ceph/src/rocksdb/utilities/blob_db/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 #ifndef ROCKSDB_LITE
   8
   9 #include <cstdint>
  10 #include <memory>
  11 #include <string>
  12
  13 #include "rocksdb/env.h"
  14 #include "rocksdb/slice.h"
  15 #include "rocksdb/statistics.h"
  16 #include "rocksdb/status.h"
  17 #include "rocksdb/types.h"
  18 #include "utilities/blob_db/blob_log_format.h"
  19
  20 namespace rocksdb {
  21
  22 class WritableFileWriter;
  23
  24 namespace blob_db {
  25
  26 /**
  27  * Writer is the blob log stream writer. It provides an append-only
  28  * abstraction for writing blob data.
  29  *
  30  *
  31  * Look at blob_db_format.h to see the details of the record formats.
  32  */
  33
  34 class Writer {
  35  public:
  36   // Create a writer that will append data to "*dest".
  37   // "*dest" must be initially empty.
  38   // "*dest" must remain live while this Writer is in use.
  39   Writer(std::unique_ptr<WritableFileWriter>&& dest, Env* env,
  40          Statistics* statistics, uint64_t log_number, uint64_t bpsync,
  41          bool use_fsync, uint64_t boffset = 0);
  42
  43   ~Writer() = default;
  44
  45   // No copying allowed
  46   Writer(const Writer&) = delete;
  47   Writer& operator=(const Writer&) = delete;
  48
  49   static void ConstructBlobHeader(std::string* buf, const Slice& key,
  50                                   const Slice& val, uint64_t expiration);
  51
  52   Status AddRecord(const Slice& key, const Slice& val, uint64_t* key_offset,
  53                    uint64_t* blob_offset);
  54
  55   Status AddRecord(const Slice& key, const Slice& val, uint64_t expiration,
  56                    uint64_t* key_offset, uint64_t* blob_offset);
  57
  58   Status EmitPhysicalRecord(const std::string& headerbuf, const Slice& key,
  59                             const Slice& val, uint64_t* key_offset,
  60                             uint64_t* blob_offset);
  61
  62   Status AppendFooter(BlobLogFooter& footer);
  63
  64   Status WriteHeader(BlobLogHeader& header);
  65
  66   WritableFileWriter* file() { return dest_.get(); }
  67
  68   const WritableFileWriter* file() const { return dest_.get(); }
  69
  70   uint64_t get_log_number() const { return log_number_; }
  71
  72   bool ShouldSync() const { return block_offset_ > next_sync_offset_; }
  73
  74   Status Sync();
  75
  76   void ResetSyncPointer() { next_sync_offset_ += bytes_per_sync_; }
  77
  78  private:
  79   std::unique_ptr<WritableFileWriter> dest_;
  80   Env* env_;
  81   Statistics* statistics_;
  82   uint64_t log_number_;
  83   uint64_t block_offset_;  // Current offset in block
  84   uint64_t bytes_per_sync_;
  85   uint64_t next_sync_offset_;
  86   bool use_fsync_;
  87
  88  public:
  89   enum ElemType { kEtNone, kEtFileHdr, kEtRecord, kEtFileFooter };
  90   ElemType last_elem_type_;
  91 };
  92
  93 }  // namespace blob_db
  94 }  // namespace rocksdb
  95 #endif  // ROCKSDB_LITE