append data to "*dest".
  33   // "*dest" must be initially empty.
  34   // "*dest" must remain live while this BlobLogWriter is in use.
  35   BlobLogWriter(std::unique_ptr<WritableFileWriter>&& dest, Env* env,
  36                 Statistics* statistics, uint64_t log_number, bool use_fsync,
  37                 uint64_t boffset = 0);
  38   // No copying allowed
  39   BlobLogWriter(const BlobLogWriter&) = delete;
  40   BlobLogWriter& operator=(const BlobLogWriter&) = delete;
  41
  42   ~BlobLogWriter();
  43
  44   static void ConstructBlobHeader(std::string* buf, const Slice& key,
  45                                   const Slice& val, uint64_t expiration);
  46
  47   Status AddRecord(const Slice& key, const Slice& val, uint64_t* key_offset,
  48                    uint64_t* blob_offset);
  49
  50   Status AddRecord(const Slice& key, const Slice& val, uint64_t expiration,
  51                    uint64_t* key_offset, uint64_t* blob_offset);
  52
  53   Status EmitPhysicalRecord(const std::string& headerbuf, const Slice& key,
  54                             const Slice& val, uint64_t* key_offset,
  55                             uint64_t* blob_offset);
  56
  57   Status AppendFooter(BlobLogFooter& footer, std::string* checksum_method,
  58                       std::string* checksum_value);
  59
  60   Status WriteHeader(BlobLogHeader& header);
  61
  62   WritableFileWriter* file() { return dest_.get(); }
  63
  64   const WritableFileWriter* file() const { return dest_.get(); }
  65
  66   uint64_t get_log_number() const { return log_number_; }
  67
  68   Status Sync();
  69
  70  private:
  71   std::unique_ptr<WritableFileWriter> dest_;
  72   Env* env_;
  73   Statistics* statistics_;
  74   uint64_t log_number_;
  75   uint64_t block_offset_;  // Current offset in block
  76   bool use_fsync_;
  77
  78  public:
  79   enum ElemType { kEtNone, kEtFileHdr, kEtRecord, kEtFileFooter };
  80   ElemType last_elem_type_;
  81 };
  82
  83 }  // namespace ROCKSDB_NAMESPACE