SH-4310/BUG-2810/MAINT-2794 Better status checking and error logging in Mesh code.

Pay correct attention to status codes coming back from services.  Generate
better and consistent error messages when problems arise.  There's more to
do in error handling, need a way to cleanly fail all request types, only
have that for LOD at this point.  Do better keeping the HTTP pipeline between
the low and high water marks.  This was made challenging because the outer
most code couldn't really see what's going on internally (whose actions are
delayed in a worker thread).  More to do here, the debug-like requests don't
honor limits, that will come later.  Made retry counts available from llcorehttp
which can be used by the throttle-anticipating logic to advance the count.
It helps but it reinforces the coupling between viewer and server which I
do not like.

3 files changed, 244 insertions, 126 deletions

diff --git a/indra/llcorehttp/httpresponse.h b/indra/llcorehttp/httpresponse.h
index a7f296e03f..bb4b59c16e 100755
--- a/indra/llcorehttp/httpresponse.h
+++ b/indra/llcorehttp/httpresponse.h
@@ -147,8 +147,14 @@ public:
 	/// Get and set retry attempt information on the request.
 	void getRetries(unsigned int * retries, unsigned int * retries_503) const
 		{
-			*retries = mRetries;
-			*retries_503 = m503Retries;
+			if (retries)
+			{
+				*retries = mRetries;
+			}
+			if (retries_503)
+			{
+				*retries_503 = m503Retries;
+			}
 		}
 
 	void setRetries(unsigned int retries, unsigned int retries_503)
diff --git a/indra/newview/llmeshrepository.cpp b/indra/newview/llmeshrepository.cpp
index 1cda0b6a71..a86f0e86f1 100755
--- a/indra/newview/llmeshrepository.cpp
+++ b/indra/newview/llmeshrepository.cpp
@@ -78,10 +78,12 @@
 
 LLMeshRepository gMeshRepo;
 
-const S32 MESH_HEADER_SIZE = 4096;
+const S32 MESH_HEADER_SIZE = 4096;						// Important:  assumption is that headers fit in this space
 const U32 MAX_MESH_REQUESTS_PER_SECOND = 100;
 const S32 REQUEST_HIGH_WATER_MIN = 32;
+const S32 REQUEST_HIGH_WATER_MAX = 80;
 const S32 REQUEST_LOW_WATER_MIN = 16;
+const S32 REQUEST_LOW_WATER_MAX = 40;
 const U32 LARGE_MESH_FETCH_THRESHOLD = 1U << 21;		// Size at which requests goes to narrow/slow queue
 const long LARGE_MESH_XFER_TIMEOUT = 240L;				// Seconds to complete xfer
 
@@ -122,6 +124,7 @@ const std::string header_lod[] =
 	"medium_lod",
 	"high_lod"
 };
+const char * const LOG_MESH = "Mesh";
 
 // Static data and functions to measure mesh load
 // time metrics for a new region scene.
@@ -211,12 +214,21 @@ void get_vertex_buffer_from_mesh(LLCDMeshData& mesh, LLModel::PhysicsMesh& res,
 	}
 }
 
-S32 LLMeshRepoThread::sActiveHeaderRequests = 0;
-S32 LLMeshRepoThread::sActiveLODRequests = 0;
+volatile S32 LLMeshRepoThread::sActiveHeaderRequests = 0;
+volatile S32 LLMeshRepoThread::sActiveLODRequests = 0;
 U32	LLMeshRepoThread::sMaxConcurrentRequests = 1;
 S32 LLMeshRepoThread::sRequestLowWater = REQUEST_LOW_WATER_MIN;
 S32 LLMeshRepoThread::sRequestHighWater = REQUEST_HIGH_WATER_MIN;
 
+// Base handler class for all mesh users of llcorehttp.
+// This is roughly equivalent to a Responder class in
+// traditional LL code.  The base is going to perform
+// common response/data handling in the inherited
+// onCompleted() method.  Derived classes, one for each
+// type of HTTP action, define processData() and
+// processFailure() methods to customize handling and
+// error messages.
+//
 class LLMeshHandlerBase : public LLCore::HttpHandler
 {
 public:
@@ -225,8 +237,10 @@ public:
 		  mMeshParams(),
 		  mProcessed(false),
 		  mHttpHandle(LLCORE_HTTP_HANDLE_INVALID)
-	{}
-	virtual ~LLMeshHandlerBase();
+		{}
+
+	virtual ~LLMeshHandlerBase()
+		{}
 
 protected:
 	LLMeshHandlerBase(const LLMeshHandlerBase &);				// Not defined
@@ -244,6 +258,9 @@ public:
 };
 
 
+// Subclass for header fetches.
+//
+// Thread:  repo
 class LLMeshHeaderHandler : public LLMeshHandlerBase
 {
 public:
@@ -265,6 +282,9 @@ public:
 };
 
 
+// Subclass for LOD fetches.
+//
+// Thread:  repo
 class LLMeshLODHandler : public LLMeshHandlerBase
 {
 public:
@@ -294,6 +314,9 @@ public:
 };
 
 
+// Subclass for skin info fetches.
+//
+// Thread:  repo
 class LLMeshSkinInfoHandler : public LLMeshHandlerBase
 {
 public:
@@ -320,6 +343,9 @@ public:
 };
 
