113 lines
3.8 KiB
C++
113 lines
3.8 KiB
C++
// 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) 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 <memory>
|
|
#include <stddef.h>
|
|
#include <stdint.h>
|
|
#include <string>
|
|
#include <vector>
|
|
#include "rocksdb/options.h"
|
|
#include "rocksdb/slice.h"
|
|
#include "rocksdb/slice_transform.h"
|
|
#include "rocksdb/table.h"
|
|
#include "util/hash.h"
|
|
#include "format.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:
|
|
explicit FilterBlockBuilder() {}
|
|
virtual ~FilterBlockBuilder() {}
|
|
|
|
virtual bool IsBlockBased() = 0; // If is blockbased filter
|
|
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
|
|
Slice Finish() { // Generate Filter
|
|
const BlockHandle empty_handle;
|
|
Status dont_care_status;
|
|
auto ret = Finish(empty_handle, &dont_care_status);
|
|
assert(dont_care_status.ok());
|
|
return ret;
|
|
}
|
|
virtual Slice Finish(const BlockHandle& tmp, Status* status) = 0;
|
|
|
|
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/Full FilterBlock would be called in the same way.
|
|
class FilterBlockReader {
|
|
public:
|
|
explicit FilterBlockReader()
|
|
: whole_key_filtering_(true), size_(0), statistics_(nullptr) {}
|
|
explicit FilterBlockReader(size_t s, Statistics* stats,
|
|
bool _whole_key_filtering)
|
|
: whole_key_filtering_(_whole_key_filtering),
|
|
size_(s),
|
|
statistics_(stats) {}
|
|
virtual ~FilterBlockReader() {}
|
|
|
|
virtual bool IsBlockBased() = 0; // If is blockbased filter
|
|
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;
|
|
virtual size_t size() const { return size_; }
|
|
virtual Statistics* statistics() const { return statistics_; }
|
|
|
|
bool whole_key_filtering() const { return whole_key_filtering_; }
|
|
|
|
// convert this object to a human readable form
|
|
virtual std::string ToString() const {
|
|
std::string error_msg("Unsupported filter \n");
|
|
return error_msg;
|
|
}
|
|
|
|
protected:
|
|
bool whole_key_filtering_;
|
|
|
|
private:
|
|
// No copying allowed
|
|
FilterBlockReader(const FilterBlockReader&);
|
|
void operator=(const FilterBlockReader&);
|
|
size_t size_;
|
|
Statistics* statistics_;
|
|
};
|
|
|
|
} // namespace rocksdb
|