Package com.couchbase.client.dcp.core.time

Class ExponentialDelay

java.lang.Object
com.couchbase.client.dcp.core.time.Delay
com.couchbase.client.dcp.core.time.ExponentialDelay
public class ExponentialDelay extends Delay
Delay which increases exponentially on every attempt.

Considering retry attempts start at 1, attempt 0 would be the initial call and will always yield 0 (or the lower bound). Then each retry step will by default yield 1 * 2 ^ (attemptNumber-1). Actually each step can be based on a different number than 1 unit of time using the growBy parameter: growBy * 2 ^ (attemptNumber-1).

By default with growBy = 1 this gives us 0 (initial attempt), 1, 2, 4, 8, 16, 32...

Each of the resulting values that is below the lowerBound will be replaced by the lower bound, and each value over the upperBound will be replaced by the upper bound.

For example, given the following: 

Delay.exponential(TimeUnit.MILLISECONDS, 4000, 0, 500)
  • the upper of 4000 means the delay will be capped at 4s
  • the lower of 0 is useful to allow for immediate execution of original attempt, attempt 0 (if we ever call the delay with a parameter of 0)
  • the growBy of 500 means that we take steps based on 500ms
This yields the following delays: 0ms, 500ms, 1s, 2s, 4s, 4s, 4s,...

In detail : 0, 500 * 2^0, 500 * 2^1, 500 * 2^2, 500 * 2^3, max(4000, 500 * 2^4), max(4000, 500 * 2^5),....

Finally, the powers used in the computation can be changed from powers of two by default to another base using the powersOf parameter.

  • Method Details

    • calculate

      public long calculate(long attempt)
      Description copied from class: Delay
      Calculate a specific delay based on the attempt passed in.

      This method is to be implemented by the child implementations and depending on the params that were set during construction time.

      Specified by:
      calculate in class Delay
      Parameters:
      attempt - the attempt to calculate the delay from.
      Returns:
      the calculate delay.

    • calculateAlternatePower

      protected long calculateAlternatePower(long attempt)

    • calculatePowerOfTwo

      protected long calculatePowerOfTwo(long attempt)

    • toString

      public String toString()
      Overrides:
      toString in class Object