 
+// Subclass for decomposition fetches.
+//
+// Thread:  repo
 class LLMeshDecompositionHandler : public LLMeshHandlerBase
 {
 public:
@@ -346,6 +372,9 @@ public:
 };
 
 
+// Subclass for physics shape fetches.
+//
+// Thread:  repo
 class LLMeshPhysicsShapeHandler : public LLMeshHandlerBase
 {
 public:
@@ -371,6 +400,7 @@ public:
 	U32			mOffset;
 };
 
+
 void log_upload_error(S32 status, const LLSD& content, std::string stage, std::string model_name)
 {
 	// Add notification popup.
@@ -555,6 +585,7 @@ public:
 LLMeshRepoThread::LLMeshRepoThread()
 : LLThread("mesh repo"),
   mWaiting(false),
+  mHttpRetries(0U),
   mHttpRequest(NULL),
   mHttpOptions(NULL),
   mHttpLargeOptions(NULL),
@@ -583,9 +614,9 @@ LLMeshRepoThread::LLMeshRepoThread()
 
 LLMeshRepoThread::~LLMeshRepoThread()
 {
-	LL_INFOS("Mesh") << "Small GETs issued:  "
-					 << mHttpGetCount << ", Large GETs issued:  "
-					 << mHttpLargeGetCount << LL_ENDL;
+	LL_INFOS(LOG_MESH) << "Small GETs issued:  " << mHttpGetCount
+					   << ", Large GETs issued:  " << mHttpLargeGetCount
+					   << LL_ENDL;
 
 	for (http_request_set::iterator iter(mHttpRequestSet.begin());
 		 iter != mHttpRequestSet.end();
@@ -631,10 +662,12 @@ void LLMeshRepoThread::run()
 	{
 		if (! mHttpRequestSet.empty())
 		{
+			// Dispatch all HttpHandler notifications
 			mHttpRequest->update(0L);
 		}
 
 		mWaiting = true;
+		ms_sleep(5);
 		mSignal->wait();
 		mWaiting = false;
 		
@@ -648,42 +681,49 @@ void LLMeshRepoThread::run()
 				last_hundred = gFrameTimeSeconds;
 				count = 0;
 			}
-
+			else
+			{
+				count += mHttpRetries;
+			}
+			mHttpRetries = 0U;
+			
 			// NOTE: throttling intentionally favors LOD requests over header requests
 			
-			while (!mLODReqQ.empty() && count < MAX_MESH_REQUESTS_PER_SECOND)
+			while (!mLODReqQ.empty() && count < MAX_MESH_REQUESTS_PER_SECOND && mHttpRequestSet.size() < sRequestHighWater)
 			{
-				if (mMutex)
+				if (! mMutex)
+				{
+					break;
+				}
+				mMutex->lock();
+				LODRequest req = mLODReqQ.front();
+				mLODReqQ.pop();
+				LLMeshRepository::sLODProcessing--;
+				mMutex->unlock();
+				if (!fetchMeshLOD(req.mMeshParams, req.mLOD, count))//failed, resubmit
 				{
 					mMutex->lock();
-					LODRequest req = mLODReqQ.front();
-					mLODReqQ.pop();
-					LLMeshRepository::sLODProcessing--;
+					mLODReqQ.push(req) ; 
+					++LLMeshRepository::sLODProcessing;
 					mMutex->unlock();
-					if (!fetchMeshLOD(req.mMeshParams, req.mLOD, count))//failed, resubmit
-					{
-						mMutex->lock();
-						mLODReqQ.push(req) ; 
-						++LLMeshRepository::sLODProcessing;
-						mMutex->unlock();
-					}
 				}
 			}
 
-			while (!mHeaderReqQ.empty() && count < MAX_MESH_REQUESTS_PER_SECOND)
+			while (!mHeaderReqQ.empty() && count < MAX_MESH_REQUESTS_PER_SECOND && mHttpRequestSet.size() < sRequestHighWater)
 			{
-				if (mMutex)
+				if (! mMutex)
+				{
+					break;
+				}
+				mMutex->lock();
+				HeaderRequest req = mHeaderReqQ.front();
+				mHeaderReqQ.pop();
+				mMutex->unlock();
+				if (!fetchMeshHeader(req.mMeshParams, count))//failed, resubmit
 				{
 					mMutex->lock();
-					HeaderRequest req = mHeaderReqQ.front();
-					mHeaderReqQ.pop();
+					mHeaderReqQ.push(req) ;
 					mMutex->unlock();
-					if (!fetchMeshHeader(req.mMeshParams, count))//failed, resubmit
-					{
-						mMutex->lock();
-						mHeaderReqQ.push(req) ;
-						mMutex->unlock();
-					}
 				}
 			}
 
@@ -697,7 +737,7 @@ void LLMeshRepoThread::run()
 						incomplete.insert(mesh_id);
 					}
 				}
-				mSkinRequests = incomplete;
+				mSkinRequests.swap(incomplete);
 			}
 
 			{ //mDecompositionRequests is protected by mSignal
@@ -710,7 +750,7 @@ void LLMeshRepoThread::run()
 						incomplete.insert(mesh_id);
 					}
 				}
-				mDecompositionRequests = incomplete;
+				mDecompositionRequests.swap(incomplete);
 			}
 
