The AdmissionContext class is currently a decoration on OperationContext that serves three purposes:

• It holds the priority the operation should have upon admission.
• It keeps track of the instant when the operation was last admitted (i.e. startProcessingTime).
  • This is used to track the duration of processing (i.e. the time during which the admission ticket was held).
• It keeps track of how many times the operation went through admission.
  • This is used to keep track of how many different operations went through the admission mechanism (i.e. the totalNewAdmissions metric).

There are several problems with this approach:

• Sharing the same AdmissionContext across different admission mechanisms means that the metrics for it will be calculated incorrectly.
• Using the startProcessingTime value to calculate the duration of processing does not take reentrancy into account.
• Not all future admission control mechanisms will necessarily tie their admission metrics to the OperationContext.

To solve this, we should:

• move the startProcessingTime inside the ticket
• make a decoration derived from AdmissionContext for each admission control mechanism that needs it