[PATCH 1 of 2] templater: do not use index.partialmatch() directly to calculate shortest()

[Martin von Zweigbergk]

On Sat, Oct 22, 2016 at 11:35 PM, Yuya Nishihara <yuya at tcha.org> wrote:
> # HG changeset patch
> # User Yuya Nishihara <yuya at tcha.org>
> # Date 1477199123 -32400
> #      Sun Oct 23 14:05:23 2016 +0900
> # Branch stable
> # Node ID f180a39d749aeacb72936e629a372623b1f88b8c
> # Parent  76c57e1fe79b0980b377b4f305635dea393d6315
> templater: do not use index.partialmatch() directly to calculate shortest()
>
> cl.index.partialmatch() isn't a drop-in replacement for cl._partialmatch().
> It has no knowledge about hidden revisions, and it can't accept a node shorter
> than the length 4. Instead, let cl._partialmatch() use index.partialmatch()
> if available.
>
> The test result is sampled with --pure.
>
> diff --git a/mercurial/templater.py b/mercurial/templater.py
> --- a/mercurial/templater.py
> +++ b/mercurial/templater.py
> @@ -840,13 +840,8 @@ def shortest(context, mapping, args):
>      cl = mapping['ctx']._repo.changelog
>      def isvalid(test):
>          try:
> -            try:
> -                cl.index.partialmatch(test)

Are there other callers of this method (index.partialmatch) or can we
remove it now?

> -            except AttributeError:
> -                # Pure mercurial doesn't support partialmatch on the index.
> -                # Fallback to the slow way.
> -                if cl._partialmatch(test) is None:
> -                    return False
> +            if cl._partialmatch(test) is None:
> +                return False

How much slower is it? Correctness is almost always more important,
but it would be good to know how much slower we're making it.

>
>              try:
>                  i = int(test)
> diff --git a/tests/test-command-template.t b/tests/test-command-template.t
> --- a/tests/test-command-template.t
> +++ b/tests/test-command-template.t
> @@ -3413,8 +3413,76 @@ Test shortest(node) function:
>    hg: parse error: shortest() expects an integer minlength
>    [255]
>
> +  $ cd ..
> +
> +Test shortest(node) with the repo having short hash collision:
> +
> +  $ hg init hashcollision
> +  $ cd hashcollision
> +  $ cat <<EOF >> .hg/hgrc
> +  > [experimental]
> +  > evolution = createmarkers
> +  > EOF
> +  $ echo 0 > a
> +  $ hg ci -qAm 0
> +  $ for i in 17 129 248 242 480 580 617 1057 2857 4025; do
> +  >   hg up -q 0
> +  >   echo $i > a
> +  >   hg ci -qm $i
> +  > done
> +  $ hg up -q null
> +  $ hg log -r0: -T '{rev}:{node}\n'
> +  0:b4e73ffab476aa0ee32ed81ca51e07169844bc6a
> +  1:11424df6dc1dd4ea255eae2b58eaca7831973bbc
> +  2:11407b3f1b9c3e76a79c1ec5373924df096f0499
> +  3:11dd92fe0f39dfdaacdaa5f3997edc533875cfc4
> +  4:10776689e627b465361ad5c296a20a487e153ca4
> +  5:a00be79088084cb3aff086ab799f8790e01a976b
> +  6:a0b0acd79b4498d0052993d35a6a748dd51d13e6
> +  7:a0457b3450b8e1b778f1163b31a435802987fe5d
> +  8:c56256a09cd28e5764f32e8e2810d0f01e2e357a
> +  9:c5623987d205cd6d9d8389bfc40fff9dbb670b48
> +  10:c562ddd9c94164376c20b86b0b4991636a3bf84f

Nice!

> +  $ hg debugobsolete a00be79088084cb3aff086ab799f8790e01a976b
> +  $ hg debugobsolete c5623987d205cd6d9d8389bfc40fff9dbb670b48
> +  $ hg debugobsolete c562ddd9c94164376c20b86b0b4991636a3bf84f
> +
> + nodes starting with '11' (we don't have the revision number '11' though)
> +
> +  $ hg log -r 1:3 -T '{rev}:{shortest(node, 0)}\n'
> +  1:1142
> +  2:1140
> +  3:11d
> +
> + '5:a00' is hidden, but still we have two nodes starting with 'a0'
> +
> +  $ hg log -r 6:7 -T '{rev}:{shortest(node, 0)}\n'
> +  6:a0b
> +  7:a04
> +
> + node '10' conflicts with the revision number '10' even if it is hidden
> + (we could exclude hidden revision numbers, but currently we don't)
> +
> +  $ hg log -r 4 -T '{rev}:{shortest(node, 0)}\n'
> +  4:107
> +  $ hg log -r 4 -T '{rev}:{shortest(node, 0)}\n' --hidden
> +  4:107
> +
> + node 'c562' should be unique if the other 'c562' nodes are hidden
> +
> +  $ hg log -r 8 -T '{rev}:{node|shortest}\n'
> +  8:c562
> +  $ hg log -r 8:10 -T '{rev}:{node|shortest}\n' --hidden
> +  8:c5625
> +  9:c5623
> +  10:c562d
> +
> +  $ cd ..
> +
>  Test pad function
>
> +  $ cd r
> +
>    $ hg log --template '{pad(rev, 20)} {author|user}\n'
>    2                    test
>    1                    {node|short}
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