MAINT-7626 Incorporate transfer changes into viewer

10 files changed, 364 insertions, 238 deletions

diff --git a/indra/llmessage/llxfer.cpp b/indra/llmessage/llxfer.cpp
index e0590dfdff..a42ecefd23 100644
--- a/indra/llmessage/llxfer.cpp
+++ b/indra/llmessage/llxfer.cpp
@@ -99,7 +99,22 @@ void LLXfer::cleanup ()
 
 S32 LLXfer::startSend (U64 xfer_id, const LLHost &remote_host)
 {
-	LL_WARNS() << "undifferentiated LLXfer::startSend for " << getFileName() << LL_ENDL;
+	LL_WARNS("Xfer") << "unexpected call to base class LLXfer::startSend for " << getFileName() << LL_ENDL;
+	return (-1);
+}
+
+///////////////////////////////////////////////////////////
+
+void LLXfer::closeFileHandle()
+{
+	LL_WARNS("Xfer") << "unexpected call to base class LLXfer::closeFileHandle for " << getFileName() << LL_ENDL;
+}
+
+///////////////////////////////////////////////////////////
+
+S32 LLXfer::reopenFileHandle()
+{
+	LL_WARNS("Xfer") << "unexpected call to base class LLXfer::reopenFileHandle for " << getFileName() << LL_ENDL;
 	return (-1);
 }
 
@@ -127,14 +142,14 @@ S32 LLXfer::receiveData (char *datap, S32 data_size)
 	S32 retval = 0;
 
 	if (((S32) mBufferLength + data_size) > getMaxBufferSize())
-	{
+	{	// Write existing data to disk if it's larger than the buffer size
 		retval = flush();
 	}
 
 	if (!retval)
 	{
 		if (datap != NULL)
-		{
+		{	// Append new data to mBuffer
 			memcpy(&mBuffer[mBufferLength],datap,data_size);	/*Flawfinder: ignore*/
 			mBufferLength += data_size;
 		}
@@ -248,7 +263,12 @@ void LLXfer::sendPacket(S32 packet_num)
 		gMessageSystem->nextBlockFast(_PREHASH_DataPacket);
 		gMessageSystem->addBinaryDataFast(_PREHASH_Data, &fdata_buf,fdata_size);
 			
-		gMessageSystem->sendMessage(mRemoteHost);
+		S32 sent_something = gMessageSystem->sendMessage(mRemoteHost);
+		if (sent_something == 0)
+		{
+			abort(LL_ERR_CIRCUIT_GONE);
+			return;
+		}
 
 		ACKTimer.reset();
 		mWaitingForACK = TRUE;
@@ -326,12 +346,15 @@ void LLXfer::abort (S32 result_code)
 	LL_INFOS() << "Aborting xfer from " << mRemoteHost << " named " << getFileName()
 			<< " - error: " << result_code << LL_ENDL;
 
-	gMessageSystem->newMessageFast(_PREHASH_AbortXfer);
-	gMessageSystem->nextBlockFast(_PREHASH_XferID);
-	gMessageSystem->addU64Fast(_PREHASH_ID, mID);
-	gMessageSystem->addS32Fast(_PREHASH_Result, result_code);
-	
-	gMessageSystem->sendMessage(mRemoteHost);
+	if (result_code != LL_ERR_CIRCUIT_GONE)
+	{
+		gMessageSystem->newMessageFast(_PREHASH_AbortXfer);
+		gMessageSystem->nextBlockFast(_PREHASH_XferID);
+		gMessageSystem->addU64Fast(_PREHASH_ID, mID);
+		gMessageSystem->addS32Fast(_PREHASH_Result, result_code);
+
+		gMessageSystem->sendMessage(mRemoteHost);
+	}
 
 	mStatus = e_LL_XFER_ABORTED;
 }
diff --git a/indra/llmessage/llxfer.h b/indra/llmessage/llxfer.h
index edf5eeb82d..3be8da4fbe 100644
--- a/indra/llmessage/llxfer.h
+++ b/indra/llmessage/llxfer.h
@@ -62,7 +62,7 @@ class LLXfer
 	S32 mXferSize;
 
 	char *mBuffer;
-	U32 mBufferLength;
+	U32 mBufferLength;			// Size of valid data, not actual allocated buffer size
 	U32 mBufferStartOffset;
 	BOOL mBufferContainsEOF;
 
@@ -90,7 +90,9 @@ class LLXfer
 	void init(S32 chunk_size);
 	virtual void cleanup();
 
-	virtual S32 startSend (U64 xfer_id, const LLHost &remote_host);
+	virtual S32 startSend(U64 xfer_id, const LLHost &remote_host);
+	virtual void closeFileHandle();
+	virtual S32 reopenFileHandle();
 	virtual void sendPacket(S32 packet_num);
 	virtual void sendNextPacket();
 	virtual void resendLastPacket();
diff --git a/indra/llmessage/llxfer_file.cpp b/indra/llmessage/llxfer_file.cpp
index 8e2ed890e7..ad55e389f3 100644
--- a/indra/llmessage/llxfer_file.cpp
+++ b/indra/llmessage/llxfer_file.cpp
@@ -206,7 +206,8 @@ S32 LLXfer_File::startSend (U64 xfer_id, const LLHost &remote_host)
 
 	mBufferLength = 0;
 	mBufferStartOffset = 0;	
-	
+
+	// We leave the file open, assuming we'll start reading and sending soon
 	mFp = LLFile::fopen(mLocalFilename,"rb");		/* Flawfinder : ignore */
 	if (mFp)
 	{
@@ -233,6 +234,36 @@ S32 LLXfer_File::startSend (U64 xfer_id, const LLHost &remote_host)
 }
 
