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git-remote-mediawiki: get rid of O(N^2) loop

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The algorithm to find a path from the local revision to the remote one
was calling "git rev-list" and parsing its output N times. Run rev-list
only once, and fill a hashtable with the result to optimize the body of
the loop.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Matthieu Moy 2012-07-16 21:46:38 +02:00 committed by Junio C Hamano
parent 2045e293eb
commit 93e92d4d7c
1 changed files with 17 additions and 7 deletions
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24
contrib/mw-to-git/git-remote-mediawiki
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@ -1196,16 +1196,26 @@ sub mw_push_revision {
if ($last_local_revid > 0) {
my $parsed_sha1 = $remoteorigin_sha1;
# Find a path from last MediaWiki commit to pushed commit
print STDERR "Computing path from local to remote ...\n";
my @local_ancestry = split(/\n/, run_git("rev-list --boundary --parents $local ^$parsed_sha1"));
my %local_ancestry;
foreach my $line (@local_ancestry) {
if (my ($child, $parents) = $line =~ m/^-?([a-f0-9]+) ([a-f0-9 ]+)/) {
foreach my $parent (split(' ', $parents)) {
$local_ancestry{$parent} = $child;
}
} elsif (!$line =~ m/^([a-f0-9]+)/) {
die "Unexpected output from git rev-list: $line";
}
}
while ($parsed_sha1 ne $HEAD_sha1) {
my @commit_info = grep(/^$parsed_sha1/, split(/\n/, run_git("rev-list --children $local")));
if (!@commit_info) {
my $child = $local_ancestry{$parsed_sha1};
if (!$child) {
printf STDERR "Cannot find a path in history from remote commit to last commit\n";
return error_non_fast_forward($remote);
}
my @commit_info_split = split(/ |\n/, $commit_info[0]);
# $commit_info_split[1] is the sha1 of the commit to export
# $commit_info_split[0] is the sha1 of its direct child
push(@commit_pairs, \@commit_info_split);
$parsed_sha1 = $commit_info_split[1];
push(@commit_pairs, [$parsed_sha1, $child]);
$parsed_sha1 = $child;
}
} else {
# No remote mediawiki revision. Export the whole