Extracting event management into a separate class

Thus pulls all event-related code out of Transaction.
The Transaction class currently creates a single instance
of this class, so it's nowhere near a "real" event manager,
but at least it has very clean integration points and will
be easy to upgrade as needed.

Signed-off-by: Luke Kanies <luke@madstop.com>

1 files changed, 90 insertions, 0 deletions

diff --git a/lib/puppet/transaction/event_manager.rb b/lib/puppet/transaction/event_manager.rb
new file mode 100644
index 000000000..370938c5e
--- /dev/null
+++ b/lib/puppet/transaction/event_manager.rb
@@ -0,0 +1,90 @@
+require 'puppet/transaction'
+
+class Puppet::Transaction::EventManager
+    attr_reader :transaction, :events
+
+    def initialize(transaction)
+        @transaction = transaction
+        @event_queues = {}
+        @events = []
+    end
+
+    def relationship_graph
+        transaction.relationship_graph
+    end
+
+    # Respond to any queued events for this resource.
+    def process_events(resource)
+        restarted = false
+        queued_events(resource) do |callback, events|
+            r = process_callback(resource, callback, events)
+            restarted ||= r
+        end
+
+        if restarted
+            queue_event(resource, resource.event(:name => :restarted, :status => "success"))
+
+            transaction.resourcemetrics[:restarted] += 1
+        end
+    end
+
+    # Queue events for other resources to respond to.  All of these events have
+    # to be from the same resource.
+    def queue_event(resource, event)
+        @events << event
+
+        # Collect the targets of any subscriptions to those events.  We pass
+        # the parent resource in so it will override the source in the events,
+        # since eval_generated children can't have direct relationships.
+        relationship_graph.matching_edges(event, resource).each do |edge|
+            next unless method = edge.callback
+            next unless edge.target.respond_to?(method)
+
+            queue_event_for_resource(resource, edge.target, method, event)
+        end
+
+        if resource.self_refresh? and ! resource.deleting?
+            queue_event_for_resource(resource, resource, :refresh, event)
+        end
+    end
+
+    def queue_event_for_resource(source, target, callback, event)
+        source.info "Scheduling #{callback} of #{target}"
+
+        @event_queues[target] ||= {}
+        @event_queues[target][callback] ||= []
+        @event_queues[target][callback] << event
+    end
+
+    def queued_events(resource)
+        return unless callbacks = @event_queues[resource]
+        callbacks.each do |callback, events|
+            yield callback, events
+        end
+    end
+
+    private
+
+    def process_callback(resource, callback, events)
+        # XXX Should it be any event, or all events?
+        process_noop_events(resource, callback, events) and return false unless events.detect { |e| e.status != "noop" }
+        resource.send(callback)
+
+        resource.notice "Triggered '#{callback}' from #{events.length} events"
+        return true
+    rescue => detail
+        resource.err "Failed to call #{callback}: #{detail}"
+
+        transaction.resourcemetrics[:failed_restarts] += 1
+        puts detail.backtrace if Puppet[:trace]
+        return false
+    end
+
+    def process_noop_events(resource, callback, events)
+        resource.notice "Would have triggered '#{callback}' from #{events.length} events"
+
+        # And then add an event for it.
+        queue_event(resource, resource.event(:status => "noop", :name => :noop_restart))
+        true # so the 'and if' works
+    end
+end