Improve with Atomics.exchange, thanks to @belochub

tshemsedinov · tshemsedinov · commit 7fb8674db338 · 2019-02-15T18:53:53.000+02:00
diff --git a/JavaScript/5-no-race.js b/JavaScript/5-no-race.js
@@ -14,8 +14,11 @@ class Mutex {
   }
 
   async enter() {
-    Atomics.wait(this.lock, 0, LOCKED);
-    Atomics.store(this.lock, 0, LOCKED);
+    let prev = Atomics.exchange(this.lock, 0, LOCKED);
+    while (prev !== UNLOCKED) {
+      Atomics.wait(this.lock, 0, LOCKED);
+      prev = Atomics.exchange(this.lock, 0, LOCKED);
+    }
     this.owner = true;
     return true;
   }

Original file line number	Diff line number	Diff line change
`@@ -14,8 +14,11 @@ class Mutex {`
`14`	`14`	`}`
`15`	`15`
`16`	`16`	`async enter() {`
`17`		`- Atomics.wait(this.lock, 0, LOCKED);`
`18`		`- Atomics.store(this.lock, 0, LOCKED);`
	`17`	`+ let prev = Atomics.exchange(this.lock, 0, LOCKED);`
	`18`	`+ while (prev !== UNLOCKED) {`
	`19`	`+ Atomics.wait(this.lock, 0, LOCKED);`
	`20`	`+ prev = Atomics.exchange(this.lock, 0, LOCKED);`
	`21`	`+ }`
`19`	`22`	`this.owner = true;`
`20`	`23`	`return true;`
`21`	`24`	`}`