Module: Async::Service::HealthChecker

Included in:
ManagedService
Defined in:
lib/async/service/health_checker.rb

Overview

A health checker for managed services.

Instance Method Summary collapse

Instance Method Details

#health_checker(instance, timeout = @evaluator.health_check_timeout, parent: Async::Task.current, &block) ⇒ Object

Start the health checker.

If a timeout is specified, a transient child task will be scheduled, which will yield the instance if a block is given, then mark the instance as ready, and finally sleep for half the health check duration (so that we guarantee that the health check runs in time).

If a timeout is not specified, the health checker will yield the instance immediately and then mark the instance as ready.



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# File 'lib/async/service/health_checker.rb', line 20

def health_checker(instance, timeout = @evaluator.health_check_timeout, parent: Async::Task.current, &block)
  if timeout
    parent.async(transient: true) do
      while true
        if block_given?
          yield(instance)
        end
        
        # We deliberately create a fiber here, to confirm that fiber creation is working.
        # If something has gone wrong with fiber allocation, we will crash here, and that's okay.
        Fiber.new do
          instance.ready!
        end.resume
        
        sleep(timeout / 2)
      end
    end
  else
    if block_given?
      yield(instance)
    end
    
    instance.ready!
  end
end