opensim – Blame information for rev 1

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1 eva 1 /*
2 * Copyright (c) Contributors, http://opensimulator.org/
3 * See CONTRIBUTORS.TXT for a full list of copyright holders.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * * Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * * Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * * Neither the name of the OpenSimulator Project nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
17 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27  
28 using System;
29  
30 namespace OpenSim.Region.Framework.Scenes
31 {
32 /// <summary>
33 /// The possible states that a scene presence can be in. This is currently orthagonal to whether a scene presence
34 /// is root or child.
35 /// </summary>
36 /// <remarks>
37 /// This is a state machine.
38 ///
39 /// [Entry] => Running
40 /// Running => PreRemove, Removing
41 /// PreRemove => Running, Removing
42 /// Removing => Removed
43 ///
44 /// All other methods should only see the scene presence in running state - this is the normal operational state
45 /// Removed state occurs when the presence has been removed. This is the end state with no exit.
46 /// </remarks>
47 public enum ScenePresenceState
48 {
49 Running, // Normal operation state. The scene presence is available.
50 PreRemove, // The presence is due to be removed but can still be returning to running.
51 Removing, // The presence is in the process of being removed from the scene via Scene.RemoveClient.
52 Removed, // The presence has been removed from the scene and is effectively dead.
53 // There is no exit from this state.
54 }
55  
56 internal class ScenePresenceStateMachine
57 {
58 private ScenePresence m_sp;
59 private ScenePresenceState m_state;
60  
61 internal ScenePresenceStateMachine(ScenePresence sp)
62 {
63 m_sp = sp;
64 m_state = ScenePresenceState.Running;
65 }
66  
67 internal ScenePresenceState GetState()
68 {
69 return m_state;
70 }
71  
72 /// <summary>
73 /// Updates the state of an agent that is already in transit.
74 /// </summary>
75 /// <param name='id'></param>
76 /// <param name='newState'></param>
77 /// <returns></returns>
78 /// <exception cref='Exception'>Illegal transitions will throw an Exception</exception>
79 internal void SetState(ScenePresenceState newState)
80 {
81 bool transitionOkay = false;
82  
83 lock (this)
84 {
85 if (newState == m_state)
86 return;
87 else if (newState == ScenePresenceState.Running && m_state == ScenePresenceState.PreRemove)
88 transitionOkay = true;
89 else if (newState == ScenePresenceState.PreRemove && m_state == ScenePresenceState.Running)
90 transitionOkay = true;
91 else if (newState == ScenePresenceState.Removing)
92 {
93 if (m_state == ScenePresenceState.Running || m_state == ScenePresenceState.PreRemove)
94 transitionOkay = true;
95 }
96 else if (newState == ScenePresenceState.Removed && m_state == ScenePresenceState.Removing)
97 transitionOkay = true;
98 }
99  
100 if (!transitionOkay)
101 {
102 throw new Exception(
103 string.Format(
104 "Scene presence {0} is not allowed to move from state {1} to new state {2} in {3}",
105 m_sp.Name, m_state, newState, m_sp.Scene.Name));
106 }
107 else
108 {
109 m_state = newState;
110 }
111 }
112 }
113 }