refactor(system): add Link.get, Link.release

Author: johnsoncodehk

src/system.ts

@@ -75,7 +75,57 @@ export function endBatch() {
 }
 
 export namespace Link {
-	export let pool: Link | undefined = undefined;
+	let pool: Link | undefined = undefined;
+
+	export function get(dep: Link['dep'], sub: Link['sub'], nextDep: Link | undefined) {
+		if (pool !== undefined) {
+			const newLink = pool;
+			pool = newLink.nextDep;
+			newLink.nextDep = nextDep;
+			newLink.dep = dep;
+			newLink.sub = sub;
+			newLink.trackId = sub.trackId;
+			return newLink;
+		} else {
+			return {
+				dep,
+				sub,
+				trackId: sub.trackId,
+				nextDep: nextDep,
+				prevSub: undefined,
+				nextSub: undefined,
+			};
+		}
+	}
+
+	export function release(link: Link) {
+		const dep = link.dep;
+		const nextSub = link.nextSub;
+		const prevSub = link.prevSub;
+
+		if (nextSub !== undefined) {
+			nextSub.prevSub = prevSub;
+		}
+		if (prevSub !== undefined) {
+			prevSub.nextSub = nextSub;
+		}
+
+		if (nextSub === undefined) {
+			dep.subsTail = prevSub;
+		}
+		if (prevSub === undefined) {
+			dep.subs = nextSub;
+		}
+
+		// @ts-ignore
+		link.dep = undefined;
+		// @ts-ignore
+		link.sub = undefined;
+		link.prevSub = undefined;
+		link.nextSub = undefined;
+		link.nextDep = pool;
+		pool = link;
+	}
 }
 
 export namespace Dependency {
@@ -89,25 +139,7 @@ export namespace Dependency {
 			: sub.deps;
 
 		if (old === undefined || old.dep !== dep) {
-			let newLink: Link;
-
-			if (Link.pool !== undefined) {
-				newLink = Link.pool;
-				Link.pool = newLink.nextDep;
-				newLink.nextDep = old;
-				newLink.dep = dep;
-				newLink.sub = sub;
-				newLink.trackId = sub.trackId;
-			} else {
-				newLink = {
-					dep,
-					sub,
-					trackId: sub.trackId,
-					nextDep: old,
-					prevSub: undefined,
-					nextSub: undefined,
-				};
-			}
+			const newLink = Link.get(dep, sub, old);
 
 			if (depsTail === undefined) {
 				sub.deps = newLink;
@@ -403,34 +435,9 @@ export namespace Subscriber {
 
 	export function clearDependencies(link: Link) {
 		do {
-			const nextDep = link.nextDep;
 			const dep = link.dep;
-			const nextSub = link.nextSub;
-			const prevSub = link.prevSub;
-
-			if (nextSub !== undefined) {
-				nextSub.prevSub = prevSub;
-			}
-			if (prevSub !== undefined) {
-				prevSub.nextSub = nextSub;
-			}
-
-			if (nextSub === undefined) {
-				dep.subsTail = prevSub;
-			}
-			if (prevSub === undefined) {
-				dep.subs = nextSub;
-			}
-
-			// @ts-ignore
-			link.dep = undefined;
-			// @ts-ignore
-			link.sub = undefined;
-			link.prevSub = undefined;
-			link.nextSub = undefined;
-			link.nextDep = Link.pool;
-			Link.pool = link;
-
+			const nextDep = link.nextDep;
+			Link.release(link);
 			if (dep.subs === undefined && 'deps' in dep) {
 				dep.dirtyLevel = DirtyLevels.Released;
 				if (dep.deps !== undefined) {
@@ -441,7 +448,6 @@ export namespace Subscriber {
 					continue;
 				}
 			}
-
 			link = nextDep!;
 		} while (link !== undefined);
 	}