Mercurial > hg > mercurial-crew-with-dirclash
changeset 5369:7530334bf301
revlog: generate trivial deltas against null revision
To avoid extra memory usage and performance issues with large files,
generate a trivial delta header for deltas against the null revision
rather than calling the usual delta generator.
We append the delta header to meta rather than prepending it to data
to avoid a large allocate and copy.
| author | Matt Mackall <mpm@selenic.com> |
|---|---|
| date | Wed, 03 Oct 2007 17:17:27 -0500 |
| parents | ff32b2725651 |
| children | 61462e7d62ed |
| files | mercurial/mdiff.py mercurial/revlog.py |
| diffstat | 2 files changed, 8 insertions(+), 1 deletions(-) [+] |
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--- a/mercurial/mdiff.py +++ b/mercurial/mdiff.py @@ -245,6 +245,9 @@ def patch(a, bin): def get_matching_blocks(a, b): return [(d[0], d[2], d[1] - d[0]) for d in bdiff.blocks(a, b)] +def trivialdiffheader(length): + return struct.pack(">lll", 0, 0, length) + patches = mpatch.patches patchedsize = mpatch.patchedsize textdiff = bdiff.bdiff
--- a/mercurial/revlog.py +++ b/mercurial/revlog.py @@ -1087,9 +1087,13 @@ class revlog(object): if infocollect is not None: infocollect(nb) - d = self.revdiff(a, b) p = self.parents(nb) meta = nb + p[0] + p[1] + lookup(nb) + if a == -1: + d = self.revision(nb) + meta += mdiff.trivialdiffheader(len(d)) + else: + d = self.revdiff(a, b) yield changegroup.genchunk("%s%s" % (meta, d)) yield changegroup.closechunk()