package Object::Remote::MiniLoop;
use IO::Select;
use Time::HiRes qw(time);
use Object::Remote::Logging qw( :log :dlog router );
use Moo;
BEGIN {
$SIG{PIPE} = sub { log_debug { "Got a PIPE signal" } };
router()->exclude_forwarding
}
# this is ro because we only actually set it using local in sub run
has is_running => (is => 'ro', clearer => 'stop');
#maximum duration that select() will block - undef means indefinite,
#0 means no blocking, otherwise maximum time in seconds
has block_duration => ( is => 'rw' );
has _read_watches => (is => 'ro', default => sub { {} });
has _read_select => (is => 'ro', default => sub { IO::Select->new });
has _write_watches => (is => 'ro', default => sub { {} });
has _write_select => (is => 'ro', default => sub { IO::Select->new });
has _timers => (is => 'ro', default => sub { [] });
sub pass_watches_to {
my ($self, $new_loop) = @_;
log_debug { "passing watches to new run loop" };
foreach my $fh ($self->_read_select->handles) {
$new_loop->watch_io(
handle => $fh,
on_read_ready => $self->_read_watches->{$fh}
);
}
foreach my $fh ($self->_write_select->handles) {
$new_loop->watch_io(
handle => $fh,
on_write_ready => $self->_write_watches->{$fh}
);
}
}
sub watch_io {
my ($self, %watch) = @_;
my $fh = $watch{handle};
Dlog_debug { "Adding IO watch for $_" } $fh;
if (my $cb = $watch{on_read_ready}) {
log_trace { "IO watcher is registering with select for reading" };
$self->_read_select->add($fh);
$self->_read_watches->{$fh} = $cb;
}
if (my $cb = $watch{on_write_ready}) {
log_trace { "IO watcher is registering with select for writing" };
$self->_write_select->add($fh);
$self->_write_watches->{$fh} = $cb;
}
return;
}
sub unwatch_io {
my ($self, %watch) = @_;
my $fh = $watch{handle};
Dlog_debug { "Removing IO watch for $_" } $fh;
if ($watch{on_read_ready}) {
log_trace { "IO watcher is removing read from select()" };
$self->_read_select->remove($fh);
delete $self->_read_watches->{$fh};
}
if ($watch{on_write_ready}) {
log_trace { "IO watcher is removing write from select()" };
$self->_write_select->remove($fh);
delete $self->_write_watches->{$fh};
}
return;
}
sub _sort_timers {
my ($self, @new) = @_;
my $timers = $self->_timers;
log_trace { "Sorting timers" };
@{$timers} = sort { $a->[0] <=> $b->[0] } @{$timers}, @new;
return;
}
sub watch_time {
my ($self, %watch) = @_;
my $at;
Dlog_trace { "watch_time() invoked with $_" } \%watch;
if (exists($watch{every})) {
$at = time() + $watch{every};
} elsif (exists($watch{after})) {
$at = time() + $watch{after};
} elsif (exists($watch{at})) {
$at = $watch{at};
} else {
die "watch_time requires every, after or at";
}
die "watch_time requires code" unless my $code = $watch{code};
my $timers = $self->_timers;
my $new = [ $at => $code, $watch{every} ];
$self->_sort_timers($new);
log_debug { "Created new timer with id '$new' that expires at '$at'" };
return "$new";
}
sub unwatch_time {
my ($self, $id) = @_;
log_trace { "Removing timer with id of '$id'" };
@$_ = grep !($_ eq $id), @$_ for $self->_timers;
return;
}
sub _next_timer_expires_delay {
my ($self) = @_;
my $timers = $self->_timers;
my $delay_max = $self->block_duration;
return $delay_max unless @$timers;
my $duration = $timers->[0]->[0] - time;
log_trace { "next timer fires in '$duration' seconds" };
if ($duration < 0) {
$duration = 0;
} elsif (defined $delay_max && $duration > $delay_max) {
$duration = $delay_max;
}
return $duration;
}
sub loop_once {
my ($self) = @_;
my $read = $self->_read_watches;
my $write = $self->_write_watches;
my $read_count = 0;
my $write_count = 0;
my @c = caller;
my $wait_time = $self->_next_timer_expires_delay;
log_trace {
sprintf("Run loop: loop_once() has been invoked by $c[1]:$c[2] with read:%i write:%i select timeout:%s",
scalar(keys(%$read)), scalar(keys(%$write)), defined $wait_time ? $wait_time : 'indefinite' )
};
my ($readable, $writeable) = IO::Select->select(
$self->_read_select, $self->_write_select, undef, $wait_time
);
log_trace {
my $readable_count = defined $readable ? scalar(@$readable) : 0;
my $writable_count = defined $writeable ? scalar(@$writeable) : 0;
"Run loop: select returned readable:$readable_count writeable:$writable_count";
};
# I would love to trap errors in the select call but IO::Select doesn't
# differentiate between an error and a timeout.
# -- no, love, mst.
log_trace { "Reading from ready filehandles" };
foreach my $fh (@$readable) {
next unless $read->{$fh};
$read_count++;
$read->{$fh}();
#FIXME this is a rough workaround for race conditions that can cause deadlocks
#under load
last;
}
log_trace { "Writing to ready filehandles" };
foreach my $fh (@$writeable) {
next unless $write->{$fh};
$write_count++;
$write->{$fh}();
#FIXME this is a rough workaround for race conditions that can cause deadlocks
#under load
last;
}
#moving the timers above the read() section exposes a deadlock
log_trace { "Read from $read_count filehandles; wrote to $write_count filehandles" };
my $timers = $self->_timers;
my $now = time();
log_trace { "Checking timers" };
while (@$timers and $timers->[0][0] <= $now) {
my $active = $timers->[0];
Dlog_trace { "Found timer that needs to be executed: '$active'" };
if (defined($active->[2])) {
#handle the case of an 'every' timer
$active->[0] = time() + $active->[2];
Dlog_trace { "scheduling timer for repeat execution at $_"} $active->[0];
$self->_sort_timers;
} else {
#it doesn't repeat again so get rid of it
shift(@$timers);
}
#execute the timer
$active->[1]->();
}
log_trace { "Run loop: single loop is completed" };
return;
}
sub want_run {
my ($self) = @_;
Dlog_debug { "Run loop: Incremeting want_running, is now $_" }
++$self->{want_running};
}
sub run_while_wanted {
my ($self) = @_;
log_debug { my $wr = $self->{want_running}; "Run loop: run_while_wanted() invoked; want_running: $wr" };
$self->loop_once while $self->{want_running};
log_debug { "Run loop: run_while_wanted() completed" };
return;
}
sub want_stop {
my ($self) = @_;
if (! $self->{want_running}) {
log_debug { "Run loop: want_stop() was called but want_running was not true" };
return;
}
Dlog_debug { "Run loop: decrimenting want_running, is now $_" }
--$self->{want_running};
}
sub run {
my ($self) = @_;
log_trace { "Run loop: run() invoked" };
local $self->{is_running} = 1;
while ($self->is_running) {
$self->loop_once;
}
log_trace { "Run loop: run() completed" };
return;
}
1;