5 files changed, 145 insertions, 99 deletions

diff --git a/indra/newview/app_settings/settings.xml b/indra/newview/app_settings/settings.xml
index 50f56cf6ff..0607579a08 100755
--- a/indra/newview/app_settings/settings.xml
+++ b/indra/newview/app_settings/settings.xml
@@ -4459,7 +4459,7 @@
     <key>HttpPipelining</key>
     <map>
       <key>Comment</key>
-      <string>If true, viewer will pipeline HTTP requests to servers.  Static.</string>
+      <string>If true, viewer will pipeline HTTP requests to servers.</string>
       <key>Persist</key>
       <integer>1</integer>
       <key>Type</key>
@@ -4470,7 +4470,7 @@
     <key>HttpRangeRequestsDisable</key>
     <map>
       <key>Comment</key>
-      <string>If true, viewer will not issued range GET requests for meshes and textures.</string>
+      <string>If true, viewer will not issued range GET requests for meshes and textures.  May resolve problems with certain ISPs and networking gear.</string>
       <key>Persist</key>
       <integer>1</integer>
       <key>Type</key>
diff --git a/indra/newview/llappcorehttp.cpp b/indra/newview/llappcorehttp.cpp
index d097f18d61..464e60948a 100755
--- a/indra/newview/llappcorehttp.cpp
+++ b/indra/newview/llappcorehttp.cpp
@@ -60,7 +60,7 @@ static const struct
 		"other"
 	},
 	{ // AP_TEXTURE
-		4,		1,		12,		0,		true,	
+		8,		1,		12,		0,		true,	
 		"TextureFetchConcurrency",
 		"texture fetch"
 	},
@@ -70,7 +70,7 @@ static const struct
 		"mesh fetch"
 	},
 	{ // AP_MESH2
-		4,		1,		32,		100,	true,	
+		8,		1,		32,		100,	true,	
 		"Mesh2MaxConcurrentRequests",
 		"mesh2 fetch"
 	},
@@ -126,14 +126,6 @@ void LLAppCoreHttp::init()
 						<< LL_ENDL;
 	}
 
-	// Global pipelining preference from settings
-	static const std::string http_pipelining("HttpPipelining");
-	if (gSavedSettings.controlExists(http_pipelining))
-	{
-		// Default to true if absent.
-		mPipelined = gSavedSettings.getBOOL(http_pipelining);
-	}
-
 	// Point to our certs or SSH/https: will fail on connect
 	status = LLCore::HttpRequest::setStaticPolicyOption(LLCore::HttpRequest::PO_CA_FILE,
 														LLCore::HttpRequest::GLOBAL_POLICY_ID,
@@ -210,12 +202,27 @@ void LLAppCoreHttp::init()
 						<< LL_ENDL;
 	}
 
-	// *NOTE:  Pipelining isn't dynamic yet.  When it is, add a global
-	// signal for the setting here.
-	
+	// Signal for global pipelining preference from settings
+	static const std::string http_pipelining("HttpPipelining");
+	if (gSavedSettings.controlExists(http_pipelining))
+	{
+		LLPointer<LLControlVariable> cntrl_ptr = gSavedSettings.getControl(http_pipelining);
+		if (cntrl_ptr.isNull())
+		{
+			LL_WARNS("Init") << "Unable to set signal on global setting '" << http_pipelining
+							 << "'" << LL_ENDL;
+		}
+		else
+		{
+			mPipelinedSignal = cntrl_ptr->getCommitSignal()->connect(boost::bind(&setting_changed));
+		}
+	}
+
 	// Register signals for settings and state changes
 	for (int i(0); i < LL_ARRAY_SIZE(init_data); ++i)
 	{
+		const EAppPolicy app_policy(static_cast<EAppPolicy>(i));
+
 		if (! init_data[i].mKey.empty() && gSavedSettings.controlExists(init_data[i].mKey))
 		{
 			LLPointer<LLControlVariable> cntrl_ptr = gSavedSettings.getControl(init_data[i].mKey);
@@ -226,7 +233,7 @@ void LLAppCoreHttp::init()
 			}
 			else
 			{
-				mHttpClasses[i].mSettingsSignal = cntrl_ptr->getCommitSignal()->connect(boost::bind(&setting_changed));
+				mHttpClasses[app_policy].mSettingsSignal = cntrl_ptr->getCommitSignal()->connect(boost::bind(&setting_changed));
 			}
 		}
 	}
@@ -282,6 +289,7 @@ void LLAppCoreHttp::cleanup()
 	{
 		mHttpClasses[i].mSettingsSignal.disconnect();
 	}
+	mPipelinedSignal.disconnect();
 	