 ///////////////////////////////////////////////////////////
+void LLXfer_File::closeFileHandle()
+{
+	if (mFp)
+	{
+		fclose(mFp);
+		mFp = NULL;
+	}
+}
+
+///////////////////////////////////////////////////////////
+
+S32 LLXfer_File::reopenFileHandle()
+{
+	S32 retval = LL_ERR_NOERR;  // presume success
+
+	if (mFp == NULL)
+	{
+		mFp = LLFile::fopen(mLocalFilename,"rb");		/* Flawfinder : ignore */
+		if (mFp == NULL)
+		{
+			LL_INFOS("Xfer") << "Warning: " << mLocalFilename << " not found when re-opening file" << LL_ENDL;
+			retval = LL_ERR_FILE_NOT_FOUND;
+		}
+	}
+
+	return retval;
+}
+
+
+///////////////////////////////////////////////////////////
 
 S32 LLXfer_File::getMaxBufferSize ()
 {
@@ -285,9 +316,12 @@ S32 LLXfer_File::flush()
 
 		if (mFp)
 		{
-			if (fwrite(mBuffer,1,mBufferLength,mFp) != mBufferLength)
+			S32 write_size = fwrite(mBuffer,1,mBufferLength,mFp);
+			if (write_size != mBufferLength)
 			{
-				LL_WARNS() << "Short write" << LL_ENDL;
+				LL_WARNS("Xfer") << "Non-matching write size, requested " << mBufferLength
+					<< " but wrote " << write_size
+					<< LL_ENDL;
 			}
 			
 //			LL_INFOS() << "******* wrote " << mBufferLength << " bytes of file xfer" << LL_ENDL;
diff --git a/indra/llmessage/llxfer_file.h b/indra/llmessage/llxfer_file.h
index a37dda6732..ab9374549e 100644
--- a/indra/llmessage/llxfer_file.h
+++ b/indra/llmessage/llxfer_file.h
@@ -61,8 +61,10 @@ class LLXfer_File : public LLXfer
 	virtual S32 startDownload();
 
 	virtual S32 processEOF();
-	
-	virtual S32 startSend (U64 xfer_id, const LLHost &remote_host);
+
+	virtual S32 startSend(U64 xfer_id, const LLHost &remote_host);
+	virtual void closeFileHandle();
+	virtual S32 reopenFileHandle();
 
 	virtual S32 suck(S32 start_position);
 	virtual S32 flush();
diff --git a/indra/llmessage/llxfer_mem.cpp b/indra/llmessage/llxfer_mem.cpp
index 3bea08f2e5..78a3e4f558 100644
--- a/indra/llmessage/llxfer_mem.cpp
+++ b/indra/llmessage/llxfer_mem.cpp
@@ -80,28 +80,6 @@ void LLXfer_Mem::setXferSize (S32 xfer_size)
 
 ///////////////////////////////////////////////////////////
 
-U64 LLXfer_Mem::registerXfer(U64 xfer_id, const void *datap, const S32 length)
-{
-	mID = xfer_id;
-
-	if (datap)
-	{
-		setXferSize(length);
-		if (mBuffer)
-		{
-			memcpy(mBuffer,datap,length);		/* Flawfinder : ignore */
-			mBufferLength = length;
-		}
-		else
-		{
-			xfer_id = 0;
-		}
-	}
-	
-	mStatus = e_LL_XFER_REGISTERED;
-	return (xfer_id);
-}
-
 S32 LLXfer_Mem::startSend (U64 xfer_id, const LLHost &remote_host)
 {
 	S32 retval = LL_ERR_NOERR;  // presume success
diff --git a/indra/llmessage/llxfer_mem.h b/indra/llmessage/llxfer_mem.h
index b5adf837df..d07779de87 100644
--- a/indra/llmessage/llxfer_mem.h
+++ b/indra/llmessage/llxfer_mem.h
@@ -53,7 +53,6 @@ class LLXfer_Mem : public LLXfer
 	virtual void cleanup();
 
 	virtual S32 startSend (U64 xfer_id, const LLHost &remote_host);
-	virtual U64 registerXfer(U64 xfer_id, const void *datap, const S32 length);
 	virtual void setXferSize (S32 data_size);
 
 	virtual S32 initializeRequest(U64 xfer_id,
diff --git a/indra/llmessage/llxfer_vfile.cpp b/indra/llmessage/llxfer_vfile.cpp
index 4a378d1d34..5d41180192 100644
--- a/indra/llmessage/llxfer_vfile.cpp
+++ b/indra/llmessage/llxfer_vfile.cpp
@@ -205,6 +205,38 @@ S32 LLXfer_VFile::startSend (U64 xfer_id, const LLHost &remote_host)
 }
 
 ///////////////////////////////////////////////////////////
+
+void LLXfer_VFile::closeFileHandle()
+{
+	if (mVFile)
+	{
+		delete mVFile;
+		mVFile = NULL;
+	}
+}
+
+///////////////////////////////////////////////////////////
+
+S32 LLXfer_VFile::reopenFileHandle()
+{
+	S32 retval = LL_ERR_NOERR;  // presume success
+
+	if (mVFile == NULL)
+	{
+		mVFile =new LLVFile(mVFS, mLocalID, mType, LLVFile::READ);
+		if (mVFile == NULL)
+		{
+			LL_WARNS("Xfer") << "LLXfer_VFile::reopenFileHandle() can't read VFS file " << mLocalID << "." << LLAssetType::lookup(mType) << LL_ENDL;
+			retval = LL_ERR_FILE_NOT_FOUND;
+		}
+	}
+
+	return retval;
+}
+
+
+///////////////////////////////////////////////////////////
+
 void LLXfer_VFile::setXferSize (S32 xfer_size)
 {	
 	LLXfer::setXferSize(xfer_size);
diff --git a/indra/llmessage/llxfer_vfile.h b/indra/llmessage/llxfer_vfile.h
index 048bf49dcc..b606c08122 100644
--- a/indra/llmessage/llxfer_vfile.h
+++ b/indra/llmessage/llxfer_vfile.h
@@ -66,8 +66,10 @@ class LLXfer_VFile : public LLXfer
 	virtual S32 startDownload();
 
