X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=dgit;h=5d1a95c532a19c0c49f6c9538e227c732cc02b76;hb=95872ab5c8650af9003677b0ad25d05c2d1ae4d0;hp=b59d00a9effe3cc84eaeaffee1b1f778d384f628;hpb=6ebc225def00c400db654fa7fa562725432fe3a7;p=dgit.git

diff --git a/dgit b/dgit
index b59d00a9..5d1a95c5 100755
--- a/dgit
+++ b/dgit
@@ -36,6 +36,7 @@ use Digest::SHA;
 use Digest::MD5;
 use List::Util qw(any);
 use List::MoreUtils qw(pairwise);
+use Carp;
 
 use Debian::Dgit;
 
@@ -157,6 +158,27 @@ sub rrref () { return server_ref($csuite); }
 sub lrfetchrefs () { return "refs/dgit-fetch/$csuite"; }
 sub lrfetchref () { return lrfetchrefs.'/'.server_branch($csuite); }
 
+# We fetch some parts of lrfetchrefs/*.  Ideally we delete these
+# locally fetched refs because they have unhelpful names and clutter
+# up gitk etc.  So we track whether we have "used up" head ref (ie,
+# whether we have made another local ref which refers to this object).
+#
+# (If we deleted them unconditionally, then we might end up
+# re-fetching the same git objects each time dgit fetch was run.)
+#
+# So, leach use of lrfetchrefs needs to be accompanied by arrangements
+# in git_fetch_us to fetch the refs in question, and possibly a call
+# to lrfetchref_used.
+
+our (%lrfetchrefs_f, %lrfetchrefs_d);
+# $lrfetchrefs_X{lrfetchrefs."/heads/whatever"} = $objid
+
+sub lrfetchref_used ($) {
+    my ($fullrefname) = @_;
+    my $objid = $lrfetchrefs_f{$fullrefname};
+    $lrfetchrefs_d{$fullrefname} = $objid if defined $objid;
+}
+
 sub stripepoch ($) {
     my ($vsn) = @_;
     $vsn =~ s/^\d+\://;
@@ -1606,10 +1628,138 @@ sub ensure_we_have_orig () {
 }
 
 sub git_fetch_us () {
-    my @specs =
-        map { "+refs/$_/*:".lrfetchrefs."/$_/*" }
-        qw(tags heads), $branchprefix;
-    runcmd_ordryrun_local @git, qw(fetch -p -n -q), access_giturl(), @specs;
+    # Want to fetch only what we are going to use, unless
+    # deliberately-not-ff, in which case we must fetch everything.
+
+    my @specs = deliberately_not_fast_forward ? qw(tags/*) :
+	map { "tags/$_" } debiantags('*',access_basedistro);
+    push @specs, server_branch($csuite);
+    push @specs, qw(heads/*) if deliberately_not_fast_forward;
+
+    # This is rather miserable:
+    # When git-fetch --prune is passed a fetchspec ending with a *,
+    # it does a plausible thing.  If there is no * then:
+    # - it matches subpaths too, even if the supplied refspec
+    #   starts refs, and behaves completely madly if the source
+    #   has refs/refs/something.  (See, for example, Debian #NNNN.)
+    # - if there is no matching remote ref, it bombs out the whole
+    #   fetch.
+    # We want to fetch a fixed ref, and we don't know in advance
+    # if it exists, so this is not suitable.
+    #
+    # Our workaround is to use git-ls-remote.  git-ls-remote has its
+    # own qairks.  Notably, it has the absurd multi-tail-matching
+    # behaviour: git-ls-remote R refs/foo can report refs/foo AND
+    # refs/refs/foo etc.
+    #
+    # Also, we want an idempotent snapshot, but we have to make two
+    # calls to the remote: one to git-ls-remote and to git-fetch.  The
+    # solution is use git-ls-remote to obtain a target state, and
+    # git-fetch to try to generate it.  If we don't manage to generate
+    # the target state, we try again.
+
+    my $specre = join '|', map {
+	my $x = $_;
+	$x =~ s/\W/\\$&/g;
+	$x =~ s/\\\*$/.*/;
+	"(?:refs/$x)";
+    } @specs;
+    printdebug "git_fetch_us specre=$specre\n";
+    my $wanted_rref = sub {
+	local ($_) = @_;
+	return m/^(?:$specre)$/o;
+    };
+
+    my $fetch_iteration = 0;
+    FETCH_ITERATION:
+    for (;;) {
+        if (++$fetch_iteration > 10) {
+	    fail "too many iterations trying to get sane fetch!";
+	}
+
+	my @look = map { "refs/$_" } @specs;
+	my @lcmd = (@git, qw(ls-remote -q --refs), access_giturl(), @look);
+	debugcmd "|",@lcmd;
+
+	my %wantr;
+	open GITLS, "-|", @lcmd or die $!;
+	while (<GITLS>) {
+	    printdebug "=> ", $_;
+	    m/^(\w+)\s+(\S+)\n/ or die "ls-remote $_ ?";
+	    my ($objid,$rrefname) = ($1,$2);
+	    if (!$wanted_rref->($rrefname)) {
+		print STDERR <<END;
+warning: git-ls-remote @look reported $rrefname; this is silly, ignoring it.
+END
+		next;
+	    }
+	    $wantr{$rrefname} = $objid;
+	}
+	$!=0; $?=0;
+	close GITLS or failedcmd @lcmd;
+
+	# OK, now %want is exactly what we want for refs in @specs
+	my @fspecs = map {
+	    return () if !m/\*$/ && !exists $wantr{"refs/$_"};
+	    "+refs/$_:".lrfetchrefs."/$_";
+	} @specs;
+
+	my @fcmd = (@git, qw(fetch -p -n -q), access_giturl(), @fspecs);
+	runcmd_ordryrun_local @git, qw(fetch -p -n -q), access_giturl(),
+	    @fspecs;
+
+	%lrfetchrefs_f = ();
+	my %objgot;
+
+	git_for_each_ref(lrfetchrefs, sub {
+	    my ($objid,$objtype,$lrefname,$reftail) = @_;
+	    $lrfetchrefs_f{$lrefname} = $objid;
+	    $objgot{$objid} = 1;
+	});
+
+	foreach my $lrefname (sort keys %lrfetchrefs_f) {
+	    my $rrefname = 'refs'.substr($lrefname, length lrfetchrefs);
+	    if (!exists $wantr{$rrefname}) {
+		if ($wanted_rref->($rrefname)) {
+		    printdebug <<END;
+git-fetch @fspecs created $lrefname which git-ls-remote @look didn't list.
+END
+		} else {
+		    print STDERR <<END
+warning: git-fetch @fspecs created $lrefname; this is silly, deleting it.
+END
+		}
+		runcmd_ordryrun_local @git, qw(update-ref -d), $lrefname;
+		delete $lrfetchrefs_f{$lrefname};
+		next;
+	    }
+	}
+	foreach my $rrefname (sort keys %wantr) {
+	    my $lrefname = lrfetchrefs.substr($rrefname, 4);
+	    my $got = $lrfetchrefs_f{$lrefname} // '<none>';
+	    my $want = $wantr{$rrefname};
+	    next if $got eq $want;
+	    if (!defined $objgot{$want}) {
+		print STDERR <<END;
+warning: git-ls-remote suggests we want $lrefname
+warning:  and it should refer to $want
+warning:  but git-fetch didn't fetch that object to any relevant ref.
+warning:  This may be due to a race with someone updating the server.
+warning:  Will try again...
+END
+		next FETCH_ITERATION;
+	    }
+	    printdebug <<END;
+git-fetch @fspecs made $lrefname=$got but want git-ls-remote @look says $want
+END
+	    runcmd_ordryrun_local @git, qw(update-ref -m),
+		"dgit fetch git-fetch fixup", $lrefname, $want;
+	    $lrfetchrefs_f{$lrefname} = $want;
+	}
+	last;
+    }
+    printdebug "git_fetch_us: git-fetch --no-insane emulation complete\n",
+	Dumper(\%lrfetchrefs_f);
 
