1179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org// Copyright (c) 2011 The LevelDB Authors. All rights reserved. 2179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org// Use of this source code is governed by a BSD-style license that can be 3179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org// found in the LICENSE file. See the AUTHORS file for names of contributors. 4179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 5179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org#ifndef STORAGE_LEVELDB_INCLUDE_OPTIONS_H_ 6179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org#define STORAGE_LEVELDB_INCLUDE_OPTIONS_H_ 7179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 8179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org#include <stddef.h> 9179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 10179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.orgnamespace leveldb { 11179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 12179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.orgclass Cache; 13179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.orgclass Comparator; 14179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.orgclass Env; 1599a7585544fc162a5f8dd39a6add00776a981efesanjay@google.comclass FilterPolicy; 16f65a55c8d0744b95be29a65d06b59b22b012f37bgabor@google.comclass Logger; 17179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.orgclass Snapshot; 18179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 19179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org// DB contents are stored in a set of blocks, each of which holds a 20179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org// sequence of key,value pairs. Each block may be compressed before 21179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org// being stored in a file. The following enum describes which 22179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org// compression method (if any) is used to compress a block. 23179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.orgenum CompressionType { 24179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // NOTE: do not change the values of existing entries, as these are 25179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // part of the persistent format on disk. 2607f3bcfb9764be2a339cc02cf0a0d6edb151defbjorlow@chromium.org kNoCompression = 0x0, 2751f892d349df9ed408f5a0e6e012667e5eae5f8bgabor@google.com kSnappyCompression = 0x1 28179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org}; 29179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 30179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org// Options to control the behavior of a database (passed to DB::Open) 31179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.orgstruct Options { 32179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // ------------------- 33179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Parameters that affect behavior 34179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 35179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Comparator used to define the order of keys in the table. 36179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Default: a comparator that uses lexicographic byte-wise ordering 37179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // 38179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // REQUIRES: The client must ensure that the comparator supplied 39179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // here has the same name and orders keys *exactly* the same as the 40179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // comparator provided to previous open calls on the same DB. 41179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org const Comparator* comparator; 42179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 43179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // If true, the database will be created if it is missing. 44179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Default: false 45179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org bool create_if_missing; 46179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 47179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // If true, an error is raised if the database already exists. 48179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Default: false 49179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org bool error_if_exists; 50179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 51179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // If true, the implementation will do aggressive checking of the 52179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // data it is processing and will stop early if it detects any 53179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // errors. This may have unforeseen ramifications: for example, a 54179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // corruption of one DB entry may cause a large number of entries to 55179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // become unreadable or for the entire DB to become unopenable. 56179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Default: false 57179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org bool paranoid_checks; 58179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 59179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Use the specified object to interact with the environment, 60179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // e.g. to read/write files, schedule background work, etc. 61179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Default: Env::Default() 62179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org Env* env; 63179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 64179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Any internal progress/error information generated by the db will 65f65a55c8d0744b95be29a65d06b59b22b012f37bgabor@google.com // be written to info_log if it is non-NULL, or to a file stored 66179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // in the same directory as the DB contents if info_log is NULL. 67179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Default: NULL 68f65a55c8d0744b95be29a65d06b59b22b012f37bgabor@google.com Logger* info_log; 69179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 70179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // ------------------- 71179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Parameters that affect performance 72179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 7395e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // Amount of data to build up in memory (backed by an unsorted log 7495e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // on disk) before converting to a sorted on-disk file. 75179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // 7695e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // Larger values increase performance, especially during bulk loads. 7795e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // Up to two write buffers may be held in memory at the same time, 7895e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // so you may wish to adjust this parameter to control memory usage. 79917b88dd720b6e658c1fd7812bc61c605f315124gabor@google.com // Also, a larger write buffer will result in a longer recovery time 80917b88dd720b6e658c1fd7812bc61c605f315124gabor@google.com // the next time the database is opened. 81179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // 8295e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // Default: 4MB 83179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org size_t write_buffer_size; 84179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 85179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Number of open files that can be used by the DB. You may need to 86179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // increase this if your database has a large working set (budget 87179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // one open file per 2MB of working set). 88179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // 89179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Default: 1000 90179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org int max_open_files; 91179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 92179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Control over blocks (user data is stored in a set of blocks, and 93179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // a block is the unit of reading from disk). 94179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 9595e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // If non-NULL, use the specified cache for blocks. 9695e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // If NULL, leveldb will automatically create and use an 8MB internal cache. 