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//------------------------------------------------------------------------------
// <copyright file="_ConnectionGroup.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Net {
using System.Collections;
using System.Threading;
//
// ConnectionGroup groups a list of connections within the ServerPoint context,
// this used to keep context for things such as proxies or seperate clients.
//
internal class ConnectionGroup {
//
// Members
//
private const int DefaultConnectionListSize = 3;
private ServicePoint m_ServicePoint;
private string m_Name;
private int m_ConnectionLimit;
private ArrayList m_ConnectionList;
private object m_Event;
private Queue m_AuthenticationRequestQueue;
internal bool m_AuthenticationGroup;
private HttpAbortDelegate m_AbortDelegate;
private bool m_NtlmNegGroup;
private int m_IISVersion = -1;
private int m_ActiveConnections;
private TimerThread.Timer m_ExpiringTimer;
//
// Constructors
//
internal ConnectionGroup(ServicePoint servicePoint, string connName) {
m_ServicePoint = servicePoint;
m_ConnectionLimit = servicePoint.ConnectionLimit;
m_ConnectionList = new ArrayList(DefaultConnectionListSize); //it may grow beyond
m_Name = MakeQueryStr(connName);
m_AbortDelegate = new HttpAbortDelegate(Abort);
GlobalLog.Print("ConnectionGroup::.ctor m_ConnectionLimit:" + m_ConnectionLimit.ToString());
// Don't start the idle timer. This group is technically idle, but it will be put to use
// immediately and has nothing to clean up right now.
}
internal string Name
{
get { return m_Name; }
}
//
// Accessors
//
internal ServicePoint ServicePoint {
get {
return m_ServicePoint;
}
}
internal int CurrentConnections {
get {
return m_ConnectionList.Count;
}
}
internal int ConnectionLimit {
get {
return m_ConnectionLimit;
}
set {
m_ConnectionLimit = value;
PruneExcesiveConnections();
GlobalLog.Print("ConnectionGroup::ConnectionLimit.set m_ConnectionLimit:" + m_ConnectionLimit.ToString());
}
}
private ManualResetEvent AsyncWaitHandle {
get {
if (m_Event == null) {
//
// lazy allocation of the event:
// if this property is never accessed this object is never created
//
Interlocked.CompareExchange(ref m_Event, new ManualResetEvent(false), null);
}
ManualResetEvent castedEvent = (ManualResetEvent)m_Event;
return castedEvent;
}
}
private Queue AuthenticationRequestQueue {
get {
if (m_AuthenticationRequestQueue == null) {
lock (m_ConnectionList) {
if (m_AuthenticationRequestQueue == null) {
m_AuthenticationRequestQueue = new Queue();
}
}
}
return m_AuthenticationRequestQueue;
}
set {
m_AuthenticationRequestQueue = value;
}
}
//
// Methods
//
internal static string MakeQueryStr(string connName) {
return ((connName == null) ? "" : connName);
}
/// <devdoc>
/// <para>
/// These methods are made available to the underlying Connection
/// object so that we don't leak them because we're keeping a local
/// reference in our m_ConnectionList.
/// Called by the Connection's constructor
/// </para>
/// </devdoc>
internal void Associate(Connection connection) {
lock (m_ConnectionList) {
m_ConnectionList.Add(connection);
}
GlobalLog.Print("ConnectionGroup::Associate() Connection:" + connection.GetHashCode());
}
/// <devdoc>
/// <para>
/// Used by the Connection's explicit finalizer (note this is
/// not a destructor, since that's never calld unless we
/// remove reference to the object from our internal list)
/// </para>
/// </devdoc>
internal void Disassociate(Connection connection) {
lock (m_ConnectionList) {
m_ConnectionList.Remove(connection);
}
}
/// <devdoc>
/// <para>
/// Called when a connection is idle and ready to process new requests
/// </para>
/// </devdoc>
internal void ConnectionGoneIdle() {
if (m_AuthenticationGroup) {
lock (m_ConnectionList) {
GlobalLog.Print("ConnectionGroup::ConnectionGoneIdle() setting the event");
AsyncWaitHandle.Set();
}
}
}
internal void IncrementConnection() {
// we need these to be atomic operations
lock (m_ConnectionList) {
m_ActiveConnections++;
if (m_ActiveConnections == 1) {
CancelIdleTimer();
}
}
}
internal void DecrementConnection() {
// we need these to be atomic operations
lock (m_ConnectionList) {
m_ActiveConnections--;
if (m_ActiveConnections == 0) {
Diagnostics.Debug.Assert(m_ExpiringTimer == null, "Timer not cleared");
m_ExpiringTimer = ServicePoint.CreateConnectionGroupTimer(this);
}
else if (m_ActiveConnections < 0) {
m_ActiveConnections = 0;
Diagnostics.Debug.Assert(false, "ConnectionGroup; Too many decrements.");
}
}
}
internal void CancelIdleTimer() {
lock (m_ConnectionList) {
TimerThread.Timer timer = m_ExpiringTimer;
m_ExpiringTimer = null;
if (timer != null)
{
timer.Cancel();
}
}
}
/// <devdoc>
/// <para>
/// Causes an abort of any aborted requests waiting in the ConnectionGroup
/// </para>
/// </devdoc>
private bool Abort(HttpWebRequest request, WebException webException)
{
lock (m_ConnectionList)
{
AsyncWaitHandle.Set();
}
return true;
}
/// <devdoc>
/// <para>
/// Removes aborted requests from our queue.