     my %here;
     my @tagpats = debiantags('*',access_basedistro);
@@ -1621,12 +1771,14 @@ sub git_fetch_us () {
     });
     git_for_each_ref([map { lrfetchrefs."/tags/".$_ } @tagpats], sub {
 	my ($objid,$objtype,$fullrefname,$reftail) = @_;
-	my $lref = "refs".substr($fullrefname, length lrfetchrefs);
+	my $lref = "refs".substr($fullrefname, length(lrfetchrefs));
 	printdebug "offered $lref=$objid\n";
 	if (!defined $here{$lref}) {
 	    my @upd = (@git, qw(update-ref), $lref, $objid, '');
 	    runcmd_ordryrun_local @upd;
+	    lrfetchref_used $fullrefname;
 	} elsif ($here{$lref} eq $objid) {
+	    lrfetchref_used $fullrefname;
 	} else {
 	    print STDERR \
 		"Not updateting $lref from $here{$lref} to $objid.\n";
@@ -1765,6 +1917,25 @@ sub fetch_from_archive () {
         Info => "Dgit field in .dsc from archive",
     };
 
+    my $cwd = getcwd();
+    my $del_lrfetchrefs = sub {
+	changedir $cwd;
+	my $gur;
+	printdebug "del_lrfetchrefs\n";
+	foreach my $fullrefname (sort keys %lrfetchrefs_d) {
+	    my $objid = $lrfetchrefs_d{$fullrefname};
+	    printdebug "del_lrfetchrefs: $fullrefname=$objid.\n";
+	    if (!$gur) {
+		$gur ||= new IO::Handle;
+		open $gur, "|-", qw(git update-ref --stdin) or die $!;
+	    }
+	    printf $gur "delete %s %s\n", $fullrefname, $objid;
+	}
+	if ($gur) {
+	    close $gur or failedcmd "git update-ref delete lrfetchrefs";
+	}
+    };
+
     if (defined $dsc_hash) {
 	fail "missing remote git history even though dsc has hash -".
 	    " could not find ref ".rref()." at ".access_giturl()
@@ -1825,6 +1996,7 @@ But we were not able to obtain any version from the archive or git.
 
 END
 	}
+	unshift @end, $del_lrfetchrefs;
 	return 0;
     }
 
@@ -1972,6 +2144,10 @@ END
 	    dryrun_report @upd_cmd;
 	}
     }
+
+    lrfetchref_used lrfetchref();
+
+    unshift @end, $del_lrfetchrefs;
     return 1;
 }