This reinstates an old optimization in .rev_db which
stored the highest revision number we scanned, allowing
us to avoid scanning the SVN log for those revisions
again in a subsequent invocation.
This means the last 24-byte record in a .rev_map file
can be a 4-byte SVN revision number with 20-bytes of
zeroes representing a non-existent commit. This record
can and will be overwritten when a new commit iff
the commit is all zeroes.
Signed-off-by: Eric Wong <normalperson@xxxxxxxx>
---
git-svn.perl | 71 ++++++++++++++++++++++++++++++++++++++++++++++-----------
1 files changed, 57 insertions(+), 14 deletions(-)
diff --git a/git-svn.perl b/git-svn.perl
index b45c7e3..55484f7 100755
--- a/git-svn.perl
+++ b/git-svn.perl
@@ -1904,7 +1904,7 @@ sub last_rev_commit {
($self->{last_rev}, $self->{last_commit}) = (undef, undef);
return (undef, undef);
}
- my ($rev, $commit) = $self->rev_map_max;
+ my ($rev, $commit) = $self->rev_map_max(1);
($self->{last_rev}, $self->{last_commit}) = ($rev, $commit);
return ($rev, $commit);
}
@@ -2534,11 +2534,16 @@ sub rebuild {
# * 4 bytes for the integer representing an SVN revision number
# * 20 bytes representing the sha1 of a git commit
# - No empty padding records like the old format
+# (except the last record, which can be overwritten)
# - new records are written append-only since SVN revision numbers
# increase monotonically
# - lookups on SVN revision number are done via a binary search
-# - Piping the file to xxd(1) -c24 is a good way of dumping it for
-# viewing or editing, should the need ever arise.
+# - Piping the file to xxd -c24 is a good way of dumping it for
+# viewing or editing (piped back through xxd -r), should the need
+# ever arise.
+# - The last record can be padding revision with an all-zero sha1
+# This is used to optimize fetch performance when using multiple
+# "fetch" directives in .git/config
#
# These files are disposable unless noMetadata or useSvmProps is set
@@ -2548,16 +2553,32 @@ sub _rev_map_set {
my $size = (stat($fh))[7];
($size % 24) == 0 or croak "inconsistent size: $size";
+ my $wr_offset = 0;
if ($size > 0) {
sysseek($fh, -24, SEEK_END) or croak "seek: $!";
my $read = sysread($fh, my $buf, 24) or croak "read: $!";
$read == 24 or croak "read only $read bytes (!= 24)";
my ($last_rev, $last_commit) = unpack(rev_map_fmt, $buf);
- if ($last_rev >= $rev) {
- croak "last_rev is higher!: $last_rev >= $rev";
+ if ($last_commit eq ('0' x40)) {
+ if ($size >= 48) {
+ sysseek($fh, -48, SEEK_END) or croak "seek: $!";
+ $read = sysread($fh, $buf, 24) or
+ croak "read: $!";
+ $read == 24 or
+ croak "read only $read bytes (!= 24)";
+ ($last_rev, $last_commit) =
+ unpack(rev_map_fmt, $buf);
+ if ($last_commit eq ('0' x40)) {
+ croak "inconsistent .rev_map\n";
+ }
+ }
+ if ($last_rev >= $rev) {
+ croak "last_rev is higher!: $last_rev >= $rev";
+ }
+ $wr_offset = -24;
}
}
- sysseek($fh, 0, SEEK_END) or croak "seek: $!";
+ sysseek($fh, $wr_offset, SEEK_END) or croak "seek: $!";
syswrite($fh, pack(rev_map_fmt, $rev, $commit), 24) == 24 or
croak "write: $!";
}
@@ -2599,7 +2620,7 @@ sub rev_map_set {
"$db => $db_lock ($!)\n";
}
- sysopen(my $fh, $db_lock, O_RDWR | O_APPEND | O_CREAT)
+ sysopen(my $fh, $db_lock, O_RDWR | O_CREAT)
or croak "Couldn't open $db_lock: $!\n";
_rev_map_set($fh, $rev, $commit);
if ($sync) {
@@ -2622,25 +2643,40 @@ sub rev_map_set {
}
}
+# If want_commit, this will return an array of (rev, commit) where
+# commit _must_ be a valid commit in the archive.
+# Otherwise, it'll return the max revision (whether or not the
+# commit is valid or just a 0x40 placeholder).
sub rev_map_max {
- my ($self) = @_;
+ my ($self, $want_commit) = @_;
$self->rebuild;
my $map_path = $self->map_path;
- stat $map_path or return wantarray ? (0, undef) : 0;
+ stat $map_path or return $want_commit ? (0, undef) : 0;
sysopen(my $fh, $map_path, O_RDONLY) or croak "open: $!";
my $size = (stat($fh))[7];
($size % 24) == 0 or croak "inconsistent size: $size";
if ($size == 0) {
close $fh or croak "close: $!";
- return wantarray ? (0, undef) : 0;
+ return $want_commit ? (0, undef) : 0;
}
- sysseek($fh, -24, SEEK_END);
+ sysseek($fh, -24, SEEK_END) or croak "seek: $!";
sysread($fh, my $buf, 24) == 24 or croak "read: $!";
- close $fh or croak "close: $!";
my ($r, $c) = unpack(rev_map_fmt, $buf);
- wantarray ? ($r, $c) : $r;
+ if ($want_commit && $c eq ('0' x40)) {
+ if ($size < 48) {
+ return $want_commit ? (0, undef) : 0;
+ }
+ sysseek($fh, -48, SEEK_END) or croak "seek: $!";
+ sysread($fh, $buf, 24) == 24 or croak "read: $!";
+ ($r, $c) = unpack(rev_map_fmt, $buf);
+ if ($c eq ('0'x40)) {
+ croak "Penultimate record is all-zeroes in $map_path";
+ }
+ }
+ close $fh or croak "close: $!";
+ $want_commit ? ($r, $c) : $r;
}
sub rev_map_get {
@@ -2672,7 +2708,7 @@ sub rev_map_get {
$u = $i - 24;
} else { # $r == $rev
close($fh) or croak "close: $!";
- return $c;
+ return $c eq ('0' x 40) ? undef : $c;
}
}
close($fh) or croak "close: $!";
@@ -3863,6 +3899,13 @@ sub gs_fetch_loop_common {
$ra_invalid = undef;
}
}
+ # pre-fill the .rev_db since it'll eventually get filled in
+ # with '0' x40 if something new gets committed
+ foreach my $gs (@$gsv) {
+ next if $gs->rev_map_max >= $max;
+ next if defined $gs->rev_map_get($max);
+ $gs->rev_map_set($max, 0 x40);
+ }
foreach my $g (@$globs) {
my $k = "svn-remote.$g->{remote}.$g->{t}-maxRev";
Git::SVN::tmp_config($k, $max);
--
1.5.3.7.1114.g6df1d
-
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