X-Git-Url: http://www.git.stargrave.org/?a=blobdiff_plain;f=lib%2FPublicInbox%2FQspawn.pm;h=cc81a4cd6d7c6d13657719513a57d688eb0a95b9;hb=5a52841422b46646c1e6d2f93c8c14d1d24a0544;hp=b80dac1f3ca5bf829bfc3c04613a89155dc0c809;hpb=da9beb99af585718c36725f3457b1b72347bcebf;p=public-inbox.git

diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index b80dac1f..cc81a4cd 100644
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -1,125 +1,341 @@
-# Copyright (C) 2016-2018 all contributors <meta@public-inbox.org>
+# Copyright (C) all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 
-# Limits the number of processes spawned
-# This does not depend on Danga::Socket or any other external
-# scheduling mechanism, you just need to call start and finish
-# appropriately
+# Like most Perl modules in public-inbox, this is internal and
+# NOT subject to any stability guarantees!  It is only documented
+# for other hackers.
+#
+# This is used to limit the number of processes spawned by the
+# PSGI server, so it acts like a semaphore and queues up extra
+# commands to be run if currently at the limit.  Multiple "limiters"
+# may be configured which give inboxes different channels to
+# operate in.  This can be useful to ensure smaller inboxes can
+# be cloned while cloning of large inboxes is maxed out.
+#
+# This does not depend on the PublicInbox::DS::event_loop or any
+# other external scheduling mechanism, you just need to call
+# start() and finish() appropriately. However, public-inbox-httpd
+# (which uses PublicInbox::DS)  will be able to schedule this
+# based on readability of stdout from the spawned process.
+# See GitHTTPBackend.pm and SolverGit.pm for usage examples.
+# It does not depend on any form of threading.
+#
+# This is useful for scheduling CGI execution of both long-lived
+# git-http-backend(1) process (for "git clone") as well as short-lived
+# processes such as git-apply(1).
+
 package PublicInbox::Qspawn;
-use strict;
-use warnings;
+use v5.12;
 use PublicInbox::Spawn qw(popen_rd);
+use PublicInbox::GzipFilter;
+use Scalar::Util qw(blessed);
+
+# n.b.: we get EAGAIN with public-inbox-httpd, and EINTR on other PSGI servers
+use Errno qw(EAGAIN EINTR);
+
 my $def_limiter;
 
-sub new ($$$;) {
-	my ($class, $cmd, $env, $opt) = @_;
-	bless { args => [ $cmd, $env, $opt ] }, $class;
+# declares a command to spawn (but does not spawn it).
+# $cmd is the command to spawn
+# $cmd_env is the environ for the child process (not PSGI env)
+# $opt can include redirects and perhaps other process spawning options
+# {qsp_err} is an optional error buffer callers may access themselves
+sub new {
+	my ($class, $cmd, $cmd_env, $opt) = @_;
+	bless { args => [ $cmd, $cmd_env, $opt ] }, $class;
 }
 
 sub _do_spawn {
-	my ($self, $cb) = @_;
+	my ($self, $start_cb, $limiter) = @_;
 	my $err;
-
-	($self->{rpipe}, $self->{pid}) = popen_rd(@{$self->{args}});
-	if (defined $self->{pid}) {
-		$self->{limiter}->{running}++;
-	} else {
-		$self->{err} = $!;
+	my ($cmd, $cmd_env, $opt) = @{delete $self->{args}};
+	my %o = %{$opt || {}};
+	$self->{limiter} = $limiter;
+	foreach my $k (@PublicInbox::Spawn::RLIMITS) {
+		if (defined(my $rlimit = $limiter->{$k})) {
+			$o{$k} = $rlimit;
+		}
 	}
-	$cb->($self->{rpipe});
+	$self->{cmd} = $cmd;
+	$self->{-quiet} = 1 if $o{quiet};
+	$o{cb_arg} = [ \&waitpid_err, $self ];
+	eval {
+		# popen_rd may die on EMFILE, ENFILE
+		$self->{rpipe} = popen_rd($cmd, $cmd_env, \%o) // die "E: $!";
+		$limiter->{running}++;
+		$start_cb->($self); # EPOLL_CTL_ADD may ENOSPC/ENOMEM
+	};
+	finish($self, $@) if $@;
 }
 