 			{ //mPhysicsShapeRequests is protected by mSignal
@@ -723,7 +763,7 @@ void LLMeshRepoThread::run()
 						incomplete.insert(mesh_id);
 					}
 				}
-				mPhysicsShapeRequests = incomplete;
+				mPhysicsShapeRequests.swap(incomplete);
 			}
 		}
 	}
@@ -796,6 +836,10 @@ void LLMeshRepoThread::loadMeshLOD(const LLVolumeParams& mesh_params, S32 lod)
 	}
 }
 
+// Constructs a Cap URL for the mesh.  Prefers a GetMesh2 cap
+// over a GetMesh cap and returns what it finds to the caller
+// as an int ([1..2]).
+//
 //static 
 std::string LLMeshRepoThread::constructUrl(LLUUID mesh_id, int * cap_version)
 {
@@ -822,14 +866,26 @@ std::string LLMeshRepoThread::constructUrl(LLUUID mesh_id, int * cap_version)
 	}
 	else
 	{
-		llwarns << "Current region does not have GetMesh capability!  Cannot load " << mesh_id << ".mesh" << llendl;
+		LL_WARNS_ONCE(LOG_MESH) << "Current region does not have GetMesh capability!  Cannot load "
+								<< mesh_id << ".mesh" << LL_ENDL;
 	}
 
 	*cap_version = version;
 	return http_url;
 }
 
-// May only be called by repo thread
+// Issue an HTTP GET request with byte range using the right
+// policy class.  Large requests go to the large request class.
+// If the current region supports GetMesh2, we prefer that for
+// smaller requests otherwise we try to use the traditional
+// GetMesh capability and connection concurrency.
+//
+// @return		Valid handle or LLCORE_HTTP_HANDLE_INVALID.
+//				If the latter, actual status is found in
+//				mHttpStatus member which is valid until the
+//				next call to this method.
+//
+// Thread:  repo
 LLCore::HttpHandle LLMeshRepoThread::getByteRange(const std::string & url, int cap_version,
 												  size_t offset, size_t len,
 												  LLCore::HttpHandler * handler)
@@ -862,6 +918,11 @@ LLCore::HttpHandle LLMeshRepoThread::getByteRange(const std::string & url, int c
 												   handler);
 		++mHttpLargeGetCount;
 	}
+	if (LLCORE_HTTP_HANDLE_INVALID == handle)
+	{
+		// Something went wrong, capture the error code for caller.
+		mHttpStatus = mHttpRequest->getStatus();
+	}
 	return handle;
 }
 
@@ -929,12 +990,13 @@ bool LLMeshRepoThread::fetchMeshSkinInfo(const LLUUID& mesh_id)
 			if (!http_url.empty())
 			{
 				LLMeshSkinInfoHandler * handler = new LLMeshSkinInfoHandler(mesh_id, offset, size);
-				// LL_WARNS("Mesh") << "MESH:  Issuing Skin Info Request" << LL_ENDL;
 				LLCore::HttpHandle handle = getByteRange(http_url, cap_version, offset, size, handler);
 				if (LLCORE_HTTP_HANDLE_INVALID == handle)
 				{
-					// *TODO:  Better error message
-					llwarns << "HTTP GET request failed for mesh " << mID << llendl;
+					LL_WARNS(LOG_MESH) << "HTTP GET request failed for skin info on mesh " << mID
+									   << ".  Reason:  " << mHttpStatus.toString()
+									   << " (" << mHttpStatus.toHex() << ")"
+									   << LL_ENDL;
 					delete handler;
 					ret = false;
 				}
@@ -1019,12 +1081,13 @@ bool LLMeshRepoThread::fetchMeshDecomposition(const LLUUID& mesh_id)
 			if (!http_url.empty())
 			{
 				LLMeshDecompositionHandler * handler = new LLMeshDecompositionHandler(mesh_id, offset, size);
-				// LL_WARNS("Mesh") << "MESH:  Issuing Decomp Request" << LL_ENDL;
 				LLCore::HttpHandle handle = getByteRange(http_url, cap_version, offset, size, handler);
 				if (LLCORE_HTTP_HANDLE_INVALID == handle)
 				{
-					// *TODO:  Better error message
-					llwarns << "HTTP GET request failed for decomposition mesh " << mID << llendl;
+					LL_WARNS(LOG_MESH) << "HTTP GET request failed for decomposition mesh " << mID
+									   << ".  Reason:  " << mHttpStatus.toString()
+									   << " (" << mHttpStatus.toHex() << ")"
+									   << LL_ENDL;
 					delete handler;
 					ret = false;
 				}
@@ -1108,12 +1171,13 @@ bool LLMeshRepoThread::fetchMeshPhysicsShape(const LLUUID& mesh_id)
 			if (!http_url.empty())
 			{
 				LLMeshPhysicsShapeHandler * handler = new LLMeshPhysicsShapeHandler(mesh_id, offset, size);
-				// LL_WARNS("Mesh") << "MESH:  Issuing Physics Shape Request" << LL_ENDL;
 				LLCore::HttpHandle handle = getByteRange(http_url, cap_version, offset, size, handler);
 				if (LLCORE_HTTP_HANDLE_INVALID == handle)
 				{
-					// *TODO:  Better error message
-					llwarns << "HTTP GET request failed for physics shape mesh " << mID << llendl;
+					LL_WARNS(LOG_MESH) << "HTTP GET request failed for physics shape on mesh " << mID
+									   << ".  Reason:  " << mHttpStatus.toString()
+									   << " (" << mHttpStatus.toHex() << ")"
+									   << LL_ENDL;
 					delete handler;
 					ret = false;
 				}
@@ -1192,7 +1256,7 @@ bool LLMeshRepoThread::fetchMeshHeader(const LLVolumeParams& mesh_params, U32& c
 	}
 