 	delete mRequest;
 	mRequest = NULL;
@@ -299,6 +307,20 @@ void LLAppCoreHttp::cleanup()
 void LLAppCoreHttp::refreshSettings(bool initial)
 {
 	LLCore::HttpStatus status;
+
+	// Global pipelining setting
+	bool pipeline_changed(false);
+	static const std::string http_pipelining("HttpPipelining");
+	if (gSavedSettings.controlExists(http_pipelining))
+	{
+		// Default to true (in ctor) if absent.
+		bool pipelined(gSavedSettings.getBOOL(http_pipelining));
+		if (pipelined != mPipelined)
+		{
+			mPipelined = pipelined;
+			pipeline_changed = true;
+		}
+	}
 	
 	for (int i(0); i < LL_ARRAY_SIZE(init_data); ++i)
 	{
@@ -323,33 +345,42 @@ void LLAppCoreHttp::refreshSettings(bool initial)
 				}
 			}
 
-			mHttpClasses[app_policy].mPipelined = false;
-			if (mPipelined && init_data[i].mPipelined)
+		}
+
+		// Init- or run-time settings.  Must use the queued request API.
+
+		// Pipelining changes
+		if (initial || pipeline_changed)
+		{
+			const bool to_pipeline(mPipelined && init_data[i].mPipelined);
+			if (to_pipeline != mHttpClasses[app_policy].mPipelined)
 			{
-				// Pipelining election is currently static (init-time).
-				// Making it dynamic isn't too hard in the SL code but verifying
-				// that libcurl handles the on-to-off transition while holding
-				// outstanding requests is something that should be tested.
+				// Pipeline election changing, set dynamic option via request
+
+				LLCore::HttpHandle handle;
+				const long new_depth(to_pipeline ? PIPELINING_DEPTH : 0);
 				
-				status = LLCore::HttpRequest::setStaticPolicyOption(LLCore::HttpRequest::PO_PIPELINING_DEPTH,
-																	mHttpClasses[app_policy].mPolicy,
-																	PIPELINING_DEPTH,
-																	NULL);
-				if (! status)
+				handle = mRequest->setPolicyOption(LLCore::HttpRequest::PO_PIPELINING_DEPTH,
+												   mHttpClasses[app_policy].mPolicy,
+												   new_depth,
+												   NULL);
+				if (LLCORE_HTTP_HANDLE_INVALID == handle)
 				{
+					status = mRequest->getStatus();
 					LL_WARNS("Init") << "Unable to set " << init_data[i].mUsage
-									 << " to pipelined mode.  Reason:  " << status.toString()
+									 << " pipelining.  Reason:  " << status.toString()
 									 << LL_ENDL;
 				}
 				else
 				{
-					mHttpClasses[app_policy].mPipelined = true;
+					LL_DEBUGS("Init") << "Changed " << init_data[i].mUsage
+									  << " pipelining.  New value:  " << new_depth
+									  << LL_ENDL;
+					mHttpClasses[app_policy].mPipelined = to_pipeline;
 				}
 			}
 		}
-
-		// Init- or run-time settings
-
+		
 		// Get target connection concurrency value
 		U32 setting(init_data[i].mDefault);
 		if (! init_data[i].mKey.empty() && gSavedSettings.controlExists(init_data[i].mKey))
@@ -362,63 +393,60 @@ void LLAppCoreHttp::refreshSettings(bool initial)
 			}
 		}
 
