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revlog: use compression engine APIs for decompression...
revlog: use compression engine APIs for decompression Now that compression engines declare their header in revlog chunks and can decompress revlog chunks, we refactor revlog.decompress() to use them. Making full use of the property that revlog compressor objects are reusable, revlog instances now maintain a dict mapping an engine's revlog header to a compressor object. This is not only a performance optimization for engines where compressor object reuse can result in better performance, but it also serves as a cache of header values so we don't need to perform redundant lookups against the compression engine manager. (Yes, I measured and the overhead of a function call versus a dict lookup was observed.) Replacing the previous inline lookup table with a dict lookup was measured to make chunk reading ~2.5% slower on changelogs and ~4.5% slower on manifests. So, the inline lookup table has been mostly preserved so we don't lose performance. This is unfortunate. But many decompression operations complete in microseconds, so Python attribute lookup, dict lookup, and function calls do matter. The impact of this change on mozilla-unified is as follows: $ hg perfrevlogchunks -c ! chunk ! wall 1.953663 comb 1.950000 user 1.920000 sys 0.030000 (best of 6) ! wall 1.946000 comb 1.940000 user 1.910000 sys 0.030000 (best of 6) ! chunk batch ! wall 1.791075 comb 1.800000 user 1.760000 sys 0.040000 (best of 6) ! wall 1.785690 comb 1.770000 user 1.750000 sys 0.020000 (best of 6) $ hg perfrevlogchunks -m ! chunk ! wall 2.587262 comb 2.580000 user 2.550000 sys 0.030000 (best of 4) ! wall 2.616330 comb 2.610000 user 2.560000 sys 0.050000 (best of 4) ! chunk batch ! wall 2.427092 comb 2.420000 user 2.400000 sys 0.020000 (best of 5) ! wall 2.462061 comb 2.460000 user 2.400000 sys 0.060000 (best of 4) Changelog chunk reading is slightly faster but manifest reading is slower. What gives? On this repo, 99.85% of changelog entries are zlib compressed (the 'x' header). On the manifest, 67.5% are zlib and 32.4% are '\0'. This patch swapped the test order of 'x' and '\0' so now 'x' is tested first. This makes changelogs faster since they almost always hit the first branch. This makes a significant percentage of manifest '\0' chunks slower because that code path now performs an extra test. Yes, I too can't believe we're able to measure the impact of an if..elif with simple string compares. I reckon this code would benefit from being written in C...
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Takumi IINO
doc: make man and html from translated documents...
 r19426 ======
hgrc
======
---------------------------------
configuration files for Mercurial
---------------------------------
:Author: Bryan O'Sullivan <bos@serpentine.com>
:Organization: Mercurial
:Manual section: 5
:Manual group: Mercurial Manual
.. contents::
:backlinks: top
:class: htmlonly
Description
===========
.. include:: hgrc.5.gendoc.txt
Author
======
Bryan O'Sullivan <bos@serpentine.com>.
Mercurial was written by Matt Mackall <mpm@selenic.com>.
See Also
========
|hg(1)|_, |hgignore(5)|_
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=======
This manual page is copyright 2005 Bryan O'Sullivan.
timeless
copyright: update to 2016
 r27925 Mercurial is copyright 2005-2016 Matt Mackall.
Takumi IINO
doc: make man and html from translated documents...
 r19426 Free use of this software is granted under the terms of the GNU General
Public License version 2 or any later version.
.. include:: common.txt