fix: allowing multiple subscribers

Author: Pratik Bhattacharya

src/global.store.ts

@@ -19,8 +19,8 @@ export class GlobalStore implements IGlobalStore {
     private _stores: { [key: string]: Store };
     private _globalActions: { [key: string]: Array<string> };
     private _globalListeners: Array<(state: any) => void>;
-    private _eagerPartnerStoreSubscribers: { [key: string]:  (state: any) => void};
-    private _eagerUnsubscribers: { [key: string]: () => void };
+    private _eagerPartnerStoreSubscribers: { [key: string]: { [key: string]: (state) => void } }
+    private _eagerUnsubscribers: { [key: string]: { [key: string]: () => void } }
     private _actionLogger: ActionLogger = null;
 
     private constructor(private _logger: ILogger = null) {
@@ -38,7 +38,7 @@ export class GlobalStore implements IGlobalStore {
      * @param {ILogger} logger Logger service.
      */
     public static Get(debugMode: boolean = false, logger: ILogger = null): IGlobalStore {
-        if(debugMode) {
+        if (debugMode) {
             this.DebugMode = debugMode;
         }
         if (debugMode && (logger === undefined || logger === null)) {
@@ -70,7 +70,7 @@ export class GlobalStore implements IGlobalStore {
         if (existingStore === null || existingStore === undefined || shouldReplaceStore) {
             if (middlewares === undefined || middlewares === null)
                 middlewares = [];
-            let appStore = createStore(appReducer, GlobalStore.DebugMode ? composeWithDevTools( applyMiddleware(...middlewares)) : applyMiddleware(...middlewares));
+            let appStore = createStore(appReducer, GlobalStore.DebugMode ? composeWithDevTools(applyMiddleware(...middlewares)) : applyMiddleware(...middlewares));
             this.RegisterStore(appName, appStore, globalActions, shouldReplaceStore);
             return appStore;
         }
@@ -100,10 +100,7 @@ export class GlobalStore implements IGlobalStore {
         this._stores[appName] = store;
         store.subscribe(this.InvokeGlobalListeners.bind(this));
         this.RegisterGlobalActions(appName, globalActions);
-        let eagerSubscription = this._eagerPartnerStoreSubscribers[appName];
-        if (eagerSubscription !== undefined && eagerSubscription !== null){
-            this._eagerUnsubscribers[appName] = this.SubscribeToPartnerState("SYS", appName, eagerSubscription);
-        }
+        this.RegisterEagerSubscriptions(appName);
         this.LogRegistration(appName, (existingStore !== undefined && existingStore !== null));
     }
 
@@ -282,13 +279,19 @@ export class GlobalStore implements IGlobalStore {
     SubscribeToPartnerState(source: string, partner: string, callback: (state: any) => void, eager: boolean = true): () => void {
         let partnerStore = this.GetPartnerStore(partner);
         if (partnerStore === undefined || partnerStore === null) {
-            if (!eager){
+            if (!eager) {
                 throw new Error(`ERROR: ${source} is trying to subscribe to partner ${partner}. Either ${partner} doesn't exist or hasn't been loaded yet`);
             }
-            
-            this._eagerPartnerStoreSubscribers[partner] = callback;
+            if (this._eagerPartnerStoreSubscribers[partner]) {
+                this._eagerPartnerStoreSubscribers[partner].source = callback;
+            } else {
+                this._eagerPartnerStoreSubscribers[partner] = {
+                    source: callback
+                }
+            }
+
             return () => {
-                this.UnsubscribeEagerSubscription(partner);
+                this.UnsubscribeEagerSubscription(source, partner);
             }
         }
         return partnerStore.subscribe(() => callback(partnerStore.getState()));
@@ -311,6 +314,18 @@ export class GlobalStore implements IGlobalStore {
         }
     }
 
