Package software.amazon.awssdk.core.internal.retry

Class RateLimitingTokenBucket

  • public class RateLimitingTokenBucket
extends Object

    • Constructor Detail

      • RateLimitingTokenBucket

        public RateLimitingTokenBucket()

    • Method Detail

      • acquire

        public boolean acquire​(double amount)
        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. 

         _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

        This is equivalent to acquire(amount, false).

        Parameters:
        amount - The amount of tokens to acquire.
        Returns:
        Whether the amount was successfully acquired.

      • acquire

        public boolean acquire​(double amount,
                       boolean fastFail)
        Acquire tokens from the bucket. If the bucket contains enough capacity to satisfy the request, this method will return immediately. Otherwise, the behavior depends on the value of fastFail. If it is true, then it will return false immediately, signaling that enough capacity could not be acquired. Otherwise if fastFail is false, then it will wait the required amount of time to fill the bucket with enough tokens to satisfy amount. 
         _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
        Parameters:
        amount - The amount of tokens to acquire.
        fastFail - Whether this method should return immediately instead of waiting if amount exceeds the current capacity.
        Returns:
        Whether the amount was successfully acquired.

      • acquireNonBlocking

        public OptionalDouble acquireNonBlocking​(double amount,
                                         boolean fastFail)
        Acquire capacity from the rate limiter without blocking the call.

        This method returns an OptionalDouble whose value, or its absence correspond to the following states:

        • Empty - If the value is not present, then the call fast failed, and no capacity was acquired.
        • Present - if the value is present, then the value is the time in seconds that caller must wait before executing the request to be within the rate imposed by the rate limiter./li>
        Returns:
        The amount of time in seconds to wait before proceeding.

      • updateClientSendingRate

        public void updateClientSendingRate​(boolean throttlingResponse)
         _UpdateClientSendingRate(response)
   _UpdateMeasuredRate()

   if IsThrottlingError(response)
     if not enabled
       rate_to_use = measured_tx_rate
     else
       rate_to_use = min(measured_tx_rate, fill_rate)

     # The fill_rate is from the token bucket.
     last_max_rate = rate_to_use
     _CalculateTimeWindow()
     last_throttle_time = time()
     calculated_rate = _CUBICThrottle(rate_to_use)
     TokenBucketEnable()
   else
     _CalculateTimeWindow()
     calculated_rate = _CUBICSuccess(time())

   new_rate = min(calculated_rate, 2 * measured_tx_rate)
   _TokenBucketUpdateRate(new_rate)