 	//either cache entry doesn't exist or is corrupt, request header from simulator	
-	bool retval = true ;
+	bool retval = true;
 	int cap_version(1);
 	std::string http_url = constructUrl(mesh_params.getSculptID(), &cap_version);
 	if (!http_url.empty())
@@ -1202,12 +1266,13 @@ bool LLMeshRepoThread::fetchMeshHeader(const LLVolumeParams& mesh_params, U32& c
 		//NOTE -- this will break of headers ever exceed 4KB		
 
 		LLMeshHeaderHandler * handler = new LLMeshHeaderHandler(mesh_params);
-		// LL_WARNS("Mesh") << "MESH:  Issuing Request" << LL_ENDL;
 		LLCore::HttpHandle handle = getByteRange(http_url, cap_version, 0, MESH_HEADER_SIZE, handler);
 		if (LLCORE_HTTP_HANDLE_INVALID == handle)
 		{
-			// *TODO:  Better error message
-			llwarns << "HTTP GET request failed for mesh " << mID << llendl;
+			LL_WARNS(LOG_MESH) << "HTTP GET request failed for mesh header " << mID
+							   << ".  Reason:  " << mHttpStatus.toString()
+							   << " (" << mHttpStatus.toHex() << ")"
+							   << LL_ENDL;
 			delete handler;
 			retval = false;
 		}
@@ -1216,8 +1281,8 @@ bool LLMeshRepoThread::fetchMeshHeader(const LLVolumeParams& mesh_params, U32& c
 			handler->mHttpHandle = handle;
 			mHttpRequestSet.insert(handler);
 			++LLMeshRepository::sHTTPRequestCount;
+			++count;
 		}
-		count++;
 	}
 
 	return retval;
@@ -1283,12 +1348,13 @@ bool LLMeshRepoThread::fetchMeshLOD(const LLVolumeParams& mesh_params, S32 lod,
 			if (!http_url.empty())
 			{
 				LLMeshLODHandler * handler = new LLMeshLODHandler(mesh_params, lod, offset, size);
-				// LL_WARNS("Mesh") << "MESH:  Issuing LOD Request" << LL_ENDL;
 				LLCore::HttpHandle handle = getByteRange(http_url, cap_version, offset, size, handler);
 				if (LLCORE_HTTP_HANDLE_INVALID == handle)
 				{
-					// *TODO:  Better error message
-					llwarns << "HTTP GET request failed for LOD mesh " << mID << llendl;
+					LL_WARNS(LOG_MESH) << "HTTP GET request failed for LOD on mesh " << mID
+									   << ".  Reason:  " << mHttpStatus.toString()
+									   << " (" << mHttpStatus.toHex() << ")"
+									   << LL_ENDL;
 					delete handler;
 					retval = false;
 				}
@@ -1297,8 +1363,8 @@ bool LLMeshRepoThread::fetchMeshLOD(const LLVolumeParams& mesh_params, S32 lod,
 					handler->mHttpHandle = handle;
 					mHttpRequestSet.insert(handler);
 					++LLMeshRepository::sHTTPRequestCount;
+					++count;
 				}
-				count++;
 			}
 			else
 			{
@@ -1320,6 +1386,7 @@ bool LLMeshRepoThread::fetchMeshLOD(const LLVolumeParams& mesh_params, S32 lod,
 
 bool LLMeshRepoThread::headerReceived(const LLVolumeParams& mesh_params, U8* data, S32 data_size)
 {
+	const LLUUID mesh_id = mesh_params.getSculptID();
 	LLSD header;
 	
 	U32 header_size = 0;
@@ -1340,7 +1407,8 @@ bool LLMeshRepoThread::headerReceived(const LLVolumeParams& mesh_params, U8* dat
 
 		if (!LLSDSerialize::fromBinary(header, stream, data_size))
 		{
-			llwarns << "Mesh header parse error.  Not a valid mesh asset!" << llendl;
+			LL_WARNS(LOG_MESH) << "Mesh header parse error.  Not a valid mesh asset!  ID:  " << mesh_id
+							   << LL_ENDL;
 			return false;
 		}
 
@@ -1348,13 +1416,12 @@ bool LLMeshRepoThread::headerReceived(const LLVolumeParams& mesh_params, U8* dat
 	}
 	else
 	{
-		llinfos
-			<< "Marking header as non-existent, will not retry." << llendl;
+		LL_INFOS(LOG_MESH) << "Non-positive data size.  Marking header as non-existent, will not retry.  ID:  " << mesh_id
+						   << LL_ENDL;
 		header["404"] = 1;
 	}
 
 	{
-		LLUUID mesh_id = mesh_params.getSculptID();
 		
