[PATCH] treemanifest: add walksubtrees api

[Augie Fackler]

On Mon, Apr 10, 2017 at 04:22:06PM -0700, Durham Goode wrote:
> # HG changeset patch
> # User Durham Goode <durham at fb.com>
> # Date 1491854867 25200
> #      Mon Apr 10 13:07:47 2017 -0700
> # Node ID a273161ab99aeec1c1beb0da627be3aeebbb513e
> # Parent  e0dc40530c5aa514feb6a09cf79ab6a3aa2ec331
> treemanifest: add walksubtrees api

Queued this, thanks.

I wonder if we can use this to make diff faster in treemanifests.

>
> Adds a new function to treemanifest that allows walking over the directories in
> the tree. Currently it only accepts a matcher to prune the walk, but in the
> future it will also accept a list of trees and will only walk over subtrees that
> differ from the versions in the list. This will be useful for identifying what
> parts of the tree are new to this revision, which is useful when deciding the
> minimal set of trees to send to a client given that they have a certain tree
> already.
>
> Since this is intended for an extension to use, the only current consumer is a
> test. In the future this function may be useful for implementing other
> algorithms like diff and changegroup generation.
>
> diff --git a/mercurial/manifest.py b/mercurial/manifest.py
> --- a/mercurial/manifest.py
> +++ b/mercurial/manifest.py
> @@ -1155,6 +1155,22 @@ class treemanifest(object):
>                  subp1, subp2 = subp2, subp1
>              writesubtree(subm, subp1, subp2)
>
> +    def walksubtrees(self, matcher=None):
> +        """Returns an iterator of the subtrees of this manifest, including this
> +        manifest itself.
> +
> +        If `matcher` is provided, it only returns subtrees that match.
> +        """
> +        if matcher and not matcher.visitdir(self._dir[:-1] or '.'):
> +            return
> +        if not matcher or matcher(self._dir[:-1]):
> +            yield self
> +
> +        self._load()
> +        for d, subm in self._dirs.iteritems():
> +            for subtree in subm.walksubtrees(matcher=matcher):
> +                yield subtree
> +
>  class manifestrevlog(revlog.revlog):
>      '''A revlog that stores manifest texts. This is responsible for caching the
>      full-text manifest contents.
> diff --git a/tests/test-manifest.py b/tests/test-manifest.py
> --- a/tests/test-manifest.py
> +++ b/tests/test-manifest.py
> @@ -467,5 +467,21 @@ class testtreemanifest(unittest.TestCase
>      def parsemanifest(self, text):
>          return manifestmod.treemanifest('', text)
>
> +    def testWalkSubtrees(self):
> +        m = self.parsemanifest(A_DEEPER_MANIFEST)
> +
> +        dirs = [s._dir for s in m.walksubtrees()]
> +        self.assertEqual(
> +            sorted(['', 'a/', 'a/c/', 'a/d/', 'a/b/', 'a/b/c/', 'a/b/d/']),
> +            sorted(dirs)
> +        )
> +
> +        match = matchmod.match('/', '', ['path:a/b/'])
> +        dirs = [s._dir for s in m.walksubtrees(matcher=match)]
> +        self.assertEqual(
> +            sorted(['a/b/', 'a/b/c/', 'a/b/d/']),
> +            sorted(dirs)
> +        )
> +
>  if __name__ == '__main__':
>      silenttestrunner.main(__name__)
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