fix: Better global ratelimit management (#2801)

* fix: better global ratelimit handling in RequestHandler

fix: Remove useless line

fix: Better global ratelimit management

* refactor: Changed RESTManager#globallyRateLimited to be a getter

* refactor: Remove RESTManager#globallyRateLimited getter

* docs: Updated comments to reflect latest changes

src/rest/RESTManager.js

@@ -9,7 +9,6 @@ class RESTManager {
   constructor(client, tokenPrefix = 'Bot') {
     this.client = client;
     this.handlers = new Collection();
-    this.globallyRateLimited = false;
     this.tokenPrefix = tokenPrefix;
     this.versioned = true;
     this.globalTimeout = null;

src/rest/RequestHandler.js

@@ -43,7 +43,7 @@ class RequestHandler {
   }
 
   get limited() {
-    return (this.manager.globallyRateLimited || this.remaining <= 0) && Date.now() < this.reset;
+    return (this.manager.globalTimeout || this.remaining <= 0) && Date.now() < this.reset;
   }
 
   get _inactive() {
@@ -85,18 +85,8 @@ class RequestHandler {
         });
       }
 
-      if (this.manager.globallyRateLimited && !this.manager.globalTimeout) {
-        // Set a global rate limit for all of the handlers instead of each one individually
-        this.manager.globalTimeout = this.manager.client.setTimeout(() => {
-          this.manager.globalTimeout = null;
-          this.manager.globallyRateLimited = false;
-          this.busy = false;
-          this.run();
-        }, timeout);
-      } else if (this.manager.globalTimeout) {
-        // Already waiting for a global rate limit to clear
-        this.queue.unshift(item);
-        return null;
+      if (this.manager.globalTimeout) {
+        await this.manager.globalTimeout;
       } else {
         // Wait for the timeout to expire in order to avoid an actual 429
         await Util.delayFor(timeout);
@@ -116,8 +106,6 @@ class RequestHandler {
     }
 
     if (res && res.headers) {
-      if (res.headers.get('x-ratelimit-global')) this.manager.globallyRateLimited = true;
-
       const serverDate = res.headers.get('date');
       const limit = res.headers.get('x-ratelimit-limit');
       const remaining = res.headers.get('x-ratelimit-remaining');
@@ -133,6 +121,18 @@ class RequestHandler {
       if (item.request.route.includes('reactions')) {
         this.reset = new Date(serverDate).getTime() - getAPIOffset(serverDate) + 250;
       }
+
+      // Handle global ratelimit
+      if (res.headers.get('x-ratelimit-global')) {
+        // Set the manager's global timeout as the promise for other requests to "wait"
+        this.manager.globalTimeout = Util.delayFor(this.retryAfter);
+
+        // Wait for the global timeout to resolve before continue
+        await this.manager.globalTimeout;
+
+        // Clean up global timeout
+        this.manager.globalTimeout = null;
+      }
     }
 
     // Finished handling headers, safe to unlock manager