-		if (! initial && setting == mHttpClasses[app_policy].mConnLimit)
+		if (initial || setting != mHttpClasses[app_policy].mConnLimit || pipeline_changed)
 		{
-			// Unchanged, try next setting
-			continue;
-		}
-		
-		// Set it and report.  Strategies depend on pipelining:
-		//
-		// No Pipelining.  Llcorehttp manages connections itself based
-		// on the PO_CONNECTION_LIMIT setting.  Set both limits to the
-		// same value for logical consistency.  In the future, may
-		// hand over connection management to libcurl after the
-		// connection cache has been better vetted.
-		//
-		// Pipelining.  Libcurl is allowed to manage connections to a
-		// great degree.  Steady state will connection limit based on
-		// the per-host setting.  Transitions (region crossings, new
-		// avatars, etc.) can request additional outbound connections
-		// to other servers via 2X total connection limit.
-		//
-		LLCore::HttpHandle handle;
-		handle = mRequest->setPolicyOption(LLCore::HttpRequest::PO_CONNECTION_LIMIT,
-										   mHttpClasses[app_policy].mPolicy,
-										   (mHttpClasses[app_policy].mPipelined ? 2 * setting : setting),
-										   NULL);
-		if (LLCORE_HTTP_HANDLE_INVALID == handle)
-		{
-			status = mRequest->getStatus();
-			LL_WARNS("Init") << "Unable to set " << init_data[i].mUsage
-							 << " concurrency.  Reason:  " << status.toString()
-							 << LL_ENDL;
-		}
-		else
-		{
-			handle = mRequest->setPolicyOption(LLCore::HttpRequest::PO_PER_HOST_CONNECTION_LIMIT,
+			// Set it and report.  Strategies depend on pipelining:
+			//
+			// No Pipelining.  Llcorehttp manages connections itself based
+			// on the PO_CONNECTION_LIMIT setting.  Set both limits to the
+			// same value for logical consistency.  In the future, may
+			// hand over connection management to libcurl after the
+			// connection cache has been better vetted.
+			//
+			// Pipelining.  Libcurl is allowed to manage connections to a
+			// great degree.  Steady state will connection limit based on
+			// the per-host setting.  Transitions (region crossings, new
+			// avatars, etc.) can request additional outbound connections
+			// to other servers via 2X total connection limit.
+			//
+			LLCore::HttpHandle handle;
+			handle = mRequest->setPolicyOption(LLCore::HttpRequest::PO_CONNECTION_LIMIT,
 											   mHttpClasses[app_policy].mPolicy,
-											   setting,
+											   (mHttpClasses[app_policy].mPipelined ? 2 * setting : setting),
 											   NULL);
 			if (LLCORE_HTTP_HANDLE_INVALID == handle)
 			{
 				status = mRequest->getStatus();
 				LL_WARNS("Init") << "Unable to set " << init_data[i].mUsage
-								 << " per-host concurrency.  Reason:  " << status.toString()
+								 << " concurrency.  Reason:  " << status.toString()
 								 << LL_ENDL;
 			}
 			else
 			{
-				LL_DEBUGS("Init") << "Changed " << init_data[i].mUsage
-								  << " concurrency.  New value:  " << setting
-								  << LL_ENDL;
-				mHttpClasses[app_policy].mConnLimit = setting;
-				if (initial && setting != init_data[i].mDefault)
+				handle = mRequest->setPolicyOption(LLCore::HttpRequest::PO_PER_HOST_CONNECTION_LIMIT,
+												   mHttpClasses[app_policy].mPolicy,
+												   setting,
+												   NULL);
+				if (LLCORE_HTTP_HANDLE_INVALID == handle)
 				{
-					LL_INFOS("Init") << "Application settings overriding default " << init_data[i].mUsage
-									 << " concurrency.  New value:  " << setting
+					status = mRequest->getStatus();
+					LL_WARNS("Init") << "Unable to set " << init_data[i].mUsage
+									 << " per-host concurrency.  Reason:  " << status.toString()
 									 << LL_ENDL;
 				}
+				else
+				{
+					LL_DEBUGS("Init") << "Changed " << init_data[i].mUsage
+									  << " concurrency.  New value:  " << setting
+									  << LL_ENDL;
+					mHttpClasses[app_policy].mConnLimit = setting;
+					if (initial && setting != init_data[i].mDefault)
+					{
+						LL_INFOS("Init") << "Application settings overriding default " << init_data[i].mUsage
+										 << " concurrency.  New value:  " << setting
+										 << LL_ENDL;
+					}
+				}
 			}
 		}
 	}
diff --git a/indra/newview/llappcorehttp.h b/indra/newview/llappcorehttp.h
index 63c8a11180..9ad4eb4b30 100755
--- a/indra/newview/llappcorehttp.h
+++ b/indra/newview/llappcorehttp.h
@@ -218,6 +218,7 @@ private:
 	bool						mStopped;
 	HttpClass					mHttpClasses[AP_COUNT];
 	bool						mPipelined;				// Global setting
+	boost::signals2::connection mPipelinedSignal;		// Signal for 'HttpPipelining' setting
 };
 