97179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Default: NULL 98179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org Cache* block_cache; 99179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 100179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Approximate size of user data packed per block. Note that the 101179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // block size specified here corresponds to uncompressed data. The 102179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // actual size of the unit read from disk may be smaller if 103179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // compression is enabled. This parameter can be changed dynamically. 104179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // 10595e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // Default: 4K 1061511be6edb54b6ade2bfad94256f76bc191e92ecdgrogan@chromium.org size_t block_size; 107179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 108179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Number of keys between restart points for delta encoding of keys. 109179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // This parameter can be changed dynamically. Most clients should 110179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // leave this parameter alone. 111179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // 112179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Default: 16 113179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org int block_restart_interval; 114179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 115179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Compress blocks using the specified compression algorithm. This 116179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // parameter can be changed dynamically. 117179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // 11807f3bcfb9764be2a339cc02cf0a0d6edb151defbjorlow@chromium.org // Default: kSnappyCompression, which gives lightweight but fast 119179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // compression. 120179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // 12107f3bcfb9764be2a339cc02cf0a0d6edb151defbjorlow@chromium.org // Typical speeds of kSnappyCompression on an Intel(R) Core(TM)2 2.4GHz: 122179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // ~200-500MB/s compression 123179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // ~400-800MB/s decompression 124179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Note that these speeds are significantly faster than most 125179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // persistent storage speeds, and therefore it is typically never 126179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // worth switching to kNoCompression. Even if the input data is 12707f3bcfb9764be2a339cc02cf0a0d6edb151defbjorlow@chromium.org // incompressible, the kSnappyCompression implementation will 128179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // efficiently detect that and will switch to uncompressed mode. 129179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org CompressionType compression; 130179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 13199a7585544fc162a5f8dd39a6add00776a981efesanjay@google.com // If non-NULL, use the specified filter policy to reduce disk reads. 13299a7585544fc162a5f8dd39a6add00776a981efesanjay@google.com // Many applications will benefit from passing the result of 13399a7585544fc162a5f8dd39a6add00776a981efesanjay@google.com // NewBloomFilterPolicy() here. 13499a7585544fc162a5f8dd39a6add00776a981efesanjay@google.com // 13599a7585544fc162a5f8dd39a6add00776a981efesanjay@google.com // Default: NULL 13699a7585544fc162a5f8dd39a6add00776a981efesanjay@google.com const FilterPolicy* filter_policy; 13799a7585544fc162a5f8dd39a6add00776a981efesanjay@google.com 138179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Create an Options object with default values for all fields. 139179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org Options(); 140179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org}; 141179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 142179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org// Options that control read operations 143179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.orgstruct ReadOptions { 144179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // If true, all data read from underlying storage will be 145179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // verified against corresponding checksums. 146179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Default: false 147179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org bool verify_checksums; 148179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 149179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Should the data read for this iteration be cached in memory? 150179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Callers may wish to set this field to false for bulk scans. 151179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Default: true 152179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org bool fill_cache; 153179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 154179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // If "snapshot" is non-NULL, read as of the supplied snapshot 155179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // (which must belong to the DB that is being read and which must 156179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // not have been released). If "snapshot" is NULL, use an impliicit 157179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // snapshot of the state at the beginning of this read operation. 158179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // Default: NULL 159179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org const Snapshot* snapshot; 160179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 161179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org ReadOptions() 162179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org : verify_checksums(false), 163179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org fill_cache(true), 164179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org snapshot(NULL) { 165179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org } 166179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org}; 167179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 168179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org// Options that control write operations 169179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.orgstruct WriteOptions { 170179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // If true, the write will be flushed from the operating system 171179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // buffer cache (by calling WritableFile::Sync()) before the write 172179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // is considered complete. If this flag is true, writes will be 173179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // slower. 174179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // 175179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // If this flag is false, and the machine crashes, some recent 176179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // writes may be lost. Note that if it is just the process that 177179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // crashes (i.e., the machine does not reboot), no writes will be 178179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // lost even if sync==false. 179179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org // 18095e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // In other words, a DB write with sync==false has similar 18195e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // crash semantics as the "write()" system call. A DB write 18295e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // with sync==true has similar crash semantics to a "write()" 18395e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // system call followed by "fsync()". 18495e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // 18595e21f32367748825123e382172ecbfd492ddb23dgrogan@chromium.org // Default: false 186179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org bool sync; 187179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 188179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org WriteOptions() 1895fb21ed7ac9e91010d473ac77e132ae68f348d6agabor@google.com : sync(false) { 190179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org } 191179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org}; 192179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 19345b9940be332834440bd5299419f396e38085ebehans@chromium.org} // namespace leveldb 194179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org 195179be588c25dccaa963df9c9c104fc6229435483jorlow@chromium.org#endif // STORAGE_LEVELDB_INCLUDE_OPTIONS_H_ 196