gecko/netwerk/protocol/http/nsAHttpConnection.h
Patrick McManus f04f8c8cf1 bug 603512 - large objects block pipelines r=honzab
the type and state patch tries hard not to form pipelines behind resources that
could become head of line blockers. But of course that requires the ability to
predict the future, and won't be perfect.

This patch reacts to a transaction that has a large response body (defined by
either a large content-length header or actually reading a large number of
chunked bytes) by cancelling any transactions that have been pipelined down the
same connection and rescheduling them elsewhere. It also changes the type of
the connection to "solo", which prevents new transactions from being pipelined
onto this one and provides class-specific negative feedback to the pipeline
manager so that near-future requests to the same host of the same type (e.g.
general) will not be pipelined but other types (e.g. img or js/css) can still
do that.

Content-Length is ideal, because it allows us to identify the problem so early.
But even actually reading the document for a fairly long time gives it a fairly
high probability of not ending soon. (i.e. long document sizes are spread over
a larger range than small ones. duh.)

The pref network.http.pipelining.maxsize controls the threshold. I set the
default at 300KB, which is roughly the bandwidth delay product of a 2mbit 120ms
rtt connection and 1 rtt is mostly what you are giving up by canceling it on
one connection and sending it on another. (modulo maybe needing a handshake).
2012-03-22 19:39:31 -04:00

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/* ***** 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
* 1.1 (the "License"); you may not use this file except in compliance with
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* The Original Code is Mozilla.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 2002
* the Initial Developer. All Rights Reserved.
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* Contributor(s):
* Darin Fisher <darin@netscape.com>
*
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* the provisions above, a recipient may use your version of this file under
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#ifndef nsAHttpConnection_h__
#define nsAHttpConnection_h__
#include "nsISupports.h"
#include "nsAHttpTransaction.h"
class nsHttpRequestHead;
class nsHttpResponseHead;
class nsHttpConnectionInfo;
class nsHttpConnection;
class nsISocketTransport;
class nsIAsyncInputStream;
class nsIAsyncOutputStream;
//-----------------------------------------------------------------------------
// Abstract base class for a HTTP connection
//-----------------------------------------------------------------------------
class nsAHttpConnection : public nsISupports
{
public:
//-------------------------------------------------------------------------
// NOTE: these methods may only be called on the socket thread.
//-------------------------------------------------------------------------
//
// called by a transaction when the response headers have all been read.
// the connection can force the transaction to reset it's response headers,
// and prepare for a new set of response headers, by setting |*reset=TRUE|.
//
// @return failure code to close the transaction.
//
virtual nsresult OnHeadersAvailable(nsAHttpTransaction *,
nsHttpRequestHead *,
nsHttpResponseHead *,
bool *reset) = 0;
//
// called by a transaction to resume either sending or receiving data
// after a transaction returned NS_BASE_STREAM_WOULD_BLOCK from its
// ReadSegments/WriteSegments methods.
//
virtual nsresult ResumeSend() = 0;
virtual nsresult ResumeRecv() = 0;
// After a connection has had ResumeSend() called by a transaction,
// and it is ready to write to the network it may need to know the
// transaction that has data to write. This is only an issue for
// multiplexed protocols like SPDY - plain HTTP or pipelined HTTP
// implicitly have this information in a 1:1 relationship with the
// transaction(s) they manage.
virtual void TransactionHasDataToWrite(nsAHttpTransaction *)
{
// by default do nothing - only multiplexed protocols need to overload
return;
}
//
// called by the connection manager to close a transaction being processed
// by this connection.
//
// @param transaction
// the transaction being closed.
// @param reason
// the reason for closing the transaction. NS_BASE_STREAM_CLOSED
// is equivalent to NS_OK.
//
virtual void CloseTransaction(nsAHttpTransaction *transaction,
nsresult reason) = 0;
// get a reference to the connection's connection info object.
virtual void GetConnectionInfo(nsHttpConnectionInfo **) = 0;
// get the transport level information for this connection. This may fail
// if it is in use.
virtual nsresult TakeTransport(nsISocketTransport **,
nsIAsyncInputStream **,
nsIAsyncOutputStream **) = 0;
// called by a transaction to get the security info from the socket.
virtual void GetSecurityInfo(nsISupports **) = 0;
// called by a transaction to determine whether or not the connection is
// persistent... important in determining the end of a response.
virtual bool IsPersistent() = 0;
// called to determine or set if a connection has been reused.
virtual bool IsReused() = 0;
virtual void DontReuse() = 0;
// called by a transaction when the transaction reads more from the socket
// than it should have (eg. containing part of the next pipelined response).
virtual nsresult PushBack(const char *data, PRUint32 length) = 0;
// Used to determine if the connection wants read events even though
// it has not written out a transaction. Used when a connection has issued
// a preamble such as a proxy ssl CONNECT sequence.
virtual bool IsProxyConnectInProgress() = 0;
// Used by a transaction to manage the state of previous response bodies on
// the same connection and work around buggy servers.
virtual bool LastTransactionExpectedNoContent() = 0;
virtual void SetLastTransactionExpectedNoContent(bool) = 0;
// Transfer the base http connection object along with a
// reference to it to the caller.
virtual nsHttpConnection *TakeHttpConnection() = 0;
// Get the nsISocketTransport used by the connection without changing
// references or ownership.
virtual nsISocketTransport *Transport() = 0;
// Cancel and reschedule transactions deeper than the current response.
// Returns the number of canceled transactions.
virtual PRUint32 CancelPipeline(nsresult originalReason) = 0;
// Read and write class of transaction that is carried on this connection
virtual nsAHttpTransaction::Classifier Classification() = 0;
virtual void Classify(nsAHttpTransaction::Classifier newclass) = 0;
};
#define NS_DECL_NSAHTTPCONNECTION \
nsresult OnHeadersAvailable(nsAHttpTransaction *, nsHttpRequestHead *, nsHttpResponseHead *, bool *reset); \
nsresult ResumeSend(); \
nsresult ResumeRecv(); \
void CloseTransaction(nsAHttpTransaction *, nsresult); \
void GetConnectionInfo(nsHttpConnectionInfo **); \
nsresult TakeTransport(nsISocketTransport **, \
nsIAsyncInputStream **, \
nsIAsyncOutputStream **); \
void GetSecurityInfo(nsISupports **); \
bool IsPersistent(); \
bool IsReused(); \
void DontReuse(); \
nsresult PushBack(const char *, PRUint32); \
bool IsProxyConnectInProgress(); \
bool LastTransactionExpectedNoContent(); \
void SetLastTransactionExpectedNoContent(bool); \
nsHttpConnection *TakeHttpConnection(); \
nsISocketTransport *Transport(); \
PRUint32 CancelPipeline(nsresult originalReason); \
nsAHttpTransaction::Classifier Classification(); \
void Classify(nsAHttpTransaction::Classifier);
#endif // nsAHttpConnection_h__