 
diff --git a/indra/newview/lltexturefetch.cpp b/indra/newview/lltexturefetch.cpp
index 4008a6948d..097a7b374f 100755
--- a/indra/newview/lltexturefetch.cpp
+++ b/indra/newview/lltexturefetch.cpp
@@ -483,12 +483,12 @@ private:
 	bool acquireHttpSemaphore()
 		{
 			llassert(! mHttpHasResource);
-			if (mFetcher->mHttpSemaphore <= 0)
+			if (mFetcher->mHttpSemaphore >= mFetcher->mHttpHighWater)
 			{
 				return false;
 			}
 			mHttpHasResource = true;
-			mFetcher->mHttpSemaphore--;
+			mFetcher->mHttpSemaphore++;
 			return true;
 		}
 
@@ -498,7 +498,8 @@ private:
 		{
 			llassert(mHttpHasResource);
 			mHttpHasResource = false;
-			mFetcher->mHttpSemaphore++;
+			mFetcher->mHttpSemaphore--;
+			llassert_always(mFetcher->mHttpSemaphore >= 0);
 		}
 	
 private:
@@ -2523,6 +2524,8 @@ LLTextureFetch::LLTextureFetch(LLTextureCache* cache, LLImageDecodeThread* image
 	mMaxBandwidth = gSavedSettings.getF32("ThrottleBandwidthKBPS");
 	mTextureInfo.setUpLogging(gSavedSettings.getBOOL("LogTextureDownloadsToViewerLog"), gSavedSettings.getBOOL("LogTextureDownloadsToSimulator"), U32Bytes(gSavedSettings.getU32("TextureLoggingThreshold")));
 
+	LLAppCoreHttp & app_core_http(LLAppViewer::instance()->getAppCoreHttp());
+	mHttpPolicyClass = app_core_http.getPolicy(LLAppCoreHttp::AP_TEXTURE);
 	mHttpRequest = new LLCore::HttpRequest;
 	mHttpOptions = new LLCore::HttpOptions;
 	mHttpOptionsWithHeaders = new LLCore::HttpOptions;
@@ -2531,21 +2534,9 @@ LLTextureFetch::LLTextureFetch(LLTextureCache* cache, LLImageDecodeThread* image
 	mHttpHeaders->append("Accept", "image/x-j2c");
 	mHttpMetricsHeaders = new LLCore::HttpHeaders;
 	mHttpMetricsHeaders->append("Content-Type", "application/llsd+xml");
-	LLAppCoreHttp & app_core_http(LLAppViewer::instance()->getAppCoreHttp());
-	mHttpPolicyClass = app_core_http.getPolicy(LLAppCoreHttp::AP_TEXTURE);
-	if (app_core_http.isPipelined(LLAppCoreHttp::AP_TEXTURE))
-	{
-		// Init-time election that will have to change for
-		// support of dynamic changes to the pipelining enable flag.
-		mHttpHighWater = HTTP_PIPE_REQUESTS_HIGH_WATER;
-		mHttpLowWater = HTTP_PIPE_REQUESTS_LOW_WATER;
-	}
-	else
-	{
-		mHttpHighWater = HTTP_NONPIPE_REQUESTS_HIGH_WATER;
-		mHttpLowWater = HTTP_NONPIPE_REQUESTS_LOW_WATER;
-	}
-	mHttpSemaphore = mHttpHighWater;
+	mHttpHighWater = HTTP_NONPIPE_REQUESTS_HIGH_WATER;
+	mHttpLowWater = HTTP_NONPIPE_REQUESTS_LOW_WATER;
+	mHttpSemaphore = 0;
 
