git: async: automatic retry on alternates change

[public-inbox.git] / lib / PublicInbox / Git.pm

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index 60236afe7bfa83e85dbbe0fd2d0e65b4fb0c0f4e..a55c48d5f523b5a9c0f43540abf0a24fa8545d04 100644 (file)
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -18,6 +18,7 @@ use base qw(Exporter);
 our @EXPORT_OK = qw(git_unquote git_quote);
 use Errno qw(EINTR);
 our $PIPE_BUFSIZ = 65536; # Linux default
+our $in_cleanup;
 
 use constant MAX_INFLIGHT =>
        (($^O eq 'linux' ? 4096 : POSIX::_POSIX_PIPE_BUF()) * 3)
@@ -155,6 +156,26 @@ sub my_readline ($$) {
        }
 }
 
+sub cat_async_retry ($$$$$) {
+       my ($self, $inflight, $req, $cb, $arg) = @_;
+
+       # {inflight} may be non-existent, but if it isn't we delete it
+       # here to prevent cleanup() from waiting:
+       delete $self->{inflight};
+       cleanup($self);
+
+       $self->{inflight} = $inflight;
+       batch_prepare($self);
+       my $buf = "$req\n";
+       for (my $i = 0; $i < @$inflight; $i += 3) {
+               $buf .= "$inflight->[$i]\n";
+       }
+       print { $self->{out} } $buf or fail($self, "write error: $!");
+       unshift(@$inflight, \$req, $cb, $arg); # \$ref to indicate retried
+
+       cat_async_step($self, $inflight); # take one step
+}
+
 sub cat_async_step ($$) {
        my ($self, $inflight) = @_;
        die 'BUG: inflight empty or odd' if scalar(@$inflight) < 3;
@@ -168,8 +189,13 @@ sub cat_async_step ($$) {
                        fail($self, defined($bref) ? 'read EOF' : "read: $!");
                chop($$bref) eq "\n" or fail($self, 'LF missing after blob');
        } elsif ($head =~ / missing$/) {
+               # ref($req) indicates it's already been retried
+               if (!ref($req) && !$in_cleanup && alternates_changed($self)) {
+                       return cat_async_retry($self, $inflight,
+                                               $req, $cb, $arg);
+               }
                $type = 'missing';
-               $oid = $req;
+               $oid = ref($req) ? $$req : $req;
        } else {
                fail($self, "Unexpected result from async git cat-file: $head");
        }
@@ -190,33 +216,18 @@ sub batch_prepare ($) {
        _bidi_pipe($_[0], qw(--batch in out pid));
 }
 
+sub _cat_file_cb {
+       my ($bref, undef, undef, $size, $result) = @_;
+       @$result = ($bref, $size);
+}
+
 sub cat_file {
-       my ($self, $obj, $sizeref) = @_;
-       my ($retried, $head, $rbuf);
+       my ($self, $oid, $sizeref) = @_;
+       my $result = [];
+       cat_async($self, $oid, \&_cat_file_cb, $result);
        cat_async_wait($self);
-again:
-       batch_prepare($self);
-       $rbuf = delete($self->{cat_rbuf}) // \(my $new = '');
-       print { $self->{out} } $obj, "\n" or fail($self, "write error: $!");
-       $head = my_readline($self->{in}, $rbuf);
-       if ($head =~ / missing$/) {
-               if (!$retried && alternates_changed($self)) {
-                       $retried = 1;
-                       cleanup($self);
-                       goto again;
-               }
-               return;
-       }
-       $head =~ /^[0-9a-f]{40} \S+ ([0-9]+)$/ or
-               fail($self, "Unexpected result from git cat-file: $head");
-
-       my $size = $1 + 0;
-       $$sizeref = $size if $sizeref;
-       my $ret = my_read($self->{in}, $rbuf, $size + 1);
-       $self->{cat_rbuf} = $rbuf if $$rbuf ne '';
-       fail($self, defined($ret) ? 'read EOF' : "read: $!") if !$ret;
-       chop($$ret) eq "\n" or fail($self, 'newline missing after blob');
-       $ret;
+       $$sizeref = $result->[1] if $sizeref;
+       $result->[0];
 }
 
 sub check {
@@ -283,6 +294,7 @@ sub qx {
 # returns true if there are pending "git cat-file" processes
 sub cleanup {
        my ($self) = @_;
+       local $in_cleanup = 1;
        if (my $ac = $self->{async_cat}) {
                $ac->close; # PublicInbox::GitAsyncCat::close -> EPOLL_CTL_DEL
        }