 	virtual S32 processEOF();
-	
-	virtual S32 startSend (U64 xfer_id, const LLHost &remote_host);
+
+	virtual S32 startSend(U64 xfer_id, const LLHost &remote_host);
+	virtual void closeFileHandle();
+	virtual S32 reopenFileHandle();
 
 	virtual S32 suck(S32 start_position);
 	virtual S32 flush();
diff --git a/indra/llmessage/llxfermanager.cpp b/indra/llmessage/llxfermanager.cpp
index 2ceb64ce8f..8f18004791 100644
--- a/indra/llmessage/llxfermanager.cpp
+++ b/indra/llmessage/llxfermanager.cpp
@@ -44,6 +44,8 @@ const S32 LL_PACKET_RETRY_LIMIT = 10;            // packet retransmission limit
 const S32 LL_DEFAULT_MAX_SIMULTANEOUS_XFERS = 10;
 const S32 LL_DEFAULT_MAX_REQUEST_FIFO_XFERS = 1000;
 
+const S32 LL_DEFAULT_MAX_HARD_LIMIT_SIMULTANEOUS_XFERS = 500;
+
 #define LL_XFER_PROGRESS_MESSAGES 0
 #define LL_XFER_TEST_REXMIT       0
 
@@ -66,10 +68,10 @@ LLXferManager::~LLXferManager ()
 
 void LLXferManager::init (LLVFS *vfs)
 {
-	mSendList = NULL;
-	mReceiveList = NULL;
+	cleanup();
 
 	setMaxOutgoingXfersPerCircuit(LL_DEFAULT_MAX_SIMULTANEOUS_XFERS);
+	setHardLimitOutgoingXfersPerCircuit(LL_DEFAULT_MAX_HARD_LIMIT_SIMULTANEOUS_XFERS);
 	setMaxIncomingXfers(LL_DEFAULT_MAX_REQUEST_FIFO_XFERS);
 
 	mVFS = vfs;
@@ -83,29 +85,14 @@ void LLXferManager::init (LLVFS *vfs)
 
 void LLXferManager::cleanup ()
 {
-	LLXfer *xferp;
-	LLXfer *delp;
-
 	for_each(mOutgoingHosts.begin(), mOutgoingHosts.end(), DeletePointer());
 	mOutgoingHosts.clear();
 
-	delp = mSendList;
-	while (delp)
-	{
-		xferp = delp->mNext;
-		delete delp;
-		delp = xferp;
-	}
-	mSendList = NULL;
+	for_each(mSendList.begin(), mSendList.end(), DeletePointer());
+	mSendList.clear();
 
-	delp = mReceiveList;
-	while (delp)
-	{
-		xferp = delp->mNext;
-		delete delp;
-		delp = xferp;
-	}
-	mReceiveList = NULL;
+	for_each(mReceiveList.begin(), mReceiveList.end(), DeletePointer());
+	mReceiveList.clear();
 }
 
 ///////////////////////////////////////////////////////////
@@ -122,6 +109,11 @@ void LLXferManager::setMaxOutgoingXfersPerCircuit(S32 max_num)
 	mMaxOutgoingXfersPerCircuit = max_num;
 }
 
+void LLXferManager::setHardLimitOutgoingXfersPerCircuit(S32 max_num)
+{
+	mHardLimitOutgoingXfersPerCircuit = max_num;
+}
+
 void LLXferManager::setUseAckThrottling(const BOOL use)
 {
 	mUseAckThrottling = use;
@@ -148,19 +140,18 @@ void LLXferManager::setAckThrottleBPS(const F32 bps)
 
 void LLXferManager::updateHostStatus()
 {
-    LLXfer *xferp;
-	LLHostStatus *host_statusp = NULL;
-
 	for_each(mOutgoingHosts.begin(), mOutgoingHosts.end(), DeletePointer());
 	mOutgoingHosts.clear();
 
-	for (xferp = mSendList; xferp; xferp = xferp->mNext)
+	for (xfer_list_t::iterator send_iter = mSendList.begin();
+			send_iter != mSendList.end(); ++send_iter)
 	{
+		LLHostStatus *host_statusp = NULL;
 		for (status_list_t::iterator iter = mOutgoingHosts.begin();
 			 iter != mOutgoingHosts.end(); ++iter)
 		{
 			host_statusp = *iter;
-			if (host_statusp->mHost == xferp->mRemoteHost)
+			if (host_statusp->mHost == (*send_iter)->mRemoteHost)
 			{
 				break;
 			}
@@ -170,23 +161,22 @@ void LLXferManager::updateHostStatus()
 			host_statusp = new LLHostStatus();
 			if (host_statusp)
 			{
-				host_statusp->mHost = xferp->mRemoteHost;
+				host_statusp->mHost = (*send_iter)->mRemoteHost;
 				mOutgoingHosts.push_front(host_statusp);
 			}
 		}
 		if (host_statusp)
 		{
-			if (xferp->mStatus == e_LL_XFER_PENDING)
+			if ((*send_iter)->mStatus == e_LL_XFER_PENDING)
 			{
 				host_statusp->mNumPending++;
 			}
-			else if (xferp->mStatus == e_LL_XFER_IN_PROGRESS)
+			else if ((*send_iter)->mStatus == e_LL_XFER_IN_PROGRESS)
 			{
 				host_statusp->mNumActive++;
 			}
 		}
-		
-	}	
+	}
 }
 
 ///////////////////////////////////////////////////////////
@@ -209,14 +199,15 @@ void LLXferManager::printHostStatus()
 
