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https://github.com/facebook/rocksdb.git
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98 lines
3.8 KiB
C++
98 lines
3.8 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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#pragma once
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#ifndef ROCKSDB_LITE
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#include "rocksdb/slice.h"
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#include "db/dbformat.h"
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namespace rocksdb {
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class WritableFile;
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struct ParsedInternalKey;
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// Helper class to write out a key to an output file
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// Actual data format of the key is documented in plain_table_factory.h
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class PlainTableKeyEncoder {
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public:
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explicit PlainTableKeyEncoder(EncodingType encoding_type,
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uint32_t user_key_len,
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const SliceTransform* prefix_extractor,
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size_t index_sparseness)
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: encoding_type_((prefix_extractor != nullptr) ? encoding_type : kPlain),
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fixed_user_key_len_(user_key_len),
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prefix_extractor_(prefix_extractor),
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index_sparseness_((index_sparseness > 1) ? index_sparseness : 1),
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key_count_for_prefix_(0) {}
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// key: the key to write out, in the format of internal key.
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// file: the output file to write out
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// offset: offset in the file. Needs to be updated after appending bytes
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// for the key
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// meta_bytes_buf: buffer for extra meta bytes
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// meta_bytes_buf_size: offset to append extra meta bytes. Will be updated
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// if meta_bytes_buf is updated.
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Status AppendKey(const Slice& key, WritableFile* file, uint64_t* offset,
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char* meta_bytes_buf, size_t* meta_bytes_buf_size);
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// Return actual encoding type to be picked
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EncodingType GetEncodingType() { return encoding_type_; }
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private:
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EncodingType encoding_type_;
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uint32_t fixed_user_key_len_;
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const SliceTransform* prefix_extractor_;
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const size_t index_sparseness_;
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size_t key_count_for_prefix_;
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IterKey pre_prefix_;
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};
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// A helper class to decode keys from input buffer
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// Actual data format of the key is documented in plain_table_factory.h
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class PlainTableKeyDecoder {
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public:
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explicit PlainTableKeyDecoder(EncodingType encoding_type,
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uint32_t user_key_len,
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const SliceTransform* prefix_extractor)
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: encoding_type_(encoding_type),
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prefix_len_(0),
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fixed_user_key_len_(user_key_len),
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prefix_extractor_(prefix_extractor),
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in_prefix_(false) {}
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// Find the next key.
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// start: char array where the key starts.
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// limit: boundary of the char array
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// parsed_key: the output of the result key
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// internal_key: if not null, fill with the output of the result key in
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// un-parsed format
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// bytes_read: how many bytes read from start. Output
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// seekable: whether key can be read from this place. Used when building
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// indexes. Output.
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Status NextKey(const char* start, const char* limit,
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ParsedInternalKey* parsed_key, Slice* internal_key,
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size_t* bytes_read, bool* seekable = nullptr);
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EncodingType encoding_type_;
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uint32_t prefix_len_;
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uint32_t fixed_user_key_len_;
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Slice saved_user_key_;
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IterKey cur_key_;
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const SliceTransform* prefix_extractor_;
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bool in_prefix_;
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private:
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Status NextPlainEncodingKey(const char* start, const char* limit,
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ParsedInternalKey* parsed_key,
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Slice* internal_key, size_t* bytes_read,
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bool* seekable = nullptr);
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Status NextPrefixEncodingKey(const char* start, const char* limit,
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ParsedInternalKey* parsed_key,
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Slice* internal_key, size_t* bytes_read,
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bool* seekable = nullptr);
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};
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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