From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: X-Spam-Status: No, score=-4.0 required=3.0 tests=ALL_TRUSTED,BAYES_00 shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from localhost (dcvr.yhbt.net [127.0.0.1]) by dcvr.yhbt.net (Postfix) with ESMTP id 29A391F4C0 for ; Sat, 29 Jun 2019 19:59:54 +0000 (UTC) From: Eric Wong To: meta@public-inbox.org Subject: [PATCH 10/11] httpd/async: switch to buffering-as-fast-as-possible Date: Sat, 29 Jun 2019 19:59:50 +0000 Message-Id: <20190629195951.32160-11-e@80x24.org> In-Reply-To: <20190629195951.32160-1-e@80x24.org> References: <20190629195951.32160-1-e@80x24.org> List-Id: With DS buffering to a temporary file nowadays, applying backpressure to git-http-backend(1) hurts overall memory usage of the system. Instead, try to get git-http-backend(1) to finish as quickly as possible and use edge-triggered notifications to reduce wakeups on our end. --- lib/PublicInbox/DS.pm | 6 ------ lib/PublicInbox/HTTP.pm | 7 ------- lib/PublicInbox/HTTPD/Async.pm | 40 +++++++++++++++++----------------------- 3 files changed, 17 insertions(+), 36 deletions(-) diff --git a/lib/PublicInbox/DS.pm b/lib/PublicInbox/DS.pm index b2f59983..a8236023 100644 --- a/lib/PublicInbox/DS.pm +++ b/lib/PublicInbox/DS.pm @@ -571,12 +571,6 @@ sub epwait ($$) { 0; } -sub watch ($$) { - my ($self, $ev) = @_; - my $sock = $self->{sock} or return; - epwait($sock, $ev); -} - # return true if complete, false if incomplete (or failure) sub accept_tls_step ($) { my ($self) = @_; diff --git a/lib/PublicInbox/HTTP.pm b/lib/PublicInbox/HTTP.pm index 680be72b..5546ac46 100644 --- a/lib/PublicInbox/HTTP.pm +++ b/lib/PublicInbox/HTTP.pm @@ -467,11 +467,4 @@ sub busy () { ($self->{rbuf} || $self->{env} || $self->{wbuf}); } -# fires after pending writes are complete: -sub restart_pass ($) { - $_[0]->{forward}->restart_read; # see PublicInbox::HTTPD::Async -} - -sub enqueue_restart_pass ($) { $_[0]->write(\&restart_pass) } - 1; diff --git a/lib/PublicInbox/HTTPD/Async.pm b/lib/PublicInbox/HTTPD/Async.pm index 35d17150..a468ed91 100644 --- a/lib/PublicInbox/HTTPD/Async.pm +++ b/lib/PublicInbox/HTTPD/Async.pm @@ -4,14 +4,15 @@ # XXX This is a totally unstable API for public-inbox internal use only # This is exposed via the 'pi-httpd.async' key in the PSGI env hash. # The name of this key is not even stable! -# Currently is is intended for use with read-only pipes. +# Currently intended for use with read-only pipes with expensive +# processes such as git-http-backend(1), cgit(1) package PublicInbox::HTTPD::Async; use strict; use warnings; use base qw(PublicInbox::DS); use fields qw(cb cleanup); -require PublicInbox::EvCleanup; use Errno qw(EAGAIN); +use PublicInbox::Syscall qw(EPOLLIN EPOLLET); sub new { my ($class, $io, $cb, $cleanup) = @_; @@ -26,14 +27,12 @@ sub new { my $self = fields::new($class); IO::Handle::blocking($io, 0); - $self->SUPER::new($io, PublicInbox::DS::EPOLLIN()); + $self->SUPER::new($io, EPOLLIN | EPOLLET); $self->{cb} = $cb; $self->{cleanup} = $cleanup; $self; } -sub restart_read ($) { $_[0]->watch(PublicInbox::DS::EPOLLIN()) } - sub main_cb ($$$) { my ($http, $fh, $bref) = @_; sub { @@ -41,25 +40,15 @@ sub main_cb ($$$) { my $r = sysread($self->{sock}, $$bref, 8192); if ($r) { $fh->write($$bref); # may call $http->close - if ($http->{sock}) { # !closed - if ($http->{wbuf}) { - # HTTP client could not keep up, so - # stop reading and buffering. - $self->watch(0); - - # Tell the HTTP socket to restart us - # when HTTP client is done draining - # $http->{wbuf}: - $http->enqueue_restart_pass; - } - # stay in EPOLLIN, but let other clients - # get some work done, too. + $self->requeue; + # let other clients get some work done, too return; } - # fall through to close below... - } elsif (!defined $r) { - return restart_read($self) if $! == EAGAIN; + + # else: fall through to close below... + } elsif (!defined $r && $! == EAGAIN) { + return; # EPOLLET means we'll be notified } # Done! Error handling will happen in $fh->close @@ -75,10 +64,15 @@ sub async_pass { # will automatically close this ($self) object. $http->{forward} = $self; $fh->write($$bref); # PublicInbox:HTTP::{chunked,identity}_wcb - $self->{cb} = main_cb($http, $fh, $bref); + my $cb = $self->{cb} = main_cb($http, $fh, $bref); + $cb->($self); # either hit EAGAIN or ->requeue to keep EPOLLET happy } -sub event_step { $_[0]->{cb}->(@_) } +sub event_step { + # {cb} may be undef after ->requeue due to $http->close happening + my $cb = $_[0]->{cb} or return; + $cb->(@_); +} sub close { my $self = $_[0]; -- EW