add token bucket

Author: baileympearson

src/token_bucket.ts

@@ -0,0 +1,36 @@
+class TokenBucket {
+  private budget: number;
+  constructor(allowance: number) {
+    this.budget = allowance;
+  }
+  deposit(tokens: number) {
+    this.budget += tokens;
+  }
+
+  consume(tokens: number): boolean {
+    if (tokens > this.budget) return false;
+
+    this.budget -= tokens;
+    return true;
+  }
+}
+
+const TOKEN_REFRESH_RATE = 0.1;
+const INITIAL_SIZE = 1000;
+const RETRY_COST = 1;
+
+export class RetryTokenBucket {
+  private bucket = new TokenBucket(INITIAL_SIZE);
+
+  onCommandSuccess(retry: boolean) {
+    this.bucket.deposit(TOKEN_REFRESH_RATE);
+
+    if (retry) {
+      this.bucket.deposit(RETRY_COST);
+    }
+  }
+
+  canRetry() {
+    return this.bucket.consume(RETRY_COST);
+  }
+}