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// Copyright (c) 2014, 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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#pragma once
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#include <stddef.h>
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#include <stdint.h>
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#include <memory>
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#include <string>
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#include <vector>
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#include "rocksdb/options.h"
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#include "rocksdb/slice.h"
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#include "rocksdb/slice_transform.h"
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#include "db/dbformat.h"
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#include "util/hash.h"
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#include "table/filter_block.h"
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namespace rocksdb {
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class FilterPolicy;
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class FilterBitsBuilder;
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class FilterBitsReader;
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// A FullFilterBlockBuilder is used to construct a full filter 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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// The format of full filter block is:
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// +----------------------------------------------------------------+
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// | full filter for all keys in sst file |
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// +----------------------------------------------------------------+
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// The full filter can be very large. At the end of it, we put
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// num_probes: how many hash functions are used in bloom filter
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//
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class FullFilterBlockBuilder : public FilterBlockBuilder {
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public:
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explicit FullFilterBlockBuilder(const SliceTransform* prefix_extractor,
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const BlockBasedTableOptions& table_opt,
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FilterBitsBuilder* filter_bits_builder);
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// bits_builder is created in filter_policy, it should be passed in here
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// directly. and be deleted here
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~FullFilterBlockBuilder() {}
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virtual bool IsBlockBased() override { return false; }
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virtual void StartBlock(uint64_t block_offset) override {}
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virtual void Add(const Slice& key) override;
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virtual Slice Finish() override;
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private:
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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 SliceTransform* prefix_extractor_;
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bool whole_key_filtering_;
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uint32_t num_added_;
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std::unique_ptr<FilterBitsBuilder> filter_bits_builder_;
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std::unique_ptr<const char[]> filter_data_;
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void AddKey(const Slice& key);
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void AddPrefix(const Slice& key);
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// No copying allowed
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FullFilterBlockBuilder(const FullFilterBlockBuilder&);
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void operator=(const FullFilterBlockBuilder&);
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};
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// A FilterBlockReader is used to parse filter from SST table.
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// KeyMayMatch and PrefixMayMatch would trigger filter checking
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class FullFilterBlockReader : public FilterBlockReader {
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public:
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// REQUIRES: "contents" and filter_bits_reader must stay live
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// while *this is live.
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explicit FullFilterBlockReader(const SliceTransform* prefix_extractor,
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const BlockBasedTableOptions& table_opt,
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const Slice& contents,
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FilterBitsReader* filter_bits_reader);
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explicit FullFilterBlockReader(const SliceTransform* prefix_extractor,
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const BlockBasedTableOptions& table_opt,
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BlockContents&& contents,
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FilterBitsReader* filter_bits_reader);
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// bits_reader is created in filter_policy, it should be passed in here
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// directly. and be deleted here
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~FullFilterBlockReader() {}
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virtual bool IsBlockBased() override { return false; }
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virtual bool KeyMayMatch(const Slice& key,
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uint64_t block_offset = kNotValid) override;
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virtual bool PrefixMayMatch(const Slice& prefix,
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uint64_t block_offset = kNotValid) override;
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virtual size_t ApproximateMemoryUsage() const override;
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private:
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const SliceTransform* prefix_extractor_;
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bool whole_key_filtering_;
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std::unique_ptr<FilterBitsReader> filter_bits_reader_;
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Slice contents_;
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BlockContents block_contents_;
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std::unique_ptr<const char[]> filter_data_;
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bool MayMatch(const Slice& entry);
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// No copying allowed
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FullFilterBlockReader(const FullFilterBlockReader&);
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void operator=(const FullFilterBlockReader&);
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};
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} // namespace rocksdb
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