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rocksdb/table/plain_table_factory.h

88 lines
3.6 KiB

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