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Prevent race conditions between two threads that call LLClientView.Close() simultaneously (e.g. ack timeout and an attempt to reconnect)

0.7.4.1
Justin Clark-Casey (justincc) 2012-07-19 22:32:27 +01:00
parent e9a121e1b2
commit ba80f137b5
3 changed files with 60 additions and 33 deletions
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58
OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs
View File

@ -347,8 +347,6 @@ namespace OpenSim.Region.ClientStack.LindenUDP
private int m_animationSequenceNumber = 1;
private bool m_SendLogoutPacketWhenClosing = true;
private AgentUpdateArgs lastarg;
private bool m_IsActive = true;
private bool m_IsLoggingOut = false;
protected Dictionary<PacketType, PacketProcessor> m_packetHandlers = new Dictionary<PacketType, PacketProcessor>();
protected Dictionary<string, GenericMessage> m_genericPacketHandlers = new Dictionary<string, GenericMessage>(); //PauPaw:Local Generic Message handlers
@ -412,16 +410,19 @@ namespace OpenSim.Region.ClientStack.LindenUDP
public uint CircuitCode { get { return m_circuitCode; } }
public int MoneyBalance { get { return m_moneyBalance; } }
public int NextAnimationSequenceNumber { get { return m_animationSequenceNumber++; } }
public bool IsActive
{
get { return m_IsActive; }
set { m_IsActive = value; }
}
public bool IsLoggingOut
{
get { return m_IsLoggingOut; }
set { m_IsLoggingOut = value; }
}
/// <summary>
/// As well as it's function in IClientAPI, in LLClientView we are locking on this property in order to
/// prevent race conditions by different threads calling Close().
/// </summary>
public bool IsActive { get; set; }
/// <summary>
/// Used to synchronise threads when client is being closed.
/// </summary>
public Object CloseSyncLock { get; private set; }
public bool IsLoggingOut { get; set; }
public bool DisableFacelights
{
@ -446,6 +447,8 @@ namespace OpenSim.Region.ClientStack.LindenUDP
{
// DebugPacketLevel = 1;
CloseSyncLock = new Object();
RegisterInterface<IClientIM>(this);
RegisterInterface<IClientInventory>(this);
RegisterInterface<IClientChat>(this);
@ -478,17 +481,40 @@ namespace OpenSim.Region.ClientStack.LindenUDP
m_prioritizer = new Prioritizer(m_scene);
RegisterLocalPacketHandlers();
IsActive = true;
}
#region Client Methods
/// <summary>
/// Shut down the client view
/// Close down the client view
/// </summary>
public void Close()
{
IsActive = false;
// We lock here to prevent race conditions between two threads calling close simultaneously (e.g.
// a simultaneous relog just as a client is being closed out due to no packet ack from the old connection.
lock (CloseSyncLock)
{
if (!IsActive)
return;
IsActive = false;
CloseWithoutChecks();
}
}
/// <summary>
/// Closes down the client view without first checking whether it is active.
/// </summary>
/// <remarks>
/// This exists because LLUDPServer has to set IsActive = false in earlier synchronous code before calling
/// CloseWithoutIsActiveCheck asynchronously.
///
/// Callers must lock ClosingSyncLock before calling.
/// </remarks>
public void CloseWithoutChecks()
{
m_log.DebugFormat(
"[CLIENT]: Close has been called for {0} attached to scene {1}",
Name, m_scene.RegionInfo.RegionName);
@ -3567,7 +3593,9 @@ namespace OpenSim.Region.ClientStack.LindenUDP
public void SendCoarseLocationUpdate(List<UUID> users, List<Vector3> CoarseLocations)
{
if (!IsActive) return; // We don't need to update inactive clients.
// We don't need to update inactive clients.
if (!IsActive)
return;
CoarseLocationUpdatePacket loc = (CoarseLocationUpdatePacket)PacketPool.Instance.GetPacket(PacketType.CoarseLocationUpdate);
loc.Header.Reliable = false;

11
OpenSim/Region/ClientStack/Linden/UDP/LLUDPServer.cs
View File

@ -1123,12 +1123,10 @@ namespace OpenSim.Region.ClientStack.LindenUDP
/// regular client pings.
/// </remarks>
/// <param name='client'></param>
private void DeactivateClientDueToTimeout(IClientAPI client)
private void DeactivateClientDueToTimeout(LLClientView client)
{
lock (client.CloseSyncLock)
{
// We must set IsActive synchronously so that we can stop the packet loop reinvoking this method, even
// though it's set later on by LLClientView.Close()
client.IsActive = false;
m_log.WarnFormat(
"[LLUDPSERVER]: Ack timeout, disconnecting {0} agent for {1} in {2}",
client.SceneAgent.IsChildAgent ? "child" : "root", client.Name, m_scene.RegionInfo.RegionName);
@ -1138,7 +1136,8 @@ namespace OpenSim.Region.ClientStack.LindenUDP
if (!client.SceneAgent.IsChildAgent)
client.Kick("Simulator logged you out due to connection timeout");
client.Close();
client.CloseWithoutChecks();
}
}
private void IncomingPacketHandler()

4
OpenSim/Region/Framework/Scenes/Scene.cs
View File

@ -3517,8 +3517,8 @@ namespace OpenSim.Region.Framework.Scenes
// We have a zombie from a crashed session.
// Or the same user is trying to be root twice here, won't work.
// Kill it.
m_log.DebugFormat(
"[SCENE]: Zombie scene presence detected for {0} {1} in {2}",
m_log.WarnFormat(
"[SCENE]: Existing root scene presence detected for {0} {1} in {2} when connecting. Removing existing presence.",
sp.Name, sp.UUID, RegionInfo.RegionName);
sp.ControllingClient.Close();