 ///////////////////////////////////////////////////////////
 
-LLXfer *LLXferManager::findXfer (U64 id, LLXfer *list_head)
+LLXfer *LLXferManager::findXfer(U64 id, xfer_list_t & xfer_list)
 {
-    LLXfer *xferp;
-	for (xferp = list_head; xferp; xferp = xferp->mNext)
+	for (xfer_list_t::iterator iter = xfer_list.begin();
+		 iter != xfer_list.end();
+		 ++iter)
 	{
-		if (xferp->mID == id)
+		if ((*iter)->mID == id)
 		{
-			return(xferp);
+			return(*iter);
 		}
 	}
 	return(NULL);
@@ -225,29 +216,34 @@ LLXfer *LLXferManager::findXfer (U64 id, LLXfer *list_head)
 
 ///////////////////////////////////////////////////////////
 
-void LLXferManager::removeXfer (LLXfer *delp, LLXfer **list_head)
+void LLXferManager::removeXfer(LLXfer *delp, xfer_list_t & xfer_list)
 {
-	// This function assumes that delp will only occur in the list
-	// zero or one times.
 	if (delp)
-	{
-		if (*list_head == delp)
+	{	
+		std::string direction = "send";
+		if (&xfer_list == &mReceiveList)
 		{
-			*list_head = delp->mNext;
-			delete (delp);
+			std::string direction = "receive";
+			xfer_list = mSendList;
 		}
-		else
+
+		// This assumes that delp will occur in the list once at most
+		// Find the pointer in the list
+		for (xfer_list_t::iterator iter = xfer_list.begin();
+			 iter != xfer_list.end();
+			 ++iter)
 		{
-			LLXfer *xferp = *list_head;
-			while (xferp->mNext)
+			if ((*iter) == delp)
 			{
-				if (xferp->mNext == delp)
-				{
-					xferp->mNext = delp->mNext;
-					delete (delp);
-					break;
-				}
-				xferp = xferp->mNext;
+				LL_DEBUGS("Xfer") << "Deleting xfer to host " << (*iter)->mRemoteHost
+					<< " of " << (*iter)->mXferSize << " bytes"
+					<< ", status " << (S32)((*iter)->mStatus)
+					<< " from the " << direction << " list"
+					<< LL_ENDL;
+
+				xfer_list.erase(iter);
+				delete (delp);
+				break;
 			}
 		}
 	}
@@ -272,7 +268,7 @@ U32 LLXferManager::numActiveListEntries(LLXfer *list_head)
 
 ///////////////////////////////////////////////////////////
 
-S32 LLXferManager::numPendingXfers(const LLHost &host)
+LLHostStatus * LLXferManager::findHostStatus(const LLHost &host)
 {
 	LLHostStatus *host_statusp = NULL;
 
@@ -282,26 +278,32 @@ S32 LLXferManager::numPendingXfers(const LLHost &host)
 		host_statusp = *iter;
 		if (host_statusp->mHost == host)
 		{
-			return (host_statusp->mNumPending);
+			return (host_statusp);
 		}
 	}
 	return 0;
 }
 
 ///////////////////////////////////////////////////////////
+ 
+S32 LLXferManager::numPendingXfers(const LLHost &host)
+{
+	LLHostStatus *host_statusp = findHostStatus(host);
+	if (host_statusp)
+	{
+		return host_statusp->mNumPending;
+	}
+	return 0;
+}
+
+///////////////////////////////////////////////////////////
 
 S32 LLXferManager::numActiveXfers(const LLHost &host)
 {
-	LLHostStatus *host_statusp = NULL;
-
-	for (status_list_t::iterator iter = mOutgoingHosts.begin();
-		 iter != mOutgoingHosts.end(); ++iter)
+	LLHostStatus *host_statusp = findHostStatus(host);
+	if (host_statusp)
 	{
-		host_statusp = *iter;
-		if (host_statusp->mHost == host)
-		{
-			return (host_statusp->mNumActive);
-		}
+		return host_statusp->mNumActive;
 	}
 	return 0;
 }
@@ -372,35 +374,6 @@ BOOL LLXferManager::isLastPacket(S32 packet_num)
 
 ///////////////////////////////////////////////////////////
 
-U64 LLXferManager::registerXfer(const void *datap, const S32 length)
-{
-	LLXfer *xferp;
-	U64 xfer_id = getNextID();
-
-	xferp = (LLXfer *) new LLXfer_Mem();
-	if (xferp)
-	{
-		xferp->mNext = mSendList;
-		mSendList = xferp;
-
-		xfer_id = ((LLXfer_Mem *)xferp)->registerXfer(xfer_id, datap,length);
-
-		if (!xfer_id)
-		{
-			removeXfer(xferp,&mSendList);
-		}
-	}
-	else
-	{
-		LL_ERRS() << "Xfer allocation error" << LL_ENDL;
-		xfer_id = 0;
-	}	
-
-    return(xfer_id);
-}
-
-///////////////////////////////////////////////////////////
-
 U64 LLXferManager::requestFile(const std::string& local_filename,
 								const std::string& remote_filename,
 								ELLPath remote_path,
@@ -411,30 +384,33 @@ U64 LLXferManager::requestFile(const std::string& local_filename,
 								BOOL is_priority,
 								BOOL use_big_packets)
 {
-	LLXfer *xferp;
+	LLXfer_File* file_xfer_p = NULL;
 
