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66 lines
2.5 KiB
Go
66 lines
2.5 KiB
Go
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package suture
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/*
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Service is the interface that describes a service to a Supervisor.
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Serve Method
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The Serve method is called by a Supervisor to start the service.
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The service should execute within the goroutine that this is
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called in. If this function either returns or panics, the Supervisor
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will call it again.
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A Serve method SHOULD do as much cleanup of the state as possible,
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to prevent any corruption in the previous state from crashing the
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service again.
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Stop Method
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This method is used by the supervisor to stop the service. Calling this
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directly on a Service given to a Supervisor will simply result in the
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Service being restarted; use the Supervisor's .Remove(ServiceToken) method
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to stop a service. A supervisor will call .Stop() only once. Thus, it may
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be as destructive as it likes to get the service to stop.
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Once Stop has been called on a Service, the Service SHOULD NOT be
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reused in any other supervisor! Because of the impossibility of
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guaranteeing that the service has actually stopped in Go, you can't
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prove that you won't be starting two goroutines using the exact
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same memory to store state, causing completely unpredictable behavior.
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Stop should not return until the service has actually stopped.
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"Stopped" here is defined as "the service will stop servicing any
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further requests in the future". For instance, a common implementation
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is to receive a message on a dedicated "stop" channel and immediately
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returning. Once the stop command has been processed, the service is
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stopped.
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Another common Stop implementation is to forcibly close an open socket
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or other resource, which will cause detectable errors to manifest in the
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service code. Bear in mind that to perfectly correctly use this
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approach requires a bit more work to handle the chance of a Stop
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command coming in before the resource has been created.
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If a service does not Stop within the supervisor's timeout duration, a log
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entry will be made with a descriptive string to that effect. This does
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not guarantee that the service is hung; it may still get around to being
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properly stopped in the future. Until the service is fully stopped,
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both the service and the spawned goroutine trying to stop it will be
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"leaked".
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Stringer Interface
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When a Service is added to a Supervisor, the Supervisor will create a
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string representation of that service used for logging.
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If you implement the fmt.Stringer interface, that will be used.
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If you do not implement the fmt.Stringer interface, a default
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fmt.Sprintf("%#v") will be used.
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*/
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type Service interface {
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Serve()
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Stop()
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}
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