/// </para>
/// </devdoc>
private void PruneAbortedRequests() {
lock (m_ConnectionList) {
Queue updatedQueue = new Queue();
foreach(HttpWebRequest request in AuthenticationRequestQueue) {
if (!request.Aborted) {
updatedQueue.Enqueue(request);
}
}
AuthenticationRequestQueue = updatedQueue;
}
}
/// <devdoc>
/// <para>
/// Removes extra connections that are found when reducing the connection limit
/// </para>
/// </devdoc>
private void PruneExcesiveConnections() {
ArrayList connectionsToClose = new ArrayList();
lock(m_ConnectionList) {
int connectionLimit = ConnectionLimit;
if (CurrentConnections > connectionLimit) {
int numberToPrune = CurrentConnections - connectionLimit;
for (int i=0; i<numberToPrune; i++) {
connectionsToClose.Add(m_ConnectionList[i]);
}
m_ConnectionList.RemoveRange(0, numberToPrune);
}
}
foreach (Connection currentConnection in connectionsToClose) {
currentConnection.CloseOnIdle();
}
}
/// <devdoc>
/// <para>
/// Forces all connections on the ConnectionGroup to not be KeepAlive.
/// </para>
/// </devdoc>
internal void DisableKeepAliveOnConnections() {
// The timer thread is allowed to call this. (It doesn't call user code and doesn't block.)
GlobalLog.ThreadContract(ThreadKinds.Unknown, ThreadKinds.SafeSources | ThreadKinds.Timer, "ConnectionGroup#" + ValidationHelper.HashString(this) + "::DisableKeepAliveOnConnections");
ArrayList connectionsToClose = new ArrayList();
lock (m_ConnectionList) {
GlobalLog.Print("ConnectionGroup#" + ValidationHelper.HashString(this) + "::DisableKeepAliveOnConnections() Name = " + m_Name + ", Count:" + m_ConnectionList.Count);
foreach (Connection currentConnection in m_ConnectionList) {
//
// For each Connection set KeepAlive to false
//
GlobalLog.Print("ConnectionGroup#" + ValidationHelper.HashString(this) + "::DisableKeepAliveOnConnections() setting KeepAlive to false Connection#" + ValidationHelper.HashString(currentConnection));
connectionsToClose.Add(currentConnection);
}
m_ConnectionList.Clear();
}
foreach (Connection currentConnection in connectionsToClose) {
currentConnection.CloseOnIdle();
}
}
/// <devdoc>
/// <para>
/// Attempts to match a request with a connection, if a connection is unassigned ie not locked with
/// a request, then the least busy connections is returned in "leastbusyConnection." If the
/// connection limit allows, and all connections are busy, a new one is allocated and returned.
///
/// RETURNS: a Connection shown to match a previously locked Request/Connection (OTHERWISE)
/// leasebusyConnection - will contain a newly allocated Connection or least Busy one
/// suiteable for requests.
///
/// NOTE: For Whidbey: try to integrate this code into FindConnection()
/// </para>
/// </devdoc>
private Connection FindMatchingConnection(HttpWebRequest request, string connName, out Connection leastbusyConnection) {
int minBusyCount = Int32.MaxValue;
bool freeConnectionsAvail = false;
leastbusyConnection = null;
lock (m_ConnectionList) {
//
// go through the list of open connections to this service point and pick the first free one or,
// if none is free, pick the least busy one. Skip all connections with non keep-alive request pipelined.
