Optimize dirstate walking This generally cuts the time for hg status/diff in half, from 2s down to 1s. The main parts I'm trying to optimize are: 1) os.walk stats every file. dirstate.changes then stats every file again. 2) os.walk yields every file and subdir to dirstate.traverse who yields every file and everything in the dirstate map. dirstate.walk then filters this mass and yields every file to the caller. There should be fewer steps in here, and fewer duplicate strings yielded. 3) dirstate.walk runs util.unique on the results from dirstate.traverse, even though it is also passing things through dirstate.seen to look for duplicates. I've turned os.walk into something hg specific that takes all the dirstate ignore and matching rules into account. The new function also takes an function arg (statmatch()) the caller supplies to help filter out files it doesn't care about. dirstate.changes uses this to update state for each file, avoiding the second stat call. dirstate.walk is changed to turn the match function it is passed into a statmatch function. The only real difference is that a statmatch function takes the stat data as a second parameter. It now calls dirstate.walkhelper, who requires a statmatch function to be passed. This fails test-walk, but right now I think this is from a sorting error fixed by this patch. Index: crew/mercurial/dirstate.py ===================================================================