hydra-notify: extract runPluginsForEvent to a TaskDispatcher

src/lib/Hydra/Task.pm

@@ -0,0 +1,15 @@
+package Hydra::Task;
+
+use strict;
+use warnings;
+
+sub new {
+    my ($self, $event, $plugin_name) = @_;
+
+    return bless {
+        "event" => $event,
+        "plugin_name" => $plugin_name,
+    }, $self;
+}
+
+1;

src/lib/Hydra/TaskDispatcher.pm

@@ -0,0 +1,157 @@
+package Hydra::TaskDispatcher;
+
+use strict;
+use warnings;
+use Hydra::Task;
+use Time::HiRes qw( gettimeofday tv_interval );
+
+=head1 Hydra::TaskDispatcher
+
+Excecute many plugins with Hydra::Event as its input.
+
+The TaskDispatcher is responsible for dealing with fanout
+from one incoming Event being executed across many plugins,
+or one Event being executed against a single plugin by first
+wrapping it in a Task.
+
+Its execution model is based on creating a Hydra::Task for
+each plugin's execution. The task represents the name of
+the plugin to run and the Event to process.
+
+=cut
+
+=head2 new
+
+Arguments:
+
+=over 1
+
+=item C<$dbh>
+L<DBI::db> The database connection.
+
+=back
+
+=item C<$prometheus>
+L<Prometheus::Tiny> A Promethues implementation, either Prometheus::Tiny
+or Prometheus::Tiny::Shared. Not compatible with Net::Prometheus.
+
+=back
+
+=item C<%plugins>
+L<Hydra::Plugin> A list of Hydra plugins to execute events and tasks against.
+
+=back
+
+=cut
+
+sub new {
+    my ($self, $db, $prometheus, $plugins) = @_;
+
+    $prometheus->declare(
+        "notify_plugin_executions",
+        type => "counter",
+        help => "Number of times each plugin has been called by channel."
+    );
+    $prometheus->declare(
+        "notify_plugin_runtime",
+        type => "histogram",
+        help => "Number of seconds spent executing each plugin by channel."
+    );
+    $prometheus->declare(
+        "notify_plugin_success",
+        type => "counter",
+        help => "Number of successful executions of this plugin on this channel."
+    );
+    $prometheus->declare(
+        "notify_plugin_error",
+        type => "counter",
+        help => "Number of failed executions of this plugin on this channel."
+    );
+
+    my %plugins_by_name = map { ref $_ => $_ } @{$plugins};
+
+    my $obj = bless {
+        "db" => $db,
+        "prometheus" => $prometheus,
+        "plugins_by_name" => \%plugins_by_name,
+    }, $self;
+}
+
+=head2 dispatch_event
+
+Execute each configured plugin against the provided L<Hydra::Event>.
+
+Arguments:
+
+=over 1
+
+=item C<$event>
+
+L<Hydra::Event> the event, usually from L<Hydra::PostgresListener>.
+
+=back
+
+=cut
+
+sub dispatch_event {
+    my ($self, $event) = @_;
+
+    foreach my $plugin_name (keys %{$self->{"plugins_by_name"}}) {
+        my $task = Hydra::Task->new($event, $plugin_name);
+        $self->dispatch_task($task);
+    }
+}
+
+=head2 dispatch_task
+
+Execute a specifi plugin against the provided L<Hydra::Task>.
+The Task includes information about what plugin should be executed.
+If the provided plugin does not exist, an error logged is logged and the
+function returns falsey.
+
+Arguments:
+
+=over 1
+
+=item C<$task>
+
+L<Hydra::Task> the task, usually from L<Hydra::Shema::Result::TaskRetries>.
+
+=back
+
+=cut
+sub dispatch_task {
+    my ($self, $task) = @_;
+
+    my $channel_name = $task->{"event"}->{'channel_name'};
+    my $plugin_name = $task->{"plugin_name"};
+    my $event_labels = {
+        channel => $channel_name,
+        plugin => $plugin_name,
+    };
+
+    my $plugin = $self->{"plugins_by_name"}->{$plugin_name};
+
+    if (!defined($plugin)) {
+        $self->{"prometheus"}->inc("notify_plugin_no_such_plugin", $event_labels);
+        print STDERR "No plugin named $plugin_name\n";
+        return 0;
+    }
+
+    $self->{"prometheus"}->inc("notify_plugin_executions", $event_labels);
+    eval {
+        my $start_time = [gettimeofday()];
+
+        $task->{"event"}->execute($self->{"db"}, $plugin);
+
+        $self->{"prometheus"}->histogram_observe("notify_plugin_runtime", tv_interval($start_time), $event_labels);
+        $self->{"prometheus"}->inc("notify_plugin_success", $event_labels);
+        1;
+    } or do {
+        $self->{"prometheus"}->inc("notify_plugin_error", $event_labels);
+        print STDERR "error running $channel_name hooks: $@\n";
+        return 0;
+    }
+}
+
+1;

