YugabyteDB (2.13.0.0-b42, bfc6a6643e7399ac8a0e81d06a3ee6d6571b33ab)

// Copyright (c) YugaByte, Inc.

//

// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except

// in compliance with the License.  You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software distributed under the License

// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express

// or implied.  See the License for the specific language governing permissions and limitations

// under the License.

//

#ifndef YB_ROCKSDB_TABLE_FIXED_SIZE_FILTER_BLOCK_H

#define YB_ROCKSDB_TABLE_FIXED_SIZE_FILTER_BLOCK_H

#include <stddef.h>

#include <stdint.h>

#include <memory>

#include <string>

#include <vector>

#include "yb/rocksdb/filter_policy.h"

#include "yb/rocksdb/options.h"

#include "yb/rocksdb/slice_transform.h"

#include "yb/rocksdb/table/filter_block.h"

#include "yb/rocksdb/table/format.h"

#include "yb/rocksdb/util/hash.h"

#include "yb/util/slice.h"

namespace rocksdb {

// A fixed size Bloom filter divides the Bloom Filter into blocks of fixed size

// in which each block holds the information of a range of keys.

// Each Bloom filter block is built as keys are inserted into the block.

// As long as the terminating condition is reached, the Bloom filter block is flushed into disk

// and its offset being written to the index block.

// Since FixedSizeFilterBlockBuilder does not buffer any key,

// FixedSizeFilterBlockBuilder treats each insertion independently

// and won't check for duplicate keys.

// The sequence of calls to FixedSizeFilterBlockBuilder must match the regexp:

//      (StartBlock Add* Finish)*

class FixedSizeFilterBlockBuilder : public FilterBlockBuilder {

 public:

  FixedSizeFilterBlockBuilder(const SliceTransform* prefix_extractor,

      const BlockBasedTableOptions& table_opt);

  ~FixedSizeFilterBlockBuilder() {

    results_.clear();

  }

  // No copying allowed

  FixedSizeFilterBlockBuilder(const FixedSizeFilterBlockBuilder&) = delete;

  void operator=(const FixedSizeFilterBlockBuilder&) = delete;

  virtual void StartBlock(uint64_t block_offset) override;

  virtual void Add(const Slice& key) override;

  virtual bool ShouldFlush() const override;

  virtual Slice Finish() override;

 private:

  void AddKey(const Slice& key);

  void AddPrefix(const Slice& key);

  // Important: all of these might point to invalid addresses at the time of destruction of this

  // filter block. Destructor should NOT dereference them.

  const FilterPolicy* policy_;

  const SliceTransform* prefix_extractor_;

  bool whole_key_filtering_;

  std::unique_ptr<FilterBitsBuilder> bits_builder_; // writer to the results

  std::unique_ptr<const char[]> active_block_data_;

  std::vector<std::unique_ptr<const char[]>> results_;

};

// A FilterBlockReader will attempt to read the block associated with the keys of interest.

// KeyMayMatch and PrefixMayMatch would trigger filter checking.

class FixedSizeFilterBlockReader : public FilterBlockReader {

 public:

  // REQUIRES: "contents" and *policy must stay live while *this is live.

  FixedSizeFilterBlockReader(const SliceTransform* prefix_extractor,

                             const BlockBasedTableOptions& table_opt,

                             bool whole_key_filtering,

                             BlockContents&& contents);

  FixedSizeFilterBlockReader(const FixedSizeFilterBlockReader&) = delete;

  void operator=(const FixedSizeFilterBlockReader&) = delete;

  virtual bool KeyMayMatch(const Slice& key,

                           uint64_t block_offset = 0) override;

  virtual bool PrefixMayMatch(const Slice& prefix,

                              uint64_t block_offset = 0) override;

  virtual size_t ApproximateMemoryUsage() const override;

  // convert this object to a human readable form

  std::string ToString() const override;

 private:

  const FilterPolicy* policy_;

  const SliceTransform* prefix_extractor_;

  bool whole_key_filtering_;

  std::unique_ptr<FilterBitsReader> reader_;

  BlockContents contents_;

  // Checks whether entry is present in filter. Entry could be any binary data, but used here for

  // either key or key prefix when calling from corresponding public methods.

  bool MayMatch(const Slice& entry);

};

}  // namespace rocksdb

#endif // YB_ROCKSDB_TABLE_FIXED_SIZE_FILTER_BLOCK_H