-	for (xferp = mReceiveList; xferp ; xferp = xferp->mNext)
+	for (xfer_list_t::iterator iter = mReceiveList.begin();
+			iter != mReceiveList.end(); ++iter)
 	{
-		if (xferp->getXferTypeTag() == LLXfer::XFER_FILE
-			&& (((LLXfer_File*)xferp)->matchesLocalFilename(local_filename))
-			&& (((LLXfer_File*)xferp)->matchesRemoteFilename(remote_filename, remote_path))
-			&& (remote_host == xferp->mRemoteHost)
-			&& (callback == xferp->mCallback)
-			&& (user_data == xferp->mCallbackDataHandle))
-
+		if ((*iter)->getXferTypeTag() == LLXfer::XFER_FILE)
 		{
-			// cout << "requested a xfer already in progress" << endl;
-			return xferp->mID;
+			file_xfer_p = (LLXfer_File*)(*iter);
+			if (file_xfer_p->matchesLocalFilename(local_filename)
+				&& file_xfer_p->matchesRemoteFilename(remote_filename, remote_path)
+				&& (remote_host == file_xfer_p->mRemoteHost)
+				&& (callback == file_xfer_p->mCallback)
+				&& (user_data == file_xfer_p->mCallbackDataHandle))
+			{
+				// Already have the request	(already in progress)
+				return (*iter)->mID;
+			}
 		}
 	}
 
 	U64 xfer_id = 0;
 
 	S32 chunk_size = use_big_packets ? LL_XFER_LARGE_PAYLOAD : -1;
-	xferp = (LLXfer *) new LLXfer_File(chunk_size);
-	if (xferp)
+	file_xfer_p = new LLXfer_File(chunk_size);
+	if (file_xfer_p)
 	{
-		addToList(xferp, mReceiveList, is_priority);
+		addToList(file_xfer_p, mReceiveList, is_priority);
 
 		// Remove any file by the same name that happens to be lying
 		// around.
@@ -447,7 +423,7 @@ U64 LLXferManager::requestFile(const std::string& local_filename,
 			LLFile::remove(local_filename, ENOENT);
 		}
 		xfer_id = getNextID();
-		((LLXfer_File *)xferp)->initializeRequest(
+		((LLXfer_File *)file_xfer_p)->initializeRequest(
 			xfer_id,
 			local_filename,
 			remote_filename,
@@ -500,28 +476,32 @@ void LLXferManager::requestVFile(const LLUUID& local_id,
 								 void** user_data,
 								 BOOL is_priority)
 {
-	LLXfer *xferp;
+	LLXfer_VFile * xfer_p = NULL;
 
-	for (xferp = mReceiveList; xferp ; xferp = xferp->mNext)
+	for (xfer_list_t::iterator iter = mReceiveList.begin();
+			iter != mReceiveList.end(); ++iter)
 	{
-		if (xferp->getXferTypeTag() == LLXfer::XFER_VFILE
-			&& (((LLXfer_VFile*)xferp)->matchesLocalFile(local_id, type))
-			&& (((LLXfer_VFile*)xferp)->matchesRemoteFile(remote_id, type))
-			&& (remote_host == xferp->mRemoteHost)
-			&& (callback == xferp->mCallback)
-			&& (user_data == xferp->mCallbackDataHandle))
-
+		if ((*iter)->getXferTypeTag() == LLXfer::XFER_VFILE)
 		{
-			// cout << "requested a xfer already in progress" << endl;
-			return;
+			xfer_p = (LLXfer_VFile*) (*iter);
+			if (xfer_p->matchesLocalFile(local_id, type)
+				&& xfer_p->matchesRemoteFile(remote_id, type)
+				&& (remote_host == xfer_p->mRemoteHost)
+				&& (callback == xfer_p->mCallback)
+				&& (user_data == xfer_p->mCallbackDataHandle))
+
+			{
+				// Have match, already in progress, don't add a duplicate
+				return;
+			}
 		}
 	}
 
-	xferp = (LLXfer *) new LLXfer_VFile();
-	if (xferp)
+	xfer_p = new LLXfer_VFile();
+	if (xfer_p)
 	{
-		addToList(xferp, mReceiveList, is_priority);
-		((LLXfer_VFile *)xferp)->initializeRequest(getNextID(),
+		addToList(xfer_p, mReceiveList, is_priority);
+		((LLXfer_VFile *)xfer_p)->initializeRequest(getNextID(),
 			vfs,
 			local_id,
 			remote_id,
@@ -663,7 +643,7 @@ void LLXferManager::processReceiveData (LLMessageSystem *mesgsys, void ** /*user
 	if (result == LL_ERR_CANNOT_OPEN_FILE)
 	{
 			xferp->abort(LL_ERR_CANNOT_OPEN_FILE);
-			removeXfer(xferp,&mReceiveList);
+			removeXfer(xferp,mReceiveList);
 			startPendingDownloads();
 			return;		
 	}
@@ -688,7 +668,7 @@ void LLXferManager::processReceiveData (LLMessageSystem *mesgsys, void ** /*user
 	if (isLastPacket(packetnum))
 	{
 		xferp->processEOF();
-		removeXfer(xferp,&mReceiveList);
+		removeXfer(xferp,mReceiveList);
 		startPendingDownloads();
 	}
 }
@@ -708,6 +688,7 @@ void LLXferManager::sendConfirmPacket (LLMessageSystem *mesgsys, U64 id, S32 pac
 	mesgsys->addU64Fast(_PREHASH_ID, id);
 	mesgsys->addU32Fast(_PREHASH_Packet, packetnum);
 
+	// Ignore a circuit failure here, we'll catch it with another message
 	mesgsys->sendMessage(remote_host);
 }
 