src/script/hydra-notify

@@ -10,9 +10,9 @@ use Hydra::Helper::AddBuilds;
 use Hydra::Helper::Nix;
 use Hydra::Plugin;
 use Hydra::PostgresListener;
+use Hydra::TaskDispatcher;
 use Parallel::ForkManager;
 use Prometheus::Tiny::Shared;
-use Time::HiRes qw( gettimeofday tv_interval );
 
 STDERR->autoflush(1);
 STDOUT->autoflush(1);
@@ -25,26 +25,6 @@ my $prom = Prometheus::Tiny::Shared->new;
 # Add a new declaration for any new metrics you create. Metrics which are
 # not pre-declared disappear when their value is null. See:
 # https://metacpan.org/pod/Prometheus::Tiny#declare
-$prom->declare(
-    "notify_plugin_executions",
-    type => "counter",
-    help => "Number of times each plugin has been called by channel."
-);
-$prom->declare(
-    "notify_plugin_runtime",
-    type => "histogram",
-    help => "Number of seconds spent executing each plugin by channel."
-);
-$prom->declare(
-    "notify_plugin_success",
-    type => "counter",
-    help => "Number of successful executions of this plugin on this channel."
-);
-$prom->declare(
-    "notify_plugin_error",
-    type => "counter",
-    help => "Number of failed executions of this plugin on this channel."
-);
 $prom->declare(
     "event_loop_iterations",
     type => "counter",
@@ -93,6 +73,7 @@ GetOptions(
 my $db = Hydra::Model::DB->new();
 
 my @plugins = Hydra::Plugin->instantiate(db => $db, config => $config);
+my $task_dispatcher = Hydra::TaskDispatcher->new($db, $prom, [@plugins]);
 
 my $dbh = $db->storage->dbh;
 
@@ -102,39 +83,16 @@ $listener->subscribe("build_finished");
 $listener->subscribe("step_finished");
 $listener->subscribe("hydra_notify_dump_metrics");
 
-sub runPluginsForEvent {
-    my ($event) = @_;
-
-    my $channelName = $event->{'channel_name'};
-
-    foreach my $plugin (@plugins) {
-        $prom->inc("notify_plugin_executions", { channel => $channelName, plugin => ref $plugin });
-        eval {
-            my $startTime = [gettimeofday()];
-            $event->execute($db, $plugin);
-
-            $prom->histogram_observe("notify_plugin_runtime", tv_interval($startTime), { channel => $channelName, plugin => ref $plugin });
-            $prom->inc("notify_plugin_success", { channel => $channelName, plugin => ref $plugin });
-            1;
-        } or do {
-            $prom->inc("notify_plugin_error", { channel => $channelName, plugin => ref $plugin });
-            print STDERR "error running $event->{'channel_name'} hooks: $@\n";
-        }
-    }
-}
-
 # Process builds that finished while hydra-notify wasn't running.
 for my $build ($db->resultset('Builds')->search(
                    { notificationpendingsince => { '!=', undef } }))
 {
     print STDERR "sending notifications for build ${\$build->id}...\n";
 
-
-    my $event = Hydra::Event::BuildFinished->new($build->id);
-    runPluginsForEvent($event);
+    my $event = Hydra::Event->new_event("build_finished", $build->id);
+    $task_dispatcher->dispatch_event($event);
 }
 
