diff options
Diffstat (limited to 'include/leveldb/options.h')
| -rw-r--r-- | include/leveldb/options.h | 95 |
1 files changed, 34 insertions, 61 deletions
diff --git a/include/leveldb/options.h b/include/leveldb/options.h index 1c42921..0f285bc 100644 --- a/include/leveldb/options.h +++ b/include/leveldb/options.h @@ -5,7 +5,8 @@ #ifndef STORAGE_LEVELDB_INCLUDE_OPTIONS_H_ #define STORAGE_LEVELDB_INCLUDE_OPTIONS_H_ -#include <stddef.h> +#include <cstddef> + #include "leveldb/export.h" namespace leveldb { @@ -24,12 +25,15 @@ class Snapshot; enum CompressionType { // NOTE: do not change the values of existing entries, as these are // part of the persistent format on disk. - kNoCompression = 0x0, + kNoCompression = 0x0, kSnappyCompression = 0x1 }; // Options to control the behavior of a database (passed to DB::Open) struct LEVELDB_EXPORT Options { + // Create an Options object with default values for all fields. + Options(); + // ------------------- // Parameters that affect behavior @@ -42,20 +46,17 @@ struct LEVELDB_EXPORT Options { const Comparator* comparator; // If true, the database will be created if it is missing. - // Default: false - bool create_if_missing; + bool create_if_missing = false; // If true, an error is raised if the database already exists. - // Default: false - bool error_if_exists; + bool error_if_exists = false; // If true, the implementation will do aggressive checking of the // data it is processing and will stop early if it detects any // errors. This may have unforeseen ramifications: for example, a // corruption of one DB entry may cause a large number of entries to // become unreadable or for the entire DB to become unopenable. - // Default: false - bool paranoid_checks; + bool paranoid_checks = false; // Use the specified object to interact with the environment, // e.g. to read/write files, schedule background work, etc. @@ -63,10 +64,9 @@ struct LEVELDB_EXPORT Options { Env* env; // Any internal progress/error information generated by the db will - // be written to info_log if it is non-NULL, or to a file stored - // in the same directory as the DB contents if info_log is NULL. - // Default: NULL - Logger* info_log; + // be written to info_log if it is non-null, or to a file stored + // in the same directory as the DB contents if info_log is null. + Logger* info_log = nullptr; // ------------------- // Parameters that affect performance @@ -79,39 +79,30 @@ struct LEVELDB_EXPORT Options { // so you may wish to adjust this parameter to control memory usage. // Also, a larger write buffer will result in a longer recovery time // the next time the database is opened. - // - // Default: 4MB - size_t write_buffer_size; + size_t write_buffer_size = 4 * 1024 * 1024; // Number of open files that can be used by the DB. You may need to // increase this if your database has a large working set (budget // one open file per 2MB of working set). - // - // Default: 1000 - int max_open_files; + int max_open_files = 1000; // Control over blocks (user data is stored in a set of blocks, and // a block is the unit of reading from disk). - // If non-NULL, use the specified cache for blocks. - // If NULL, leveldb will automatically create and use an 8MB internal cache. - // Default: NULL - Cache* block_cache; + // If non-null, use the specified cache for blocks. + // If null, leveldb will automatically create and use an 8MB internal cache. + Cache* block_cache = nullptr; // Approximate size of user data packed per block. Note that the // block size specified here corresponds to uncompressed data. The // actual size of the unit read from disk may be smaller if // compression is enabled. This parameter can be changed dynamically. - // - // Default: 4K - size_t block_size; + size_t block_size = 4 * 1024; // Number of keys between restart points for delta encoding of keys. // This parameter can be changed dynamically. Most clients should // leave this parameter alone. - // - // Default: 16 - int block_restart_interval; + int block_restart_interval = 16; // Leveldb will write up to this amount of bytes to a file before // switching to a new one. @@ -121,9 +112,7 @@ struct LEVELDB_EXPORT Options { // compactions and hence longer latency/performance hiccups. // Another reason to increase this parameter might be when you are // initially populating a large database. - // - // Default: 2MB - size_t max_file_size; + size_t max_file_size = 2 * 1024 * 1024; // Compress blocks using the specified compression algorithm. This // parameter can be changed dynamically. @@ -139,53 +128,43 @@ struct LEVELDB_EXPORT Options { // worth switching to kNoCompression. Even if the input data is // incompressible, the kSnappyCompression implementation will // efficiently detect that and will switch to uncompressed mode. - CompressionType compression; + CompressionType compression = kSnappyCompression; // EXPERIMENTAL: If true, append to existing MANIFEST and log files // when a database is opened. This can significantly speed up open. // // Default: currently false, but may become true later. - bool reuse_logs; + bool reuse_logs = false; - // If non-NULL, use the specified filter policy to reduce disk reads. + // If non-null, use the specified filter policy to reduce disk reads. // Many applications will benefit from passing the result of // NewBloomFilterPolicy() here. - // - // Default: NULL - const FilterPolicy* filter_policy; - - // Create an Options object with default values for all fields. - Options(); + const FilterPolicy* filter_policy = nullptr; }; // Options that control read operations struct LEVELDB_EXPORT ReadOptions { + ReadOptions() = default; + // If true, all data read from underlying storage will be // verified against corresponding checksums. - // Default: false - bool verify_checksums; + bool verify_checksums = false; // Should the data read for this iteration be cached in memory? // Callers may wish to set this field to false for bulk scans. - // Default: true - bool fill_cache; + bool fill_cache = true; - // If "snapshot" is non-NULL, read as of the supplied snapshot + // If "snapshot" is non-null, read as of the supplied snapshot // (which must belong to the DB that is being read and which must - // not have been released). If "snapshot" is NULL, use an implicit + // not have been released). If "snapshot" is null, use an implicit // snapshot of the state at the beginning of this read operation. - // Default: NULL - const Snapshot* snapshot; - - ReadOptions() - : verify_checksums(false), - fill_cache(true), - snapshot(NULL) { - } + const Snapshot* snapshot = nullptr; }; // Options that control write operations struct LEVELDB_EXPORT WriteOptions { + WriteOptions() = default; + // If true, the write will be flushed from the operating system // buffer cache (by calling WritableFile::Sync()) before the write // is considered complete. If this flag is true, writes will be @@ -200,13 +179,7 @@ struct LEVELDB_EXPORT WriteOptions { // crash semantics as the "write()" system call. A DB write // with sync==true has similar crash semantics to a "write()" // system call followed by "fsync()". - // - // Default: false - bool sync; - - WriteOptions() - : sync(false) { - } + bool sync = false; }; } // namespace leveldb |