-sub finish ($) {
+sub finalize ($) {
 	my ($self) = @_;
-	my $limiter = $self->{limiter};
-	my $running;
-	if (delete $self->{rpipe}) {
-		my $pid = delete $self->{pid};
-		$self->{err} = $pid == waitpid($pid, 0) ? $? :
-				"PID:$pid still running?";
-		$running = --$limiter->{running};
-	}
 
-	# limiter->{max} may change dynamically
-	if (($running || $limiter->{running}) < $limiter->{max}) {
-		if (my $next = shift @{$limiter->{run_queue}}) {
-			_do_spawn(@$next);
+	# process is done, spawn whatever's in the queue
+	my $limiter = delete $self->{limiter} or return;
+	my $running = --$limiter->{running};
+
+	if ($running < $limiter->{max}) {
+		if (my $next = shift(@{$limiter->{run_queue}})) {
+			_do_spawn(@$next, $limiter);
 		}
 	}
-	$self->{err};
+	if (my $err = $self->{_err}) { # set by finish or waitpid_err
+		utf8::decode($err);
+		if (my $dst = $self->{qsp_err}) {
+			$$dst .= $$dst ? " $err" : "; $err";
+		}
+		warn "@{$self->{cmd}}: $err" if !$self->{-quiet};
+	}
+
+	my ($env, $qx_cb, $qx_arg, $qx_buf) =
+		delete @$self{qw(psgi_env qx_cb qx_arg qx_buf)};
+	if ($qx_cb) {
+		eval { $qx_cb->($qx_buf, $qx_arg) };
+		return unless $@;
+		warn "E: $@"; # hope qspawn.wcb can handle it
+	}
+	return if $self->{passed}; # another command chained it
+	if (my $wcb = delete $env->{'qspawn.wcb'}) {
+		# have we started writing, yet?
+		my $code = delete $env->{'qspawn.fallback'} // 500;
+		require PublicInbox::WwwStatic;
+		$wcb->(PublicInbox::WwwStatic::r($code));
+	}
 }
 
-sub start {
-	my ($self, $limiter, $cb) = @_;
-	$self->{limiter} = $limiter;
+sub DESTROY { finalize($_[0]) } # ->finalize is idempotent
 
+sub waitpid_err { # callback for awaitpid
+	my (undef, $self) = @_; # $_[0]: pid
+	$self->{_err} = ''; # for defined check in ->finish
+	if ($?) {
+		my $status = $? >> 8;
+		my $sig = $? & 127;
+		$self->{_err} .= "exit status=$status";
+		$self->{_err} .= " signal=$sig" if $sig;
+	}
+	finalize($self) if !$self->{rpipe};
+}
+
+sub finish ($;$) {
+	my ($self, $err) = @_;
+	$self->{_err} //= $err; # only for $@
+
+	# we can safely finalize if pipe was closed before, or if
+	# {_err} is defined by waitpid_err.  Deleting {rpipe} will
+	# trigger PublicInbox::ProcessPipe::DESTROY -> waitpid_err,
+	# but it may not fire right away if inside the event loop.
+	my $closed_before = !delete($self->{rpipe});
+	finalize($self) if $closed_before || defined($self->{_err});
+}
+
+sub start ($$$) {
+	my ($self, $limiter, $start_cb) = @_;
 	if ($limiter->{running} < $limiter->{max}) {
-		_do_spawn($self, $cb);
+		_do_spawn($self, $start_cb, $limiter);
 	} else {
-		push @{$limiter->{run_queue}}, [ $self, $cb ];
+		push @{$limiter->{run_queue}}, [ $self, $start_cb ];
 	}
 }
 
