lei: avoid deadlock on inotify/EVFILT_VNODE wakeups

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

diff --git a/lib/PublicInbox/IPC.pm b/lib/PublicInbox/IPC.pm
index 6c189b6410aa3798a736a6071a96826815b651be..7486267322b082f6d326a20bb03b3a02189e8726 100644 (file)
--- a/lib/PublicInbox/IPC.pm
+++ b/lib/PublicInbox/IPC.pm
@@ -1,4 +1,4 @@
-# Copyright (C) 2020-2021 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>
 
 # base class for remote IPC calls and workqueues, requires Storable or Sereal
@@ -43,10 +43,14 @@ if ($enc && $dec) { # should be custom ops
 }
 
 my $recv_cmd = PublicInbox::Spawn->can('recv_cmd4');
-my $send_cmd = PublicInbox::Spawn->can('send_cmd4') // do {
+our $send_cmd = PublicInbox::Spawn->can('send_cmd4') // do {
        require PublicInbox::CmdIPC4;
        $recv_cmd //= PublicInbox::CmdIPC4->can('recv_cmd4');
        PublicInbox::CmdIPC4->can('send_cmd4');
+} // do {
+       require PublicInbox::Syscall;
+       $recv_cmd //= PublicInbox::Syscall->can('recv_cmd4');
+       PublicInbox::Syscall->can('send_cmd4');
 };
 
 sub _get_rec ($) {
@@ -134,16 +138,22 @@ sub ipc_worker_spawn {
 
 sub ipc_worker_reap { # dwaitpid callback
        my ($args, $pid) = @_;
+       my ($self, @uargs) = @$args;
+       delete $self->{-wq_workers}->{$pid};
+       return $self->{-reap_do}->($args, $pid) if $self->{-reap_do};
        return if !$?;
-       # TERM(15) is our default exit signal, PIPE(13) is likely w/ pager
        my $s = $? & 127;
-       warn "PID:$pid died with \$?=$?\n" if $s != 15 && $s != 13;
+       # TERM(15) is our default exit signal, PIPE(13) is likely w/ pager
+       warn "$self->{-wq_ident} PID:$pid died \$?=$?\n" if $s != 15 && $s != 13
 }
 
-sub wq_wait_old {
-       my ($self, $cb, @args) = @_;
-       my $pids = delete $self->{"-wq_old_pids.$$"} or return;
-       dwaitpid($_, $cb // \&ipc_worker_reap, [$self, @args]) for @$pids;
+sub wq_wait_async {
+       my ($self, $cb, @uargs) = @_;
+       local $PublicInbox::DS::in_loop = 1;
+       $self->{-reap_async} = 1;
+       $self->{-reap_do} = $cb;
+       my @pids = keys %{$self->{-wq_workers}};
+       dwaitpid($_, \&ipc_worker_reap, [ $self, @uargs ]) for @pids;
 }
 
 # for base class, override in sub classes
@@ -241,7 +251,7 @@ sub recv_and_run {
        undef $buf;
        my $sub = shift @$args;
        eval { $self->$sub(@$args) };
-       warn "$$ $0 wq_worker: $@" if $@;
+       warn "$$ $0 wq_worker: $sub: $@" if $@;
        delete @$self{0..($nfd-1)};
        $n;
 }
@@ -338,6 +348,24 @@ sub wq_do {
        }
 }
 
+sub prepare_nonblock {
+       ($_[0]->{-wq_s1} // die 'BUG: no {-wq_s1}')->blocking(0);
+       $_[0]->{-reap_async} or die 'BUG: {-reap_async} needed for nonblock';
+       require PublicInbox::WQBlocked;
+}
+
+sub wq_nonblock_do { # always async
+       my ($self, $sub, @args) = @_;
+       my $buf = ipc_freeze([$sub, @args]);
+       if ($self->{wqb}) { # saturated once, assume saturated forever
+               $self->{wqb}->flush_send($buf);
+       } else {
+               $send_cmd->($self->{-wq_s1}, [], $buf, MSG_EOR) //
+                       ($!{EAGAIN} ? PublicInbox::WQBlocked->new($self, $buf)
+                                       : croak("sendmsg: $!"));
+       }
+}
+
 sub _wq_worker_start ($$$$) {
        my ($self, $oldset, $fields, $one) = @_;
        my ($bcast1, $bcast2);
@@ -394,42 +422,28 @@ sub wq_workers_start {
 }
 
 sub wq_close {
-       my ($self, $nohang, $cb, @args) = @_;
-       delete @$self{qw(-wq_s1 -wq_s2)} or return;
-       my $ppid = delete $self->{-wq_ppid} or return;
-       my $workers = delete $self->{-wq_workers} // die 'BUG: no wq_workers';
-       return if $ppid != $$; # can't reap siblings or parents
-       my @pids = map { $_ + 0 } keys %$workers;
-       if ($nohang) {
-               push @{$self->{"-wq_old_pids.$$"}}, @pids;
-       } else {
-               $cb //= \&ipc_worker_reap;
-               unshift @args, $self;
-               dwaitpid($_, $cb, \@args) for @pids;
+       my ($self) = @_;
+       if (my $wqb = delete $self->{wqb}) {
+               $self->{-reap_async} or die 'BUG: {-reap_async} unset';
+               $wqb->enq_close;
        }
-}
-
-sub wq_kill_old {
-       my ($self, $sig) = @_;
-       my $pids = $self->{"-wq_old_pids.$$"} or return;
-       kill($sig // 'TERM', @$pids);
+       delete @$self{qw(-wq_s1 -wq_s2)} or return;
+       return if $self->{-reap_async};
+       my @pids = keys %{$self->{-wq_workers}};
+       dwaitpid($_, \&ipc_worker_reap, [ $self ]) for @pids;
 }
 
 sub wq_kill {
        my ($self, $sig) = @_;
-       my $workers = $self->{-wq_workers} or return;
-       kill($sig // 'TERM', keys %$workers);
+       kill($sig // 'TERM', keys %{$self->{-wq_workers}});
 }
 
 sub DESTROY {
        my ($self) = @_;
        my $ppid = $self->{-wq_ppid};
        wq_kill($self) if $ppid && $ppid == $$;
-       my $err = $?;
        wq_close($self);
-       wq_wait_old($self);
        ipc_worker_stop($self);
-       $? = $err if $err;
 }
 
 sub detect_nproc () {