view: make /$INBOX/$MSGID/ permalink async

This will allow -httpd to handle other requusts if waiting on
an HDD seek or git to decode a blob.

2 files changed, 53 insertions, 25 deletions

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index 24352826..98445f0e 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -27,24 +27,22 @@ use constant TCHILD => '` ';
 sub th_pfx ($) { $_[0] == 0 ? '' : TCHILD };
 
 sub msg_page_i {
-        my ($ctx) = @_;
-        my $cur = delete $ctx->{smsg} or return; # undef: done
-        my $nxt;
-        if (my $over = $ctx->{-inbox}->over) {
-                $nxt = $ctx->{smsg} = $over->next_by_mid(@{$ctx->{next_arg}});
+        my ($ctx, $eml) = @_;
+        if ($eml) { # called by WwwStream::async_eml or getline
+                my $smsg = $ctx->{smsg};
+                $ctx->{smsg} = $ctx->{over}->next_by_mid(@{$ctx->{next_arg}});
+                $ctx->{mhref} = ($ctx->{nr} || $ctx->{smsg}) ?
+                                "../${\mid_href($smsg->{mid})}/" : '';
+                my $hdr = $eml->header_obj;
+                my $obuf = $ctx->{obuf} = _msg_page_prepare_obuf($hdr, $ctx);
+                multipart_text_as_html($eml, $ctx);
+                delete $ctx->{obuf};
+                $$obuf .= '</pre><hr>';
+                $$obuf .= html_footer($ctx, $ctx->{first_hdr}) if !$ctx->{smsg};
+                $$obuf;
+        } else { # called by WwwStream::async_next or getline
+                $ctx->{smsg}; # may be undef
         }
-        $ctx->{mhref} = ($ctx->{nr} || $nxt) ?
-                        "../${\mid_href($cur->{mid})}/" : '';
-        my $eml = $ctx->{-inbox}->smsg_eml($cur) or return;
-        my $hdr = $eml->header_obj;
-        my $obuf = $ctx->{obuf} = _msg_page_prepare_obuf($hdr, $ctx);
-        multipart_text_as_html($eml, $ctx);
-        delete $ctx->{obuf};
-        $$obuf .= '</pre><hr>';
-        # we want to at least show the message if something
-        # here crashes:
-        eval { $$obuf .= html_footer($ctx, $ctx->{first_hdr}) } if !$nxt;
-        $$obuf;
 }
 
 # /$INBOX/$MESSAGE_ID/ for unindexed v1 inboxes
@@ -74,11 +72,11 @@ sub msg_page {
         my ($ctx) = @_;
         my $ibx = $ctx->{-inbox};
         $ctx->{-obfs_ibx} = $ibx->{obfuscate} ? $ibx : undef;
-        my $over = $ibx->over or return no_over_html($ctx);
+        my $over = $ctx->{over} = $ibx->over or return no_over_html($ctx);
         my ($id, $prev);
         my $next_arg = $ctx->{next_arg} = [ $ctx->{mid}, \$id, \$prev ];
-        $ctx->{smsg} = $over->next_by_mid(@$next_arg) or return;
-        PublicInbox::WwwStream::response($ctx, 200, \&msg_page_i);
+        $ctx->{smsg} = $over->next_by_mid(@$next_arg) or return; # undef == 404
+        PublicInbox::WwwStream::aresponse($ctx, 200, \&msg_page_i);
 }
 
 # /$INBOX/$MESSAGE_ID/#R
diff --git a/lib/PublicInbox/WwwStream.pm b/lib/PublicInbox/WwwStream.pm
index 42fb183f..eecc2701 100644
--- a/lib/PublicInbox/WwwStream.pm
+++ b/lib/PublicInbox/WwwStream.pm
@@ -15,9 +15,6 @@ use PublicInbox::Hval qw(ascii_html prurl);
 our $TOR_URL = 'https://www.torproject.org/';
 our $CODE_URL = 'https://public-inbox.org/public-inbox.git';
 
-# noop for HTTP.pm (and any other PSGI servers)
-sub close {}
-
 sub base_url ($) {
         my $ctx = shift;
         my $base_url = $ctx->{-inbox}->base_url($ctx->{env});
@@ -40,6 +37,11 @@ sub response {
         [ $code, $res_hdr, $ctx ]
 }
 
+sub async_eml { # ->{async_eml} for async_blob_cb
+        my ($ctx, $eml) = @_;
+        $ctx->{http_out}->write($ctx->translate($ctx->{cb}->($ctx, $eml)));
+}
+
 sub html_top ($) {
         my ($ctx) = @_;
         my $ibx = $ctx->{-inbox};
@@ -157,8 +159,14 @@ EOF
 sub getline {
         my ($ctx) = @_;
         my $cb = $ctx->{cb} or return;
-        if (defined(my $buf = $cb->($ctx))) {
-                return $ctx->translate($buf);
+        while (defined(my $x = $cb->($ctx))) { # x = smsg or scalar non-ref
+                if (ref($x)) { # smsg
+                        my $eml = $ctx->{-inbox}->smsg_eml($x) or next;
+                        $ctx->{smsg} = $x;
+                        return $ctx->translate($cb->($ctx, $eml));
+                } else { # scalar
+                        return $ctx->translate($x);
+                }
         }
         delete $ctx->{cb};
         $ctx->zflush(_html_end($ctx));
@@ -179,4 +187,26 @@ sub html_oneshot ($$;$) {
         [ $code, $res_hdr, \@bdy ]
 }
 
+sub async_next ($) {
+        my ($http) = @_; # PublicInbox::HTTP
+        my $ctx = $http->{forward} or return;
+        eval {
+                if (my $smsg = $ctx->{smsg} = $ctx->{cb}->($ctx)) {
+                        $ctx->smsg_blob($smsg);
+                } else {
+                        $ctx->{http_out}->write(
+                                        $ctx->translate(_html_end($ctx)));
+                        $ctx->close; # GzipFilter->close
+                }
+        };
+        warn "E: $@" if $@;
+}
+
+sub aresponse {
+        my ($ctx, $code, $cb) = @_;
+        my $res_hdr = [ 'Content-Type' => 'text/html; charset=UTF-8' ];
+        init($ctx, $cb);
+        $ctx->psgi_response($code, $res_hdr, \&async_next, \&async_eml);
+}
+
 1;