//
minBusyCount = Int32.MaxValue;
foreach (Connection currentConnection in m_ConnectionList) {
GlobalLog.Print("ConnectionGroup::FindMatchingConnection currentConnection.BusyCount:" + currentConnection.BusyCount.ToString());
if (currentConnection.LockedRequest == request) {
leastbusyConnection = currentConnection;
return currentConnection;
}
GlobalLog.Print("ConnectionGroup::FindMatchingConnection: lockedRequest# " + ((currentConnection.LockedRequest == null) ? "null" : currentConnection.LockedRequest.GetHashCode().ToString()));
if (!currentConnection.NonKeepAliveRequestPipelined && currentConnection.BusyCount < minBusyCount && currentConnection.LockedRequest == null) {
leastbusyConnection = currentConnection;
minBusyCount = currentConnection.BusyCount;
if (minBusyCount == 0) {
freeConnectionsAvail = true;
}
}
}
//
// If there is NOT a Connection free, then we allocate a new Connection
//
if (!freeConnectionsAvail && CurrentConnections < ConnectionLimit) {
//
// If we can create a new connection, then do it,
// this may have complications in pipeling because
// we may wish to optimize this case by actually
// using existing connections, rather than creating new ones
//
// Note: this implicately results in a this.Associate being called.
//
GlobalLog.Print("ConnectionGroup::FindMatchingConnection [returning new Connection] CurrentConnections:" + CurrentConnections.ToString() + " ConnectionLimit:" + ConnectionLimit.ToString());
leastbusyConnection = new Connection(this);
}
}
return null; // only if we have a locked Connection that matches can return non-null
}
/// <devdoc>
/// <para>
/// Used by the ServicePoint to find a free or new Connection
/// for use in making Requests, this is done with the cavet,
/// that once a Connection is "locked" it can only be used
/// by a specific request.
///
/// NOTE: For Whidbey: try to integrate this code into FindConnection()
/// </para>
/// </devdoc>
private Connection FindConnectionAuthenticationGroup(HttpWebRequest request, string connName) {
Connection leastBusyConnection = null;
GlobalLog.Print("ConnectionGroup::FindConnectionAuthenticationGroup [" + connName + "] for request#" + request.GetHashCode() +", m_ConnectionList.Count:" + m_ConnectionList.Count.ToString());
//
// First try and find a free Connection (i.e. one not busy with Authentication handshake)
// or try to find a Request that has already locked a specific Connection,
// if a matching Connection is found, then we're done
//
lock (m_ConnectionList) {
Connection matchingConnection;
matchingConnection = FindMatchingConnection(request, connName, out leastBusyConnection);
if (matchingConnection != null) {
matchingConnection.MarkAsReserved();
return matchingConnection;
}
if (AuthenticationRequestQueue.Count == 0) {
if (leastBusyConnection != null) {
if (request.LockConnection) {
m_NtlmNegGroup = true;
m_IISVersion = leastBusyConnection.IISVersion;
}
if(request.LockConnection || (m_NtlmNegGroup && !request.Pipelined && request.UnsafeOrProxyAuthenticatedConnectionSharing && m_IISVersion >= 6)){
GlobalLog.Print("Assigning New Locked Request#" + request.GetHashCode().ToString());
leastBusyConnection.LockedRequest = request;
}
leastBusyConnection.MarkAsReserved();
return leastBusyConnection;
}
}
else if (leastBusyConnection != null) {
AsyncWaitHandle.Set();
}
AuthenticationRequestQueue.Enqueue(request);
}
//
// If all the Connections are busy, then we queue ourselves and need to wait. As soon as
// one of the Connections are free, we grab the lock, and see if we find ourselves
// at the head of the queue. If not, we loop backaround.
// Care is taken to examine the request when we wakeup, in case the request is aborted.
//
while (true) {
GlobalLog.Print("waiting");
request.AbortDelegate = m_AbortDelegate;
if (!request.Aborted)
AsyncWaitHandle.WaitOne();
GlobalLog.Print("wait up");
lock(m_ConnectionList) {
if (request.Aborted)
{
PruneAbortedRequests();
// Note that request is not on any connection and it will not be submitted
return null;
}
FindMatchingConnection(request, connName, out leastBusyConnection);
if (AuthenticationRequestQueue.Peek() == request) {
GlobalLog.Print("dequeue");
AuthenticationRequestQueue.Dequeue();
if (leastBusyConnection != null) {
if (request.LockConnection) {
m_NtlmNegGroup = true;
m_IISVersion = leastBusyConnection.IISVersion;
}
if(request.LockConnection || (m_NtlmNegGroup && !request.Pipelined && request.UnsafeOrProxyAuthenticatedConnectionSharing && m_IISVersion >= 6)){
leastBusyConnection.LockedRequest = request;
}
leastBusyConnection.MarkAsReserved();
return leastBusyConnection;
}
AuthenticationRequestQueue.Enqueue(request);
}
if (leastBusyConnection == null) {
AsyncWaitHandle.Reset();
}
}
}
}
/// <devdoc>
/// <para>
/// Used by the ServicePoint to find a free or new Connection
/// for use in making Requests. Under NTLM and Negotiate requests,
/// this function deprecates itself and switches the object over to
/// using a new code path (see FindConnectionAuthenticationGroup).
