public boolean acquire(double amount) {
        return acquire(amount, false);
    }
Acquire tokens from the bucket. If the bucket contains enough capacity
to satisfy the request, this method will return immediately, otherwise
the method will block the calling thread until enough tokens are refilled.
<p>
<pre>
_TokenBucketAcquire(amount)
  # Client side throttling is not enabled until we see a throttling error.
  if not enabled
    return

  _TokenBucketRefill()
  # Next see if we have enough capacity for the requested amount.
  if amount <= current_capacity
    current_capacity = current_capacity - amount
  else
    sleep((amount - current_capacity) / fill_rate)
    current_capacity = current_capacity - amount
  return
</pre>
<p>
This is equivalent to {@code acquire(amount, false)}.

@param amount The amount of tokens to acquire.

@return Whether the amount was successfully acquired.
aws-java-sdk-core/src/main/java/com/amazonaws/internal/TokenBucket.java