+    UnsubscribeEagerSubscription(source: string, partnerName: string) {
+        if (!partnerName || !source)
+            return;
+
+        if (!this._eagerUnsubscribers[partnerName])
+            return;
+
+        let unsubscriber = this._eagerUnsubscribers[partnerName].source;
+        if (unsubscriber)
+            unsubscriber();
+    }
+
     SetLogger(logger: ILogger) {
         if (this._logger === undefined || this._logger === null)
             this._logger = logger;
@@ -319,6 +334,26 @@ export class GlobalStore implements IGlobalStore {
         this._actionLogger.SetLogger(logger);
     }
 
+    private RegisterEagerSubscriptions(appName: string) {
+        let eagerCallbacksRegistrations = this._eagerPartnerStoreSubscribers[appName];
+        if (eagerCallbacksRegistrations === undefined || eagerCallbacksRegistrations === undefined)
+            return;
+        let registeredApps = Object.keys(eagerCallbacksRegistrations);
+        registeredApps.forEach(sourceApp => {
+            let callback = eagerCallbacksRegistrations[sourceApp];
+            if (callback) {
+                let unregistrationCallback = this.SubscribeToPartnerState(sourceApp, appName, callback, false);
+                if (this._eagerPartnerStoreSubscribers[appName]) {
+                    this._eagerPartnerStoreSubscribers[appName].sourceApp = unregistrationCallback;
+                } else {
+                    this._eagerPartnerStoreSubscribers[appName] = {
+                        sourceApp: unregistrationCallback
+                    };
+                }
+            }
+        });
+    }
+
     private InvokeGlobalListeners(): void {
         let globalState = this.GetGlobalState();
         this._globalListeners.forEach(globalListener => {
@@ -341,21 +376,12 @@ export class GlobalStore implements IGlobalStore {
 
     private IsActionRegisteredAsGlobal(appName: string, action: IAction<any>): boolean {
         let registeredGlobalActions = this._globalActions[appName];
-            if (registeredGlobalActions === undefined || registeredGlobalActions === null) {
-                return false;
-            }
+        if (registeredGlobalActions === undefined || registeredGlobalActions === null) {
+            return false;
+        }
         return registeredGlobalActions.some(registeredAction => registeredAction === action.type || registeredAction === GlobalStore.AllowAll);
     }
 
-    private UnsubscribeEagerSubscription(partnerName: string) {
-        if (!partnerName)
-            return;
-
-        let unsubscriber = this._eagerUnsubscribers[partnerName];
-        if (unsubscriber)
-            unsubscriber();
-    }
-
     private LogRegistration(appName: string, isReplaced: boolean) {
         try {
             let properties = {

test/global.store.tests.ts

@@ -358,6 +358,7 @@ describe("Global Store", () => {
             // Arrange
             let partnerAppName = "SamplePartner-102";
             let isPartnerStateChanged = false;
+            
             // Act
             globalStore.SubscribeToPartnerState("Test", partnerAppName, (state) => {
                 isPartnerStateChanged = true;
@@ -374,6 +375,37 @@ describe("Global Store", () => {
             // Assert
             expect(isPartnerStateChanged).toBeTruthy();
         });
+
+        it("Should attach eager multiple subscribers", () => {
+            // Arrange
+            let partnerAppName_1 = "SamplePartner-112";
+            let isPartnerStateChanged_1 = false;
+
+            let partnerAppName_2 = "SamplePartner-114";
+            let isPartnerStateChanged_2 = false;
+            
+            // Act
+            globalStore.SubscribeToPartnerState("Test", partnerAppName_1, (state) => {
+                isPartnerStateChanged_1 = true;
+            }, true);
+
+            globalStore.SubscribeToPartnerState("Test", partnerAppName_2, (state) => {
+                isPartnerStateChanged_2 = true;
+            }, true);
+
+            globalStore.CreateStore(partnerAppName_1, dummyPartnerReducer, [], ["Global"], false, false);
+            globalStore.CreateStore(partnerAppName_2, dummyPartnerReducer, [], ["Global"], false, false);
+            globalStore.DispatchGlobalAction("Test",
+                {
+                    type: "Global",
+                    payload: null
+                });
+
+
+            // Assert
+            expect(isPartnerStateChanged_1).toBeTruthy();
+            expect(isPartnerStateChanged_2).toBeTruthy();
+        });
     });
 
     describe("SubscribeToGlobalState", () => {