Token Bucket Rate Limiter

Design and implement a token bucket rate limiter. The token bucket algorithm is used to control the rate at which actions or events are allowed to occur. Your implementation should adhere to the following specifications:

• Token Bucket Parameters: The rate limiter should be initialized with a specified 'bucket capacity' (maximum number of tokens) and a 'token refill rate' (number of tokens added per time unit).

• Methods: Implement a method (or function) that can be called each time an action is attempted. This method should determine if the action is permitted or rejected based on the tokens currently available. If permitted, a token should be deducted from the bucket.

• Token Refill: Ensure that tokens are replenished over time up to the maximum capacity according to the refill rate.

• Concurrency: If applicable in your language of choice, make sure your rate limiter implementation is thread-safe such that multiple concurrent requests do not result in race conditions.

• Usage Example: Provide an example demonstrating your rate limiter in action. Your example should simulate a series of incoming requests (actions) and show how the limiter accepts or rejects each request based on available tokens.

Your solution should be efficient and handle edge cases (for example, when the system's clock or time drift may affect token refilling). Good luck!