 		{
 			LLMutexLock lock(mHeaderMutex);
@@ -1416,7 +1483,8 @@ bool LLMeshRepoThread::skinInfoReceived(const LLUUID& mesh_id, U8* data, S32 dat
 
 		if (!unzip_llsd(skin, stream, data_size))
 		{
-			llwarns << "Mesh skin info parse error.  Not a valid mesh asset!" << llendl;
+			LL_WARNS(LOG_MESH) << "Mesh skin info parse error.  Not a valid mesh asset!  ID:  " << mesh_id
+							   << LL_ENDL;
 			return false;
 		}
 	}
@@ -1444,7 +1512,8 @@ bool LLMeshRepoThread::decompositionReceived(const LLUUID& mesh_id, U8* data, S3
 
 		if (!unzip_llsd(decomp, stream, data_size))
 		{
-			llwarns << "Mesh decomposition parse error.  Not a valid mesh asset!" << llendl;
+			LL_WARNS(LOG_MESH) << "Mesh decomposition parse error.  Not a valid mesh asset!  ID:  " << mesh_id
+							   << LL_ENDL;
 			return false;
 		}
 	}
@@ -1860,7 +1929,8 @@ void LLMeshUploadThread::doWholeModelUpload()
 
 	if (mWholeModelUploadURL.empty())
 	{
-		llinfos << "unable to upload, fee request failed" << llendl;
+		LL_WARNS(LOG_MESH) << "Missing mesh upload capability, unable to upload, fee request failed."
+						   << LL_ENDL;
 	}
 	else
 	{
@@ -1941,6 +2011,12 @@ void LLMeshRepoThread::notifyLoadedMeshes()
 		return;
 	}
 
+	if (!mLoadedQ.empty() || !mUnavailableQ.empty())
+	{
+		// Ping time-to-load metrics for mesh download operations.
+		LLMeshRepository::metricsProgress(0);
+	}
+	
 	while (!mLoadedQ.empty())
 	{
 		mMutex->lock();
@@ -2058,12 +2134,17 @@ void LLMeshRepository::cacheOutgoingMesh(LLMeshUploadData& data, LLSD& header)
 
 }
 
-LLMeshHandlerBase::~LLMeshHandlerBase()
-{}
-
 void LLMeshHandlerBase::onCompleted(LLCore::HttpHandle handle, LLCore::HttpResponse * response)
 {
 	mProcessed = true;
+
+	// Accumulate retries, we'll use these to offset the HTTP
+	// count and maybe hold to a throttle better.
+	unsigned int retries(0U);
+	response->getRetries(NULL, &retries);
+	gMeshRepo.mThread->mHttpRetries += retries;
+	LLMeshRepository::sHTTPRetryCount += retries;
+
 	LLCore::HttpStatus status(response->getStatus());
 	if (! status)
 	{
@@ -2090,7 +2171,7 @@ void LLMeshHandlerBase::onCompleted(LLCore::HttpHandle handle, LLCore::HttpRespo
 			// that support BufferArray directly.
 			data = new U8[data_size];
 			body->read(0, (char *) data, data_size);
-			LLMeshRepository::sBytesReceived += llmin(data_size, MESH_HEADER_SIZE);
+			LLMeshRepository::sBytesReceived += data_size;
 		}
 
 		processData(body, data, data_size);
@@ -2100,7 +2181,6 @@ void LLMeshHandlerBase::onCompleted(LLCore::HttpHandle handle, LLCore::HttpRespo
 
 	// Release handler
 	gMeshRepo.mThread->mHttpRequestSet.erase(this);
-
 	delete this;		// Must be last statement
 }
 
@@ -2112,8 +2192,7 @@ LLMeshHeaderHandler::~LLMeshHeaderHandler()
 		if (! mProcessed)
 		{
 			// something went wrong, retry
-			llwarns << "Timeout or service unavailable, retrying." << llendl;
-			LLMeshRepository::sHTTPRetryCount++;
+			LL_WARNS(LOG_MESH) << "Mesh header fetch canceled unexpectedly, retrying." << LL_ENDL;
 			LLMeshRepoThread::HeaderRequest req(mMeshParams);
 			LLMutexLock lock(gMeshRepo.mThread->mMutex);
 			gMeshRepo.mThread->mHeaderReqQ.push(req);
@@ -2124,36 +2203,39 @@ LLMeshHeaderHandler::~LLMeshHeaderHandler()
 
 void LLMeshHeaderHandler::processFailure(LLCore::HttpStatus status)
 {
-	LL_WARNS("Mesh") << "MESH:  Processing Failure" << LL_ENDL;
 	if (is_retryable(status))
 	{
-		llwarns << "Timeout or service unavailable, retrying." << llendl;
-		LLMeshRepository::sHTTPRetryCount++;
+		LL_WARNS(LOG_MESH) << "Error during mesh header handling.  Reason:  " << status.toString()
+						   << " (" << status.toHex() << ").  Retrying."
+						   << LL_ENDL;
 		LLMeshRepoThread::HeaderRequest req(mMeshParams);
 		LLMutexLock lock(gMeshRepo.mThread->mMutex);
 		gMeshRepo.mThread->mHeaderReqQ.push(req);
 	}
 	else
 	{
-		// *TODO:  better error message
-		llwarns << "Unhandled status." << llendl;
+		// *TODO:  Mark mesh unavailable
+		LL_WARNS(LOG_MESH) << "Error during mesh header handling.  Reason:  " << status.toString()
+						   << " (" << status.toHex() << ").  Not retrying."
+						   << LL_ENDL;
 	}
 }
 
