doc: various comments on async handling

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

diff --git a/lib/PublicInbox/GitHTTPBackend.pm b/lib/PublicInbox/GitHTTPBackend.pm
index b684988d06b18edba847c1641874caff6cc01664..a069fd9473649c09c970e358aff3b620307be2b0 100644 (file)
--- a/lib/PublicInbox/GitHTTPBackend.pm
+++ b/lib/PublicInbox/GitHTTPBackend.pm
@@ -7,11 +7,15 @@ package PublicInbox::GitHTTPBackend;
 use strict;
 use warnings;
 use Fcntl qw(:seek);
-use IO::File;
+use IO::Handle;
 use HTTP::Date qw(time2str);
 use HTTP::Status qw(status_message);
+use Plack::Util;
 use PublicInbox::Qspawn;
 
+# 32 is same as the git-daemon connection limit
+my $default_limiter = PublicInbox::Qspawn::Limiter->new(32);
+
 # n.b. serving "description" and "cloneurl" should be innocuous enough to
 # not cause problems.  serving "config" might...
 my @text = qw[HEAD info/refs
@@ -192,7 +196,14 @@ sub serve_smart {
                my $val = $env->{$name};
                $env{$name} = $val if defined $val;
        }
-       my $git_dir = ref $git ? $git->{git_dir} : $git;
+       my ($git_dir, $limiter);
+       if (ref $git) {
+               $limiter = $git->{-httpbackend_limiter} || $default_limiter;
+               $git_dir = $git->{git_dir};
+       } else {
+               $limiter = $default_limiter;
+               $git_dir = $git;
+       }
        $env{GIT_HTTP_EXPORT_ALL} = '1';
        $env{PATH_TRANSLATED} = "$git_dir/$path";
        my %rdr = ( 0 => fileno($in) );
@@ -216,7 +227,7 @@ sub serve_smart {
                $r->[0] == 403 ? serve_dumb($env, $git, $path) : $r;
        };
        my $res;
-       my $async = $env->{'pi-httpd.async'};
+       my $async = $env->{'pi-httpd.async'}; # XXX unstable API
        my $io = $env->{'psgix.io'};
        my $cb = sub {
                my $r = $rd_hdr->() or return;
@@ -247,7 +258,7 @@ sub serve_smart {
                # holding the input here is a waste of FDs and memory
                $env->{'psgi.input'} = undef;
 
-               $x->start(sub { # may run later, much later...
+               $x->start($limiter, sub { # may run later, much later...
                        ($rpipe) = @_;
                        $in = undef;
                        if ($async) {
@@ -261,7 +272,11 @@ sub serve_smart {
 
 sub input_to_file {
        my ($env) = @_;
-       my $in = IO::File->new_tmpfile;
+       open(my $in, '+>', undef);
+       unless (defined $in) {
+               err($env, "could not open temporary file: $!");
+               return;
+       }
        my $input = $env->{'psgi.input'};
        my $buf;
        while (1) {
@@ -270,11 +285,22 @@ sub input_to_file {
                        err($env, "error reading input: $!");
                        return;
                }
-               last if ($r == 0);
-               $in->write($buf);
+               my $off = 0;
+               while ($r > 0) {
+                       my $w = syswrite($in, $buf, $r, $off);
+                       if (defined $w) {
+                               $r -= $w;
+                               $off += $w;
+                       } else {
+                               err($env, "error writing temporary file: $!");
+                               return;
+                       }
+               }
+       }
+       unless (defined(sysseek($in, 0, SEEK_SET))) {
+               err($env, "error seeking temporary file: $!");
+               return;
        }
-       $in->flush;
-       $in->sysseek(0, SEEK_SET);
        return $in;
 }