@@ -825,7 +806,7 @@ void LLXferManager::processFileRequest (LLMessageSystem *mesgsys, void ** /*user
 	LLXfer *xferp;
 
 	if (uuid != LLUUID::null)
-	{
+	{	// Request for an asset - use a VFS file
 		if(NULL == LLAssetType::lookup(type))
 		{
 			LL_WARNS() << "Invalid type for xfer request: " << uuid << ":"
@@ -844,8 +825,7 @@ void LLXferManager::processFileRequest (LLMessageSystem *mesgsys, void ** /*user
 		xferp = (LLXfer *)new LLXfer_VFile(mVFS, uuid, type);
 		if (xferp)
 		{
-			xferp->mNext = mSendList;
-			mSendList = xferp;	
+			mSendList.push_front(xferp);
 			result = xferp->startSend(id,mesgsys->getSender());
 		}
 		else
@@ -854,7 +834,7 @@ void LLXferManager::processFileRequest (LLMessageSystem *mesgsys, void ** /*user
 		}
 	}
 	else if (!local_filename.empty())
-	{
+	{	// Was given a file name to send
 		// See DEV-21775 for detailed security issues
 
 		if (local_path == LL_PATH_NONE)
@@ -912,8 +892,7 @@ void LLXferManager::processFileRequest (LLMessageSystem *mesgsys, void ** /*user
 		
 		if (xferp)
 		{
-			xferp->mNext = mSendList;
-			mSendList = xferp;	
+			mSendList.push_front(xferp);
 			result = xferp->startSend(id,mesgsys->getSender());
 		}
 		else
@@ -922,7 +901,7 @@ void LLXferManager::processFileRequest (LLMessageSystem *mesgsys, void ** /*user
 		}
 	}
 	else
-	{
+	{	// no uuid or filename - use the ID sent
 		char U64_BUF[MAX_STRING];		/* Flawfinder : ignore */
 		LL_INFOS() << "starting memory transfer: "
 			<< U64_to_str(id, U64_BUF, sizeof(U64_BUF)) << " to "
@@ -946,7 +925,7 @@ void LLXferManager::processFileRequest (LLMessageSystem *mesgsys, void ** /*user
 		if (xferp)
 		{
 			xferp->abort(result);
-			removeXfer(xferp,&mSendList);
+			removeXfer(xferp, mSendList);
 		}
 		else // can happen with a memory transfer not found
 		{
@@ -960,24 +939,86 @@ void LLXferManager::processFileRequest (LLMessageSystem *mesgsys, void ** /*user
 			mesgsys->sendMessage(mesgsys->getSender());		
 		}
 	}
-	else if(xferp && (numActiveXfers(xferp->mRemoteHost) < mMaxOutgoingXfersPerCircuit))
-	{
-		xferp->sendNextPacket();
-		changeNumActiveXfers(xferp->mRemoteHost,1);
-//		LL_INFOS() << "***STARTING XFER IMMEDIATELY***" << LL_ENDL;
-	}
-	else
+	else if(xferp)
 	{
-		if(xferp)
+		// Figure out how many transfers the host has requested
+		LLHostStatus *host_statusp = findHostStatus(xferp->mRemoteHost);
+		if (host_statusp)
 		{
-			LL_INFOS() << "  queueing xfer request, " << numPendingXfers(xferp->mRemoteHost) << " ahead of this one" << LL_ENDL;
+			if (host_statusp->mNumActive < mMaxOutgoingXfersPerCircuit)
+			{	// Not many transfers in progress already, so start immediately
+				xferp->sendNextPacket();
+				changeNumActiveXfers(xferp->mRemoteHost,1);
+				LL_DEBUGS("Xfer") << "Starting xfer ID " << U64_to_str(id) << " immediately" << LL_ENDL;
+			}
+			else if (mHardLimitOutgoingXfersPerCircuit == 0 ||
+				     (host_statusp->mNumActive + host_statusp->mNumPending) < mHardLimitOutgoingXfersPerCircuit)
+			{	// Must close the file handle and wait for earlier ones to complete
+				LL_INFOS("Xfer") << "  queueing xfer request id " << U64_to_str(id) << ", " 
+								 << host_statusp->mNumActive << " active and "
+								 << host_statusp->mNumPending << " pending ahead of this one" 
+								 << LL_ENDL;
+				xferp->closeFileHandle();	// Close the file handle until we're ready to send again
+			}
+			else if (mHardLimitOutgoingXfersPerCircuit > 0)
+			{	// Way too many requested ... it's time to stop being nice and kill the circuit
+				xferp->closeFileHandle();	// Close the file handle in any case
+				LLCircuitData *cdp = gMessageSystem->mCircuitInfo.findCircuit(xferp->mRemoteHost);
+				if (cdp)
+				{
+					if (cdp->getTrusted())
+					{	// Trusted internal circuit - don't kill it
+						LL_WARNS("Xfer") << "Trusted circuit to " << xferp->mRemoteHost << " has too many xfer requests in the queue " 
+										<< host_statusp->mNumActive << " active and "
+										<< host_statusp->mNumPending << " pending ahead of this one" 
+										<< LL_ENDL;
+					}
+					else
+					{	// Untrusted circuit - time to stop messing around and kill it
+						LL_WARNS("Xfer") << "Killing circuit to " << xferp->mRemoteHost << " for having too many xfer requests in the queue " 
+										<< host_statusp->mNumActive << " active and "
+										<< host_statusp->mNumPending << " pending ahead of this one" 
+										<< LL_ENDL;
+						gMessageSystem->disableCircuit(xferp->mRemoteHost);
+					}
+				}
+				else
+				{	// WTF?   Why can't we find a circuit?  Try to kill it off
+					LL_WARNS("Xfer") << "Backlog with circuit to " << xferp->mRemoteHost << " with too many xfer requests in the queue " 
+									<< host_statusp->mNumActive << " active and "
+									<< host_statusp->mNumPending << " pending ahead of this one" 
+									<< " but no LLCircuitData found???"
+									<< LL_ENDL;
+					gMessageSystem->disableCircuit(xferp->mRemoteHost);
+				}
+			}
 		}
 		else
 		{
-			LL_WARNS() << "LLXferManager::processFileRequest() - no xfer found!"
-					<< LL_ENDL;
+			LL_WARNS("Xfer") << "LLXferManager::processFileRequest() - no LLHostStatus found for id " << U64_to_str(id)	
+				<< " host " << xferp->mRemoteHost << LL_ENDL;
 		}
 	}
+	else
+	{
+		LL_WARNS("Xfer") << "LLXferManager::processFileRequest() - no xfer found for id " << U64_to_str(id)	<< LL_ENDL;
+	}
+}
+ 
+///////////////////////////////////////////////////////////
+
+// Return true if host is in a transfer-flood sitation.  Same check for both internal and external hosts
+bool LLXferManager::isHostFlooded(const LLHost & host)
+{
+	bool flooded = false;
+	LLHostStatus *host_statusp = findHostStatus(host);
+	if (host_statusp)
+	{
+		flooded = (mHardLimitOutgoingXfersPerCircuit > 0 &&
+				    (host_statusp->mNumActive + host_statusp->mNumPending) >= (S32)(mHardLimitOutgoingXfersPerCircuit * 0.8f));
+	}
+
+	return flooded;
 }
 
