Summary:
In RocksDB 10.6 with https://github.com/facebook/rocksdb/issues/13805, due to inaccurate testing of an async system, it went undetected at the time that LZ4 compression was using more CPU despite making a change to reuse stream objects which dramatically improved LZ4HC compression efficiency.
This change switches to using a basic LZ4 compress API which appears to be faster than all of these:
* Legacy behavior of creating LZ4_stream_t for each compression
* 10.6-10.7 behavior of re-using streams between compressions for the same file (with stream-as-WorkingArea)
* using LZ4's extState APIs without streams (with extState-as-WorkingArea) (data not shown in below results)
Also in this PR: more improvements to sst_dump --recompress, which is arguably the best SST construction benchmark right now since db_bench seems to be so noisy due to backgroun flush+compaction, even with no compaction (FIFO). Streamlined some output and added a SST read time test, mostly for decompression performance.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/14017
Test Plan:
Performance test using sst_dump --recompress with newer sst_dump back-ported to 10.5:
```
./sst_dump --command=recompress --compression_types=kLZ4Compression
test5.sst --compression_level_from=-6 --compression_level_to=-1
```
and with default compression level.
10.5:
```
Cx level: -6 Cx size: 61608137 Write usec: 880404
Cx level: -5 Cx size: 60793749 Write usec: 840903
Cx level: -4 Cx size: 58134030 Write usec: 836365
Cx level: -3 Cx size: 55193773 Write usec: 857113
Cx level: -2 Cx size: 54013891 Write usec: 855642
Cx level: -1 Cx size: 50400393 Write usec: 865194
Cx level: 32767 Cx size: 50400393 Write usec: 886310
```
Before this change (showing the regression, more time, from 10.6:
```
Cx level: -6 Cx size: 61608137 Write usec: 933448
Cx level: -5 Cx size: 60793749 Write usec: 893826
Cx level: -4 Cx size: 58134030 Write usec: 891138
Cx level: -3 Cx size: 55193773 Write usec: 898461
Cx level: -2 Cx size: 54013891 Write usec: 897485
Cx level: -1 Cx size: 50400393 Write usec: 936970
Cx level: 32767 Cx size: 50400393 Write usec: 958764
```
After this change (faster than both the above):
```
Cx level: -6 Cx size: 63641883 Write usec: 874190
Cx level: -5 Cx size: 58860032 Write usec: 834662
Cx level: -4 Cx size: 57150188 Write usec: 832707
Cx level: -3 Cx size: 58791894 Write usec: 850305
Cx level: -2 Cx size: 53145885 Write usec: 839574
Cx level: -1 Cx size: 49809139 Write usec: 845639
Cx level: 32767 Cx size: 49809139 Write usec: 875199
```
Similar tests with dictionary compression show essentially no difference (need to use stream APIs and reuse doesn't seem to matter). LZ4HC also unaffected (still improved vs. 10.5)
Reviewed By: hx235
Differential Revision: D83722880
Pulled By: pdillinger
fbshipit-source-id: 30149dd187686d5dd98321e6aa7d74bd7653a905
c44a283847