 void LLMeshHeaderHandler::processData(LLCore::BufferArray * body, U8 * data, S32 data_size)
 {
-	// LL_WARNS("Mesh") << "MESH:  Processing Data" << LL_ENDL;
+	LLUUID mesh_id = mMeshParams.getSculptID();
 	bool success = gMeshRepo.mThread->headerReceived(mMeshParams, data, data_size);
 	llassert(success);
 	if (! success)
 	{
+		// *TODO:  Mark mesh unavailable
 		// *TODO:  Get real reason for parse failure here
-		llwarns << "Unable to parse mesh header: " << llendl;
+		LL_WARNS(LOG_MESH) << "Unable to parse mesh header.  ID:  " << mesh_id
+						   << LL_ENDL;
 	}
 	else if (data && data_size > 0)
 	{
 		// header was successfully retrieved from sim, cache in vfs
-		LLUUID mesh_id = mMeshParams.getSculptID();
 		LLSD header = gMeshRepo.mThread->mMeshHeader[mesh_id];
 
 		S32 version = header["version"].asInteger();
@@ -2192,15 +2274,14 @@ void LLMeshHeaderHandler::processData(LLCore::BufferArray * body, U8 * data, S32
 			
 				// zero out the rest of the file 
 				U8 block[MESH_HEADER_SIZE];
-				memset(block, 0, MESH_HEADER_SIZE);
+				memset(block, 0, sizeof(block));
 
-				while (bytes-file.tell() > MESH_HEADER_SIZE)
+				while (bytes-file.tell() > sizeof(block))
 				{
-					file.write(block, MESH_HEADER_SIZE);
+					file.write(block, sizeof(block));
 				}
 
 				S32 remaining = bytes-file.tell();
-					
 				if (remaining > 0)
 				{
 					file.write(block, remaining);
@@ -2216,8 +2297,7 @@ LLMeshLODHandler::~LLMeshLODHandler()
 	{
 		if (! mProcessed)
 		{
-			llwarns << "Killed without being processed, retrying." << llendl;
-			LLMeshRepository::sHTTPRetryCount++;
+			LL_WARNS(LOG_MESH) << "Mesh LOD fetch canceled unexpectedly, retrying." << LL_ENDL;
 			gMeshRepo.mThread->lockAndLoadMeshLOD(mMeshParams, mLOD);
 		}
 		LLMeshRepoThread::decActiveLODRequests();
@@ -2228,15 +2308,21 @@ void LLMeshLODHandler::processFailure(LLCore::HttpStatus status)
 {
 	if (is_retryable(status))
 	{
-		llwarns << "Timeout or service unavailable, retrying." << llendl;
-		LLMeshRepository::sHTTPRetryCount++;
-		// *FIXME:  Is this safe?  Does this need locking?
-		gMeshRepo.mThread->loadMeshLOD(mMeshParams, mLOD);
+		LL_WARNS(LOG_MESH) << "Error during mesh header handling.  Reason:  " << status.toString()
+						   << " (" << status.toHex() << ").  Retrying."
+						   << LL_ENDL;
+		{
+			LLMutexLock lock(gMeshRepo.mThread->mMutex);
+
+			gMeshRepo.mThread->loadMeshLOD(mMeshParams, mLOD);
+		}
 	}
 	else
 	{
-		// *TODO:  better error message
-		llwarns << "Unhandled status." << llendl;
+		// *TODO:  Mark mesh unavailable
+		LL_WARNS(LOG_MESH) << "Error during mesh LOD handling.  Reason:  " << status.toString()
+						   << " (" << status.toHex() << ").  Not retrying."
+						   << LL_ENDL;
 	}
 }
 
@@ -2257,6 +2343,7 @@ void LLMeshLODHandler::processData(LLCore::BufferArray * body, U8 * data, S32 da
 			LLMeshRepository::sCacheBytesWritten += size;
 		}
 	}
+	// *TODO:  Mark mesh unavailable on error
 }
 
 LLMeshSkinInfoHandler::~LLMeshSkinInfoHandler()
@@ -2268,15 +2355,21 @@ void LLMeshSkinInfoHandler::processFailure(LLCore::HttpStatus status)
 {
 	if (is_retryable(status))
 	{
-		llwarns << "Timeout or service unavailable, retrying." << llendl;
-		LLMeshRepository::sHTTPRetryCount++;
-		// *FIXME:  Is this safe?  Does this need locking?
-		gMeshRepo.mThread->loadMeshSkinInfo(mMeshID);
+		LL_WARNS(LOG_MESH) << "Error during mesh skin info handling.  Reason:  " << status.toString()
+						   << " (" << status.toHex() << ").  Retrying."
+						   << LL_ENDL;
+		{
+			LLMutexLock lock(gMeshRepo.mThread->mMutex);
+
+			gMeshRepo.mThread->loadMeshSkinInfo(mMeshID);
+		}
 	}
 	else
 	{
-		// *TODO:  better error message
-		llwarns << "Unhandled status." << llendl;
+		// *TODO:  Mark mesh unavailable on error
+		LL_WARNS(LOG_MESH) << "Error during mesh skin info handling.  Reason:  " << status.toString()
+						   << " (" << status.toHex() << ").  Not retrying."
+						   << LL_ENDL;
 	}
 }
 
