Ilia Denisov
52 lines
1.8 KiB
Go
52 lines
1.8 KiB
Go
package runtime
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// transitionKey stores one `(from, to)` pair in the allowed-transitions
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// table.
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type transitionKey struct {
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from Status
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to Status
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}
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// allowedTransitions stores the set of permitted `(from, to)` status
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// pairs. The four pairs mirror the lifecycle flows frozen in
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// `galaxy/rtmanager/README.md §Lifecycles`:
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//
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// - running → stopped: graceful stop, observed Docker exit, or
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// reconcile observing an exited container.
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// - running → removed: reconcile_dispose when Docker no longer reports
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// the container at all.
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// - stopped → running: restart and patch inner start steps.
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// - stopped → removed: cleanup_container, both the periodic TTL worker
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// and the admin DELETE endpoint.
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var allowedTransitions = map[transitionKey]struct{}{
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{StatusRunning, StatusStopped}: {},
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{StatusRunning, StatusRemoved}: {},
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{StatusStopped, StatusRunning}: {},
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{StatusStopped, StatusRemoved}: {},
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}
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// AllowedTransitions returns a copy of the `(from, to)` allowed
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// transitions table used by Transition. The returned map is safe to
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// mutate; callers should not rely on iteration order.
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func AllowedTransitions() map[Status][]Status {
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result := make(map[Status][]Status)
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for key := range allowedTransitions {
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result[key.from] = append(result[key.from], key.to)
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}
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return result
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}
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// Transition reports whether from may transition to next. The function
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// returns nil when the pair is permitted, and an *InvalidTransitionError
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// wrapping ErrInvalidTransition otherwise. It does not touch any store
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// and is safe to call from any layer.
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func Transition(from Status, next Status) error {
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if !from.IsKnown() || !next.IsKnown() {
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return &InvalidTransitionError{From: from, To: next}
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}
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if _, ok := allowedTransitions[transitionKey{from: from, to: next}]; !ok {
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return &InvalidTransitionError{From: from, To: next}
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}
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return nil
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}
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