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author | Ilya Zhuravlev <zhuravlevilya@ya.ru> | 2012-10-23 01:18:44 +0400 |
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committer | Sfan5 <sfan5@live.de> | 2013-09-09 22:50:50 +0200 |
commit | 58841ef12f6cba1bb622353c1fcaa0e3c6fb46c9 (patch) | |
tree | 6012bbb1905231025dff89aa73782a7c38666839 /src/leveldb/table/filter_block.h | |
parent | 71a8769bb5ded4acb3f9e5a8502bb8af277f824d (diff) | |
download | minetest-58841ef12f6cba1bb622353c1fcaa0e3c6fb46c9.tar.gz minetest-58841ef12f6cba1bb622353c1fcaa0e3c6fb46c9.tar.bz2 minetest-58841ef12f6cba1bb622353c1fcaa0e3c6fb46c9.zip |
Add dummy and LevelDB database backends
Diffstat (limited to 'src/leveldb/table/filter_block.h')
-rw-r--r-- | src/leveldb/table/filter_block.h | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/src/leveldb/table/filter_block.h b/src/leveldb/table/filter_block.h new file mode 100644 index 000000000..c67d010bd --- /dev/null +++ b/src/leveldb/table/filter_block.h @@ -0,0 +1,68 @@ +// 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_ |