mirror of https://github.com/facebook/rocksdb.git
88 lines
3.6 KiB
C++
88 lines
3.6 KiB
C++
// Copyright (c) 2011 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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#ifndef ROCKSDB_LITE
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#pragma once
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#include <memory>
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#include <stdint.h>
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#include "rocksdb/options.h"
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#include "rocksdb/table.h"
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namespace rocksdb {
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struct Options;
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struct EnvOptions;
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using std::unique_ptr;
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class Status;
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class RandomAccessFile;
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class WritableFile;
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class Table;
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class TableBuilder;
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// IndexedTable requires fixed length key, configured as a constructor
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// parameter of the factory class. Output file format:
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// +-------------+-----------------+
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// | version | user_key_length |
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// +------------++------------------------------+ <= key1 offset
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// | [key_size] | key1 | value_size | |
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// +------------+-------------+-------------+ |
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// | value1 |
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// | |
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// +----------------------------------------+---+ <= key2 offset
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// | [key_size] | key2 | value_size | |
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// +------------+-------------+-------------+ |
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// | value2 |
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// | |
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// | ...... |
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// +-----------------+--------------------------+
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// If user_key_length = kPlainTableVariableLength, it means the key is variable
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// length, there will be an extra field for key size encoded before every key.
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class PlainTableFactory : public TableFactory {
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public:
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~PlainTableFactory() {}
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// user_key_size is the length of the user key. If it is set to be
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// kPlainTableVariableLength, then it means variable length. Otherwise, all
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// the keys need to have the fix length of this value. bloom_bits_per_key is
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// number of bits used for bloom filer per key. hash_table_ratio is
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// the desired utilization of the hash table used for prefix hashing.
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// hash_table_ratio = number of prefixes / #buckets in the hash table
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// hash_table_ratio = 0 means skip hash table but only replying on binary
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// search.
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// index_sparseness determines index interval for keys
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// inside the same prefix. It will be the maximum number of linear search
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// required after hash and binary search.
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// index_sparseness = 0 means index for every key.
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explicit PlainTableFactory(uint32_t user_key_len = kPlainTableVariableLength,
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int bloom_bits_per_key = 0,
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double hash_table_ratio = 0.75,
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size_t index_sparseness = 16)
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: user_key_len_(user_key_len),
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bloom_bits_per_key_(bloom_bits_per_key),
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hash_table_ratio_(hash_table_ratio),
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index_sparseness_(index_sparseness) {}
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const char* Name() const override { return "PlainTable"; }
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Status NewTableReader(const Options& options, const EnvOptions& soptions,
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const InternalKeyComparator& internal_comparator,
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unique_ptr<RandomAccessFile>&& file, uint64_t file_size,
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unique_ptr<TableReader>* table) const override;
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TableBuilder* NewTableBuilder(const Options& options,
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const InternalKeyComparator& icomparator,
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WritableFile* file,
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CompressionType compression_type) const
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override;
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static const char kValueTypeSeqId0 = 0xFF;
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private:
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uint32_t user_key_len_;
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int bloom_bits_per_key_;
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double hash_table_ratio_;
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size_t index_sparseness_;
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};
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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