A class that handles restarts of components via multiple threads. Specifically, if a component needs to be restarted
and several threads may demand a restart but only one thread should be allowed to restart the component, then use
What this class guarantees is that several threads may come in while a component is being restarted, but they will
block until the restart is complete.
This is different from other techniques in that:
- A simple compare-and-swap to check whether another thread
is already performing a restart will result in the requesting thread returning immediately and potentially attempting
to use the resource being restarted.
- A synchronized method or use of a lock would result in the thread
waiting for the restart to complete, but on completion will attempt to restart the component again.
implementation combines a compare-and-swap to detect a concurrent restart, as well as registering for notification
for when the restart completes and then parking the thread if the CAS variable still indicates a restart in progress,
and finally deregistering itself in the end.