REST API speed improvement (#1577)

src/client/rest/APIRouter.js

@@ -1,37 +1,30 @@
 const util = require('util');
 
 const methods = ['get', 'post', 'delete', 'patch', 'put'];
-// Paramable exists so we don't return a function unless we actually need one #savingmemory
-const paramable = [
-  'channels', 'users', 'guilds', 'members',
-  'bans', 'emojis', 'pins', 'permissions',
-  'reactions', 'webhooks', 'messages',
-  'notes', 'roles', 'applications',
-  'invites', 'bot',
+const reflectors = [
+  'toString', 'valueOf', 'inspect', 'constructor',
+  Symbol.toPrimitive, util.inspect.custom,
 ];
-const reflectors = ['toString', 'valueOf', 'inspect', Symbol.toPrimitive, util.inspect.custom];
 
 module.exports = restManager => {
   const handler = {
     get(list, name) {
-      if (reflectors.includes(name)) return () => list.join('/');
-      if (paramable.includes(name)) {
+      if (name === 'opts') {
         function toReturn(...args) { // eslint-disable-line no-inner-declarations
-          list = list.concat(name);
-          for (const arg of args) {
-            if (arg !== null && typeof arg !== 'undefined') list = list.concat(arg);
-          }
+          list.push(...args.filter(x => x !== null && typeof x !== 'undefined'));
           return new Proxy(list, handler);
         }
         const directJoin = () => `${list.join('/')}/${name}`;
         for (const r of reflectors) toReturn[r] = directJoin;
         for (const method of methods) {
-          toReturn[method] = options => restManager.request(method, `${list.join('/')}/${name}`, options);
+          toReturn[method] = options => restManager.request(method, directJoin(), options);
         }
         return toReturn;
       }
+      if (reflectors.includes(name)) return () => list.join('/');
       if (methods.includes(name)) return options => restManager.request(name, list.join('/'), options);
-      return new Proxy(list.concat(name), handler);
+      list.push(name);
+      return new Proxy(list, handler);
     },
   };
 

src/client/rest/DiscordAPIError.js

@@ -3,12 +3,18 @@
  * @extends Error
  */
 class DiscordAPIError extends Error {
-  constructor(error) {
+  constructor(path, error) {
     super();
     const flattened = error.errors ? `\n${this.constructor.flattenErrors(error.errors).join('\n')}` : '';
     this.name = 'DiscordAPIError';
     this.message = `${error.message}${flattened}`;
 
+    /**
+     * The path of the request relative to the HTTP endpoint
+     * @type {string}
+     */
+    this.path = path;
+
     /**
      * HTTP error code returned by Discord
      * @type {number}

src/client/rest/RESTManager.js

@@ -12,8 +12,10 @@ class RESTManager {
     this.userAgentManager = new UserAgentManager(this);
     this.rateLimitedEndpoints = {};
     this.globallyRateLimited = false;
+  }
 
-    this.api = mountApi(this);
+  get api() {
+    return mountApi(this);
   }
 
   destroy() {

src/client/rest/RequestHandlers/Burst.js

@@ -41,7 +41,7 @@ class BurstRequestHandler extends RequestHandler {
             this.resetTimeout = null;
           }, Number(res.headers['retry-after']) + this.client.options.restTimeOffset);
         } else {
-          item.reject(err.status === 400 ? new DiscordAPIError(res.body) : err);
+          item.reject(err.status === 400 ? new DiscordAPIError(res.request.path, res.body) : err);
           this.handle();
         }
       } else {

src/client/rest/RequestHandlers/Sequential.js

@@ -65,7 +65,7 @@ class SequentialRequestHandler extends RequestHandler {
             }, Number(res.headers['retry-after']) + this.restManager.client.options.restTimeOffset);
             if (res.headers['x-ratelimit-global']) this.globalLimit = true;
           } else {
-            item.reject(err.status >= 400 && err.status < 500 ? new DiscordAPIError(res.body) : err);
+            item.reject(err.status >= 400 && err.status < 500 ? new DiscordAPIError(res.request.path, res.body) : err);
             resolve(err);
           }
         } else {