[PATCH 4/5] clone|fetch|--mirror: cull manifest in partial mirrors

[Eric Wong <e@80x24.org>]

This makes it easier for users to enable fetching on a
previously read-only epoch.  Prior to this change, users were
required to delete manifest.js.gz in addition to adding the
writable bit.  Now, they just have to "chmod +w $EPOCH_DIR".
---
 lib/PublicInbox/Fetch.pm     | 17 +++++++++++++++--
 lib/PublicInbox/LeiMirror.pm | 24 ++++++++++++++++++++----
 t/v2mirror.t                 | 24 ++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 6 deletions(-)

diff --git a/lib/PublicInbox/Fetch.pm b/lib/PublicInbox/Fetch.pm
index 464ffe12..7f60b619 100644
--- a/lib/PublicInbox/Fetch.pm
+++ b/lib/PublicInbox/Fetch.pm
@@ -12,6 +12,8 @@ use PublicInbox::LEI;
 use PublicInbox::LeiCurl;
 use PublicInbox::LeiMirror;
 use File::Temp ();
+use PublicInbox::Config;
+use IO::Compress::Gzip qw(gzip $GzipError);
 
 sub new { bless {}, __PACKAGE__ }
 
@@ -81,7 +83,7 @@ sub do_manifest ($$$) {
 	}
 	my (undef, $v1_path, @v2_epochs) =
 		PublicInbox::LeiMirror::deduce_epochs($mdiff, $ibx_uri->path);
-	[ 200, $v1_path, \@v2_epochs, $muri, $ft, $mf ];
+	[ 200, $v1_path, \@v2_epochs, $muri, $ft, $mf, $m1 ];
 }
 
 sub get_fingerprint2 {
@@ -133,7 +135,7 @@ EOM
 	PublicInbox::LeiMirror::write_makefile($dir, $ibx_ver);
 	$lei->qerr("# inbox URL: $ibx_uri/");
 	my $res = do_manifest($lei, $dir, $ibx_uri) or return;
-	my ($code, $v1_path, $v2_epochs, $muri, $ft, $mf) = @$res;
+	my ($code, $v1_path, $v2_epochs, $muri, $ft, $mf, $m1) = @$res;
 	if ($code == 404) {
 		# any pre-manifest.js.gz instances running? Just fetch all
 		# existing ones and unconditionally try cloning the next
@@ -145,6 +147,7 @@ EOM
 	} else {
 		$code == 200 or die "BUG unexpected code $code\n";
 	}
+	my $mculled;
 	if ($ibx_ver == 2) {
 		defined($v1_path) and warn <<EOM;
 E: got v1 `$v1_path' when expecting v2 epoch(s) in <$muri>, WTF?
@@ -153,6 +156,12 @@ EOM
 				my ($nr) = (m!/([0-9]+)\.git\z!g);
 				$skip->{$nr} ? () : $nr;
 			} @$v2_epochs;
+		if ($m1 && scalar keys %$skip) {
+			my $re = join('|', keys %$skip);
+			my @del = grep(m!/git/$re\.git\z!, keys %$m1);
+			delete @$m1{@del};
+			$mculled = 1;
+		}
 	} else {
 		$git_dir[0] = $dir;
 	}
@@ -193,6 +202,10 @@ EOM
 	for my $i (@new_epoch) { $mg->epoch_cfg_set($i) }
 	if ($ft) {
 		my $fn = $ft->filename;
+		if ($mculled) {
+			my $json = PublicInbox::Config->json->encode($m1);
+			gzip(\$json => $fn) or die "gzip: $GzipError";
+		}
 		rename($fn, $mf) or die "E: rename($fn, $mf): $!\n";
 		$ft->unlink_on_destroy(0);
 	}
diff --git a/lib/PublicInbox/LeiMirror.pm b/lib/PublicInbox/LeiMirror.pm
index fe81b967..1ab5e0d8 100644
--- a/lib/PublicInbox/LeiMirror.pm
+++ b/lib/PublicInbox/LeiMirror.pm
@@ -6,7 +6,9 @@ package PublicInbox::LeiMirror;
 use strict;
 use v5.10.1;
 use parent qw(PublicInbox::IPC);
+use PublicInbox::Config;
 use IO::Uncompress::Gunzip qw(gunzip $GunzipError);
+use IO::Compress::Gzip qw(gzip $GzipError);
 use PublicInbox::Spawn qw(popen_rd spawn run_die);
 use File::Temp ();
 use Fcntl qw(SEEK_SET O_CREAT O_EXCL O_WRONLY);
@@ -267,14 +269,14 @@ EOM
 	close $fh or die "close:($f): $!";
 }
 
