README.md

Rate Limit

Requirement

Imagine you have a bucket that gets filled with tokens at the rate of 1 token per second. The bucket can hold a maximum of N tokens. Implement a thread-safe class that lets threads get a token when one is available. If no token is available, then the token-requesting threads should block.

The class should expose an API called getToken that various threads can call to get a token

Notes

• 1 request per second is a slowest
• Synchronized keyword on a method
• wait() always must be called inside a loop read more

Code

public synchronized void getToken() throws InterruptedException {

        possibleTokens += (System.currentTimeMillis() - lastRequestTime) / delay;

        if (possibleTokens > maxTokens) {
            possibleTokens = maxTokens;
        }

        if (possibleTokens == 0) {
            Thread.sleep(delay);
        } else {
            possibleTokens--;
        }
        lastRequestTime = System.currentTimeMillis();

        System.out.println("Granting " + Thread.currentThread().getName() + " token at " + (Instant.now()));

    }

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