From 53214d5aa49fe4a4c85c9a6ebc0941de476d96c5 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Sun, 9 Aug 2020 17:40:46 +0800
Subject: Refactor subscription hub.

---
 Timeline/ClientApp/src/app/data/SubscriptionHub.ts | 106 +++++++++------------
 1 file changed, 46 insertions(+), 60 deletions(-)

(limited to 'Timeline/ClientApp/src')

diff --git a/Timeline/ClientApp/src/app/data/SubscriptionHub.ts b/Timeline/ClientApp/src/app/data/SubscriptionHub.ts
index 24f1885d..7c24983b 100644
--- a/Timeline/ClientApp/src/app/data/SubscriptionHub.ts
+++ b/Timeline/ClientApp/src/app/data/SubscriptionHub.ts
@@ -3,14 +3,6 @@ import { Observable } from 'rxjs';
 
 export type Subscriber<TData> = (data: TData) => void;
 
-export class Subscription {
-  constructor(private _onUnsubscribe: () => void) {}
-
-  unsubscribe(): void {
-    this._onUnsubscribe();
-  }
-}
-
 export interface ISubscriptionLine<TData> {
   readonly value: undefined | TData;
   next(value: TData): void;
@@ -25,15 +17,14 @@ export class SubscriptionLine<TData> implements ISubscriptionLine<TData> {
     private config?: { destroyable?: (value: TData | undefined) => boolean }
   ) {}
 
-  subscribe(subscriber: Subscriber<TData>): Subscription {
+  subscribe(subscriber: Subscriber<TData>): void {
     this._observers.push(subscriber);
     if (this._current !== undefined) {
       subscriber(this._current);
     }
-    return new Subscription(() => this.unsubscribe(subscriber));
   }
 
-  private unsubscribe(subscriber: Subscriber<TData>): void {
+  unsubscribe(subscriber: Subscriber<TData>): void {
     if (!this._observers.includes(subscriber)) return;
     pull(this._observers, subscriber);
   }
@@ -57,12 +48,7 @@ export class SubscriptionLine<TData> implements ISubscriptionLine<TData> {
   }
 }
 
-export interface ISubscriptionHub<TKey, TData> {
-  subscribe(key: TKey, subscriber: Subscriber<TData>): Subscription;
-}
-
-export class SubscriptionHub<TKey, TData>
-  implements ISubscriptionHub<TKey, TData> {
+export class SubscriptionHub<TKey, TData> {
   private keyToString: (key: TKey) => string;
   private setup?: (
     key: TKey,
@@ -72,10 +58,7 @@ export class SubscriptionHub<TKey, TData>
 
   private readonly subscriptionLineMap = new Map<
     string,
-    {
-      line: SubscriptionLine<TData>;
-      destroyer: (() => void) | undefined;
-    }
+    SubscriptionLine<TData>
   >();
 
   private cleanTimerId = 0;
@@ -83,7 +66,7 @@ export class SubscriptionHub<TKey, TData>
   // setup is called after creating line and if it returns a function as destroyer, then when the line is destroyed the destroyer will be called.
   constructor(config?: {
     keyToString?: (key: TKey) => string;
-    setup?: (key: TKey, line: ISubscriptionLine<TData>) => (() => void) | void;
+    setup?: (key: TKey, line: ISubscriptionLine<TData>) => void;
     destroyable?: (key: TKey, value: TData | undefined) => boolean;
   }) {
     this.keyToString =
@@ -102,9 +85,8 @@ export class SubscriptionHub<TKey, TData>
 
   private cleanLines(): void {
     const toDelete: string[] = [];
-    for (const [key, info] of this.subscriptionLineMap.entries()) {
-      if (info.line.destroyable) {
-        info.destroyer?.();
+    for (const [key, line] of this.subscriptionLineMap.entries()) {
+      if (line.destroyable) {
         toDelete.push(key);
       }
     }
@@ -121,54 +103,58 @@ export class SubscriptionHub<TKey, TData>
     }
   }
 
-  subscribe(key: TKey, subscriber: Subscriber<TData>): Subscription {
+  private createLine(key: TKey, useSetup = true): SubscriptionLine<TData> {
     const keyString = this.keyToString(key);
-    const line = (() => {
-      const info = this.subscriptionLineMap.get(keyString);
-      if (info == null) {
-        const { setup, destroyable } = this;
-        const newLine = new SubscriptionLine<TData>({
-          destroyable:
-            destroyable != null
-              ? (value) => destroyable(key, value)
-              : undefined,
-        });
-        this.subscriptionLineMap.set(keyString, {
-          line: newLine,
-          destroyer: undefined,
-        });
-        const destroyer = setup?.(key, newLine);
-        if (this.subscriptionLineMap.size === 0) {
-          this.cleanTimerId = window.setInterval(
-            this.cleanLines.bind(this),
-            20000
-          );
-        }
-        this.subscriptionLineMap.set(keyString, {
-          line: newLine,
-          destroyer: destroyer != null ? destroyer : undefined,
-        });
-        return newLine;
-      } else {
-        return info.line;
-      }
-    })();
+    const { setup, destroyable } = this;
+    const newLine = new SubscriptionLine<TData>({
+      destroyable:
+        destroyable != null ? (value) => destroyable(key, value) : undefined,
+    });
+    this.subscriptionLineMap.set(keyString, newLine);
+    if (useSetup) {
+      setup?.(key, newLine);
+    }
+    if (this.subscriptionLineMap.size === 1) {
+      this.cleanTimerId = window.setInterval(this.cleanLines.bind(this), 20000);
+    }
+    return newLine;
+  }
+
+  subscribe(key: TKey, subscriber: Subscriber<TData>): void {
+    const keyString = this.keyToString(key);
+    const line =
+      this.subscriptionLineMap.get(keyString) ?? this.createLine(key);
     return line.subscribe(subscriber);
   }
 
+  unsubscribe(key: TKey, subscriber: Subscriber<TData>): void {
+    const keyString = this.keyToString(key);
+    const line = this.subscriptionLineMap.get(keyString);
+    return line?.unsubscribe(subscriber);
+  }
+
   getObservable(key: TKey): Observable<TData> {
     return new Observable((observer) => {
-      const sub = this.subscribe(key, (data) => {
+      const f = (data: TData): void => {
         observer.next(data);
-      });
+      };
+
+      this.subscribe(key, f);
       return () => {
-        sub.unsubscribe();
+        this.unsubscribe(key, f);
       };
     });
   }
 
   getLine(key: TKey): ISubscriptionLine<TData> | null {
     const keyString = this.keyToString(key);
-    return this.subscriptionLineMap.get(keyString)?.line ?? null;
+    return this.subscriptionLineMap.get(keyString) ?? null;
+  }
+
+  getLineOrCreateWithoutSetup(key: TKey): ISubscriptionLine<TData> {
+    const keyString = this.keyToString(key);
+    return (
+      this.subscriptionLineMap.get(keyString) ?? this.createLine(key, false)
+    );
   }
 }
-- 
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