-sub clone_v2 ($$) {
-	my ($self, $v2_epochs) = @_;
+sub clone_v2 ($$;$) {
+	my ($self, $v2_epochs, $m) = @_; # $m => manifest.js.gz hashref
 	my $lei = $self->{lei};
 	my $curl = $self->{curl} //= PublicInbox::LeiCurl->new($lei) or return;
 	my $pfx = $curl->torsocks($lei, (values %$v2_epochs)[0]) or return;
 	my $dst = $self->{dst};
 	my $want = parse_epochs($lei->{opt}->{epoch}, $v2_epochs);
-	my (@src_edst, @read_only);
+	my (@src_edst, @read_only, @skip_nr);
 	for my $nr (sort { $a <=> $b } keys %$v2_epochs) {
 		my $uri = $v2_epochs->{$nr};
 		my $src = $uri->as_string;
@@ -289,8 +291,15 @@ failed to extract epoch number from $src
 		} else { # create a placeholder so users only need to chmod +w
 			init_placeholder($src, $edst);
 			push @read_only, $edst;
+			push @skip_nr, $nr;
 		}
 	}
+	if (@skip_nr) { # filter out the epochs we skipped
+		my $re = join('|', @skip_nr);
+		my @del = grep(m!/git/$re\.git\z!, keys %$m);
+		delete @$m{@del};
+		$self->{-culled_manifest} = 1;
+	}
 	my $lk = bless { lock_path => "$dst/inbox.lock" }, 'PublicInbox::Lock';
 	_try_config($self);
 	my $on_destroy = $lk->lock_for_scope($$);
@@ -379,13 +388,20 @@ EOM
 			my ($n) = ("$uri" =~ m!/([0-9]+)\.git\z!);
 			$n => $uri->clone
 		} @v2_epochs;
-		clone_v2($self, \%v2_epochs);
+		clone_v2($self, \%v2_epochs, $m);
 	} elsif (defined $v1_path) {
 		clone_v1($self);
 	} else {
 		die "E: confused by <$uri>, possible matches:\n\t",
 			join(', ', sort keys %$m), "\n";
 	}
+	if (delete $self->{-culled_manifest}) { # set by clone_v2
+		# write the smaller manifest if epochs were skipped so
+		# users won't have to delete manifest if they +w an
+		# epoch they no longer want to skip
+		my $json = PublicInbox::Config->json->encode($m);
+		gzip(\$json => $fn) or die "gzip: $GzipError";
+	}
 	my $fin = "$self->{dst}/manifest.js.gz";
 	rename($fn, $fin) or die "E: rename($fn, $fin): $!";
 	$ft->unlink_on_destroy(0);
diff --git a/t/v2mirror.t b/t/v2mirror.t
index 1231b72d..fa4a717d 100644
--- a/t/v2mirror.t
+++ b/t/v2mirror.t
@@ -9,6 +9,7 @@ use PublicInbox::Spawn qw(which);
 require_git(2.6);
 require_cmd('curl');
 local $ENV{HOME} = abs_path('t');
+use IO::Uncompress::Gunzip qw(gunzip $GunzipError);
 
 # Integration tests for HTTP cloning + mirroring
 require_mods(qw(Plack::Util Plack::Builder
@@ -288,6 +289,29 @@ if ('test read-only epoch dirs') {
 	is_deeply(\@g2, \@g, 'cloned again');
 	is(scalar(grep { -w $_ } @g2), scalar(@w) + 1,
 		'got one more cloned epoch');
+
+	# make 0.git writable and fetch into it, relies on culled manifest
+	chmod(0755, $g2[0]) or xbail "chmod: $!";
+	my @before = glob("$g2[0]/objects/*/*");
+	run_script([qw(-fetch -q)], undef, { -C => $dst });
+	is($?, 0, 'no error from partial fetch');
+	my @after = glob("$g2[0]/objects/*/*");
+	ok(scalar(@before) < scalar(@after), 'fetched after chmod 0755 0.git');
+
+	# ensure culled manifest is maintained after fetch
+	gunzip("$dst/manifest.js.gz" => \(my $m), MultiStream => 1) or
+		xbail "gunzip: $GunzipError";
+	$m = PublicInbox::Config->json->decode($m);
+	for my $k (keys %$m) { # /$name/git/$N.git
+		my ($nr) = ($k =~ m!/git/([0-9]+)\.git\z!);
+		ok(-w "$dst/git/$nr.git", "writable $nr.git in manifest");
+	}
+	for my $ro (grep { !-w $_ } @g2) {
+		my ($nr) = ($ro =~ m!/git/([0-9]+)\.git\z!);
+		is(grep(m!/git/$nr\.git\z!, keys %$m), 0,
+			"read-only $nr.git not in manifest")
+			or xbail([sort keys %$m]);
+	}
 }
 
 my $err = '';