From 82625748223dd8977f6c1b8cfe53f7353399bd34 Mon Sep 17 00:00:00 2001 From: Dair Grant Date: Thu, 5 Nov 2015 10:26:15 +0000 Subject: [PATCH] git-svn: improve rebase/mkdirs performance Processing empty_dir directives becomes extremely slow for svn repositories with a large enough history. This is due to using a single hash to store the list of empty directories, with the expensive step being purging items from that hash using grep+delete. Storing directories in a hash of hashes improves the performance of this purge step and removes a potentially lengthy delay after every rebase/mkdirs command. The svn repository with this behaviour has 110K commits with unhandled.log containing 170K empty_dir directives. This takes 10 minutes to process when using a single hash, vs 3 seconds with a hash of hashes. Signed-off-by: Dair Grant Signed-off-by: Eric Wong --- perl/Git/SVN.pm | 84 ++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 76 insertions(+), 8 deletions(-) diff --git a/perl/Git/SVN.pm b/perl/Git/SVN.pm index 152fb7e927..b2c14e2ff5 100644 --- a/perl/Git/SVN.pm +++ b/perl/Git/SVN.pm @@ -1211,20 +1211,87 @@ sub do_fetch { sub mkemptydirs { my ($self, $r) = @_; + # add/remove/collect a paths table + # + # Paths are split into a tree of nodes, stored as a hash of hashes. + # + # Each node contains a 'path' entry for the path (if any) associated + # with that node and a 'children' entry for any nodes under that + # location. + # + # Removing a path requires a hash lookup for each component then + # dropping that node (and anything under it), which is substantially + # faster than a grep slice into a single hash of paths for large + # numbers of paths. + # + # For a large (200K) number of empty_dir directives this reduces + # scanning time to 3 seconds vs 10 minutes for grep+delete on a single + # hash of paths. + sub add_path { + my ($paths_table, $path) = @_; + my $node_ref; + + foreach my $x (split('/', $path)) { + if (!exists($paths_table->{$x})) { + $paths_table->{$x} = { children => {} }; + } + + $node_ref = $paths_table->{$x}; + $paths_table = $paths_table->{$x}->{children}; + } + + $node_ref->{path} = $path; + } + + sub remove_path { + my ($paths_table, $path) = @_; + my $nodes_ref; + my $node_name; + + foreach my $x (split('/', $path)) { + if (!exists($paths_table->{$x})) { + return; + } + + $nodes_ref = $paths_table; + $node_name = $x; + + $paths_table = $paths_table->{$x}->{children}; + } + + delete($nodes_ref->{$node_name}); + } + + sub collect_paths { + my ($paths_table, $paths_ref) = @_; + + foreach my $v (values %$paths_table) { + my $p = $v->{path}; + my $c = $v->{children}; + + collect_paths($c, $paths_ref); + + if (defined($p)) { + push(@$paths_ref, $p); + } + } + } + sub scan { - my ($r, $empty_dirs, $line) = @_; + my ($r, $paths_table, $line) = @_; if (defined $r && $line =~ /^r(\d+)$/) { return 0 if $1 > $r; } elsif ($line =~ /^ \+empty_dir: (.+)$/) { - $empty_dirs->{$1} = 1; + add_path($paths_table, $1); } elsif ($line =~ /^ \-empty_dir: (.+)$/) { - my @d = grep {m[^\Q$1\E(/|$)]} (keys %$empty_dirs); - delete @$empty_dirs{@d}; + remove_path($paths_table, $1); } 1; # continue }; - my %empty_dirs = (); + my @empty_dirs; + my %paths_table; + my $gz_file = "$self->{dir}/unhandled.log.gz"; if (-f $gz_file) { if (!can_compress()) { @@ -1235,7 +1302,7 @@ sub mkemptydirs { die "Unable to open $gz_file: $!\n"; my $line; while ($gz->gzreadline($line) > 0) { - scan($r, \%empty_dirs, $line) or last; + scan($r, \%paths_table, $line) or last; } $gz->gzclose; } @@ -1244,13 +1311,14 @@ sub mkemptydirs { if (open my $fh, '<', "$self->{dir}/unhandled.log") { binmode $fh or croak "binmode: $!"; while (<$fh>) { - scan($r, \%empty_dirs, $_) or last; + scan($r, \%paths_table, $_) or last; } close $fh; } + collect_paths(\%paths_table, \@empty_dirs); my $strip = qr/\A\Q@{[$self->path]}\E(?:\/|$)/; - foreach my $d (sort keys %empty_dirs) { + foreach my $d (sort @empty_dirs) { $d = uri_decode($d); $d =~ s/$strip//; next unless length($d);