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 ===================================================================

+ hg init
+ hg add a
+ hg commit -m test -d 0 0
+ hg history
changeset:   0:acb14030fe0a
tag:         tip
user:        test
date:        Thu Jan  1 00:00:00 1970
summary:     test

+ hg tag -d 0 0 bleah
+ hg history
changeset:   1:863197ef0378
tag:         tip
user:        test
date:        Thu Jan  1 00:00:00 1970
summary:     Added tag bleah for changeset acb14030fe0a21b60322c440ad2d20cf7685a376

changeset:   0:acb14030fe0a
tag:         bleah
user:        test
date:        Thu Jan  1 00:00:00 1970
summary:     test

+ hg tag -d 0 0 bleah2
abort: working copy of .hgtags is changed!
(please commit .hgtags manually)
failed