From 4f868db3675eeee5994edc4fe79a9a2583623747 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Mon, 24 Jun 2019 02:52:56 +0000
Subject: ds: reimplement IO::Poll support to look like epoll

At least the subset of epoll we use.  EPOLLET might be
difficult to emulate if we end up using it.
---
 lib/PublicInbox/DS.pm     | 16 +++++++------
 lib/PublicInbox/DSPoll.pm | 58 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 7 deletions(-)
 create mode 100644 lib/PublicInbox/DSPoll.pm

(limited to 'lib')

diff --git a/lib/PublicInbox/DS.pm b/lib/PublicInbox/DS.pm
index d6ef0b8d..e3479e66 100644
--- a/lib/PublicInbox/DS.pm
+++ b/lib/PublicInbox/DS.pm
@@ -142,15 +142,17 @@ sub _InitPoller
     return if $DoneInit;
     $DoneInit = 1;
 
-    if (!PublicInbox::Syscall::epoll_defined())  {
-        $Epoll = eval {
-            require PublicInbox::DSKQXS;
-            PublicInbox::DSKQXS->import;
-            PublicInbox::DSKQXS->new;
-        };
-    } else {
+    if (PublicInbox::Syscall::epoll_defined())  {
         $Epoll = epoll_create();
         set_cloexec($Epoll) if (defined($Epoll) && $Epoll >= 0);
+    } else {
+        my $cls;
+        for (qw(DSKQXS DSPoll)) {
+            $cls = "PublicInbox::$_";
+            last if eval "require $cls";
+        }
+        $cls->import;
+        $Epoll = $cls->new;
     }
     *EventLoop = *EpollEventLoop;
 }
diff --git a/lib/PublicInbox/DSPoll.pm b/lib/PublicInbox/DSPoll.pm
new file mode 100644
index 00000000..e65640a8
--- /dev/null
+++ b/lib/PublicInbox/DSPoll.pm
@@ -0,0 +1,58 @@
+# Copyright (C) 2019 all contributors <meta@public-inbox.org>
+# Licensed the same as Danga::Socket (and Perl5)
+# License: GPL-1.0+ or Artistic-1.0-Perl
+#  <https://www.gnu.org/licenses/gpl-1.0.txt>
+#  <https://dev.perl.org/licenses/artistic.html>
+#
+# poll(2) via IO::Poll core module.  This makes poll look
+# like epoll to simplify the code in DS.pm.  This is NOT meant to be
+# an all encompassing emulation of epoll via IO::Poll, but just to
+# support cases public-inbox-nntpd/httpd care about.
+package PublicInbox::DSPoll;
+use strict;
+use warnings;
+use parent qw(Exporter);
+use IO::Poll;
+use PublicInbox::Syscall qw(EPOLLONESHOT EPOLLIN EPOLLOUT EPOLL_CTL_DEL);
+our @EXPORT = qw(epoll_ctl epoll_wait);
+
+sub new { bless {}, $_[0] } # fd => events
+
+sub epoll_ctl {
+	my ($self, $op, $fd, $ev) = @_;
+
+	# not wasting time on error checking
+	if ($op != EPOLL_CTL_DEL) {
+		$self->{$fd} = $ev;
+	} else {
+		delete $self->{$fd};
+	}
+	0;
+}
+
+sub epoll_wait {
+	my ($self, $maxevents, $timeout_msec, $events) = @_;
+	my @pset;
+	while (my ($fd, $events) = each %$self) {
+		my $pevents = $events & EPOLLIN ? POLLIN : 0;
+		$pevents |= $events & EPOLLOUT ? POLLOUT : 0;
+		push(@pset, $fd, $pevents);
+	}
+	@$events = ();
+	my $n = IO::Poll::_poll($timeout_msec, @pset);
+	if ($n >= 0) {
+		for (my $i = 0; $i < @pset; ) {
+			my $fd = $pset[$i++];
+			my $revents = $pset[$i++] or next;
+			delete($self->{$fd}) if $self->{$fd} & EPOLLONESHOT;
+			push @$events, [ $fd ];
+		}
+		my $nevents = scalar @$events;
+		if ($n != $nevents) {
+			warn "BUG? poll() returned $n, but got $nevents";
+		}
+	}
+	$n;
+}
+
+1;
-- 
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