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package persist

// Watcher is the interface for Casbin watchers.
type Watcher interface {
	// SetUpdateCallback sets the callback function that the watcher will call
	// when the policy in DB has been changed by other instances.
	// A classic callback is Enforcer.LoadPolicy().
	SetUpdateCallback(func(string)) error
	// Update calls the update callback of other instances to synchronize their policy.
	// It is usually called after changing the policy in DB, like Enforcer.SavePolicy(),
	// Enforcer.AddPolicy(), Enforcer.RemovePolicy(), etc.
	Update() error
	// Close stops and releases the watcher, the callback function will not be called any more.
	Close()
}