watch: improve fairness during full rescans

We need to ensure new messages are being processed
fairly during full rescans, so have the ->scan subroutine
yield and reschedule itself.  Additionally, having a
long-running task inside the signal handler is dangerous
and subject to reentrancy bugs.

Due to the limitations of the Filesys::Notify::Simple interface,
we cannot rely on multiplexing I/O interfaces (select, IO::Poll,
Danga::Socket, etc...) for this.  Forking a separate process
was considered, but it is more expensive for a mostly-idle
process.

So, we use a variant of the "self-pipe trick" via inotify (or
whatever Filesys::Notify::Simple gives us).  Instead of writing
to our own pipe, we write to a file in our own temporary
directory watched by Filesys::Notify::Simple to trigger events
in signal handlers.

diff --git a/lib/PublicInbox/WatchMaildir.pm b/lib/PublicInbox/WatchMaildir.pm
index f81a917c5ab74070425a309c3ae3f25a93981fd4..0e2a6d2c3c5d6f6ea50580b5ad8e25eb9314278f 100644 (file)
--- a/lib/PublicInbox/WatchMaildir.pm
+++ b/lib/PublicInbox/WatchMaildir.pm
@@ -13,25 +13,27 @@ use PublicInbox::Git;
 use PublicInbox::Import;
 use PublicInbox::MDA;
 use PublicInbox::Spawn qw(spawn);
 use PublicInbox::Import;
 use PublicInbox::MDA;
 use PublicInbox::Spawn qw(spawn);

+use File::Temp qw//;

 
 sub new {
        my ($class, $config) = @_;
 
 sub new {
        my ($class, $config) = @_;

-       my (%mdmap, @mdir, $spamc);
+       my (%mdmap, @mdir, $spamc, $spamdir);

 
        # "publicinboxwatch" is the documented namespace
        # "publicinboxlearn" is legacy but may be supported
        # indefinitely...
        foreach my $pfx (qw(publicinboxwatch publicinboxlearn)) {
                my $k = "$pfx.watchspam";
 
        # "publicinboxwatch" is the documented namespace
        # "publicinboxlearn" is legacy but may be supported
        # indefinitely...
        foreach my $pfx (qw(publicinboxwatch publicinboxlearn)) {
                my $k = "$pfx.watchspam";

-               if (my $spamdir = $config->{$k}) {
-                       if ($spamdir =~ s/\Amaildir://) {
-                               $spamdir =~ s!/+\z!!;
+               if (my $dir = $config->{$k}) {
+                       if ($dir =~ s/\Amaildir://) {
+                               $dir =~ s!/+\z!!;

                                # skip "new", no MUA has seen it, yet.
                                # skip "new", no MUA has seen it, yet.

-                               my $cur = "$spamdir/cur";
+                               my $cur = "$dir/cur";
+                               $spamdir = $cur;

                                push @mdir, $cur;
                                $mdmap{$cur} = 'watchspam';
                        } else {
                                push @mdir, $cur;
                                $mdmap{$cur} = 'watchspam';
                        } else {

-                               warn "unsupported $k=$spamdir\n";
+                               warn "unsupported $k=$dir\n";

                        }
                }
        }
                        }
                }
        }


@@ -77,21 +79,41 @@ sub new {
        $mdre = qr!\A($mdre)/!;
        bless {
                spamcheck => $spamcheck,
        $mdre = qr!\A($mdre)/!;
        bless {
                spamcheck => $spamcheck,

+               spamdir => $spamdir,

                mdmap => \%mdmap,
                mdir => \@mdir,
                mdre => $mdre,
                config => $config,
                importers => {},
                mdmap => \%mdmap,
                mdir => \@mdir,
                mdre => $mdre,
                config => $config,
                importers => {},

+               opendirs => {}, # dirname => dirhandle (in progress scans)

        }, $class;
 }
 
 sub _done_for_now {
        }, $class;
 }
 
 sub _done_for_now {

-       $_->done foreach values %{$_[0]->{importers}};
+       my ($self) = @_;
+       my $opendirs = $self->{opendirs};
+
+       # spamdir scanning means every importer remains open
+       my $spamdir = $self->{spamdir};
+       return if defined($spamdir) && $opendirs->{$spamdir};
+
+       foreach my $im (values %{$self->{importers}}) {
+               # not done if we're scanning
+               next if $opendirs->{$im->{git}->{git_dir}};
+               $im->done;
+       }

 }
 
 sub _try_fsn_paths {
 }
 
 sub _try_fsn_paths {

-       my ($self, $paths) = @_;
-       _try_path($self, $_->{path}) foreach @$paths;
+       my ($self, $scan_re, $paths) = @_;
+       foreach (@$paths) {
+               my $path = $_->{path};
+               if ($path =~ $scan_re) {
+                       scan($self, $path);
+               } else {
+                       _try_path($self, $path);
+               }
+       }

