speed up bot async mode by running 25 iterations per chunk

src/ai/mcts-bot.js

@@ -8,6 +8,12 @@
 import { CreateGameReducer } from '../core/reducer';
 import { Bot } from './bot';
 
+/**
+ * The number of iterations to run before yielding to
+ * the JS event loop (in async mode).
+ */
+const CHUNK_SIZE = 25;
+
 /**
  * Bot that uses Monte-Carlo Tree Search to find promising moves.
  */
@@ -229,11 +235,17 @@ export class MCTSBot extends Bot {
 
     return new Promise(resolve => {
       const iteration = () => {
-        const leaf = this.select(root);
-        const child = this.expand(leaf);
-        const result = this.playout(child);
-        this.backpropagate(child, result);
-        this.iterationCounter++;
+        for (
+          let i = 0;
+          i < CHUNK_SIZE && this.iterationCounter < numIterations;
+          i++
+        ) {
+          const leaf = this.select(root);
+          const child = this.expand(leaf);
+          const result = this.playout(child);
+          this.backpropagate(child, result);
+          this.iterationCounter++;
+        }
         this.iterationCallback(this.iterationCounter);
       };
 

src/client/debug/ai/AI.svelte

@@ -86,12 +86,13 @@
     client.reset();
     botAction = null;
     iterationCounter = 0;
+    Exit();
   }
 
   function OnKeyDown(e) {
     // ESC.
     if (e.keyCode == 27) {
-      Reset();
+      Exit();
     }
   }