[PATCH 3 of 3] manifest: postpone calling array.array() until needed

[Augie Fackler]

On Thu, Feb 26, 2015 at 04:02:49PM -0800, Martin von Zweigbergk wrote:
> # HG changeset patch
> # User Martin von Zweigbergk <martinvonz at google.com>
> # Date 1424802971 28800
> #      Tue Feb 24 10:36:11 2015 -0800
> # Node ID 1d3fe60a20d4f6284bc295af27f9f272af30dcdd
> # Parent  ef7dde10dc5941491a19dbd17ccb47a776f0dadd
> manifest: postpone calling array.array() until needed

These three look good, queued.

>
> We currently convert a string to an array in manifest.read(), only to
> store the result in the manifest cache. In most cases, the array will
> not be used, so let's store the original string instead. Storage cost
> should be similar assuming strings are stored in memory as byte
> arrays. The only disadvantage should be that the conversion can be
> done several times if multiple new revisions are created based on the
> same cached revision.
>
> diff -r ef7dde10dc59 -r 1d3fe60a20d4 mercurial/manifest.py
> --- a/mercurial/manifest.py	Tue Feb 24 09:08:54 2015 -0800
> +++ b/mercurial/manifest.py	Tue Feb 24 10:36:11 2015 -0800
> @@ -246,9 +246,8 @@
>          if node in self._mancache:
>              return self._mancache[node][0]
>          text = self.revision(node)
> -        arraytext = array.array('c', text)
>          m = _parse(text)
> -        self._mancache[node] = (m, arraytext)
> +        self._mancache[node] = (m, text)
>          return m
>
>      def find(self, node, f):
> @@ -280,7 +279,8 @@
>              # since the lists are already sorted
>              work.sort()
>
> -            arraytext, deltatext = m.fastdelta(self._mancache[p1][1], work)
> +            base = self._mancache[p1][1]
> +            arraytext, deltatext = m.fastdelta(array.array('c', base), work)
>              cachedelta = self.rev(p1), deltatext
>              text = util.buffer(arraytext)
>          else:
> @@ -289,10 +289,9 @@
>              # through to the revlog layer, and let it handle the delta
>              # process.
>              text = m.text()
> -            arraytext = array.array('c', text)
>              cachedelta = None
>
>          n = self.addrevision(text, transaction, link, p1, p2, cachedelta)
> -        self._mancache[n] = (m, arraytext)
> +        self._mancache[n] = (m, text)
>
>          return n
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