sapling/mercurial/pure
Siddharth Agarwal f40a94a790 parsers: inline fields of dirstate values in C version
Previously, while unpacking the dirstate we'd create 3-4 new CPython objects
for most dirstate values:

- the state is a single character string, which is pooled by CPython
- the mode is a new object if it isn't 0 due to being in the lookup set
- the size is a new object if it is greater than 255
- the mtime is a new object if it isn't -1 due to being in the lookup set
- the tuple to contain them all

In some cases such as regular hg status, we actually look at all the objects.
In other cases like hg add, hg status for a subdirectory, or hg status with the
third-party hgwatchman enabled, we look at almost none of the objects.

This patch eliminates most object creation in these cases by defining a custom
C struct that is exposed to Python with an interface similar to a tuple. Only
when tuple elements are actually requested are the respective objects created.

The gains, where they're expected, are significant. The following tests are run
against a working copy with over 270,000 files.

parse_dirstate becomes significantly faster:

$ hg perfdirstate
before: wall 0.186437 comb 0.180000 user 0.160000 sys 0.020000 (best of 35)
after:  wall 0.093158 comb 0.100000 user 0.090000 sys 0.010000 (best of 95)

and as a result, several commands benefit:

$ time hg status  # with hgwatchman enabled
before: 0.42s user 0.14s system 99% cpu 0.563 total
after:  0.34s user 0.12s system 99% cpu 0.471 total

$ time hg add new-file
before: 0.85s user 0.18s system 99% cpu 1.033 total
after:  0.76s user 0.17s system 99% cpu 0.931 total

There is a slight regression in regular status performance, but this is fixed
in an upcoming patch.
2014-05-27 14:27:41 -07:00
..
__init__.py pure: quiesce build warnings 2012-04-16 08:50:40 -07:00
base85.py pure/base85: align exception type/msg on base85.c 2012-05-07 21:49:45 +02:00
bdiff.py mdiff: replace wscleanup() regexps with C loops 2011-11-18 14:23:03 +01:00
diffhelpers.py cleanup: use x in (a, b) instead of x == a or x == b 2010-09-23 00:02:31 -05:00
mpatch.py cleanup: eradicate long lines 2012-05-12 15:54:54 +02:00
osutil.py osutil: consider WindowsError's behaviour to support python 2.4 on Windows 2013-07-12 11:14:42 +09:00
parsers.py parsers: inline fields of dirstate values in C version 2014-05-27 14:27:41 -07:00