/Users/deen/code/yugabyte-db/src/yb/rocksdb/table/table_reader.h
Line | Count | Source (jump to first uncovered line) |
1 | | // Copyright (c) 2011-present, Facebook, Inc. All rights reserved. |
2 | | // This source code is licensed under the BSD-style license found in the |
3 | | // LICENSE file in the root directory of this source tree. An additional grant |
4 | | // of patent rights can be found in the PATENTS file in the same directory. |
5 | | // |
6 | | // The following only applies to changes made to this file as part of YugaByte development. |
7 | | // |
8 | | // Portions Copyright (c) YugaByte, Inc. |
9 | | // |
10 | | // Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except |
11 | | // in compliance with the License. You may obtain a copy of the License at |
12 | | // |
13 | | // http://www.apache.org/licenses/LICENSE-2.0 |
14 | | // |
15 | | // Unless required by applicable law or agreed to in writing, software distributed under the License |
16 | | // is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express |
17 | | // or implied. See the License for the specific language governing permissions and limitations |
18 | | // under the License. |
19 | | // |
20 | | // Copyright (c) 2011 The LevelDB Authors. All rights reserved. |
21 | | // Use of this source code is governed by a BSD-style license that can be |
22 | | // found in the LICENSE file. See the AUTHORS file for names of contributors. |
23 | | |
24 | | #ifndef YB_ROCKSDB_TABLE_TABLE_READER_H |
25 | | #define YB_ROCKSDB_TABLE_TABLE_READER_H |
26 | | |
27 | | #include <memory> |
28 | | |
29 | | #include "yb/rocksdb/status.h" |
30 | | |
31 | | #include "yb/util/result.h" |
32 | | |
33 | | namespace rocksdb { |
34 | | |
35 | | class Iterator; |
36 | | struct ParsedInternalKey; |
37 | | class Arena; |
38 | | struct ReadOptions; |
39 | | struct TableProperties; |
40 | | class GetContext; |
41 | | class InternalIterator; |
42 | | class RandomAccessFileReader; |
43 | | class WritableFile; |
44 | | |
45 | | // A Table is a sorted map from strings to strings. Tables are |
46 | | // immutable and persistent. A Table may be safely accessed from |
47 | | // multiple threads without external synchronization. |
48 | | class TableReader { |
49 | | public: |
50 | 79.0k | virtual ~TableReader() {} |
51 | | |
52 | | // Returns whether SST is split into data and metadata files. |
53 | | virtual bool IsSplitSst() const = 0; |
54 | | |
55 | | // Set data file reader for SST split into data and metadata files. |
56 | | virtual void SetDataFileReader(std::unique_ptr<RandomAccessFileReader>&& data_file) = 0; |
57 | | |
58 | | // Returns a new iterator over the table contents. |
59 | | // The result of NewIterator() is initially invalid (caller must |
60 | | // call one of the Seek methods on the iterator before using it). |
61 | | // arena: If not null, the arena needs to be used to allocate the Iterator. |
62 | | // When destroying the iterator, the caller will not call "delete" |
63 | | // but Iterator::~Iterator() directly. The destructor needs to destroy |
64 | | // all the states but those allocated in arena. |
65 | | // skip_filters: disables checking the bloom filters even if they exist. This |
66 | | // option is effective only for block-based table format. |
67 | | virtual InternalIterator* NewIterator(const ReadOptions&, |
68 | | Arena* arena = nullptr, |
69 | | bool skip_filters = false) = 0; |
70 | | |
71 | | // Given a key, return an approximate byte offset in the file where |
72 | | // the data for that key begins (or would begin if the key were |
73 | | // present in the file). The returned value is in terms of file |
74 | | // bytes, and so includes effects like compression of the underlying data. |
75 | | // E.g., the approximate offset of the last key in the table will |
76 | | // be close to the file length. |
77 | | virtual uint64_t ApproximateOffsetOf(const Slice& key) = 0; |
78 | | |
79 | | // Set up the table for Compaction. Might change some parameters with |
80 | | // posix_fadvise |
81 | | virtual void SetupForCompaction() = 0; |
82 | | |
83 | | virtual std::shared_ptr<const TableProperties> GetTableProperties() const = 0; |
84 | | |
85 | | // Prepare work that can be done before the real Get() |
86 | 71.4k | virtual void Prepare(const Slice& target) {} |
87 | | |
88 | | // Report an approximation of how much memory has been used. |
89 | | virtual size_t ApproximateMemoryUsage() const = 0; |
90 | | |
91 | | // Calls get_context->SaveValue() repeatedly, starting with |
92 | | // the entry found after a call to Seek(key), until it returns false. |
93 | | // May not make such a call if filter policy says that key is not present. |
94 | | // |
95 | | // get_context->MarkKeyMayExist needs to be called when it is configured to be |
96 | | // memory only and the key is not found in the block cache. |
97 | | // |
98 | | // readOptions is the options for the read |
99 | | // internal_key is the internal key (encoded representation of InternalKey) to search for |
100 | | // skip_filters: disables checking the bloom filters even if they exist. This |
101 | | // option is effective only for block-based table format. |
102 | | virtual Status Get(const ReadOptions& readOptions, const Slice& internal_key, |
103 | | GetContext* get_context, bool skip_filters = false) = 0; |
104 | | |
105 | | // Prefetch data corresponding to a give range of keys |
106 | | // Typically this functionality is required for table implementations that |
107 | | // persists the data on a non volatile storage medium like disk/SSD |
108 | | virtual Status Prefetch(const Slice* begin = nullptr, |
109 | 0 | const Slice* end = nullptr) { |
110 | 0 | (void) begin; |
111 | 0 | (void) end; |
112 | 0 | // Default implementation is NOOP. |
113 | 0 | // The child class should implement functionality when applicable |
114 | 0 | return Status::OK(); |
115 | 0 | } |
116 | | |
117 | | // convert db file to a human readable form |
118 | 0 | virtual Status DumpTable(WritableFile* out_file) { |
119 | 0 | return STATUS(NotSupported, "DumpTable() not supported"); |
120 | 0 | } Unexecuted instantiation: rocksdb::TableReader::DumpTable(rocksdb::WritableFile*) Unexecuted instantiation: rocksdb::TableReader::DumpTable(rocksdb::WritableFile*) |
121 | | |
122 | | // Returns approximate middle key which divides SST file into two parts containing roughly the |
123 | | // same amount of keys. |
124 | 0 | virtual yb::Result<std::string> GetMiddleKey() { |
125 | 0 | return STATUS(NotSupported, "GetMiddleKey() not supported"); |
126 | 0 | } Unexecuted instantiation: rocksdb::TableReader::GetMiddleKey() Unexecuted instantiation: rocksdb::TableReader::GetMiddleKey() |
127 | | }; |
128 | | |
129 | | } // namespace rocksdb |
130 | | |
131 | | #endif // YB_ROCKSDB_TABLE_TABLE_READER_H |