Merge pull request #22655 from agrare/prevent_more_than_one_event_han…

…dler_from_running

Prevent more than 1 event_handler from running

app/models/miq_event_handler.rb

@@ -6,6 +6,7 @@ class MiqEventHandler < MiqQueueWorkerBase
   self.required_roles               = ["event"]
   self.default_queue_name           = "ems"
   self.miq_messaging_subscribe_mode = "topic"
+  self.maximum_workers_count        = 1
 
   def self.kill_priority
     MiqWorkerType::KILL_PRIORITY_EVENT_HANDLERS

lib/vmdb/settings/validator.rb

@@ -197,6 +197,12 @@ def workers(data)
             valid = false
             errors += new_errors
           end
+
+          result, new_errors = validate_worker_count(worker_class, data)
+          if result == false
+            valid = false
+            errors += new_errors
+          end
         end
 
         return valid, errors
@@ -238,6 +244,22 @@ def validate_worker_request_limit(worker_class, data)
         end
         return valid, errors
       end
+
+      def validate_worker_count(worker_class, data)
+        valid  = true
+        errors = []
+
+        worker_settings = worker_class.fetch_worker_settings_from_options_hash(data[:config])
+
+        count                 = worker_settings[:count]
+        maximum_workers_count = worker_class.maximum_workers_count
+
+        if maximum_workers_count.kind_of?(Integer) && count > maximum_workers_count
+          valid = false
+          errors << [:count, "#{worker_class.settings_name}: count: #{count} exceeds maximum worker count: #{maximum_workers_count}"]
+        end
+        return valid, errors
+      end
     end
   end
 end

spec/lib/vmdb/settings/validator_spec.rb

@@ -156,5 +156,19 @@
       expect(result).to eql(true)
       expect(errors.empty?).to eql(true)
     end
+
+    it "changing count is valid for a scalable worker" do
+      stub_settings_merge(:workers => {:worker_base => {:queue_worker_base => {:generic_worker => {:count => 4}}}})
+      result, errors = subject.validate
+      expect(result).to be_truthy
+      expect(errors.empty?).to eql(true)
+    end
+
+    it "changing count is invalid for a non-scalable worker" do
+      stub_settings_merge(:workers => {:worker_base => {:queue_worker_base => {:event_handler => {:count => 2}}}})
+      result, errors = subject.validate
+      expect(result).to be_falsey
+      expect(errors).to include("workers-count" => "event_handler: count: 2 exceeds maximum worker count: 1")
+    end
   end
 end