ds: rely on autovivification for $later_queue

[public-inbox.git] / lib / PublicInbox / DS.pm

diff --git a/lib/PublicInbox/DS.pm b/lib/PublicInbox/DS.pm
index 2f41ea456d72cd11854bad753761a6292243733f..673c24eb86a81315eccd8b41457385d51072aba1 100644 (file)
--- a/lib/PublicInbox/DS.pm
+++ b/lib/PublicInbox/DS.pm
@@ -39,8 +39,8 @@ use Errno qw(EAGAIN EINVAL);
 use Carp qw(confess carp);
 
 my $nextq; # queue for next_tick
-my $WaitPids; # list of [ pid, callback, callback_arg ]
-my $later_queue; # callbacks
+my $wait_pids; # list of [ pid, callback, callback_arg ]
+my $later_queue; # list of callbacks to run at some later interval
 my $EXPMAP; # fd -> [ idle_time, $self ]
 our $EXPTIME = 180; # 3 minutes
 my ($later_timer, $reap_timer, $exp_timer);
@@ -71,8 +71,7 @@ Reset all state
 =cut
 sub Reset {
     %DescriptorMap = ();
-    $WaitPids = [];
-    $later_queue = [];
+    $wait_pids = $later_queue = undef;
     $EXPMAP = {};
     $nextq = $ToClose = $reap_timer = $later_timer = $exp_timer = undef;
     $LoopTimeout = -1;  # no timeout by default
@@ -226,25 +225,23 @@ sub RunTimers {
 }
 
 # We can't use waitpid(-1) safely here since it can hit ``, system(),
-# and other things.  So we scan the $WaitPids list, which is hopefully
-# not too big.
+# and other things.  So we scan the $wait_pids list, which is hopefully
+# not too big.  We keep $wait_pids small by not calling dwaitpid()
+# until we've hit EOF when reading the stdout of the child.
 sub reap_pids {
-    my $tmp = $WaitPids;
-    $WaitPids = [];
-    $reap_timer = undef;
+    my $tmp = $wait_pids or return;
+    $wait_pids = $reap_timer = undef;
     foreach my $ary (@$tmp) {
         my ($pid, $cb, $arg) = @$ary;
         my $ret = waitpid($pid, WNOHANG);
         if ($ret == 0) {
-            push @$WaitPids, $ary;
+            push @$wait_pids, $ary; # autovivifies @$wait_pids
         } elsif ($cb) {
             eval { $cb->($arg, $pid) };
         }
     }
-    if (@$WaitPids) {
-        # we may not be donea, and we may miss our
-        $reap_timer = add_timer(1, \&reap_pids);
-    }
+    # we may not be done, yet, and could've missed/masked a SIGCHLD:
+    $reap_timer = add_timer(1, \&reap_pids) if $wait_pids;
 }
 
 # reentrant SIGCHLD handler (since reap_pids is not reentrant)
@@ -626,28 +623,22 @@ sub shutdn ($) {
 
 # must be called with eval, PublicInbox::DS may not be loaded (see t/qspawn.t)
 sub dwaitpid ($$$) {
-    my ($pid, $cb, $arg) = @_;
-    if ($in_loop) {
-        push @$WaitPids, [ $pid, $cb, $arg ];
+       die "Not in EventLoop\n" unless $in_loop;
+       push @$wait_pids, [ @_ ]; # [ $pid, $cb, $arg ]
 
-        # We could've just missed our SIGCHLD, cover it, here:
-        requeue(\&reap_pids);
-    } else {
-        die "Not in EventLoop\n";
-    }
+       # We could've just missed our SIGCHLD, cover it, here:
+       requeue(\&reap_pids);
 }
 
 sub _run_later () {
-    my $run = $later_queue;
-    $later_timer = undef;
-    $later_queue = [];
-    $_->() for @$run;
+       my $run = $later_queue or return;
+       $later_timer = $later_queue = undef;
+       $_->() for @$run;
 }
 
 sub later ($) {
-    my ($cb) = @_;
-    push @$later_queue, $cb;
-    $later_timer //= add_timer(60, \&_run_later);
+       push @$later_queue, $_[0]; # autovivifies @$later_queue
+       $later_timer //= add_timer(60, \&_run_later);
 }
 
 sub expire_old () {