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

def demandload(scope, modules):
    class d:
        def __getattr__(self, name):
            mod = self.__dict__["mod"]
            scope = self.__dict__["scope"]
            scope[mod] = __import__(mod, scope, scope, [])
            return getattr(scope[mod], name)

    for m in modules.split():
        dl = d()
        dl.mod = m
        dl.scope = scope
        scope[m] = dl