-sub psgi_return {
-	my ($self, $env, $limiter, $parse_hdr) = @_;
-	my ($fh, $rpipe);
-	my $end = sub {
-		if (my $err = $self->finish) {
-			$err = join(' ', @{$self->{args}->[0]}).": $err\n";
-			$env->{'psgi.errors'}->print($err);
-		}
-		$fh->close if $fh; # async-only
-	};
+sub psgi_qx_init_cb { # this may be PublicInbox::HTTPD::Async {cb}
+	my ($self) = @_;
+	my ($r, $buf);
+reread:
+	$r = sysread($self->{rpipe}, $buf, 65536);
+	if (!defined($r)) {
+		return if $! == EAGAIN; # try again when notified
+		goto reread if $! == EINTR;
+		event_step($self, $!);
+	} elsif (my $as = delete $self->{async}) { # PublicInbox::HTTPD::Async
+		$as->async_pass($self->{psgi_env}->{'psgix.io'},
+				$self->{qx_fh}, \$buf);
+	} elsif ($r) { # generic PSGI:
+		print { $self->{qx_fh} } $buf;
+	} else { # EOF
+		event_step($self, undef);
+	}
+}
 
-	# Danga::Socket users, we queue up the read_enable callback to
-	# fire after pending writes are complete:
-	my $buf = '';
-	my $rd_hdr = sub {
-		my $r = sysread($rpipe, $buf, 1024, length($buf));
-		return if !defined($r) && ($!{EINTR} || $!{EAGAIN});
-		$parse_hdr->($r, \$buf);
-	};
-	my $res;
-	my $async = $env->{'pi-httpd.async'};
-	my $cb = sub {
-		my $r = $rd_hdr->() or return;
-		$rd_hdr = undef;
-		if (scalar(@$r) == 3) { # error
-			if ($async) {
-				$async->close; # calls rpipe->close
-			} else {
-				$rpipe->close;
-				$end->();
+sub psgi_qx_start {
+	my ($self) = @_;
+	if (my $async = $self->{psgi_env}->{'pi-httpd.async'}) {
+		# PublicInbox::HTTPD::Async->new(rpipe, $cb, cb_arg, $end_obj)
+		$self->{async} = $async->($self->{rpipe},
+					\&psgi_qx_init_cb, $self, $self);
+		# init_cb will call ->async_pass or ->close
+	} else { # generic PSGI
+		psgi_qx_init_cb($self) while $self->{qx_fh};
+	}
+}
+
+# Similar to `backtick` or "qx" ("perldoc -f qx"), it calls $qx_cb with
+# the stdout of the given command when done; but respects the given limiter
+# $env is the PSGI env.  As with ``/qx; only use this when output is small
+# and safe to slurp.
+sub psgi_qx {
+	my ($self, $env, $limiter, $qx_cb, $qx_arg) = @_;
+	$self->{psgi_env} = $env;
+	my $qx_buf = '';
+	open(my $qx_fh, '+>', \$qx_buf) or die; # PerlIO::scalar
+	$self->{qx_cb} = $qx_cb;
+	$self->{qx_arg} = $qx_arg;
+	$self->{qx_fh} = $qx_fh;
+	$self->{qx_buf} = \$qx_buf;
+	$limiter ||= $def_limiter ||= PublicInbox::Qspawn::Limiter->new(32);
+	start($self, $limiter, \&psgi_qx_start);
+}
+
+# this is called on pipe EOF to reap the process, may be called
+# via PublicInbox::DS event loop OR via GetlineBody for generic
+# PSGI servers.
+sub event_step {
+	my ($self, $err) = @_; # $err: $!
+	warn "psgi_{return,qx} $err" if defined($err);
+	finish($self);
+	my ($fh, $qx_fh) = delete(@$self{qw(qfh qx_fh)});
+	$fh->close if $fh; # async-only (psgi_return)
+}
+
+sub rd_hdr ($) {
+	my ($self) = @_;
+	# typically used for reading CGI headers
+	# We also need to check EINTR for generic PSGI servers.
+	my $ret;
+	my $total_rd = 0;
+	my $hdr_buf = $self->{hdr_buf};
+	my ($ph_cb, $ph_arg) = @{$self->{parse_hdr}};
+	until (defined($ret)) {
+		my $r = sysread($self->{rpipe}, $$hdr_buf, 4096,
+				length($$hdr_buf));
+		if (defined($r)) {
+			$total_rd += $r;
+			eval { $ret = $ph_cb->($total_rd, $hdr_buf, $ph_arg) };
+			if ($@) {
+				warn "parse_hdr: $@";
+				$ret = [ 500, [], [ "Internal error\n" ] ];
+			} elsif (!defined($ret) && !$r) {
+				warn <<EOM;
+EOF parsing headers from @{$self->{cmd}} ($self->{psgi_env}->{REQUEST_URI})
+EOM
+				$ret = [ 500, [], [ "Internal error\n" ] ];
 			}
-			$res->($r);
-		} elsif ($async) {
-			$fh = $res->($r); # scalar @$r == 2
-			$async->async_pass($env->{'psgix.io'}, $fh, \$buf);
-		} else { # for synchronous PSGI servers
-			require PublicInbox::GetlineBody;
-			$r->[2] = PublicInbox::GetlineBody->new($rpipe, $end,
-								$buf);
-			$res->($r);
+		} else {
+			# caller should notify us when it's ready:
+			return if $! == EAGAIN;
+			next if $! == EINTR; # immediate retry
+			warn "error reading header: $!";
+			$ret = [ 500, [], [ "Internal error\n" ] ];
 		}
-	};
+	}
+	delete $self->{parse_hdr}; # done parsing headers
+	$ret;
+}
+
+sub psgi_return_init_cb { # this may be PublicInbox::HTTPD::Async {cb}
