69 lines
2.2 KiB
C
69 lines
2.2 KiB
C
|
// 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.
|
||
|
|
|
||
|
|
#ifndef STORAGE_LEVELDB_TABLE_FILTER_BLOCK_H_
|
||
|
|
#define STORAGE_LEVELDB_TABLE_FILTER_BLOCK_H_
|
||
|
|
|
||
|
|
#include <stddef.h>
|
||
|
|
#include <stdint.h>
|
||
|
|
#include <string>
|
||
|
|
#include <vector>
|
||
|
|
#include "leveldb/slice.h"
|
||
|
|
#include "util/hash.h"
|
||
|
|
|
||
|
|
namespace leveldb {
|
||
|
|
|
||
|
|
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 AddKey*)* Finish
|
||
|
|
class FilterBlockBuilder {
|
||
|
|
public:
|
||
|
|
explicit FilterBlockBuilder(const FilterPolicy*);
|
||
|
|
|
||
|
|
void StartBlock(uint64_t block_offset);
|
||
|
|
void AddKey(const Slice& key);
|
||
|
|
Slice Finish();
|
||
|
|
|
||
|
|
private:
|
||
|
|
void GenerateFilter();
|
||
|
|
|
||
|
|
const FilterPolicy* policy_;
|
||
|
|
std::string keys_; // Flattened key contents
|
||
|
|
std::vector<size_t> start_; // Starting index in keys_ of each key
|
||
|
|
std::string result_; // Filter data computed so far
|
||
|
|
std::vector<Slice> tmp_keys_; // policy_->CreateFilter() argument
|
||
|
|
std::vector<uint32_t> filter_offsets_;
|
||
|
|
|
||
|
|
// No copying allowed
|
||
|
|
FilterBlockBuilder(const FilterBlockBuilder&);
|
||
|
|
void operator=(const FilterBlockBuilder&);
|
||
|
|
};
|
||
|
|
|
||
|
|
class FilterBlockReader {
|
||
|
|
public:
|
||
|
|
// REQUIRES: "contents" and *policy must stay live while *this is live.
|
||
|
|
FilterBlockReader(const FilterPolicy* policy, const Slice& contents);
|
||
|
|
bool KeyMayMatch(uint64_t block_offset, const Slice& key);
|
||
|
|
|
||
|
|
private:
|
||
|
|
const FilterPolicy* policy_;
|
||
|
|
const char* data_; // Pointer to filter data (at block-start)
|
||
|
|
const char* offset_; // Pointer to beginning of offset array (at block-end)
|
||
|
|
size_t num_; // Number of entries in offset array
|
||
|
|
size_t base_lg_; // Encoding parameter (see kFilterBaseLg in .cc file)
|
||
|
|
};
|
||
|
|
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif // STORAGE_LEVELDB_TABLE_FILTER_BLOCK_H_
|