main handler to implement where we attempt to init this stage if we return None, then the init was okay but stopped at this level (waiting for further input)

can be used to track closeables created with this class that should be cleaned up after this stage

the attempt and store handler that runs sequential on the init queue it will attempt to create the next stage and store it in the current atomic reference

Blocks until all earlier tasks have completed and then prevents further tasks from being run.

Check whether we're closing. Susceptible to race conditions; unless you're using using this as a flag to the retry lib or you really know what you're doing, prefer performUnlessClosing and friends.

track running futures on shutdown

set to true to get detailed information about all futures that did not complete during shutdown. if set to false, we don't do anything.

Performs the task given by f unless a shutdown has been initiated. The shutdown will only begin after f completes, but other tasks may execute concurrently with f, if started using this function, or one of the other variants (performUnlessClosingF and performUnlessClosingEitherT). The tasks are assumed to take less than closingTimeout to complete.

DO NOT CALL this.close as part of f, because it will result in a deadlock.

Performs the EitherT[Future] given by etf unless a shutdown has been initiated, in which case the provided error is returned instead. Both etf and the error are lazy; etf is only evaluated if there is no shutdown, the error only if we're shutting down. The shutdown will only begin after etf completes, but other tasks may execute concurrently with etf, if started using this function, or one of the other variants (performUnlessClosing and performUnlessClosingF). The tasks are assumed to take less than closingTimeout to complete.

DO NOT CALL this.close as part of etf, because it will result in a deadlock.

Performs the Future given by f unless a shutdown has been initiated. The future is lazy and not evaluated during shutdown. The shutdown will only begin after f completes, but other tasks may execute concurrently with f, if started using this function, or one of the other variants (performUnlessClosing and performUnlessClosingEitherT). The tasks are assumed to take less than closingTimeout to complete.

DO NOT CALL this.close as part of f, because it will result in a deadlock.

Register a task to run when shutdown is initiated.

You can use this for example to register tasks that cancel long-running computations, whose termination you can then wait for in "closeAsync".

iterative start handler which will attempt to start the stages until we are either up and running or awaiting some init action by the user