Implementing Rate Limiting

plugins:
  - name: rate-limiting
    config:
      second: 10
      minute: 600
      hour: 10000
      policy: redis
      redis_host: redis.internal
      fault_tolerant: true
      hide_client_headers: false

plugins:
  - name: rate-limiting
    config:
      limit_by: consumer  # or credential, ip, header
      header_name: X-User-Id
      minute: 100

class TokenBucket {
  private double tokens;
  private final double capacity, refillPerSec;
  private long lastRefillNanos;

  synchronized boolean tryConsume(int n) {
    long now = System.nanoTime();
    double add = (now - lastRefillNanos) / 1e9 * refillPerSec;
    tokens = Math.min(capacity, tokens + add);
    lastRefillNanos = now;
    if (tokens >= n) { tokens -= n; return true; }
    return false;
  }
}