solver: break @todo loop into a callback

This will allow each patch search via Xapian to "yield" the
current client in favor of another client in the PSGI web
interface for fairness.

diff --git a/lib/PublicInbox/SolverGit.pm b/lib/PublicInbox/SolverGit.pm
index beafa42da2e61b30508bb249b2eab9c5fb2c4056..51be2cdf91f0d6fed4e41f8b11dc7c3eda2cdc48 100644 (file)
--- a/lib/PublicInbox/SolverGit.pm
+++ b/lib/PublicInbox/SolverGit.pm
@@ -290,15 +290,21 @@ sub di_url ($) {
        defined($url) ? "$url$mid/" : "<$mid>";
 }
 
+# reconstruct the oid_b blob using patches we found:
 sub apply_patches_cb ($$$$$) {
        my ($self, $out, $found, $patches, $oid_b) = @_;
+
+       my $tot = scalar(@$patches) or return sub {
+               print $out "no patch(es) for $oid_b\n";
+               undef;
+       };
+
        my $wt = do_git_init_wt($self);
        my $wt_dir = $wt->dirname;
        my $wt_git = PublicInbox::Git->new("$wt_dir/.git");
        $wt_git->{-wt} = $wt;
 
        my $cur = 0;
-       my $tot = scalar @$patches;
        my ($apply_pid, $rd, $di);
 
        # returns an empty string if in progress, undef if not found,
@@ -362,8 +368,15 @@ sub solve ($$$$) {
        my $found = {}; # { abbrev => [ ::Git, oid_full, type, size, $di ] }
        my $patches = []; # [ array of $di hashes ]
        my $max = $self->{max_patches} || 200;
+       my $apply_cb;
+       my $cb = sub {
+               my $want = pop @todo;
+               unless ($want) {
+                       $apply_cb ||= apply_patches_cb($self, $out, $found,
+                                                      $patches, $oid_b);
+                       return $apply_cb->();
+               }
 
-       while (defined(my $want = pop @todo)) {
                if (scalar(@$patches) > $max) {
                        print $out "Aborting, too many steps to $oid_b\n";
                        return;
@@ -376,7 +389,7 @@ sub solve ($$$$) {
 
                        return $existing if $want_oid eq $oid_b; # DONE!
                        $found->{$want_oid} = $existing;
-                       last; # ok, one blob resolved, more to go?
+                       return ''; # ok, one blob resolved, more to go?
                }
 
                # scan through inboxes to look for emails which results in
@@ -403,19 +416,13 @@ sub solve ($$$$) {
                        print $out "$want_oid could not be found\n";
                        return;
                }
-       }
-
-       unless (scalar(@$patches)) {
-               print $out "no patch(es) for $oid_b\n";
-               return;
-       }
+               ''; # continue onto next @todo item;
+       };
 
-       # reconstruct the oid_b blob using patches we found:
-       my $cb = apply_patches_cb($self, $out, $found, $patches, $oid_b);
-       my $ret;
        while (1) {
-               $ret = $cb->();
+               my $ret = $cb->();
                return $ret if (ref($ret) || !defined($ret));
+               # $ret == ''; so continue looping here
        }
 }