# HG changeset patch # User Gregory Szorc # Date 1533317702 25200 # Node ID 23ae0c07a3e13859b4888faedd47e5b7e8678a2e # Parent 6e999a2d8fe7b235ed020c92289a50b2088aaf29 changegroup: control delta parent behavior via constructor The last remaining override on cg2packer related to parent delta computation. We pass a parameter to the constructor to control whether to delta against the previous revision and we inline all parent delta logic into a single function. With this change, cg2packer is empty, so it has been deleted. Differential Revision: https://phab.mercurial-scm.org/D4083 diff -r 6e999a2d8fe7 -r 23ae0c07a3e1 mercurial/changegroup.py --- a/mercurial/changegroup.py Fri Aug 03 10:01:58 2018 -0700 +++ b/mercurial/changegroup.py Fri Aug 03 10:35:02 2018 -0700 @@ -521,8 +521,8 @@ class cg1packer(object): def __init__(self, repo, filematcher, version, allowreorder, - builddeltaheader, manifestsend, sendtreemanifests, - bundlecaps=None): + useprevdelta, builddeltaheader, manifestsend, + sendtreemanifests, bundlecaps=None): """Given a source repo, construct a bundler. filematcher is a matcher that matches on files to include in the @@ -532,6 +532,9 @@ This value is used when ``bundle.reorder`` is ``auto`` or isn't set. + useprevdelta controls whether revisions should always delta against + the previous revision in the changegroup. + builddeltaheader is a callable that constructs the header for a group delta. @@ -548,6 +551,7 @@ self._filematcher = filematcher self.version = version + self._useprevdelta = useprevdelta self._builddeltaheader = builddeltaheader self._manifestsend = manifestsend self._sendtreemanifests = sendtreemanifests @@ -950,9 +954,51 @@ progress.complete() def deltaparent(self, store, rev, p1, p2, prev): - if not store.candelta(prev, rev): - raise error.ProgrammingError('cg1 should not be used in this case') - return prev + if self._useprevdelta: + if not store.candelta(prev, rev): + raise error.ProgrammingError( + 'cg1 should not be used in this case') + return prev + + # Narrow ellipses mode. + if util.safehasattr(self, 'full_nodes'): + # TODO: send better deltas when in narrow mode. + # + # changegroup.group() loops over revisions to send, + # including revisions we'll skip. What this means is that + # `prev` will be a potentially useless delta base for all + # ellipsis nodes, as the client likely won't have it. In + # the future we should do bookkeeping about which nodes + # have been sent to the client, and try to be + # significantly smarter about delta bases. This is + # slightly tricky because this same code has to work for + # all revlogs, and we don't have the linkrev/linknode here. + return p1 + + dp = store.deltaparent(rev) + if dp == nullrev and store.storedeltachains: + # Avoid sending full revisions when delta parent is null. Pick prev + # in that case. It's tempting to pick p1 in this case, as p1 will + # be smaller in the common case. However, computing a delta against + # p1 may require resolving the raw text of p1, which could be + # expensive. The revlog caches should have prev cached, meaning + # less CPU for changegroup generation. There is likely room to add + # a flag and/or config option to control this behavior. + base = prev + elif dp == nullrev: + # revlog is configured to use full snapshot for a reason, + # stick to full snapshot. + base = nullrev + elif dp not in (p1, p2, prev): + # Pick prev when we can't be sure remote has the base revision. + return prev + else: + base = dp + + if base != nullrev and not store.candelta(base, rev): + base = nullrev + + return base def revchunk(self, store, rev, prev, linknode): if util.safehasattr(self, 'full_nodes'): @@ -1125,51 +1171,13 @@ deltachunks=(diffheader, data), ) -class cg2packer(cg1packer): - def deltaparent(self, store, rev, p1, p2, prev): - # Narrow ellipses mode. - if util.safehasattr(self, 'full_nodes'): - # TODO: send better deltas when in narrow mode. - # - # changegroup.group() loops over revisions to send, - # including revisions we'll skip. What this means is that - # `prev` will be a potentially useless delta base for all - # ellipsis nodes, as the client likely won't have it. In - # the future we should do bookkeeping about which nodes - # have been sent to the client, and try to be - # significantly smarter about delta bases. This is - # slightly tricky because this same code has to work for - # all revlogs, and we don't have the linkrev/linknode here. - return p1 - - dp = store.deltaparent(rev) - if dp == nullrev and store.storedeltachains: - # Avoid sending full revisions when delta parent is null. Pick prev - # in that case. It's tempting to pick p1 in this case, as p1 will - # be smaller in the common case. However, computing a delta against - # p1 may require resolving the raw text of p1, which could be - # expensive. The revlog caches should have prev cached, meaning - # less CPU for changegroup generation. There is likely room to add - # a flag and/or config option to control this behavior. - base = prev - elif dp == nullrev: - # revlog is configured to use full snapshot for a reason, - # stick to full snapshot. - base = nullrev - elif dp not in (p1, p2, prev): - # Pick prev when we can't be sure remote has the base revision. - return prev - else: - base = dp - if base != nullrev and not store.candelta(base, rev): - base = nullrev - return base - def _makecg1packer(repo, filematcher, bundlecaps): builddeltaheader = lambda d: _CHANGEGROUPV1_DELTA_HEADER.pack( d.node, d.p1node, d.p2node, d.linknode) - return cg1packer(repo, filematcher, b'01', allowreorder=None, + return cg1packer(repo, filematcher, b'01', + useprevdelta=True, + allowreorder=None, builddeltaheader=builddeltaheader, manifestsend=b'', sendtreemanifests=False, bundlecaps=bundlecaps) @@ -1181,7 +1189,9 @@ # Since generaldelta is directly supported by cg2, reordering # generally doesn't help, so we disable it by default (treating # bundle.reorder=auto just like bundle.reorder=False). - return cg2packer(repo, filematcher, b'02', allowreorder=False, + return cg1packer(repo, filematcher, b'02', + useprevdelta=False, + allowreorder=False, builddeltaheader=builddeltaheader, manifestsend=b'', sendtreemanifests=False, bundlecaps=bundlecaps) @@ -1190,7 +1200,9 @@ builddeltaheader = lambda d: _CHANGEGROUPV3_DELTA_HEADER.pack( d.node, d.p1node, d.p2node, d.basenode, d.linknode, d.flags) - return cg2packer(repo, filematcher, b'03', allowreorder=False, + return cg1packer(repo, filematcher, b'03', + useprevdelta=False, + allowreorder=False, builddeltaheader=builddeltaheader, manifestsend=closechunk(), sendtreemanifests=True, bundlecaps=bundlecaps)