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7c673cae | 1 | // Copyright (c) 2011-present, Facebook, Inc. All rights reserved. |
11fdf7f2 TL |
2 | // This source code is licensed under both the GPLv2 (found in the |
3 | // COPYING file in the root directory) and Apache 2.0 License | |
4 | // (found in the LICENSE.Apache file in the root directory). | |
7c673cae FG |
5 | #pragma once |
6 | ||
7 | #include <stdint.h> | |
8 | #include "rocksdb/status.h" | |
9 | ||
10 | namespace rocksdb { | |
11 | ||
12 | class Comparator; | |
13 | class Iterator; | |
14 | class Slice; | |
15 | class SliceTransform; | |
16 | ||
17 | // Build a hash-based index to speed up the lookup for "index block". | |
18 | // BlockHashIndex accepts a key and, if found, returns its restart index within | |
19 | // that index block. | |
20 | class BlockPrefixIndex { | |
21 | public: | |
7c673cae FG |
22 | // Maps a key to a list of data blocks that could potentially contain |
23 | // the key, based on the prefix. | |
24 | // Returns the total number of relevant blocks, 0 means the key does | |
25 | // not exist. | |
26 | uint32_t GetBlocks(const Slice& key, uint32_t** blocks); | |
27 | ||
28 | size_t ApproximateMemoryUsage() const { | |
29 | return sizeof(BlockPrefixIndex) + | |
494da23a | 30 | (num_block_array_buffer_entries_ + num_buckets_) * sizeof(uint32_t); |
7c673cae FG |
31 | } |
32 | ||
33 | // Create hash index by reading from the metadata blocks. | |
34 | // @params prefixes: a sequence of prefixes. | |
35 | // @params prefix_meta: contains the "metadata" to of the prefixes. | |
36 | static Status Create(const SliceTransform* hash_key_extractor, | |
37 | const Slice& prefixes, const Slice& prefix_meta, | |
38 | BlockPrefixIndex** prefix_index); | |
39 | ||
40 | ~BlockPrefixIndex() { | |
41 | delete[] buckets_; | |
42 | delete[] block_array_buffer_; | |
43 | } | |
44 | ||
45 | private: | |
46 | class Builder; | |
47 | friend Builder; | |
48 | ||
49 | BlockPrefixIndex(const SliceTransform* internal_prefix_extractor, | |
494da23a | 50 | uint32_t num_buckets, uint32_t* buckets, |
7c673cae FG |
51 | uint32_t num_block_array_buffer_entries, |
52 | uint32_t* block_array_buffer) | |
53 | : internal_prefix_extractor_(internal_prefix_extractor), | |
54 | num_buckets_(num_buckets), | |
55 | num_block_array_buffer_entries_(num_block_array_buffer_entries), | |
56 | buckets_(buckets), | |
57 | block_array_buffer_(block_array_buffer) {} | |
58 | ||
59 | const SliceTransform* internal_prefix_extractor_; | |
60 | uint32_t num_buckets_; | |
61 | uint32_t num_block_array_buffer_entries_; | |
62 | uint32_t* buckets_; | |
63 | uint32_t* block_array_buffer_; | |
64 | }; | |
65 | ||
66 | } // namespace rocksdb |