Refactor SubscriptionHub.

1 files changed, 23 insertions, 20 deletions

diff --git a/Timeline/ClientApp/src/app/data/SubscriptionHub.ts b/Timeline/ClientApp/src/app/data/SubscriptionHub.ts
index 92a54bc7..f09cd9f8 100644
--- a/Timeline/ClientApp/src/app/data/SubscriptionHub.ts
+++ b/Timeline/ClientApp/src/app/data/SubscriptionHub.ts
@@ -8,7 +8,6 @@
 // There might be some bugs, especially memory leaks and in asynchronization codes.

 

 import * as rxjs from 'rxjs';

-import { filter } from 'rxjs/operators';

 

 export type Subscriber<TData> = (data: TData) => void;

 

@@ -26,25 +25,25 @@ class SubscriptionToken {
 

 class SubscriptionLine<TData> {

   private _lastDataPromise: Promise<TData>;

-  private _dataSubject = new rxjs.BehaviorSubject<TData | undefined>(undefined);

-  private _data$: rxjs.Observable<TData> = this._dataSubject.pipe(

-    filter((d) => d !== undefined)

-  ) as rxjs.Observable<TData>;

+  private _dataSubject: rxjs.BehaviorSubject<TData>;

   private _refCount = 0;

 

   constructor(

-    _creator: () => Promise<TData>,

+    defaultValueProvider: () => TData,

+    setup: ((old: TData) => Promise<TData>) | undefined,

     private _destroyer: ((data: TData) => void) | undefined,

     private _onZeroRef: (self: SubscriptionLine<TData>) => void

   ) {

-    this._lastDataPromise = _creator().then((data) => {

-      this._dataSubject.next(data);

-      return data;

-    });

+    const initValue = defaultValueProvider();

+    this._lastDataPromise = Promise.resolve(initValue);

+    this._dataSubject = new rxjs.BehaviorSubject<TData>(initValue);

+    if (setup != null) {

+      this.next(setup);

+    }

   }

 

   subscribe(subscriber: Subscriber<TData>): SubscriptionToken {

-    const subscription = this._data$.subscribe(subscriber);

+    const subscription = this._dataSubject.subscribe(subscriber);

     this._refCount += 1;

     return new SubscriptionToken(subscription);

   }

@@ -53,11 +52,12 @@ class SubscriptionLine<TData> {
     token._subscription.unsubscribe();

     this._refCount -= 1;

     if (this._refCount === 0) {

-      void this._lastDataPromise.then((data) => {

-        if (this._destroyer != null && data !== undefined) {

-          this._destroyer(data);

-        }

-      });

+      const { _destroyer: destroyer } = this;

+      if (destroyer != null) {

+        void this._lastDataPromise.then((data) => {

+          destroyer(data);

+        });

+      }

       this._onZeroRef(this);

     }

   }

@@ -67,7 +67,7 @@ class SubscriptionLine<TData> {
       .then((old) => updator(old))

       .then((data) => {

         const last = this._dataSubject.value;

-        if (this._destroyer != null && last !== undefined) {

+        if (this._destroyer != null) {

           this._destroyer(last);

         }

         this._dataSubject.next(data);

@@ -82,9 +82,11 @@ export interface ISubscriptionHub<TKey, TData> {
 

 export class SubscriptionHub<TKey, TData>

   implements ISubscriptionHub<TKey, TData> {

+  // If setup is set, update is called with setup immediately after setting default value.

   constructor(

     public keyToString: (key: TKey) => string,

-    public creator: (key: TKey) => Promise<TData>,

+    public defaultValueProvider: (key: TKey) => TData,

+    public setup?: (key: TKey) => Promise<TData>,

     public destroyer?: (key: TKey, data: TData) => void

   ) {}

 

@@ -95,9 +97,10 @@ export class SubscriptionHub<TKey, TData>
     const line = (() => {

       const savedLine = this.subscriptionLineMap.get(keyString);

       if (savedLine == null) {

-        const { destroyer } = this;

+        const { setup, destroyer } = this;

         const newLine = new SubscriptionLine<TData>(

-          () => this.creator(key),

+          () => this.defaultValueProvider(key),

+          setup != null ? () => setup(key) : undefined,

           destroyer != null

             ? (data) => {

                 destroyer(key, data);