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 f7c8ad2ba085d2b1654b596e6e4393e5cf40460e..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);
@@ -71,11 +71,9 @@ Reset all state
 =cut
 sub Reset {
     %DescriptorMap = ();
-    $nextq = [];
-    $WaitPids = [];
-    $later_queue = [];
+    $wait_pids = $later_queue = undef;
     $EXPMAP = {};
-    $ToClose = $reap_timer = $later_timer = $exp_timer = undef;
+    $nextq = $ToClose = $reap_timer = $later_timer = $exp_timer = undef;
     $LoopTimeout = -1;  # no timeout by default
     @Timers = ();
 
@@ -179,8 +177,8 @@ sub FirstTimeEventLoop {
 sub now () { clock_gettime(CLOCK_MONOTONIC) }
 
 sub next_tick () {
-    my $q = $nextq;
-    $nextq = [];
+    my $q = $nextq or return;
+    $nextq = undef;
     for (@$q) {
         # we avoid "ref" on blessed refs to workaround a Perl 5.16.3 leak:
         # https://rt.perl.org/Public/Bug/Display.html?id=114340
@@ -196,7 +194,7 @@ sub next_tick () {
 sub RunTimers {
     next_tick();
 
-    return ((@$nextq || $ToClose) ? 0 : $LoopTimeout) unless @Timers;
+    return (($nextq || $ToClose) ? 0 : $LoopTimeout) unless @Timers;
 
     my $now = now();
 
@@ -207,7 +205,7 @@ sub RunTimers {
     }
 
     # timers may enqueue into nextq:
-    return 0 if (@$nextq || $ToClose);
+    return 0 if ($nextq || $ToClose);
 
     return $LoopTimeout unless @Timers;
 
@@ -227,29 +225,27 @@ 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)
-sub enqueue_reap ($) { push @$nextq, \&reap_pids };
+sub enqueue_reap ($) { push @$nextq, \&reap_pids }; # autovivifies
 
 sub in_loop () { $in_loop }
 
@@ -353,7 +349,7 @@ sub new {
 ### I N S T A N C E   M E T H O D S
 #####################################################################
 
-sub requeue ($) { push @$nextq, $_[0] }
+sub requeue ($) { push @$nextq, $_[0] } # autovivifies
 
 =head2 C<< $obj->close >>
 
@@ -627,28 +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 () {