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*/
using System;
namespace OpenSim.Region.Framework.Scenes
{
///
/// The possible states that a scene presence can be in. This is currently orthagonal to whether a scene presence
/// is root or child.
///
///
/// This is a state machine.
///
/// [Entry] => Running
/// Running => Removing
/// Removing => Removed
///
/// All other methods should only see the scene presence in running state - this is the normal operational state
/// Removed state occurs when the presence has been removed. This is the end state with no exit.
///
public enum ScenePresenceState
{
Running, // Normal operation state. The scene presence is available.
Removing, // The presence is in the process of being removed from the scene via Scene.RemoveClient.
Removed, // The presence has been removed from the scene and is effectively dead.
// There is no exit from this state.
}
internal class ScenePresenceStateMachine
{
private ScenePresence m_sp;
private ScenePresenceState m_state;
internal ScenePresenceStateMachine(ScenePresence sp)
{
m_sp = sp;
m_state = ScenePresenceState.Running;
}
internal ScenePresenceState GetState()
{
return m_state;
}
///
/// Updates the state of an agent that is already in transit.
///
///
///
///
/// Illegal transitions will throw an Exception
internal void SetState(ScenePresenceState newState)
{
bool transitionOkay = false;
lock (this)
{
if (newState == ScenePresenceState.Removing && m_state == ScenePresenceState.Running)
transitionOkay = true;
else if (newState == ScenePresenceState.Removed && m_state == ScenePresenceState.Removing)
transitionOkay = true;
}
if (!transitionOkay)
{
throw new Exception(
string.Format(
"Scene presence {0} is not allowed to move from state {1} to new state {2} in {3}",
m_sp.Name, m_state, newState, m_sp.Scene.Name));
}
else
{
m_state = newState;
}
}
}
}