        _done_for_now($self);
 }
 
        _done_for_now($self);
 }
 


@@ -183,31 +205,61 @@ sub quit { $_[0]->{quit} = 1 }
 
 sub watch {
        my ($self) = @_;
 
 sub watch {
        my ($self) = @_;

-       my $cb = sub { _try_fsn_paths($self, \@_) };
-       my $mdir = $self->{mdir};
+       my $scan = File::Temp->newdir("public-inbox-watch.$$.scan.XXXXXX",
+                                       TMPDIR => 1);
+       my $scandir = $self->{scandir} = $scan->dirname;
+       my $re = qr!\A$scandir/!;
+       my $cb = sub { _try_fsn_paths($self, $re, \@_) };

 
        # lazy load here, we may support watching via IMAP IDLE
        # in the future...
        require Filesys::Notify::Simple;
 
        # lazy load here, we may support watching via IMAP IDLE
        # in the future...
        require Filesys::Notify::Simple;

-       my $watcher = Filesys::Notify::Simple->new($mdir);
-       $watcher->wait($cb) until ($self->{quit});
+       my $fsn = Filesys::Notify::Simple->new([@{$self->{mdir}}, $scandir]);
+       $fsn->wait($cb) until ($self->{quit});
+}
+
+sub trigger_scan {
+       my ($self, $base) = @_;
+       my $dir = $self->{scandir} or die "not watch-ing, yet\n";
+       open my $fh, '>', "$dir/$base" or die "open $dir/$base failed: $!\n";
+       close $fh or die "close $dir/$base failed: $!\n";

 }
 
 sub scan {
 }
 
 sub scan {

-       my ($self) = @_;
-       my $mdir = $self->{mdir};
-       foreach my $dir (@$mdir) {
-               my $ok = opendir(my $dh, $dir);
-               unless ($ok) {
-                       warn "failed to open $dir: $!\n";
-                       next;
-               }
+       my ($self, $path) = @_;
+       my $max = 10;
+       my $opendirs = $self->{opendirs};
+       my @dirnames = keys %$opendirs;
+       foreach my $dir (@dirnames) {
+               my $dh = delete $opendirs->{$dir};
+               my $n = $max;

                while (my $fn = readdir($dh)) {
                        _try_path($self, "$dir/$fn");
                while (my $fn = readdir($dh)) {
                        _try_path($self, "$dir/$fn");

+                       last if --$n < 0;

                }
                }

-               closedir $dh;
+               $opendirs->{$dir} = $dh if $n < 0;
+       }
+       if ($path =~ /full\z/) {
+               foreach my $dir (@{$self->{mdir}}) {
+                       next if $opendirs->{$dir}; # already in progress
+                       my $ok = opendir(my $dh, $dir);
+                       unless ($ok) {
+                               warn "failed to open $dir: $!\n";
+                               next;
+                       }
+                       my $n = $max;
+                       while (my $fn = readdir($dh)) {
+                               _try_path($self, "$dir/$fn");
+                               last if --$n < 0;
+                       }
+                       $opendirs->{$dir} = $dh if $n < 0;
+               }
+       }
+       if (keys %$opendirs) { # do we have more work to do?
+               trigger_scan($self, 'cont');
+       } else {
+               _done_for_now($self);

        }
        }

-       _done_for_now($self);

 }
 
 sub _path_to_mime {
 }
 
 sub _path_to_mime {

diff --git a/script/public-inbox-watch b/script/public-inbox-watch
index a72180c90b74c89f35315196e237a632953671f0..51f1baa29c98868c6d9ded5c57702540fc1d3a46 100755 (executable)
--- a/script/public-inbox-watch
+++ b/script/public-inbox-watch
@@ -13,7 +13,7 @@ my $reload = sub {
 };
 $reload->();
 if ($watch_md) {
 };
 $reload->();
 if ($watch_md) {

-       my $scan = sub { $watch_md->scan if $watch_md };
+       my $scan = sub { $watch_md->trigger_scan('full') if $watch_md };

        $SIG{HUP} = $reload;
        $SIG{USR1} = $scan;
        $SIG{ALRM} = sub { $SIG{ALRM} = 'DEFAULT'; $scan->() };
        $SIG{HUP} = $reload;
        $SIG{USR1} = $scan;
        $SIG{ALRM} = sub { $SIG{ALRM} = 'DEFAULT'; $scan->() };

diff --git a/t/watch_maildir.t b/t/watch_maildir.t
index 3969c80d6ce6171720891b02f4fd7f4662302acb..e12e0836b824d3f6b7141d31194f1dd48c9f8429 100644 (file)
--- a/t/watch_maildir.t
+++ b/t/watch_maildir.t
@@ -42,7 +42,7 @@ my $config = PublicInbox::Config->new({
        "publicinboxlearn.watchspam" => "maildir:$spamdir",
 });
 
        "publicinboxlearn.watchspam" => "maildir:$spamdir",
 });
 