+	my ($self) = @_;
+	my $r = rd_hdr($self) or return;
+	my $env = $self->{psgi_env};
+	my $filter;
+
+	# this is for RepoAtom since that can fire after parse_cgi_headers
+	if (ref($r) eq 'ARRAY' && blessed($r->[2]) && $r->[2]->can('attach')) {
+		$filter = pop @$r;
+	}
+	$filter //= delete($env->{'qspawn.filter'}) // (ref($r) eq 'ARRAY' ?
+		PublicInbox::GzipFilter::qsp_maybe($r->[1], $env) : undef);
+
+	my $wcb = delete $env->{'qspawn.wcb'};
+	my $async = delete $self->{async}; # PublicInbox::HTTPD::Async
+	if (ref($r) ne 'ARRAY' || scalar(@$r) == 3) { # error
+		if ($async) { # calls rpipe->close && ->event_step
+			$async->close; # PublicInbox::HTTPD::Async::close
+		} else { # generic PSGI, use PublicInbox::ProcessPipe::CLOSE
+			delete($self->{rpipe})->close;
+			event_step($self);
+		}
+		if (ref($r) eq 'ARRAY') { # error
+			$wcb->($r)
+		} elsif (ref($r) eq 'CODE') { # chain another command
+			$r->($wcb);
+			$self->{passed} = 1;
+		}
+		# else do nothing
+	} elsif ($async) {
+		# done reading headers, handoff to read body
+		my $fh = $wcb->($r); # scalar @$r == 2
+		$fh = $filter->attach($fh) if $filter;
+		$self->{qfh} = $fh;
+		$async->async_pass($env->{'psgix.io'}, $fh,
+					delete($self->{hdr_buf}));
+	} else { # for synchronous PSGI servers
+		require PublicInbox::GetlineBody;
+		my $buf = delete $self->{hdr_buf};
+		$r->[2] = PublicInbox::GetlineBody->new($self->{rpipe},
+					\&event_step, $self, $$buf, $filter);
+		$wcb->($r);
+	}
+}
+
+sub psgi_return_start { # may run later, much later...
+	my ($self) = @_;
+	if (my $cb = $self->{psgi_env}->{'pi-httpd.async'}) {
+		# PublicInbox::HTTPD::Async->new(rpipe, $cb, $cb_arg, $end_obj)
+		$self->{async} = $cb->($self->{rpipe},
+					\&psgi_return_init_cb, $self, $self);
+	} else { # generic PSGI
+		psgi_return_init_cb($self) while $self->{parse_hdr};
+	}
+}
+
+# Used for streaming the stdout of one process as a PSGI response.
+#
+# $env is the PSGI env.
+# optional keys in $env:
+#   $env->{'qspawn.wcb'} - the write callback from the PSGI server
+#                          optional, use this if you've already
+#                          captured it elsewhere.  If not given,
+#                          psgi_return will return an anonymous
+#                          sub for the PSGI server to call
+#
+#   $env->{'qspawn.filter'} - filter object, responds to ->attach for
+#                             pi-httpd.async and ->translate for generic
+#                             PSGI servers
+#
+# $limiter - the Limiter object to use (uses the def_limiter if not given)
+#
+# $parse_hdr - Initial read function; often for parsing CGI header output.
+#              It will be given the return value of sysread from the pipe
+#              and a string ref of the current buffer.  Returns an arrayref
+#              for PSGI responses.  2-element arrays in PSGI mean the
+#              body will be streamed, later, via writes (push-based) to
+#              psgix.io.  3-element arrays means the body is available
+#              immediately (or streamed via ->getline (pull-based)).
+sub psgi_return {
+	my ($self, $env, $limiter, $parse_hdr, $hdr_arg) = @_;
+	$self->{psgi_env} = $env;
+	$self->{hdr_buf} = \(my $hdr_buf = '');
+	$self->{parse_hdr} = [ $parse_hdr, $hdr_arg ];
 	$limiter ||= $def_limiter ||= PublicInbox::Qspawn::Limiter->new(32);
+
+	# the caller already captured the PSGI write callback from
+	# the PSGI server, so we can call ->start, here:
+	$env->{'qspawn.wcb'} and
+		return start($self, $limiter, \&psgi_return_start);
+
+	# the caller will return this sub to the PSGI server, so
+	# it can set the response callback (that is, for
+	# PublicInbox::HTTP, the chunked_wcb or identity_wcb callback),
+	# but other HTTP servers are supported:
 	sub {
-		($res) = @_;
-		$self->start($limiter, sub { # may run later, much later...
-			($rpipe) = @_;
-			if ($async) {
-			# PublicInbox::HTTPD::Async->new($rpipe, $cb, $end)
-				$async = $async->($rpipe, $cb, $end);
-			} else { # generic PSGI
-				$cb->() while $rd_hdr;
-			}
-		});
-	};
+		$env->{'qspawn.wcb'} = $_[0];
+		start($self, $limiter, \&psgi_return_start);
+	}
 }
 
