* [PATCH] http|nntp: avoid recursion inside ->write
@ 2019-07-10 8:26 Eric Wong
0 siblings, 0 replies; only message in thread
From: Eric Wong @ 2019-07-10 8:26 UTC (permalink / raw)
To: meta
In HTTP.pm, we can use the same technique NNTP.pm uses with
long_response with the $long_cb callback and avoid storing
$pull in the per-client structure at all. We can also reuse
the same logic to push the callback into wbuf from NNTP.
This does NOT introduce a new circular reference, but documents
it more clearly.
---
lib/PublicInbox/HTTP.pm | 64 ++++++++++++++++++++---------------------
lib/PublicInbox/NNTP.pm | 3 +-
2 files changed, 34 insertions(+), 33 deletions(-)
diff --git a/lib/PublicInbox/HTTP.pm b/lib/PublicInbox/HTTP.pm
index 60b287c4..5afe167e 100644
--- a/lib/PublicInbox/HTTP.pm
+++ b/lib/PublicInbox/HTTP.pm
@@ -11,7 +11,7 @@ package PublicInbox::HTTP;
use strict;
use warnings;
use base qw(PublicInbox::DS);
-use fields qw(httpd env input_left remote_addr remote_port forward pull);
+use fields qw(httpd env input_left remote_addr remote_port forward);
use bytes (); # only for bytes::length
use Fcntl qw(:seek);
use Plack::HTTPParser qw(parse_http_request); # XS or pure Perl
@@ -260,48 +260,49 @@ sub response_done_cb ($$) {
}
}
-sub getline_cb ($$$) {
+sub getline_response ($$$) {
my ($self, $write, $close) = @_;
- local $/ = \8192;
- my $forward = $self->{forward};
- # limit our own running time for fairness with other
- # clients and to avoid buffering too much:
- if ($forward) {
- my $buf = eval { $forward->getline };
+ my $pull; # DANGER: self-referential
+ $pull = sub {
+ my $forward = $self->{forward};
+ # limit our own running time for fairness with other
+ # clients and to avoid buffering too much:
+ my $buf = eval {
+ local $/ = \8192;
+ $forward->getline;
+ } if $forward;
+
if (defined $buf) {
$write->($buf); # may close in PublicInbox::DS::write
+
if ($self->{sock}) {
- my $next = $self->{pull};
- if ($self->{wbuf}) {
- $self->write($next);
- } else {
- PublicInbox::DS::requeue($next);
- }
- return;
+ my $wbuf = $self->{wbuf} ||= [];
+ push @$wbuf, $pull;
+
+ # wbuf may be populated by $write->($buf),
+ # no need to rearm if so:
+ $self->requeue if scalar(@$wbuf) == 1;
+ return; # likely
}
} elsif ($@) {
err($self, "response ->getline error: $@");
- $forward = undef;
$self->close;
}
- }
- delete @$self{qw(forward pull)};
- # avoid recursion
- if ($forward) {
- eval { $forward->close };
- if ($@) {
- err($self, "response ->close error: $@");
- $self->close; # idempotent
+ $pull = undef; # all done!
+ # avoid recursion
+ if (delete $self->{forward}) {
+ eval { $forward->close };
+ if ($@) {
+ err($self, "response ->close error: $@");
+ $self->close; # idempotent
+ }
}
- }
- $close->();
-}
+ $forward = undef;
+ $close->(); # call response_done_cb
+ };
-sub getline_response ($$$) {
- my ($self, $write, $close) = @_;
- my $pull = $self->{pull} = sub { getline_cb($self, $write, $close) };
- $pull->();
+ $pull->(); # kick-off!
}
sub response_write {
@@ -453,7 +454,6 @@ sub close {
if (my $env = delete $self->{env}) {
delete $env->{'psgix.io'}; # prevent circular references
}
- delete $self->{pull};
if (my $forward = delete $self->{forward}) {
eval { $forward->close };
err($self, "forward ->close error: $@") if $@;
diff --git a/lib/PublicInbox/NNTP.pm b/lib/PublicInbox/NNTP.pm
index 6796a3c4..f4208f87 100644
--- a/lib/PublicInbox/NNTP.pm
+++ b/lib/PublicInbox/NNTP.pm
@@ -658,7 +658,8 @@ sub long_response ($$) {
$long_cb = undef;
res($self, '.');
out($self, " deferred[$fd] done - %0.6f", now() - $t0);
- $self->requeue unless $self->{wbuf};
+ my $wbuf = $self->{wbuf};
+ $self->requeue unless $wbuf && @$wbuf;
}
};
$self->write($long_cb); # kick off!
--
EW
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2019-07-10 8:26 [PATCH] http|nntp: avoid recursion inside ->write Eric Wong
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