YugabyteDB (2.13.0.0-b42, bfc6a6643e7399ac8a0e81d06a3ee6d6571b33ab)

//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.

//  This source code is licensed under the BSD-style license found in the

//  LICENSE file in the root directory of this source tree. An additional grant

//  of patent rights can be found in the PATENTS file in the same directory.

//

// The following only applies to changes made to this file as part of YugaByte development.

//

// Portions 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.

//

// Copyright (c) 2012 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.

//

// A filter block is stored near the end of a Table file.  It contains

// filters (e.g., bloom filters) for all data blocks in the table combined

// into a single filter block.

//

// It is a base class for BlockBasedFilter and FullFilter.

// These two are both used in BlockBasedTable. The first one contain filter

// For a part of keys in sst file, the second contain filter for all keys

// in sst file.

#pragma once

#include <stddef.h>

#include <stdint.h>

#include <memory>

#include <string>

#include "yb/util/slice.h"

namespace rocksdb {

const uint64_t kNotValid = ULLONG_MAX;

class FilterPolicy;

// A FilterBlockBuilder is used to construct all of the filters for a

// particular Table.  It generates a single string which is stored as

// a special block in the Table.

//

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

//      (StartBlock Add*)* Finish

//

// BlockBased/Full FilterBlock would be called in the same way.

class FilterBlockBuilder {

 public:

  FilterBlockBuilder() {}

  virtual ~FilterBlockBuilder() {}

  virtual void StartBlock(uint64_t block_offset) = 0;  // Start new block filter

  virtual void Add(const Slice& key) = 0;           // Add a key to current filter

  virtual Slice Finish() = 0;                     // Generate Filter

  virtual bool ShouldFlush() const = 0;  // flush policy for fixed size filter

 private:

  // No copying allowed

  FilterBlockBuilder(const FilterBlockBuilder&);

  void operator=(const FilterBlockBuilder&);

};

// A FilterBlockReader is used to parse filter from SST table.

// KeyMayMatch and PrefixMayMatch would trigger filter checking

//

// BlockBased/FullFilter/FixedSizeFilter Block would be called in the same way.

class FilterBlockReader {

 public:

  FilterBlockReader() {}

  virtual ~FilterBlockReader() {}

  virtual bool KeyMayMatch(const Slice& key,

                           uint64_t block_offset = kNotValid) = 0;

  virtual bool PrefixMayMatch(const Slice& prefix,

                              uint64_t block_offset = kNotValid) = 0;

  virtual size_t ApproximateMemoryUsage() const = 0;

  // convert this object to a human readable form

  virtual std::string ToString() const {

    std::string error_msg("Unsupported filter \n");

    return error_msg;

  }

 private:

  // No copying allowed

  FilterBlockReader(const FilterBlockReader&);

  void operator=(const FilterBlockReader&);

};

}  // namespace rocksdb