feat: add command domain invariants

internal/domain/lifecycle.go

@@ -0,0 +1,85 @@
+package domain
+
+import (
+	"fmt"
+
+	rvboxv1 "github.com/rvbox/rvbox/gen/go/rvbox/v1"
+)
+
+// CanTransition reports whether a public lifecycle change is legal. Duplicate
+// events are handled by sequence validation and are not state transitions.
+func CanTransition(from, to rvboxv1.CommandLifecycle) bool {
+	switch from {
+	case rvboxv1.CommandLifecycle_COMMAND_QUEUED:
+		return to == rvboxv1.CommandLifecycle_COMMAND_DISPATCHED ||
+			to == rvboxv1.CommandLifecycle_COMMAND_CANCELLED ||
+			to == rvboxv1.CommandLifecycle_COMMAND_EXPIRED
+	case rvboxv1.CommandLifecycle_COMMAND_DISPATCHED:
+		return to == rvboxv1.CommandLifecycle_COMMAND_QUEUED ||
+			to == rvboxv1.CommandLifecycle_COMMAND_ACCEPTED ||
+			to == rvboxv1.CommandLifecycle_COMMAND_REJECTED ||
+			to == rvboxv1.CommandLifecycle_COMMAND_CANCELLED ||
+			to == rvboxv1.CommandLifecycle_COMMAND_INTERRUPTED
+	case rvboxv1.CommandLifecycle_COMMAND_ACCEPTED:
+		return to == rvboxv1.CommandLifecycle_COMMAND_RUNNING ||
+			to == rvboxv1.CommandLifecycle_COMMAND_REJECTED ||
+			to == rvboxv1.CommandLifecycle_COMMAND_CANCELLED ||
+			to == rvboxv1.CommandLifecycle_COMMAND_INTERRUPTED
+	case rvboxv1.CommandLifecycle_COMMAND_RUNNING:
+		return to == rvboxv1.CommandLifecycle_COMMAND_SUCCEEDED ||
+			to == rvboxv1.CommandLifecycle_COMMAND_FAILED ||
+			to == rvboxv1.CommandLifecycle_COMMAND_TERMINATED ||
+			to == rvboxv1.CommandLifecycle_COMMAND_INTERRUPTED
+	default:
+		return false
+	}
+}
+
+// ValidateTransition rejects unspecified, repeated, terminal-origin, and
+// otherwise impossible public lifecycle changes.
+func ValidateTransition(from, to rvboxv1.CommandLifecycle) error {
+	if CanTransition(from, to) {
+		return nil
+	}
+	return NewError(
+		rvboxv1.ControlError_PROTOCOL_ERROR,
+		fmt.Sprintf("illegal command lifecycle transition %s -> %s", from, to),
+		"",
+	)
+}
+
+// IsTerminal reports whether no further public lifecycle transition is legal.
+func IsTerminal(state rvboxv1.CommandLifecycle) bool {
+	switch state {
+	case rvboxv1.CommandLifecycle_COMMAND_SUCCEEDED,
+		rvboxv1.CommandLifecycle_COMMAND_FAILED,
+		rvboxv1.CommandLifecycle_COMMAND_TERMINATED,
+		rvboxv1.CommandLifecycle_COMMAND_CANCELLED,
+		rvboxv1.CommandLifecycle_COMMAND_INTERRUPTED,
+		rvboxv1.CommandLifecycle_COMMAND_EXPIRED,
+		rvboxv1.CommandLifecycle_COMMAND_REJECTED:
+		return true
+	default:
+		return false
+	}
+}
+
+// LaunchPhase is durable client-only state between accepted and running.
+type LaunchPhase uint8
+
+const (
+	LaunchPhaseNone LaunchPhase = iota
+	LaunchPhasePrepared
+	LaunchPhaseAuthorized
+)
+
+// CanAdvanceLaunchPhase permits only the one-way launch barrier.
+func CanAdvanceLaunchPhase(from, to LaunchPhase) bool {
+	return (from == LaunchPhaseNone && to == LaunchPhasePrepared) ||
+		(from == LaunchPhasePrepared && to == LaunchPhaseAuthorized)
+}
+
+// MayRedispatch is false once command code may have been released.
+func MayRedispatch(phase LaunchPhase) bool {
+	return phase == LaunchPhaseNone || phase == LaunchPhasePrepared
+}