dir_idle: treat IN_MOVED_FROM as a gone event

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

diff --git a/lib/PublicInbox/FakeInotify.pm b/lib/PublicInbox/FakeInotify.pm
index 9275861368a0a00df5b95ff8acb4776413568d34..6d2696019d8324fc3676d4e49efb783e10efc15a 100644 (file)
--- a/lib/PublicInbox/FakeInotify.pm
+++ b/lib/PublicInbox/FakeInotify.pm
@@ -1,20 +1,36 @@
-# Copyright (C) 2020 all contributors <meta@public-inbox.org>
+# Copyright (C) 2020-2021 all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 
 # for systems lacking Linux::Inotify2 or IO::KQueue, just emulates
 # enough of Linux::Inotify2
 package PublicInbox::FakeInotify;
 use strict;
+use v5.10.1;
+use parent qw(Exporter);
 use Time::HiRes qw(stat);
-use PublicInbox::DS;
+use PublicInbox::DS qw(add_timer);
 sub IN_MODIFY () { 0x02 } # match Linux inotify
+# my $IN_MOVED_FROM     0x00000040     /* File was moved from X.  */
 # my $IN_MOVED_TO = 0x80;
 # my $IN_CREATE = 0x100;
 sub MOVED_TO_OR_CREATE () { 0x80 | 0x100 }
+sub IN_DELETE () { 0x200 }
+sub IN_DELETE_SELF () { 0x400 }
+sub IN_MOVE_SELF () { 0x800 }
+
+our @EXPORT_OK = qw(fill_dirlist on_dir_change);
 
 my $poll_intvl = 2; # same as Filesys::Notify::Simple
 
-sub new { bless { watch => {} }, __PACKAGE__ }
+sub new { bless { watch => {}, dirlist => {} }, __PACKAGE__ }
+
+sub fill_dirlist ($$$) {
+       my ($self, $path, $dh) = @_;
+       my $dirlist = $self->{dirlist}->{$path} = {};
+       while (defined(my $n = readdir($dh))) {
+               $dirlist->{$n} = undef if $n !~ /\A\.\.?\z/;
+       }
+}
 
 # behaves like Linux::Inotify2->watch
 sub watch {
@@ -22,11 +38,19 @@ sub watch {
        my @st = stat($path) or return;
        my $k = "$path\0$mask";
        $self->{watch}->{$k} = $st[10]; # 10 - ctime
+       if ($mask & IN_DELETE) {
+               opendir(my $dh, $path) or return;
+               fill_dirlist($self, $path, $dh);
+       }
        bless [ $self->{watch}, $k ], 'PublicInbox::FakeInotify::Watch';
 }
 
-sub on_new_files ($$$$) {
-       my ($events, $dh, $path, $old_ctime) = @_;
+# also used by KQNotify since it kevent requires readdir on st_nlink
+# count changes.
+sub on_dir_change ($$$$$) {
+       my ($events, $dh, $path, $old_ctime, $dirlist) = @_;
+       my $oldlist = $dirlist->{$path};
+       my $newlist = $oldlist ? {} : undef;
        while (defined(my $base = readdir($dh))) {
                next if $base =~ /\A\.\.?\z/;
                my $full = "$path/$base";
@@ -35,7 +59,19 @@ sub on_new_files ($$$$) {
                        push @$events,
                                bless(\$full, 'PublicInbox::FakeInotify::Event')
                }
+               if (!@st) {
+                       # ignore ENOENT due to race
+                       warn "unhandled stat($full) error: $!\n" if !$!{ENOENT};
+               } elsif ($newlist) {
+                       $newlist->{$base} = undef;
+               }
        }
+       return if !$newlist;
+       delete @$oldlist{keys %$newlist};
+       $dirlist->{$path} = $newlist;
+       push(@$events, map {
+               bless \"$path/$_", 'PublicInbox::FakeInotify::GoneEvent'
+       } keys %$oldlist);
 }
 
 # behaves like non-blocking Linux::Inotify2->read
@@ -43,30 +79,43 @@ sub read {
        my ($self) = @_;
        my $watch = $self->{watch} or return ();
        my $events = [];
+       my @watch_gone;
        for my $x (keys %$watch) {
                my ($path, $mask) = split(/\0/, $x, 2);
-               my @now = stat($path) or next;
+               my @now = stat($path);
+               if (!@now && $!{ENOENT} && ($mask & IN_DELETE_SELF)) {
+                       push @$events, bless(\$path,
+                               'PublicInbox::FakeInotify::SelfGoneEvent');
+                       push @watch_gone, $x;
+                       delete $self->{dirlist}->{$path};
+               }
+               next if !@now;
                my $old_ctime = $watch->{$x};
                $watch->{$x} = $now[10];
                next if $old_ctime == $now[10];
                if ($mask & IN_MODIFY) {
                        push @$events,
                                bless(\$path, 'PublicInbox::FakeInotify::Event')
-               } elsif ($mask & MOVED_TO_OR_CREATE) {
-                       opendir(my $dh, $path) or do {
+               } elsif ($mask & (MOVED_TO_OR_CREATE | IN_DELETE)) {
+                       if (opendir(my $dh, $path)) {
+                               on_dir_change($events, $dh, $path, $old_ctime,
+                                               $self->{dirlist});
+                       } elsif ($!{ENOENT}) {
+                               push @watch_gone, $x;
+                               delete $self->{dirlist}->{$path};
+                       } else {
                                warn "W: opendir $path: $!\n";
-                               next;
-                       };
-                       on_new_files($events, $dh, $path, $old_ctime);
+                       }
                }
        }
+       delete @$watch{@watch_gone};
        @$events;
 }
 
 sub poll_once {
        my ($obj) = @_;
        $obj->event_step; # PublicInbox::InboxIdle::event_step
-       PublicInbox::DS::add_timer($poll_intvl, \&poll_once, $obj);
+       add_timer($poll_intvl, \&poll_once, $obj);
 }
 
 package PublicInbox::FakeInotify::Watch;
@@ -86,4 +135,22 @@ package PublicInbox::FakeInotify::Event;
 use strict;
 
 sub fullname { ${$_[0]} }
+
+sub IN_DELETE { 0 }
+sub IN_MOVED_FROM { 0 }
+sub IN_DELETE_SELF { 0 }
+
+package PublicInbox::FakeInotify::GoneEvent;
+use strict;
+our @ISA = qw(PublicInbox::FakeInotify::Event);
+
+sub IN_DELETE { 1 }
+sub IN_MOVED_FROM { 0 }
+
+package PublicInbox::FakeInotify::SelfGoneEvent;
+use strict;
+our @ISA = qw(PublicInbox::FakeInotify::GoneEvent);
+
+sub IN_DELETE_SELF { 1 }
+
 1;