add message service

awx/ui/client/features/output/index.js

@@ -8,6 +8,7 @@ import RenderService from '~features/output/render.service';
 import ScrollService from '~features/output/scroll.service';
 import EngineService from '~features/output/engine.service';
 import StatusService from '~features/output/status.service';
+import MessageService from '~features/output/message.service';
 import LegacyRedirect from '~features/output/legacy.route';
 
 import DetailsDirective from '~features/output/details.directive';
@@ -221,6 +222,7 @@ angular
     .service('JobRenderService', RenderService)
     .service('JobEventEngine', EngineService)
     .service('JobStatusService', StatusService)
+    .service('JobMessageService', MessageService)
     .directive('atJobDetails', DetailsDirective)
     .directive('atJobSearch', SearchDirective)
     .directive('atJobStats', StatsDirective)

awx/ui/client/features/output/message.service.js

@@ -0,0 +1,41 @@
+function MessageService () {
+    const listeners = {};
+    const registry = {};
+
+    this.subscribe = (key, listener) => {
+        registry[key] = registry[key] || 0;
+
+        listeners[key] = listeners[key] || {};
+        listeners[key][registry[key]] = listener;
+
+        const unsubscribe = this.createCallback(key, registry[key]);
+
+        registry[key]++;
+
+        return unsubscribe;
+    };
+
+    this.dispatch = (key, data) => {
+        if (!listeners[key]) {
+            return;
+        }
+
+        const indices = Object.keys(listeners[key]);
+
+        for (let i = 0; i < indices.length; i++) {
+            listeners[key][indices[i]](data);
+        }
+    };
+
+    this.createCallback = (key, index) => {
+        const callback = () => {
+            if (listeners[key]) {
+                delete listeners[key][index];
+            }
+        };
+
+        return callback;
+    };
+}
+
+export default MessageService;