-
 # Process incoming notifications.
 while (!$queued_only) {
     $prom->inc("event_loop_iterations");
@@ -154,7 +112,7 @@ while (!$queued_only) {
 
         eval {
             my $event = Hydra::Event->new_event($channelName, $message->{"payload"});
-            runPluginsForEvent($event);
+            $task_dispatcher->dispatch_event($event);
 
             1;
         } or do {

t/TaskDispatcher.t

@@ -0,0 +1,122 @@
+use strict;
+use warnings;
+use Setup;
+
+use Hydra::TaskDispatcher;
+use Prometheus::Tiny::Shared;
+
+use Test2::V0;
+use Test2::Tools::Mock qw(mock_obj);
+
+my $db = "bogus db";
+my $prometheus  = Prometheus::Tiny::Shared->new;
+
+sub make_noop_plugin {
+    my ($name) = @_;
+    my $plugin = {
+        "name" => $name,
+    };
+    my $mock_plugin = mock_obj $plugin => ();
+
+    return $mock_plugin;
+}
+
+sub make_fake_event {
+    my ($channel_name) = @_;
+
+    my $event = {
+        channel_name => $channel_name,
+        called_with => [],
+    };
+    my $mock_event = mock_obj $event => (
+        add => [
+            "execute" => sub {
+                my ($self, $db, $plugin) = @_;
+                push @{$self->{"called_with"}}, $plugin;
+            }
+        ]
+    );
+
+    return $mock_event;
+}
+
+sub make_failing_event {
+    my ($channel_name) = @_;
+
+    my $event = {
+        channel_name => $channel_name,
+        called_with => [],
+    };
+    my $mock_event = mock_obj $event => (
+        add => [
+            "execute" => sub {
+                my ($self, $db, $plugin) = @_;
+                push @{$self->{"called_with"}}, $plugin;
+                die "Failing plugin."
+            }
+        ]
+    );
+
+    return $mock_event;
+}
+
+subtest "dispatch_event" => sub {
+    subtest "every plugin gets called once, even if it fails all of them." => sub {
+        my @plugins = [make_noop_plugin("bogus-1"), make_noop_plugin("bogus-2")];
+
+        my $dispatcher = Hydra::TaskDispatcher->new($db, $prometheus, @plugins);
+
+        my $event = make_failing_event("bogus-channel");
+        $dispatcher->dispatch_event($event);
+
+        is(@{$event->{"called_with"}}, 2, "Both plugins should be called");
+
+        my @expected_names = [ "bogus-1", "bogus-2" ];
+        my @actual_names = sort([
+                $event->{"called_with"}[0]->name,
+                $event->{"called_with"}[1]->name
+        ]);
+
+        is(
+            @actual_names,
+            @expected_names,
+            "Both plugins should be executed, but not in any particular order."
+        );
+    };
+};
+
+subtest "dispatch_task" => sub {
+    subtest "every plugin gets called once" => sub {
+        my $bogus_plugin = make_noop_plugin("bogus-1");
+        my @plugins = [$bogus_plugin, make_noop_plugin("bogus-2")];
+
+        my $dispatcher = Hydra::TaskDispatcher->new($db, $prometheus, @plugins);
+
+        my $event = make_fake_event("bogus-channel");
+        my $task = Hydra::Task->new($event, ref $bogus_plugin);
+        is($dispatcher->dispatch_task($task), 1, "Calling dispatch_task returns truthy.");
+
+        is(@{$event->{"called_with"}}, 1, "Just one plugin should be called");
+
+        is(
+            $event->{"called_with"}[0]->name,
+            "bogus-1",
+            "Just bogus-1 should be executed."
+        );
+    };
+    subtest "a task with an invalid plugin is not fatal" => sub {
+        my $bogus_plugin = make_noop_plugin("bogus-1");
+        my @plugins = [$bogus_plugin, make_noop_plugin("bogus-2")];
+
+        my $dispatcher = Hydra::TaskDispatcher->new($db, $prometheus, @plugins);
+
+        my $event = make_fake_event("bogus-channel");
+        my $task = Hydra::Task->new($event, "this-plugin-does-not-exist");
+        is($dispatcher->dispatch_task($task), 0, "Calling dispatch_task returns falsey.");
+
+        is(@{$event->{"called_with"}}, 0, "No plugins are called");
+    };
+};
+
+
+done_testing;