5665e5e285
Summary: As a preparation to support updating some options dynamically, I'd like to first introduce ImmutableOptions, which is a subset of Options that cannot be changed during the course of a DB lifetime without restart. ColumnFamily will keep both Options and ImmutableOptions. Any component below ColumnFamily should only take ImmutableOptions in their constructor. Other options should be taken from APIs, which will be allowed to adjust dynamically. I am yet to make changes to memtable and other related classes to take ImmutableOptions in their ctor. That can be done in a seprate diff as this one is already pretty big. Test Plan: make all check Reviewers: yhchiang, igor, sdong Reviewed By: sdong Subscribers: leveldb, dhruba Differential Revision: https://reviews.facebook.net/D22545
96 lines
3.3 KiB
C++
96 lines
3.3 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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//
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// A filter block is stored near the end of a Table file. It contains
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// filters (e.g., bloom filters) for all data blocks in the table combined
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// into a single filter block.
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#pragma once
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#include <memory>
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#include <stddef.h>
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#include <stdint.h>
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#include <string>
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#include <vector>
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#include "rocksdb/slice.h"
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#include "rocksdb/slice_transform.h"
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#include "rocksdb/table.h"
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#include "util/hash.h"
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namespace rocksdb {
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class FilterPolicy;
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// A FilterBlockBuilder is used to construct all of the filters for a
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// particular Table. It generates a single string which is stored as
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// a special block in the Table.
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//
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// The sequence of calls to FilterBlockBuilder must match the regexp:
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// (StartBlock AddKey*)* Finish
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class FilterBlockBuilder {
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public:
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explicit FilterBlockBuilder(const SliceTransform* prefix_extractor,
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const BlockBasedTableOptions& table_opt,
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const Comparator* internal_comparator);
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void StartBlock(uint64_t block_offset);
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void AddKey(const Slice& key);
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Slice Finish();
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private:
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bool SamePrefix(const Slice &key1, const Slice &key2) const;
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void GenerateFilter();
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// important: all of these might point to invalid addresses
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// at the time of destruction of this filter block. destructor
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// should NOT dereference them.
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const FilterPolicy* policy_;
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const SliceTransform* prefix_extractor_;
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bool whole_key_filtering_;
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const Comparator* comparator_;
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std::string entries_; // Flattened entry contents
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std::vector<size_t> start_; // Starting index in entries_ of each entry
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std::string result_; // Filter data computed so far
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std::vector<Slice> tmp_entries_; // policy_->CreateFilter() argument
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std::vector<uint32_t> filter_offsets_;
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// No copying allowed
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FilterBlockBuilder(const FilterBlockBuilder&);
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void operator=(const FilterBlockBuilder&);
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};
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class FilterBlockReader {
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public:
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// REQUIRES: "contents" and *policy must stay live while *this is live.
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FilterBlockReader(
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const SliceTransform* prefix_extractor,
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const BlockBasedTableOptions& table_opt,
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const Slice& contents,
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bool delete_contents_after_use = false);
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bool KeyMayMatch(uint64_t block_offset, const Slice& key);
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bool PrefixMayMatch(uint64_t block_offset, const Slice& prefix);
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size_t ApproximateMemoryUsage() const;
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private:
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const FilterPolicy* policy_;
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const SliceTransform* prefix_extractor_;
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bool whole_key_filtering_;
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const char* data_; // Pointer to filter data (at block-start)
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const char* offset_; // Pointer to beginning of offset array (at block-end)
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size_t num_; // Number of entries in offset array
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size_t base_lg_; // Encoding parameter (see kFilterBaseLg in .cc file)
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std::unique_ptr<const char[]> filter_data;
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bool MayMatch(uint64_t block_offset, const Slice& entry);
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};
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}
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