dirstate walking optimizations
The repo walking code introduces a number of calls to dirstate.map.copy(),
significantly slowing down the walk on large trees. When a list of
files is passed to the walking code, we should only look at map entries
relevant to the file list passed in.
dirstate.filterfiles() is added to return a subset of the dirstate map.
The subset includes in files passed in, and if one of the files requested
is actually a directory, it includes any files inside that directory tree.
This brings the time for hg diff Makefile down from 1.7s to .3s on
a linux kernel repo.
Also, the diff command was unconditionally calling makewalk, leading
to an extra pass through repo.changes. This patch avoids the call
to makewalk when commands.diff isn't given a list of patterns, cutting
the time for hg diff (with no args) in half.
Index: mine/mercurial/hg.py
===================================================================
#!/bin/sh
hg --debug init
echo this is a1 > a
hg add a
hg commit -m0 -d "0 0"
echo this is b1 > b
hg add b
hg commit -m1 -d "0 0"
hg manifest 1
echo this is c1 > c
hg rawcommit -p 1 -d "0 0" -m2 c
hg manifest 2
hg parents
rm b
hg rawcommit -p 2 -d "0 0" -m3 b
hg manifest 3
hg parents
echo this is a22 > a
hg rawcommit -p 3 -d "0 0" -m4 a
hg manifest 4
hg parents
echo this is c22 > c
hg rawcommit -p 1 -d "0 0" -m5 c
hg manifest 5
hg parents
# merge, but no files changed
hg rawcommit -p 4 -p 5 -d "0 0" -m6
hg manifest 6
hg parents
# no changes what-so-ever
hg rawcommit -p 6 -d "0 0" -m7
hg manifest 7
hg parents