Better support for dynamic option changes in llcorehttp. Libcurl has

some problems disabling pipelining on a multi handle with outstanding
requests so build a more conservative system that allows requests
to drain before setting curl multi options.  Would rather not have
this but it is significantly safer.  "HttpPipelining" debug setting
is now fully dynamic.  Connection limits can also be made dynamic
in the near future.  Upped the default connection count back to 8 for
now but will revisit this in the tuning phase.  It might be time to
combine mesh and textures into a single asset class.  For normal
server operations that would be a clear path, but for server under
load, the current scheme may be better.  Minor cleanup in logging
to elminate some redundant strings.  Might add some more tracing to the
stall logic 'just in case'.

1 files changed, 137 insertions, 61 deletions

diff --git a/indra/llcorehttp/_httplibcurl.cpp b/indra/llcorehttp/_httplibcurl.cpp
index fb907f6318..b46833a1f3 100755
--- a/indra/llcorehttp/_httplibcurl.cpp
+++ b/indra/llcorehttp/_httplibcurl.cpp
@@ -40,6 +40,8 @@ namespace
 void check_curl_multi_code(CURLMcode code);
 void check_curl_multi_code(CURLMcode code, int curl_setopt_option);
 
+static const char * const LOG_CORE("CoreHttp");
+
 } // end anonymous namespace
 
 
@@ -51,7 +53,8 @@ HttpLibcurl::HttpLibcurl(HttpService * service)
 	: mService(service),
 	  mPolicyCount(0),
 	  mMultiHandles(NULL),
-	  mActiveHandles(NULL)
+	  mActiveHandles(NULL),
+	  mDirtyPolicy(NULL)
 {}
 
 
@@ -90,6 +93,9 @@ void HttpLibcurl::shutdown()
 
 		delete [] mActiveHandles;
 		mActiveHandles = NULL;
+
+		delete [] mDirtyPolicy;
+		mDirtyPolicy = NULL;
 	}
 
 	mPolicyCount = 0;
@@ -101,44 +107,21 @@ void HttpLibcurl::start(int policy_count)
 	llassert_always(policy_count <= HTTP_POLICY_CLASS_LIMIT);
 	llassert_always(! mMultiHandles);					// One-time call only
 	
-	HttpPolicy & policy(mService->getPolicy());
 	mPolicyCount = policy_count;
 	mMultiHandles = new CURLM * [mPolicyCount];
 	mActiveHandles = new int [mPolicyCount];
+	mDirtyPolicy = new bool [mPolicyCount];
 	
 	for (int policy_class(0); policy_class < mPolicyCount; ++policy_class)
 	{
-		HttpPolicyClass & options(policy.getClassOptions(policy_class));
-
-		mActiveHandles[policy_class] = 0;
 		if (NULL == (mMultiHandles[policy_class] = curl_multi_init()))
 		{
-			LL_ERRS("CoreHttp") << "Failed to allocate multi handle in libcurl."
-								<< LL_ENDL;
-		}
-				
-		if (options.mPipelining > 1)
-		{
-			CURLMcode code;
-			
-			// We'll try to do pipelining on this multihandle
-			code = curl_multi_setopt(mMultiHandles[policy_class],
-									 CURLMOPT_PIPELINING,
-									 1L);
-			check_curl_multi_code(code, CURLMOPT_PIPELINING);
-			code = curl_multi_setopt(mMultiHandles[policy_class],
-									 CURLMOPT_MAX_PIPELINE_LENGTH,
-									 long(options.mPipelining));
-			check_curl_multi_code(code, CURLMOPT_MAX_PIPELINE_LENGTH);
-			code = curl_multi_setopt(mMultiHandles[policy_class],
-									 CURLMOPT_MAX_HOST_CONNECTIONS,
-									 long(options.mPerHostConnectionLimit));
-			check_curl_multi_code(code, CURLMOPT_MAX_HOST_CONNECTIONS);
-			code = curl_multi_setopt(mMultiHandles[policy_class],
-									 CURLMOPT_MAX_TOTAL_CONNECTIONS,
-									 long(options.mConnectionLimit));
-			check_curl_multi_code(code, CURLMOPT_MAX_TOTAL_CONNECTIONS);
+			LL_ERRS(LOG_CORE) << "Failed to allocate multi handle in libcurl."
+							  << LL_ENDL;
 		}
+		mActiveHandles[policy_class] = 0;
+		mDirtyPolicy[policy_class] = false;
+		policyUpdated(policy_class);
 	}
 }
 
@@ -156,8 +139,19 @@ HttpService::ELoopSpeed HttpLibcurl::processTransport()
 	// Give libcurl some cycles to do I/O & callbacks
 	for (int policy_class(0); policy_class < mPolicyCount; ++policy_class)
 	{
-		if (! mActiveHandles[policy_class] || ! mMultiHandles[policy_class])
+		if (! mMultiHandles[policy_class])
 		{
+			// No handle, nothing to do.
+			continue;
+		}
+		if (! mActiveHandles[policy_class])
+		{
+			// If we've gone quiet and there's a dirty update, apply it,
+			// otherwise we're done.
+			if (mDirtyPolicy[policy_class])
+			{
+				policyUpdated(policy_class);
+			}
 			continue;
 		}
 		
