rocksdb/table/cuckoo/cuckoo_table_reader.h

//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under both the GPLv2 (found in the
//  COPYING file in the root directory) and Apache 2.0 License
//  (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

#pragma once
#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "file/random_access_file_reader.h"
#include "rocksdb/env.h"
#include "rocksdb/options.h"
#include "table/table_reader.h"

namespace ROCKSDB_NAMESPACE {

class Arena;
class TableReader;
struct ImmutableOptions;

class CuckooTableReader : public TableReader {
 public:
  CuckooTableReader(const ImmutableOptions& ioptions,
                    std::unique_ptr<RandomAccessFileReader>&& file,
                    uint64_t file_size, const Comparator* user_comparator,
                    uint64_t (*get_slice_hash)(const Slice&, uint32_t,
                                               uint64_t));
  ~CuckooTableReader() {}

  std::shared_ptr<const TableProperties> GetTableProperties() const override {
    return table_props_;
  }

  Status status() const { return status_; }

  Status Get(const ReadOptions& readOptions, const Slice& key,
             GetContext* get_context, const SliceTransform* prefix_extractor,
             bool skip_filters = false) override;

  // Returns a new iterator over table contents
  // compaction_readahead_size: its value will only be used if for_compaction =
  // true
  InternalIterator* NewIterator(const ReadOptions&,
                                const SliceTransform* prefix_extractor,
                                Arena* arena, bool skip_filters,
                                TableReaderCaller caller,
                                size_t compaction_readahead_size = 0,
                                bool allow_unprepared_value = false) override;
  void Prepare(const Slice& target) override;

  // Report an approximation of how much memory has been used.
  size_t ApproximateMemoryUsage() const override;

  // Following methods are not implemented for Cuckoo Table Reader
  uint64_t ApproximateOffsetOf(const Slice& /*key*/,
                               TableReaderCaller /*caller*/) override {
    return 0;
  }

  uint64_t ApproximateSize(const Slice& /*start*/, const Slice& /*end*/,
                           TableReaderCaller /*caller*/) override {
    return 0;
  }

  void SetupForCompaction() override {}
  // End of methods not implemented.

 private:
  friend class CuckooTableIterator;
  void LoadAllKeys(std::vector<std::pair<Slice, uint32_t>>* key_to_bucket_id);
  std::unique_ptr<RandomAccessFileReader> file_;
  Slice file_data_;
  bool is_last_level_;
  bool identity_as_first_hash_;
  bool use_module_hash_;
  std::shared_ptr<const TableProperties> table_props_;
  Status status_;
  uint32_t num_hash_func_;
  std::string unused_key_;
  uint32_t key_length_;
  uint32_t user_key_length_;
  uint32_t value_length_;
  uint32_t bucket_length_;
  uint32_t cuckoo_block_size_;
  uint32_t cuckoo_block_bytes_minus_one_;
  uint64_t table_size_;
  const Comparator* ucomp_;
  uint64_t (*get_slice_hash_)(const Slice& s, uint32_t index,
                              uint64_t max_num_buckets);
};

}  // namespace ROCKSDB_NAMESPACE