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Merge fastCover into DictBuilder (#1274)

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* Minor fix

* Run non-optimize FASTCOVER 5 times in benchmark

* Merge fastCover into dictBuilder

* Fix mixed declaration issue

* Add fastcover to symbol.c

* Add fastCover.c and cover.h to build

* Change fastCover.c to fastcover.c

* Update benchmark to run FASTCOVER in dictBuilder

* Undo spliting fastcover_param into cover_param and f

* Remove convert param functions

* Assign f to parameter

* Add zdict.h to Makefile in lib

* Add cover.h to BUCK

* Cast 1 to U64 before shifting

* Remove trimming of zero freq head and tail in selectSegment and rebenchmark

* Remove f as a separate parameter of tryParam

* Read 8 bytes when d is 6

* Add trimming off zero frequency head and tail

* Use best functions from COVER and remove trimming part(which leads to worse compression ratio after previous bugs were fixed)

* Add finalize= argument to FASTCOVER to specify percentage of training samples passed to ZDICT_finalizeDictionary

* Change nbDmer to always read 8 bytes even when d=6

* Add skip=# argument to allow skipping dmers in computeFrequency in FASTCOVER

* Update comments and benchmarking result

* Change default method of ZDICT_trainFromBuffer to ZDICT_optimizeTrainFromBuffer_fastCover

* Add dictType enum and fix bug about passing zParam when converting to coverParam

* Combine finalize and skip into a single parameter

* Update acceleration parameters and benchmark on 3 sample sets

* Change default splitPoint of FASTCOVER to 0.75 and benchmark first 3 sample sets

* Initialize variables outside of for loop in benchmark.c

* Update benchmark result for hg-manifest

* Remove cover.h from install-includes

* Add explanation of f

* Set default compression level for trainFromBuffer to 3

* Add assertion of fastCoverParams in DiB_trainFromFiles

* Add checkTotalCompressedSize function + some minor fixes

* Add test for multithreading fastCovr

* Initialize segmentFreqs in every FASTCOVER_selectSegment and move mutex_unnlock to end of COVER_best_finish

* Free segmentFreqs

* Initialize segmentFreqs before calling FASTCOVER_buildDictionary instead of in FASTCOVER_selectSegment

* Add FASTCOVER_MEMMULT

* Minor fix

* Update benchmarking result
This commit is contained in:
Jennifer Liu
2018-08-23 12:06:20 -07:00
committed by Nick Terrell
parent 1af27a7ed7
commit 9d6ed9def3
26 changed files with 1999 additions and 246 deletions
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programs/zstd.1.md
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@@ -254,6 +254,26 @@ Compression of small files similar to the sample set will be greatly improved.
`zstd --train-cover=k=50,split=60 FILEs`
* `--train-fastcover[=k#,d=#,f=#,steps=#,split=#,accel=#]`:
Same as cover but with extra parameters _f_ and _accel_ and different default value of split
If _split_ is not specified, then it tries _split_ = 75.
If _f_ is not specified, then it tries _f_ = 18.
Requires that 0 < _f_ < 32.
If _accel_ is not specified, then it tries _accel_ = 1.
Requires that 0 < _accel_ <= 10.
Requires that _d_ = 6 or _d_ = 8.
_f_ is log of size of array that keeps track of frequency of subsegments of size _d_.
The subsegment is hashed to an index in the range [0,2^_f_ - 1].
It is possible that 2 different subsegments are hashed to the same index, and they are considered as the same subsegment when computing frequency.
Using a higher _f_ reduces collision but takes longer.
Examples:
`zstd --train-fastcover FILEs`
`zstd --train-fastcover=d=8,f=15,accel=2 FILEs`
* `--train-legacy[=selectivity=#]`:
Use legacy dictionary builder algorithm with the given dictionary
_selectivity_ (default: 9).