/// </para>
/// </devdoc>
internal Connection FindConnection(HttpWebRequest request, string connName, out bool forcedsubmit) {
Connection leastbusyConnection = null;
Connection newConnection = null;
bool freeConnectionsAvail = false;
ArrayList closedConnections = new ArrayList();
forcedsubmit = false;
if (m_AuthenticationGroup || request.LockConnection) {
m_AuthenticationGroup = true;
return FindConnectionAuthenticationGroup(request, connName);
}
GlobalLog.Print("ConnectionGroup::FindConnection [" + connName + "] m_ConnectionList.Count:" + m_ConnectionList.Count.ToString());
lock (m_ConnectionList) {
//
// go through the list of open connections to this service point and pick the connection as follows:
// - free connection
// - if there is no free connection and if we are under connection limit, create new connection
// - pick the least busy connection which does not have non-keep alive request pipelined
// - pick the least busy connection which may have non-keep alive request pipelined
// If we pick the connection with non keep-alive request pipelined on it, we set forcedsubmit to true.
// This will make sure that we don't start the request immediately and it gets queued on the connection.
//
int minBusyCount = Int32.MaxValue;
bool foundLiveConnection = false;
foreach (Connection currentConnection in m_ConnectionList) {
GlobalLog.Print("ConnectionGroup::FindConnection currentConnection.BusyCount:" + currentConnection.BusyCount.ToString());
bool useThisConnection = false;
if (!currentConnection.IsInitalizing && !currentConnection.NetworkStream.Connected) {
// This is a closed connection probably due to a previous Abort(). Remove it
// from the list of eligible connections.
closedConnections.Add(currentConnection);
}
else {
if (foundLiveConnection) {
useThisConnection = (!currentConnection.NonKeepAliveRequestPipelined && minBusyCount > currentConnection.BusyCount);
} else {
useThisConnection = (!currentConnection.NonKeepAliveRequestPipelined || minBusyCount > currentConnection.BusyCount);
}
}
if (useThisConnection) {
leastbusyConnection = currentConnection;
minBusyCount = currentConnection.BusyCount;
if (!foundLiveConnection) {
foundLiveConnection = !currentConnection.NonKeepAliveRequestPipelined;
}
if (foundLiveConnection && minBusyCount == 0) {
freeConnectionsAvail = true;
break;
}
}
}
//
// Remove closed connections.
//
GlobalLog.Print("ConnectionGroup::FindConnection, closed connections to remove: " + closedConnections.Count.ToString());
foreach (Connection closedConnection in closedConnections) {
closedConnection.RemoveFromConnectionList();
}
//
// If there is NOT a Connection free, then we allocate a new Connection
//
if (!freeConnectionsAvail && CurrentConnections < ConnectionLimit) {
//
// If we can create a new connection, then do it,
// this may have complications in pipeling because
// we may wish to optimize this case by actually
// using existing connections, rather than creating new ones
//
// Note: this implicitly results in a this.Associate() being called.
//
GlobalLog.Print("ConnectionGroup::FindConnection [returning new Connection] freeConnectionsAvail:" + freeConnectionsAvail.ToString() + " CurrentConnections:" + CurrentConnections.ToString() + " ConnectionLimit:" + ConnectionLimit.ToString());
newConnection = new Connection(this);
forcedsubmit = false;
}
else {
//
// All connections are busy, use the least busy one
//
GlobalLog.Print("ConnectionGroup::FindConnection [returning leastbusyConnection] freeConnectionsAvail:" + freeConnectionsAvail.ToString() + " CurrentConnections:" + CurrentConnections.ToString() + " ConnectionLimit:" + ConnectionLimit.ToString());
GlobalLog.Assert(leastbusyConnection != null, "Connect.leastbusyConnection != null|All connections have BusyCount equal to Int32.MaxValue.");
newConnection = leastbusyConnection;
forcedsubmit = !foundLiveConnection;
}
newConnection.MarkAsReserved();
}
return newConnection;
}
[System.Diagnostics.Conditional("DEBUG")]
internal void DebugMembers(int requestHash) {
foreach(Connection connection in m_ConnectionList) {
connection.DebugMembers(requestHash);
}
}
}
}
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