LevelDB-course-Lab

小组成员：10215300402-朱维清 & 10222140408 谷杰

leveldb Team 1d6e8d64ee Add support for Zstd-based compression in LevelDB. This change implements support for Zstd-based compression in LevelDB. Building up from the Snappy compression (which has been supported since inception), this change adds Zstd as an alternate compression algorithm. We are implementing this to provide alternative options for users who might have different performance and efficiency requirements. For instance, the Zstandard website (https://facebook.github.io/zstd/) claims that the Zstd algorithm can achieve around 30% higher compression ratios than Snappy, with relatively smaller (~10%) slowdowns in de/compression speeds. Benchmarking results: $ blaze-bin/third_party/leveldb/db_bench LevelDB: version 1.23 Date: Thu Feb 2 18:50:06 2023 CPU: 56 * Intel(R) Xeon(R) CPU E5-2690 v4 @ 2.60GHz CPUCache: 35840 KB Keys: 16 bytes each Values: 100 bytes each (50 bytes after compression) Entries: 1000000 RawSize: 110.6 MB (estimated) FileSize: 62.9 MB (estimated) ------------------------------------------------ fillseq : 2.613 micros/op; 42.3 MB/s fillsync : 3924.432 micros/op; 0.0 MB/s (1000 ops) fillrandom : 3.609 micros/op; 30.7 MB/s overwrite : 4.508 micros/op; 24.5 MB/s readrandom : 6.136 micros/op; (864322 of 1000000 found) readrandom : 5.446 micros/op; (864083 of 1000000 found) readseq : 0.180 micros/op; 613.3 MB/s readreverse : 0.321 micros/op; 344.7 MB/s compact : 827043.000 micros/op; readrandom : 4.603 micros/op; (864105 of 1000000 found) readseq : 0.169 micros/op; 656.3 MB/s readreverse : 0.315 micros/op; 350.8 MB/s fill100K : 854.009 micros/op; 111.7 MB/s (1000 ops) crc32c : 1.227 micros/op; 3184.0 MB/s (4K per op) snappycomp : 3.610 micros/op; 1081.9 MB/s (output: 55.2%) snappyuncomp : 0.691 micros/op; 5656.3 MB/s zstdcomp : 15.731 micros/op; 248.3 MB/s (output: 44.1%) zstduncomp : 4.218 micros/op; 926.2 MB/s PiperOrigin-RevId: 509957778		1 рік тому
..
README.md	Moved port/README to port/README.md.	5 роки тому
port.h	Format all files IAW the Google C++ Style Guide.	5 роки тому
port_config.h.in	Add support for Zstd-based compression in LevelDB.	1 рік тому
port_example.h	Add support for Zstd-based compression in LevelDB.	1 рік тому
port_stdcxx.h	Add support for Zstd-based compression in LevelDB.	1 рік тому
thread_annotations.h	Format all files IAW the Google C++ Style Guide.	5 роки тому

README.md

This directory contains interfaces and implementations that isolate the rest of the package from platform details.

Code in the rest of the package includes "port.h" from this directory. "port.h" in turn includes a platform specific "port_.h" file that provides the platform specific implementation.

See port_stdcxx.h for an example of what must be provided in a platform specific header file.