@@ -2297,6 +2390,7 @@ void LLMeshSkinInfoHandler::processData(LLCore::BufferArray * body, U8 * data, S
 			file.write(data, size);
 		}
 	}
+	// *TODO:  Mark mesh unavailable on error
 }
 
 LLMeshDecompositionHandler::~LLMeshDecompositionHandler()
@@ -2308,15 +2402,21 @@ void LLMeshDecompositionHandler::processFailure(LLCore::HttpStatus status)
 {
 	if (is_retryable(status))
 	{
-		llwarns << "Timeout or service unavailable, retrying." << llendl;
-		LLMeshRepository::sHTTPRetryCount++;
-		// *FIXME:  Is this safe?  Does this need locking?
-		gMeshRepo.mThread->loadMeshDecomposition(mMeshID);
+		LL_WARNS(LOG_MESH) << "Error during mesh decomposition handling.  Reason:  " << status.toString()
+						   << " (" << status.toHex() << ").  Retrying."
+						   << LL_ENDL;
+		{
+			LLMutexLock lock(gMeshRepo.mThread->mMutex);
+
+			gMeshRepo.mThread->loadMeshDecomposition(mMeshID);
+		}
 	}
 	else
 	{
-		// *TODO:  better error message
-		llwarns << "Unhandled status." << llendl;
+		// *TODO:  Mark mesh unavailable on error
+		LL_WARNS(LOG_MESH) << "Error during mesh decomposition handling.  Reason:  " << status.toString()
+						   << " (" << status.toHex() << ").  Not retrying."
+						   << LL_ENDL;
 	}
 }
 
@@ -2337,6 +2437,7 @@ void LLMeshDecompositionHandler::processData(LLCore::BufferArray * body, U8 * da
 			file.write(data, size);
 		}
 	}
+	// *TODO:  Mark mesh unavailable on error
 }
 
 LLMeshPhysicsShapeHandler::~LLMeshPhysicsShapeHandler()
@@ -2348,15 +2449,21 @@ void LLMeshPhysicsShapeHandler::processFailure(LLCore::HttpStatus status)
 {
 	if (is_retryable(status))
 	{
-		llwarns << "Timeout or service unavailable, retrying." << llendl;
-		LLMeshRepository::sHTTPRetryCount++;
-		// *FIXME:  Is this safe?  Does this need locking?
-		gMeshRepo.mThread->loadMeshPhysicsShape(mMeshID);
+		LL_WARNS(LOG_MESH) << "Error during mesh physics shape handling.  Reason:  " << status.toString()
+						   << " (" << status.toHex() << ").  Retrying."
+						   << LL_ENDL;
+		{
+			LLMutexLock lock(gMeshRepo.mThread->mMutex);
+
+			gMeshRepo.mThread->loadMeshPhysicsShape(mMeshID);
+		}
 	}
 	else
 	{
-		// *TODO:  better error message
-		llwarns << "Unhandled status." << llendl;
+		// *TODO:  Mark mesh unavailable on error
+		LL_WARNS(LOG_MESH) << "Error during mesh physics shape handling.  Reason:  " << status.toString()
+						   << " (" << status.toHex() << ").  Not retrying."
+						   << LL_ENDL;
 	}
 }
 
@@ -2377,6 +2484,7 @@ void LLMeshPhysicsShapeHandler::processData(LLCore::BufferArray * body, U8 * dat
 			file.write(data, size);
 		}
 	}
+	// *TODO:  Mark mesh unavailable on error
 }
 
 LLMeshRepository::LLMeshRepository()
@@ -2574,12 +2682,15 @@ S32 LLMeshRepository::loadMesh(LLVOVolume* vobj, const LLVolumeParams& mesh_para
 void LLMeshRepository::notifyLoadedMeshes()
 { //called from main thread
 	// *FIXME:  Scaling down the setting by a factor of 4 for now to reflect
-	// target goal.  May want to rename the setting before release.
+	// target goal.  May want to rename the setting before release.  Also
+	// want/need to get these in a coordinated fashion from llappcorehttp.
 	LLMeshRepoThread::sMaxConcurrentRequests = gSavedSettings.getU32("MeshMaxConcurrentRequests") / 4;
-	LLMeshRepoThread::sRequestHighWater = llmax(50 * S32(LLMeshRepoThread::sMaxConcurrentRequests),
-												REQUEST_HIGH_WATER_MIN);
-	LLMeshRepoThread::sRequestLowWater = llmax(LLMeshRepoThread::sRequestLowWater / 2,
-											   REQUEST_LOW_WATER_MIN);
+	LLMeshRepoThread::sRequestHighWater = llclamp(10 * S32(LLMeshRepoThread::sMaxConcurrentRequests),
+												  REQUEST_HIGH_WATER_MIN,
+												  REQUEST_HIGH_WATER_MAX);
+	LLMeshRepoThread::sRequestLowWater = llclamp(LLMeshRepoThread::sRequestHighWater / 2,
+												 REQUEST_LOW_WATER_MIN,
+												 REQUEST_LOW_WATER_MAX);
 	