@@ -192,9 +186,9 @@ HttpService::ELoopSpeed HttpLibcurl::processTransport()
 			}
 			else
 			{
-				LL_WARNS_ONCE("CoreHttp") << "Unexpected message from libcurl.  Msg code:  "
-										  << msg->msg
-										  << LL_ENDL;
+				LL_WARNS_ONCE(LOG_CORE) << "Unexpected message from libcurl.  Msg code:  "
+										<< msg->msg
+										<< LL_ENDL;
 			}
 			msgs_in_queue = 0;
 		}
@@ -230,11 +224,11 @@ void HttpLibcurl::addOp(HttpOpRequest * op)
 	{
 		HttpPolicy & policy(mService->getPolicy());
 		
-		LL_INFOS("CoreHttp") << "TRACE, ToActiveQueue, Handle:  "
-							 << static_cast<HttpHandle>(op)
-							 << ", Actives:  " << mActiveOps.size()
-							 << ", Readies:  " << policy.getReadyCount(op->mReqPolicy)
-							 << LL_ENDL;
+		LL_INFOS(LOG_CORE) << "TRACE, ToActiveQueue, Handle:  "
+						   << static_cast<HttpHandle>(op)
+						   << ", Actives:  " << mActiveOps.size()
+						   << ", Readies:  " << policy.getReadyCount(op->mReqPolicy)
+						   << LL_ENDL;
 	}
 	
 	// On success, make operation active
@@ -286,10 +280,10 @@ void HttpLibcurl::cancelRequest(HttpOpRequest * op)
 	// Tracing
 	if (op->mTracing > HTTP_TRACE_OFF)
 	{
-		LL_INFOS("CoreHttp") << "TRACE, RequestCanceled, Handle:  "
-							 << static_cast<HttpHandle>(op)
-							 << ", Status:  " << op->mStatus.toTerseString()
-							 << LL_ENDL;
+		LL_INFOS(LOG_CORE) << "TRACE, RequestCanceled, Handle:  "
+						   << static_cast<HttpHandle>(op)
+						   << ", Status:  " << op->mStatus.toTerseString()
+						   << LL_ENDL;
 	}
 
 	// Cancel op and deliver for notification
@@ -306,18 +300,18 @@ bool HttpLibcurl::completeRequest(CURLM * multi_handle, CURL * handle, CURLcode
 
 	if (handle != op->mCurlHandle || ! op->mCurlActive)
 	{
-		LL_WARNS("CoreHttp") << "libcurl handle and HttpOpRequest handle in disagreement or inactive request."
-							 << "  Handle:  " << static_cast<HttpHandle>(handle)
-							 << LL_ENDL;
+		LL_WARNS(LOG_CORE) << "libcurl handle and HttpOpRequest handle in disagreement or inactive request."
+						   << "  Handle:  " << static_cast<HttpHandle>(handle)
+						   << LL_ENDL;
 		return false;
 	}
 
 	active_set_t::iterator it(mActiveOps.find(op));
 	if (mActiveOps.end() == it)
 	{
-		LL_WARNS("CoreHttp") << "libcurl completion for request not on active list.  Continuing."
-							 << "  Handle:  " << static_cast<HttpHandle>(handle)
-							 << LL_ENDL;
+		LL_WARNS(LOG_CORE) << "libcurl completion for request not on active list.  Continuing."
+						   << "  Handle:  " << static_cast<HttpHandle>(handle)
+						   << LL_ENDL;
 		return false;
 	}
 
@@ -348,9 +342,9 @@ bool HttpLibcurl::completeRequest(CURLM * multi_handle, CURL * handle, CURLcode
 		}
 		else
 		{
-			LL_WARNS("CoreHttp") << "Invalid HTTP response code ("
-								 << http_status << ") received from server."
-								 << LL_ENDL;
+			LL_WARNS(LOG_CORE) << "Invalid HTTP response code ("
+							   << http_status << ") received from server."
+							   << LL_ENDL;
 			op->mStatus = HttpStatus(HttpStatus::LLCORE, HE_INVALID_HTTP_STATUS);
 		}
 	}
@@ -363,10 +357,10 @@ bool HttpLibcurl::completeRequest(CURLM * multi_handle, CURL * handle, CURLcode
 	// Tracing
 	if (op->mTracing > HTTP_TRACE_OFF)
 	{
-		LL_INFOS("CoreHttp") << "TRACE, RequestComplete, Handle:  "
-							 << static_cast<HttpHandle>(op)
-							 << ", Status:  " << op->mStatus.toTerseString()
-							 << LL_ENDL;
+		LL_INFOS(LOG_CORE) << "TRACE, RequestComplete, Handle:  "
+						   << static_cast<HttpHandle>(op)
+						   << ", Status:  " << op->mStatus.toTerseString()
+						   << LL_ENDL;
 	}
 
