From d78f50649a5545d66a61b5465ca7f5ce4be398ea Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Sat, 19 Sep 2020 09:37:14 +0000
Subject: gcf2: wire up read-only daemons and rm -gcf2 script

It seems easiest to have a singleton Gcf2Client client object
per daemon worker for all inboxes to use.  This reduces overall
FD usage from pipes.

The `public-inbox-gcf2' command + manpage are gone and a `$^X'
one-liner is used, instead.  This saves inodes for internal
commands and hopefully makes it easier to avoid mismatched
PERL5LIB include paths (as noticed during development :x).

We'll also make the existing cat-file process management
infrastructure more resilient to BOFHs on process killing
sprees (or in case our libgit2-based code fails on us).

(Rare) PublicInbox::WWW PSGI users NOT using public-inbox-httpd
won't automatically benefit from this change, and extra
configuration will be required (to be documented later).
---
 lib/PublicInbox/GitAsyncCat.pm | 55 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 51 insertions(+), 4 deletions(-)

(limited to 'lib/PublicInbox/GitAsyncCat.pm')

diff --git a/lib/PublicInbox/GitAsyncCat.pm b/lib/PublicInbox/GitAsyncCat.pm
index 8a54c608..b9dbe0cc 100644
--- a/lib/PublicInbox/GitAsyncCat.pm
+++ b/lib/PublicInbox/GitAsyncCat.pm
@@ -11,23 +11,49 @@
 package PublicInbox::GitAsyncCat;
 use strict;
 use parent qw(PublicInbox::DS Exporter);
+use POSIX qw(WNOHANG);
 use PublicInbox::Syscall qw(EPOLLIN EPOLLET);
-our @EXPORT = qw(git_async_cat);
+our @EXPORT = qw(git_async_cat git_async_prefetch);
+use PublicInbox::Git ();
+
+our $GCF2C; # singleton PublicInbox::Gcf2Client
+
+sub close {
+	my ($self) = @_;
+
+	if (my $gitish = delete $self->{gitish}) {
+		PublicInbox::Git::cat_async_abort($gitish);
+	}
+	$self->SUPER::close; # PublicInbox::DS::close
+}
 
 sub event_step {
 	my ($self) = @_;
-	my $gitish = $self->{gitish};
+	my $gitish = $self->{gitish} or return;
 	return $self->close if ($gitish->{in} // 0) != ($self->{sock} // 1);
 	my $inflight = $gitish->{inflight};
 	if ($inflight && @$inflight) {
 		$gitish->cat_async_step($inflight);
-		$self->requeue if @$inflight || exists $gitish->{cat_rbuf};
+
+		# child death?
+		if (($gitish->{in} // 0) != ($self->{sock} // 1)) {
+			$self->close;
+		} elsif (@$inflight || exists $gitish->{cat_rbuf}) {
+			# ok, more to do, requeue for fairness
+			$self->requeue;
+		}
+	} elsif ((my $pid = waitpid($gitish->{pid}, WNOHANG)) > 0) {
+		# May happen if the child process is killed by a BOFH
+		# (or segfaults)
+		delete $gitish->{pid};
+		warn "E: gitish $pid exited with \$?=$?\n";
+		$self->close;
 	}
 }
 
 sub git_async_cat ($$$$) {
 	my ($git, $oid, $cb, $arg) = @_;
-	my $gitish = $git->{gcf2c}; # PublicInbox::Gcf2Client
+	my $gitish = $GCF2C;
 	if ($gitish) {
 		$oid .= " $git->{git_dir}";
 	} else {
@@ -41,4 +67,25 @@ sub git_async_cat ($$$$) {
 	};
 }
 
+# this is safe to call inside $cb, but not guaranteed to enqueue
+# returns true if successful, undef if not.
+sub git_async_prefetch {
+	my ($git, $oid, $cb, $arg) = @_;
+	if ($GCF2C) {
+		if ($GCF2C->{async_cat} && !$GCF2C->{wbuf}) {
+			$oid .= " $git->{git_dir}";
+			return $GCF2C->cat_async($oid, $cb, $arg);
+		}
+	} elsif ($git->{async_cat} && (my $inflight = $git->{inflight})) {
+		# we could use MAX_INFLIGHT here w/o the halving,
+		# but lets not allow one client to monopolize a git process
+		if (@$inflight < int(PublicInbox::Git::MAX_INFLIGHT/2)) {
+			print { $git->{out} } $oid, "\n" or
+						$git->fail("write error: $!");
+			return push(@$inflight, $oid, $cb, $arg);
+		}
+	}
+	undef;
+}
+
 1;
-- 
cgit v1.2.3-24-ge0c7