 	//clean up completed upload threads
 	for (std::vector<LLMeshUploadThread*>::iterator iter = mUploads.begin(); iter != mUploads.end(); )
@@ -2672,6 +2783,10 @@ void LLMeshRepository::notifyLoadedMeshes()
 			region_name = gAgent.getRegion()->getName();
 			mGetMeshCapability = gAgent.getRegion()->getCapability("GetMesh");
 			mGetMesh2Capability = gAgent.getRegion()->getCapability("GetMesh2");
+			LL_DEBUGS(LOG_MESH) << "Retrieving caps for region '" << region_name
+								<< "', GetMesh2:  " << mGetMesh2Capability
+								<< ", GetMesh:  " << mGetMeshCapability
+								<< LL_ENDL;
 		}
 	}
 
@@ -2810,9 +2925,6 @@ void LLMeshRepository::notifyDecompositionReceived(LLModel::Decomposition* decom
 
 void LLMeshRepository::notifyMeshLoaded(const LLVolumeParams& mesh_params, LLVolume* volume)
 { //called from main thread
-	// Manage time-to-load metrics for mesh download operations.
-	metricsProgress(0);
-	
 	S32 detail = LLVolumeLODGroup::getVolumeDetailFromScale(volume->getDetail());
 
 	//get list of objects waiting to be notified this mesh is loaded
@@ -2823,7 +2935,8 @@ void LLMeshRepository::notifyMeshLoaded(const LLVolumeParams& mesh_params, LLVol
 		//make sure target volume is still valid
 		if (volume->getNumVolumeFaces() <= 0)
 		{
-			llwarns << "Mesh loading returned empty volume." << llendl;
+			LL_WARNS(LOG_MESH) << "Mesh loading returned empty volume.  ID:  " << mesh_params.getSculptID()
+							   << LL_ENDL;
 		}
 		
 		{ //update system volume
@@ -2836,7 +2949,8 @@ void LLMeshRepository::notifyMeshLoaded(const LLVolumeParams& mesh_params, LLVol
 			}
 			else
 			{
-				llwarns << "Couldn't find system volume for given mesh." << llendl;
+				LL_WARNS(LOG_MESH) << "Couldn't find system volume for mesh " << mesh_params.getSculptID()
+								   << LL_ENDL;
 			}
 		}
 
@@ -2856,9 +2970,6 @@ void LLMeshRepository::notifyMeshLoaded(const LLVolumeParams& mesh_params, LLVol
 
 void LLMeshRepository::notifyMeshUnavailable(const LLVolumeParams& mesh_params, S32 lod)
 { //called from main thread
-	// Manage time-to-load metrics for mesh download operations.
-	metricsProgress(0);
-	
 	//get list of objects waiting to be notified this mesh is loaded
 	mesh_load_map::iterator obj_iter = mLoadingMeshes[lod].find(mesh_params);
 
@@ -3029,7 +3140,7 @@ LLSD& LLMeshRepoThread::getMeshHeader(const LLUUID& mesh_id)
 
 
 void LLMeshRepository::uploadModel(std::vector<LLModelInstance>& data, LLVector3& scale, bool upload_textures,
-									bool upload_skin, bool upload_joints, std::string upload_url, bool do_upload,
+								   bool upload_skin, bool upload_joints, std::string upload_url, bool do_upload,
 								   LLHandle<LLWholeModelFeeObserver> fee_observer, LLHandle<LLWholeModelUploadObserver> upload_observer)
 {
 	LLMeshUploadThread* thread = new LLMeshUploadThread(data, scale, upload_textures, upload_skin, upload_joints, upload_url, 
@@ -3058,7 +3169,6 @@ S32 LLMeshRepository::getMeshSize(const LLUUID& mesh_id, S32 lod)
 	}
 
 	return -1;
-
 }
 
 void LLMeshUploadThread::decomposeMeshMatrix(LLMatrix4& transformation,
@@ -3880,7 +3990,7 @@ void LLMeshRepository::metricsUpdate()
 		metrics["scope"] = "Login";
 		metrics["start"] = started;
 		metrics["stop"] = stopped;
-		metrics["downloads"] = LLSD::Integer(total_count);
+		metrics["fetches"] = LLSD::Integer(total_count);
 		metrics["teleports"] = LLSD::Integer(metrics_teleport_start_count);
 		metrics["user_cpu"] = double(user_cpu) / 1.0e6;
 		metrics["sys_cpu"] = double(sys_cpu) / 1.0e6;
diff --git a/indra/newview/llmeshrepository.h b/indra/newview/llmeshrepository.h
index 74690e5a2a..e90ab4dd23 100755
--- a/indra/newview/llmeshrepository.h
+++ b/indra/newview/llmeshrepository.h
@@ -221,8 +221,8 @@ class LLMeshRepoThread : public LLThread
 {
 public:
 
-	static S32 sActiveHeaderRequests;
-	static S32 sActiveLODRequests;
+	volatile static S32 sActiveHeaderRequests;
+	volatile static S32 sActiveLODRequests;
 	static U32 sMaxConcurrentRequests;
 	static S32 sRequestLowWater;
 	static S32 sRequestHighWater;
@@ -323,6 +323,8 @@ public:
 	pending_lod_map mPendingLOD;
 
 	// llcorehttp library interface objects.
+	LLCore::HttpStatus					mHttpStatus;
+	unsigned int						mHttpRetries;
 	LLCore::HttpRequest *				mHttpRequest;
 	LLCore::HttpOptions *				mHttpOptions;
 	LLCore::HttpOptions *				mHttpLargeOptions;