 	// Dispatch to next stage
@@ -390,6 +384,88 @@ int HttpLibcurl::getActiveCountInClass(int policy_class) const
 	return mActiveHandles ? mActiveHandles[policy_class] : 0;
 }
 
+void HttpLibcurl::policyUpdated(int policy_class)
+{
+	if (policy_class < 0 || policy_class >= mPolicyCount || ! mMultiHandles)
+	{
+		return;
+	}
+	
+	HttpPolicy & policy(mService->getPolicy());
+	
+	if (! mActiveHandles[policy_class])
+	{
+		// Clear to set options.  As of libcurl 7.37.0, if a pipelining
+		// multi handle has active requests and you try to set the
+		// multi handle to non-pipelining, the library gets very angry
+		// and goes off the rails corrupting memory.  A clue that you're
+		// about to crash is that you'll get a missing server response
+		// error (curl code 9).  So, if options are to be set, we let
+		// the multi handle run out of requests, then set options, and
+		// re-enable request processing.
+		//
+		// All of this stall mechanism exists for this reason.  If
+		// libcurl becomes more resilient later, it should be possible
+		// to remove all of this.  The connection limit settings are fine,
+		// it's just that pipelined-to-non-pipelined transition that
+		// is fatal at the moment.
+		
+		HttpPolicyClass & options(policy.getClassOptions(policy_class));
+		CURLM * multi_handle(mMultiHandles[policy_class]);
+		CURLMcode code;
+
+		// Enable policy if stalled
+		policy.stallPolicy(policy_class, false);
+		mDirtyPolicy[policy_class] = false;
+		
+		if (options.mPipelining > 1)
+		{
+			// We'll try to do pipelining on this multihandle
+			code = curl_multi_setopt(multi_handle,
+									 CURLMOPT_PIPELINING,
+									 1L);
+			check_curl_multi_code(code, CURLMOPT_PIPELINING);
+			code = curl_multi_setopt(multi_handle,
+									 CURLMOPT_MAX_PIPELINE_LENGTH,
+									 long(options.mPipelining));
+			check_curl_multi_code(code, CURLMOPT_MAX_PIPELINE_LENGTH);
+			code = curl_multi_setopt(multi_handle,
+									 CURLMOPT_MAX_HOST_CONNECTIONS,
+									 long(options.mPerHostConnectionLimit));
+			check_curl_multi_code(code, CURLMOPT_MAX_HOST_CONNECTIONS);
+			code = curl_multi_setopt(multi_handle,
+									 CURLMOPT_MAX_TOTAL_CONNECTIONS,
+									 long(options.mConnectionLimit));
+			check_curl_multi_code(code, CURLMOPT_MAX_TOTAL_CONNECTIONS);
+		}
+		else
+		{
+			code = curl_multi_setopt(multi_handle,
+									 CURLMOPT_PIPELINING,
+									 0L);
+			check_curl_multi_code(code, CURLMOPT_PIPELINING);
+			code = curl_multi_setopt(multi_handle,
+									 CURLMOPT_MAX_HOST_CONNECTIONS,
+									 0L);
+			check_curl_multi_code(code, CURLMOPT_MAX_HOST_CONNECTIONS);
+			code = curl_multi_setopt(multi_handle,
+									 CURLMOPT_MAX_TOTAL_CONNECTIONS,
+									 long(options.mConnectionLimit));
+			check_curl_multi_code(code, CURLMOPT_MAX_TOTAL_CONNECTIONS);
+		}
+	}
+	else if (! mDirtyPolicy[policy_class])
+	{
+		// Mark policy dirty and request a stall in the policy.
+		// When policy goes idle, we'll re-invoke this method
+		// and perform the change.  Don't allow this thread to
+		// sleep while we're waiting for quiescence, we'll just
+		// stop processing.
+		mDirtyPolicy[policy_class] = true;
+		policy.stallPolicy(policy_class, true);
+	}
+}
+
 
 // ---------------------------------------
 // Free functions
@@ -424,9 +500,9 @@ void check_curl_multi_code(CURLMcode code, int curl_setopt_option)
 {
 	if (CURLM_OK != code)
 	{
-		LL_WARNS("CoreHttp") << "libcurl multi error detected:  " << curl_multi_strerror(code)
-							 << ", curl_multi_setopt option:  " << curl_setopt_option
-							 << LL_ENDL;
+		LL_WARNS(LOG_CORE) << "libcurl multi error detected:  " << curl_multi_strerror(code)
+						   << ", curl_multi_setopt option:  " << curl_setopt_option
+						   << LL_ENDL;
 	}
 }
 
@@ -435,8 +511,8 @@ void check_curl_multi_code(CURLMcode code)
 {
 	if (CURLM_OK != code)
 	{
-		LL_WARNS("CoreHttp") << "libcurl multi error detected:  " << curl_multi_strerror(code)
-							 << LL_ENDL;
+		LL_WARNS(LOG_CORE) << "libcurl multi error detected:  " << curl_multi_strerror(code)
+						   << LL_ENDL;
 	}
 }