scheduling

type Constraints struct {
	// SandboxClass must equal the worker's sandbox class. Snapshots are not
	// portable across sandbox classes, so this is never relaxed.
	SandboxClass string

	// TemplateSelector and ActorSelector must both match the worker's labels.
	TemplateSelector labels.Selector
	ActorSelector    labels.Selector

	// RequiredNodes, when non-empty, restricts placement to workers running
	// on one of these nodes. Used when the actor's latest snapshot is local
	// to specific node VMs.
	RequiredNodes []string

	// Limits are the actor's declared resource limits, named as a Worker names
	// the capacity it reports, so the two subtract.
	Limits *ateapipb.Resources
}

type Option func(*scheduler)

type Scheduler interface {
	// Schedule returns a free worker satisfying constraints.
	// Returns ErrNoCapacity when no free worker satisfies the requested constraints.
	Schedule(ctx context.Context, constraints Constraints) (*ateapipb.Worker, error)

	// Applies reports whether worker satisfies non-capacity constraints. Capacity
	// is excluded so an existing assignment does not make its Worker ineligible.
	Applies(worker *ateapipb.Worker, constraints Constraints) bool

	// HasRoom reports whether worker's remaining capacity admits one more actor
	// of this size, in every dimension. Independent of Applies.
	HasRoom(worker *ateapipb.Worker, constraints Constraints) bool
}

type WorkerSource interface {
	Workers() ([]*ateapipb.Worker, error)
}