-PublicInbox::WatchMaildir->new($config)->scan;
+PublicInbox::WatchMaildir->new($config)->scan('full');

 my $git = PublicInbox::Git->new($git_dir);
 my @list = $git->qx(qw(rev-list refs/heads/master));
 is(scalar @list, 1, 'one revision in rev-list');
 my $git = PublicInbox::Git->new($git_dir);
 my @list = $git->qx(qw(rev-list refs/heads/master));
 is(scalar @list, 1, 'one revision in rev-list');


@@ -59,7 +59,7 @@ my $write_spam = sub {
 };
 $write_spam->();
 is(unlink(glob("$maildir/new/*")), 1, 'unlinked old spam');
 };
 $write_spam->();
 is(unlink(glob("$maildir/new/*")), 1, 'unlinked old spam');

-PublicInbox::WatchMaildir->new($config)->scan;
+PublicInbox::WatchMaildir->new($config)->scan('full');

 @list = $git->qx(qw(rev-list refs/heads/master));
 is(scalar @list, 2, 'two revisions in rev-list');
 @list = $git->qx(qw(ls-tree -r --name-only refs/heads/master));
 @list = $git->qx(qw(rev-list refs/heads/master));
 is(scalar @list, 2, 'two revisions in rev-list');
 @list = $git->qx(qw(ls-tree -r --name-only refs/heads/master));


@@ -72,7 +72,7 @@ To unsubscribe from this list: send the line "unsubscribe git" in
 the body of a message to majordomo\@vger.kernel.org
 More majordomo info at  http://vger.kernel.org/majordomo-info.html\n);
        PublicInbox::Emergency->new($maildir)->prepare(\$msg);
 the body of a message to majordomo\@vger.kernel.org
 More majordomo info at  http://vger.kernel.org/majordomo-info.html\n);
        PublicInbox::Emergency->new($maildir)->prepare(\$msg);

-       PublicInbox::WatchMaildir->new($config)->scan;
+       PublicInbox::WatchMaildir->new($config)->scan('full');

        @list = $git->qx(qw(ls-tree -r --name-only refs/heads/master));
        is(scalar @list, 1, 'tree has one file');
        my $mref = $git->cat_file('HEAD:'.$list[0]);
        @list = $git->qx(qw(ls-tree -r --name-only refs/heads/master));
        is(scalar @list, 1, 'tree has one file');
        my $mref = $git->cat_file('HEAD:'.$list[0]);


@@ -80,7 +80,7 @@ More majordomo info at  http://vger.kernel.org/majordomo-info.html\n);
 
        is(unlink(glob("$maildir/new/*")), 1, 'unlinked spam');
        $write_spam->();
 
        is(unlink(glob("$maildir/new/*")), 1, 'unlinked spam');
        $write_spam->();

-       PublicInbox::WatchMaildir->new($config)->scan;
+       PublicInbox::WatchMaildir->new($config)->scan('full');

        @list = $git->qx(qw(ls-tree -r --name-only refs/heads/master));
        is(scalar @list, 0, 'tree is empty');
        @list = $git->qx(qw(rev-list refs/heads/master));
        @list = $git->qx(qw(ls-tree -r --name-only refs/heads/master));
        is(scalar @list, 0, 'tree is empty');
        @list = $git->qx(qw(rev-list refs/heads/master));


@@ -96,7 +96,7 @@ More majordomo info at  http://vger.kernel.org/majordomo-info.html\n);
        $config->{'publicinboxwatch.spamcheck'} = 'spamc';
        {
                local $SIG{__WARN__} = sub {}; # quiet spam check warning
        $config->{'publicinboxwatch.spamcheck'} = 'spamc';
        {
                local $SIG{__WARN__} = sub {}; # quiet spam check warning

-               PublicInbox::WatchMaildir->new($config)->scan;
+               PublicInbox::WatchMaildir->new($config)->scan('full');

        }
        @list = $git->qx(qw(ls-tree -r --name-only refs/heads/master));
        is(scalar @list, 0, 'tree has no files spamc checked');
        }
        @list = $git->qx(qw(ls-tree -r --name-only refs/heads/master));
        is(scalar @list, 0, 'tree has no files spamc checked');


@@ -111,7 +111,7 @@ More majordomo info at  http://vger.kernel.org/majordomo-info.html\n);
        PublicInbox::Emergency->new($maildir)->prepare(\$msg);
        $config->{'publicinboxwatch.spamcheck'} = 'spamc';
        @list = $git->qx(qw(ls-tree -r --name-only refs/heads/master));
        PublicInbox::Emergency->new($maildir)->prepare(\$msg);
        $config->{'publicinboxwatch.spamcheck'} = 'spamc';
        @list = $git->qx(qw(ls-tree -r --name-only refs/heads/master));

-       PublicInbox::WatchMaildir->new($config)->scan;
+       PublicInbox::WatchMaildir->new($config)->scan('full');

        @list = $git->qx(qw(ls-tree -r --name-only refs/heads/master));
        is(scalar @list, 1, 'tree has one file after spamc checked');
 
        @list = $git->qx(qw(ls-tree -r --name-only refs/heads/master));
        is(scalar @list, 1, 'tree has one file after spamc checked');