 
@@ -1002,52 +1043,57 @@ void LLXferManager::processConfirmation (LLMessageSystem *mesgsys, void ** /*use
 		}
 		else
 		{
-			removeXfer(xferp, &mSendList);
+			removeXfer(xferp, mSendList);
 		}
 	}
 }
 
 ///////////////////////////////////////////////////////////
 
-void LLXferManager::retransmitUnackedPackets ()
+void LLXferManager::retransmitUnackedPackets()
 {
 	LLXfer *xferp;
-	LLXfer *delp;
-	xferp = mReceiveList;
-	while(xferp)
+
+	xfer_list_t::iterator iter = mReceiveList.begin();
+	while (iter != mReceiveList.end())
 	{
+		xferp = (*iter);
 		if (xferp->mStatus == e_LL_XFER_IN_PROGRESS)
 		{
 			// if the circuit dies, abort
 			if (! gMessageSystem->mCircuitInfo.isCircuitAlive( xferp->mRemoteHost ))
 			{
-				LL_INFOS() << "Xfer found in progress on dead circuit, aborting" << LL_ENDL;
+				LL_WARNS("Xfer") << "Xfer found in progress on dead circuit, aborting transfer to " 
+					<< xferp->mRemoteHost.getIPandPort()
+					<< LL_ENDL;
 				xferp->mCallbackResult = LL_ERR_CIRCUIT_GONE;
 				xferp->processEOF();
-				delp = xferp;
-				xferp = xferp->mNext;
-				removeXfer(delp,&mReceiveList);
+
+				iter = mReceiveList.erase(iter);	// iter is set to next one after the deletion point
+				delete (xferp);
 				continue;
  			}
 				
 		}
-		xferp = xferp->mNext;
+		++iter;
 	}
 
-	xferp = mSendList; 
 	updateHostStatus();
+
 	F32 et;
-	while (xferp)
+	iter = mSendList.begin();
+	while (iter != mSendList.end())
 	{
+		xferp = (*iter);
 		if (xferp->mWaitingForACK && ( (et = xferp->ACKTimer.getElapsedTimeF32()) > LL_PACKET_TIMEOUT))
 		{
 			if (xferp->mRetries > LL_PACKET_RETRY_LIMIT)
 			{
 				LL_INFOS() << "dropping xfer " << xferp->mRemoteHost << ":" << xferp->getFileName() << " packet retransmit limit exceeded, xfer dropped" << LL_ENDL;
 				xferp->abort(LL_ERR_TCP_TIMEOUT);
-				delp = xferp;
-				xferp = xferp->mNext;
-				removeXfer(delp,&mSendList);
+				iter = mSendList.erase(iter);
+				delete xferp;
+				continue;
 			}
 			else
 			{
@@ -1060,25 +1106,37 @@ void LLXferManager::retransmitUnackedPackets ()
 		{
 			LL_INFOS() << "registered xfer never requested, xfer dropped" << LL_ENDL;
 			xferp->abort(LL_ERR_TCP_TIMEOUT);
-			delp = xferp;
-			xferp = xferp->mNext;
-			removeXfer(delp,&mSendList);
+			iter = mSendList.erase(iter);
+			delete xferp;
+			continue;
 		}
 		else if (xferp->mStatus == e_LL_XFER_ABORTED)
 		{
 			LL_WARNS() << "Removing aborted xfer " << xferp->mRemoteHost << ":" << xferp->getFileName() << LL_ENDL;
-			delp = xferp;
-			xferp = xferp->mNext;
-			removeXfer(delp,&mSendList);
+			iter = mSendList.erase(iter);
+			delete xferp;
+			continue;
 		}
 		else if (xferp->mStatus == e_LL_XFER_PENDING)
 		{
 //			LL_INFOS() << "*** numActiveXfers = " << numActiveXfers(xferp->mRemoteHost) << "        mMaxOutgoingXfersPerCircuit = " << mMaxOutgoingXfersPerCircuit << LL_ENDL;   
 			if (numActiveXfers(xferp->mRemoteHost) < mMaxOutgoingXfersPerCircuit)
 			{
-//			    LL_INFOS() << "bumping pending xfer to active" << LL_ENDL;
-				xferp->sendNextPacket();
-				changeNumActiveXfers(xferp->mRemoteHost,1);
+				if (xferp->reopenFileHandle())
+				{
+					LL_WARNS("Xfer") << "Error re-opening file handle for xfer ID " << U64_to_str(xferp->mID)
+						<< " to host " << xferp->mRemoteHost << LL_ENDL;
+					xferp->abort(LL_ERR_CANNOT_OPEN_FILE);
+					iter = mSendList.erase(iter);
+					delete xferp;
+					continue;
+				}
+				else
+				{	// No error re-opening the file, send the first packet
+					LL_DEBUGS("Xfer") << "Moving pending xfer ID " << U64_to_str(xferp->mID) << " to active" << LL_ENDL;
+					xferp->sendNextPacket();
+					changeNumActiveXfers(xferp->mRemoteHost,1);
+				}
 			}			
 			xferp = xferp->mNext;
 		}
@@ -1124,7 +1182,7 @@ void LLXferManager::abortRequestById(U64 xfer_id, S32 result_code)
 		{
 			xferp->mCallbackResult = result_code;
 			xferp->processEOF(); //should notify requester
-			removeXfer(xferp, &mReceiveList);
+			removeXfer(xferp, mReceiveList);
 		}
 		// Since already removed or marked as aborted no need
 		// to wait for processAbort() to start new download
@@ -1148,7 +1206,7 @@ void LLXferManager::processAbort (LLMessageSystem *mesgsys, void ** /*user_data*
 	{
 		xferp->mCallbackResult = result_code;
 		xferp->processEOF();
-		removeXfer(xferp, &mReceiveList);
+		removeXfer(xferp, mReceiveList);
 		startPendingDownloads();
 	}
 }
@@ -1164,12 +1222,15 @@ void LLXferManager::startPendingDownloads()
 	// requests get pushed toward the back. Thus, if we didn't do a
 	// stateful iteration, it would be possible for old requests to
 	// never start.
-	LLXfer* xferp = mReceiveList;
+	LLXfer* xferp;
 	std::list<LLXfer*> pending_downloads;
 	S32 download_count = 0;
 	S32 pending_count = 0;
-	while(xferp)
+	for (xfer_list_t::iterator iter = mReceiveList.begin();
+		 iter != mReceiveList.end();
+		 ++iter)
 	{
+		xferp = (*iter);
 		if(xferp->mStatus == e_LL_XFER_PENDING)
 		{
 			++pending_count;
@@ -1209,29 +1270,15 @@ void LLXferManager::startPendingDownloads()
 
