ceph/src/rocksdb/db/blob/blob_file_reader.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 <cinttypes>
   9 #include <memory>
  10
  11 #include "file/random_access_file_reader.h"
  12 #include "rocksdb/compression_type.h"
  13 #include "rocksdb/rocksdb_namespace.h"
  14
  15 namespace ROCKSDB_NAMESPACE {
  16
  17 class Status;
  18 struct ImmutableCFOptions;
  19 struct FileOptions;
  20 class HistogramImpl;
  21 struct ReadOptions;
  22 class Slice;
  23 class PinnableSlice;
  24
  25 class BlobFileReader {
  26  public:
  27   static Status Create(const ImmutableCFOptions& immutable_cf_options,
  28                        const FileOptions& file_options,
  29                        uint32_t column_family_id,
  30                        HistogramImpl* blob_file_read_hist,
  31                        uint64_t blob_file_number,
  32                        std::unique_ptr<BlobFileReader>* reader);
  33
  34   BlobFileReader(const BlobFileReader&) = delete;
  35   BlobFileReader& operator=(const BlobFileReader&) = delete;
  36
  37   ~BlobFileReader();
  38
  39   Status GetBlob(const ReadOptions& read_options, const Slice& user_key,
  40                  uint64_t offset, uint64_t value_size,
  41                  CompressionType compression_type, PinnableSlice* value) const;
  42
  43  private:
  44   BlobFileReader(std::unique_ptr<RandomAccessFileReader>&& file_reader,
  45                  uint64_t file_size, CompressionType compression_type);
  46
  47   static Status OpenFile(const ImmutableCFOptions& immutable_cf_options,
  48                          const FileOptions& file_opts,
  49                          HistogramImpl* blob_file_read_hist,
  50                          uint64_t blob_file_number, uint64_t* file_size,
  51                          std::unique_ptr<RandomAccessFileReader>* file_reader);
  52
  53   static Status ReadHeader(const RandomAccessFileReader* file_reader,
  54                            uint32_t column_family_id,
  55                            CompressionType* compression_type);
  56
  57   static Status ReadFooter(uint64_t file_size,
  58                            const RandomAccessFileReader* file_reader);
  59
  60   using Buffer = std::unique_ptr<char[]>;
  61
  62   static Status ReadFromFile(const RandomAccessFileReader* file_reader,
  63                              uint64_t read_offset, size_t read_size,
  64                              Slice* slice, Buffer* buf,
  65                              AlignedBuf* aligned_buf);
  66
  67   static Status VerifyBlob(const Slice& record_slice, const Slice& user_key,
  68                            uint64_t value_size);
  69
  70   static Status UncompressBlobIfNeeded(const Slice& value_slice,
  71                                        CompressionType compression_type,
  72                                        PinnableSlice* value);
  73
  74   static void SaveValue(const Slice& src, PinnableSlice* dst);
  75
  76   std::unique_ptr<RandomAccessFileReader> file_reader_;
  77   uint64_t file_size_;
  78   CompressionType compression_type_;
  79 };
  80
  81 }  // namespace ROCKSDB_NAMESPACE