 package PublicInbox::Qspawn::Limiter;
-use strict;
-use warnings;
+use v5.12;
 
 sub new {
 	my ($class, $max) = @_;
@@ -128,7 +344,36 @@ sub new {
 		max => $max || 32,
 		running => 0,
 		run_queue => [],
+		# RLIMIT_CPU => undef,
+		# RLIMIT_DATA => undef,
+		# RLIMIT_CORE => undef,
 	}, $class;
 }
 
+sub setup_rlimit {
+	my ($self, $name, $cfg) = @_;
+	foreach my $rlim (@PublicInbox::Spawn::RLIMITS) {
+		my $k = lc($rlim);
+		$k =~ tr/_//d;
+		$k = "publicinboxlimiter.$name.$k";
+		defined(my $v = $cfg->{$k}) or next;
+		my @rlimit = split(/\s*,\s*/, $v);
+		if (scalar(@rlimit) == 1) {
+			push @rlimit, $rlimit[0];
+		} elsif (scalar(@rlimit) != 2) {
+			warn "could not parse $k: $v\n";
+		}
+		eval { require BSD::Resource };
+		if ($@) {
+			warn "BSD::Resource missing for $rlim";
+			next;
+		}
+		foreach my $i (0..$#rlimit) {
+			next if $rlimit[$i] ne 'INFINITY';
+			$rlimit[$i] = BSD::Resource::RLIM_INFINITY();
+		}
+		$self->{$rlim} = \@rlimit;
+	}
+}
+
 1;