 ///////////////////////////////////////////////////////////
 
-void LLXferManager::addToList(LLXfer* xferp, LLXfer*& head, BOOL is_priority)
+void LLXferManager::addToList(LLXfer* xferp, xfer_list_t & xfer_list, BOOL is_priority)
 {
 	if(is_priority)
 	{
-		xferp->mNext = NULL;
-		LLXfer* next = head;
-		if(next)
-		{
-			while(next->mNext)
-			{
-				next = next->mNext;
-			}
-			next->mNext = xferp;
-		}
-		else
-		{
-			head = xferp;
-		}
+		xfer_list.push_back(xferp);
 	}
 	else
 	{
-		xferp->mNext = head;
-		head = xferp;
+		xfer_list.push_front(xferp);
 	}
 }
 
diff --git a/indra/llmessage/llxfermanager.h b/indra/llmessage/llxfermanager.h
index d258f0a5ce..ebe8e57ee2 100644
--- a/indra/llmessage/llxfermanager.h
+++ b/indra/llmessage/llxfermanager.h
@@ -77,6 +77,7 @@ class LLXferManager
 
  protected:
 	S32    mMaxOutgoingXfersPerCircuit;
+	S32    mHardLimitOutgoingXfersPerCircuit;	// At this limit, kill off the connection
 	S32    mMaxIncomingXfers;
 
 	BOOL	mUseAckThrottling; // Use ack throttling to cap file xfer bandwidth
@@ -92,8 +93,10 @@ class LLXferManager
 		HIGH_PRIORITY = TRUE,
 	};
 
-	LLXfer *mSendList;
-	LLXfer *mReceiveList;
+	// Linked FIFO list, add to the front and pull from back
+	typedef std::deque<LLXfer *> xfer_list_t;
+	xfer_list_t mSendList;
+	xfer_list_t mReceiveList;
 
 	typedef std::list<LLHostStatus*> status_list_t;
 	status_list_t mOutgoingHosts;
@@ -102,7 +105,7 @@ class LLXferManager
  protected:
 	// implementation methods
 	virtual void startPendingDownloads();
-	virtual void addToList(LLXfer* xferp, LLXfer*& head, BOOL is_priority);
+	virtual void addToList(LLXfer* xferp, xfer_list_t & list, BOOL is_priority);
 	std::multiset<std::string> mExpectedTransfers; // files that are authorized to transfer out
 	std::multiset<std::string> mExpectedRequests;  // files that are authorized to be downloaded on top of
 
@@ -117,14 +120,18 @@ class LLXferManager
 	void setAckThrottleBPS(const F32 bps);
 
 // list management routines
-	virtual LLXfer *findXfer(U64 id, LLXfer *list_head);
-	virtual void removeXfer (LLXfer *delp, LLXfer **list_head);
+	virtual LLXfer *findXfer(U64 id, xfer_list_t & xfer_list);
+	virtual void removeXfer (LLXfer *delp, xfer_list_t & xfer_list);
+
+	LLHostStatus * findHostStatus(const LLHost &host);
 	virtual U32 numActiveListEntries(LLXfer *list_head);
 	virtual S32 numActiveXfers(const LLHost &host);
 	virtual S32 numPendingXfers(const LLHost &host);
+
 	virtual void changeNumActiveXfers(const LLHost &host, S32 delta);
 
 	virtual void setMaxOutgoingXfersPerCircuit (S32 max_num);
+	virtual void setHardLimitOutgoingXfersPerCircuit(S32 max_num);
 	virtual void setMaxIncomingXfers(S32 max_num);
 	virtual void updateHostStatus();
 	virtual void printHostStatus();
@@ -136,8 +143,6 @@ class LLXferManager
 	virtual S32 decodePacketNum(S32 packet_num);	
 	virtual BOOL isLastPacket(S32 packet_num);
 
-	virtual U64 registerXfer(const void *datap, const S32 length);
-
 // file requesting routines
 // .. to file
 	virtual U64 requestFile(const std::string& local_filename,
@@ -204,6 +209,8 @@ class LLXferManager
 // error handling
 	void abortRequestById(U64 xfer_id, S32 result_code);
 	virtual void processAbort (LLMessageSystem *mesgsys, void **user_data);
+
+	virtual bool isHostFlooded(const LLHost & host);
 };
 
 extern LLXferManager*	gXferManager;