 	// Conditionally construct debugger object after 'this' is
 	// fully initialized.
@@ -3032,6 +3023,20 @@ bool LLTextureFetch::runCondition()
 // Threads:  Ttf
 void LLTextureFetch::commonUpdate()
 {
+	// Update low/high water levels based on pipelining.  We pick
+	// up setting eventually, so the semaphore/request level can
+	// fall outside the [0..HIGH_WATER] range.  Expect that.
+	if (LLAppViewer::instance()->getAppCoreHttp().isPipelined(LLAppCoreHttp::AP_TEXTURE))
+	{
+		mHttpHighWater = HTTP_PIPE_REQUESTS_HIGH_WATER;
+		mHttpLowWater = HTTP_PIPE_REQUESTS_LOW_WATER;
+	}
+	else
+	{
+		mHttpHighWater = HTTP_NONPIPE_REQUESTS_HIGH_WATER;
+		mHttpLowWater = HTTP_NONPIPE_REQUESTS_LOW_WATER;
+	}
+
 	// Release waiters
 	releaseHttpWaiters();
 	
@@ -3693,8 +3698,16 @@ void LLTextureFetch::releaseHttpWaiters()
 {
 	// Use mHttpSemaphore rather than mHTTPTextureQueue.size()
 	// to avoid a lock.  
-	if (mHttpSemaphore < (mHttpHighWater - mHttpLowWater))
+	if (mHttpSemaphore >= mHttpLowWater)
 		return;
+	S32 needed(mHttpHighWater - mHttpSemaphore);
+	if (needed <= 0)
+	{
+		// Would only happen if High/LowWater were changed behind
+		// our back.  In that case, defer fill until usage falls within
+		// limits.
+		return;
+	}
 
 	// Quickly make a copy of all the LLUIDs.  Get off the
 	// mutex as early as possible.
@@ -3743,10 +3756,10 @@ void LLTextureFetch::releaseHttpWaiters()
 	tids.clear();
 
 	// Sort into priority order, if necessary and only as much as needed
-	if (tids2.size() > mHttpSemaphore)
+	if (tids2.size() > needed)
 	{
 		LLTextureFetchWorker::Compare compare;
-		std::partial_sort(tids2.begin(), tids2.begin() + mHttpSemaphore, tids2.end(), compare);
+		std::partial_sort(tids2.begin(), tids2.begin() + needed, tids2.end(), compare);
 	}
 
 	// Release workers up to the high water mark.  Since we aren't
diff --git a/indra/newview/lltexturefetch.h b/indra/newview/lltexturefetch.h
index d13736997f..89d18e2c67 100755
--- a/indra/newview/lltexturefetch.h
+++ b/indra/newview/lltexturefetch.h
@@ -356,8 +356,8 @@ private:
 	LLCore::HttpHeaders *				mHttpHeaders;					// Ttf
 	LLCore::HttpHeaders *				mHttpMetricsHeaders;			// Ttf
 	LLCore::HttpRequest::policy_t		mHttpPolicyClass;				// T*
-	S32									mHttpHighWater;					// T* (ro)
-	S32									mHttpLowWater;					// T* (ro)
+	S32									mHttpHighWater;					// Ttf
+	S32									mHttpLowWater;					// Ttf
 	
 	// We use a resource semaphore to keep HTTP requests in
 	// WAIT_HTTP_RESOURCE2 if there aren't sufficient slots in the
@@ -366,7 +366,11 @@ private:
 	// where it's more expensive to get at them.  Requests in either
 	// SEND_HTTP_REQ or WAIT_HTTP_REQ charge against the semaphore
 	// and tracking state transitions is critical to liveness.
-	LLAtomicS32							mHttpSemaphore;					// Ttf + Tmain
+	//
+	// Originally implemented as a traditional semaphore (heading towards
+	// zero), it now is an outstanding request count that is allowed to
+	// exceed the high water level (but not go below zero).
+	LLAtomicS32							mHttpSemaphore;					// Ttf
 	
 	typedef std::set<LLUUID> wait_http_res_queue_t;
 	wait_http_res_queue_t				mHttpWaitResource;				// Mfnq