gecko/netwerk/protocol/http/nsHttpConnection.h
Patrick McManus b46439ff28 Bug 592284 - Accelerate TCP connection retries in HTTP. r=honzab a=blocking2.0
Losing a TCP SYN requires a long painful (typically 3 second) delay
before being retried. This patch creates a second parallel connection
attempt for any nsHttpConnection which has not become writable before
a timeout occurs.

If you assume .5% packet loss, this converts a full 3 second delay
from a 1 in 200 event into a 1 in 40,000 event.

Whichever connection establishes itself first is used. If another one
has been started and it does connect before the one being used is
closed then the extra one is handed to the connection manager for use
by a different transaction - essentially a persistent connection with
0 previous transactions on it. (Another way to think about is
pre-fetching a 3WHS on a high latency connection).

The pref network.http.connection-retry-timeout controls the amount of
time in ms to wait for success on the initial connection before beginning
the second one. Setting it to 0 disables the parallel connection, the
default is 250.
2010-11-21 09:50:36 +01:00

196 lines
7.9 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
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* the License. You may obtain a copy of the License at
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* The Original Code is Mozilla.
*
* The Initial Developer of the Original Code is
* Netscape Communications.
* Portions created by the Initial Developer are Copyright (C) 2001
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Darin Fisher <darin@netscape.com> (original author)
*
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* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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#ifndef nsHttpConnection_h__
#define nsHttpConnection_h__
#include "nsHttp.h"
#include "nsHttpConnectionInfo.h"
#include "nsAHttpConnection.h"
#include "nsAHttpTransaction.h"
#include "nsXPIDLString.h"
#include "nsCOMPtr.h"
#include "prlock.h"
#include "nsIStreamListener.h"
#include "nsISocketTransport.h"
#include "nsIAsyncInputStream.h"
#include "nsIAsyncOutputStream.h"
#include "nsIInterfaceRequestor.h"
#include "nsITimer.h"
//-----------------------------------------------------------------------------
// nsHttpConnection - represents a connection to a HTTP server (or proxy)
//
// NOTE: this objects lives on the socket thread only. it should not be
// accessed from any other thread.
//-----------------------------------------------------------------------------
class nsHttpConnection : public nsAHttpSegmentReader
, public nsAHttpSegmentWriter
, public nsIInputStreamCallback
, public nsIOutputStreamCallback
, public nsITransportEventSink
, public nsIInterfaceRequestor
{
public:
NS_DECL_ISUPPORTS
NS_DECL_NSAHTTPSEGMENTREADER
NS_DECL_NSAHTTPSEGMENTWRITER
NS_DECL_NSIINPUTSTREAMCALLBACK
NS_DECL_NSIOUTPUTSTREAMCALLBACK
NS_DECL_NSITRANSPORTEVENTSINK
NS_DECL_NSIINTERFACEREQUESTOR
nsHttpConnection();
virtual ~nsHttpConnection();
// Initialize the connection:
// info - specifies the connection parameters.
// maxHangTime - limits the amount of time this connection can spend on a
// single transaction before it should no longer be kept
// alive. a value of 0xffff indicates no limit.
nsresult Init(nsHttpConnectionInfo *info, PRUint16 maxHangTime);
// Activate causes the given transaction to be processed on this
// connection. It fails if there is already an existing transaction.
nsresult Activate(nsAHttpTransaction *, PRUint8 caps);
// Close the underlying socket transport.
void Close(nsresult reason);
//-------------------------------------------------------------------------
// XXX document when these are ok to call
PRBool SupportsPipelining() { return mSupportsPipelining; }
PRBool IsKeepAlive() { return mKeepAliveMask && mKeepAlive; }
PRBool CanReuse(); // can this connection be reused?
// Returns time in seconds for how long connection can be reused.
PRUint32 TimeToLive();
void DontReuse() { mKeepAliveMask = PR_FALSE;
mKeepAlive = PR_FALSE;
mIdleTimeout = 0; }
void DropTransport() { DontReuse(); mSocketTransport = 0; }
nsAHttpTransaction *Transaction() { return mTransaction; }
nsHttpConnectionInfo *ConnectionInfo() { return mConnInfo; }
// nsAHttpConnection compatible methods (non-virtual):
nsresult OnHeadersAvailable(nsAHttpTransaction *, nsHttpRequestHead *, nsHttpResponseHead *, PRBool *reset);
void CloseTransaction(nsAHttpTransaction *, nsresult reason);
void GetConnectionInfo(nsHttpConnectionInfo **ci) { NS_IF_ADDREF(*ci = mConnInfo); }
void GetSecurityInfo(nsISupports **);
PRBool IsPersistent() { return IsKeepAlive(); }
PRBool IsReused() { return mIsReused; }
nsresult PushBack(const char *data, PRUint32 length) { NS_NOTREACHED("PushBack"); return NS_ERROR_UNEXPECTED; }
nsresult ResumeSend();
nsresult ResumeRecv();
static NS_METHOD ReadFromStream(nsIInputStream *, void *, const char *,
PRUint32, PRUint32, PRUint32 *);
private:
// called to cause the underlying socket to start speaking SSL
nsresult ProxyStartSSL();
nsresult CreateTransport(PRUint8 caps);
nsresult CreateTransport(PRUint8 caps,
nsISocketTransport **sock,
nsIAsyncInputStream **instream,
nsIAsyncOutputStream **outstream);
nsresult OnTransactionDone(nsresult reason);
nsresult OnSocketWritable();
nsresult OnSocketReadable();
nsresult SetupSSLProxyConnect();
PRBool IsAlive();
PRBool SupportsPipelining(nsHttpResponseHead *);
static void IdleSynTimeout(nsITimer *, void *);
nsresult SelectPrimaryTransport(nsIAsyncOutputStream *out);
nsresult ReleaseBackupTransport(nsISocketTransport *sock,
nsIAsyncOutputStream *outs,
nsIAsyncInputStream *ins);
private:
nsCOMPtr<nsISocketTransport> mSocketTransport;
nsCOMPtr<nsIAsyncInputStream> mSocketIn;
nsCOMPtr<nsIAsyncOutputStream> mSocketOut;
nsresult mSocketInCondition;
nsresult mSocketOutCondition;
nsCOMPtr<nsIInputStream> mSSLProxyConnectStream;
nsCOMPtr<nsIInputStream> mRequestStream;
nsAHttpTransaction *mTransaction; // hard ref
nsHttpConnectionInfo *mConnInfo; // hard ref
PRLock *mLock;
PRUint32 mLastReadTime;
PRUint16 mMaxHangTime; // max download time before dropping keep-alive status
PRUint16 mIdleTimeout; // value of keep-alive: timeout=
PRPackedBool mKeepAlive;
PRPackedBool mKeepAliveMask;
PRPackedBool mSupportsPipelining;
PRPackedBool mIsReused;
PRPackedBool mCompletedSSLConnect;
PRUint32 mActivationCount;
// These items are used to implement a parallel connection opening
// attempt when network.http.connection-retry-timeout has expired
PRUint8 mSocketCaps;
nsCOMPtr<nsITimer> mIdleSynTimer;
nsCOMPtr<nsISocketTransport> mSocketTransport1;
nsCOMPtr<nsIAsyncInputStream> mSocketIn1;
nsCOMPtr<nsIAsyncOutputStream> mSocketOut1;
nsCOMPtr<nsISocketTransport> mSocketTransport2;
nsCOMPtr<nsIAsyncInputStream> mSocketIn2;
nsCOMPtr<nsIAsyncOutputStream> mSocketOut2;
};
#endif // nsHttpConnection_h__