Added mutex for gettng object model, incomplete fix for issue #995

src/GCodes/GCodes.cpp

@@ -4933,10 +4933,13 @@ void GCodes::CheckReportDue(GCodeBuffer& gb, const StringRef& reply) const noexc
 		if (lastAuxStatusReportType >= 0 && platform.IsAuxEnabled(0) && gb.IsReportDue())
 		{
 			// Send a standard status response for PanelDue
-			OutputBuffer * const statusBuf =
-									(lastAuxStatusReportType == ObjectModelAuxStatusReportType)		// PanelDueFirmware v3.2 or later, using M409 to retrieve object model
-										? reprap.GetModelResponse(&gb, "", "d99fi")
-										: GenerateJsonStatusResponse(lastAuxStatusReportType, -1, ResponseSource::AUX);		// older PanelDueFirmware using M408
+			OutputBuffer * statusBuf;
+			{
+				MutexLocker lock(reprap.GetObjectModelReportMutex());
+				statusBuf = (lastAuxStatusReportType == ObjectModelAuxStatusReportType)		// PanelDueFirmware v3.2 or later, using M409 to retrieve object model
+								? reprap.GetModelResponse(&gb, "", "d99fi")
+								: GenerateJsonStatusResponse(lastAuxStatusReportType, -1, ResponseSource::AUX);		// older PanelDueFirmware using M408
+			}
 			if (statusBuf != nullptr)
 			{
 				platform.AppendAuxReply(0, statusBuf, true);

src/GCodes/GCodes2.cpp

@@ -3127,12 +3127,14 @@ bool GCodes::HandleMcode(GCodeBuffer& gb, const StringRef& reply) THROWS(GCodeEx
 					{
 						lastAuxStatusReportType = ObjectModelAuxStatusReportType;
 					}
-					outBuf = reprap.GetModelResponse(&gb, key.c_str(), flags.c_str());
-					if (outBuf == nullptr)
 					{
-						OutputBuffer::ReleaseAll(outBuf);
-						// We don't delay and retry here, in case the user asked for too much of the object model in one go for the output buffers to contain it
-						reply.copy("{\"err\":-1}\n");
+						MutexLocker lock(reprap.GetObjectModelReportMutex());				// grab the mutex to prevent PanelDue retrieving the OM at the same time, which can result in running out of buffers
+						outBuf = reprap.GetModelResponse(&gb, key.c_str(), flags.c_str());
+						if (outBuf == nullptr)
+						{
+							// We don't delay and retry here, in case the user asked for too much of the object model in one go for the output buffers to contain it
+							reply.copy("{\"err\":-1}\n");
+						}
 					}
 					if (&gb == AuxGCode())
 					{

src/Networking/HttpResponder.cpp

@@ -648,6 +648,8 @@ bool HttpResponder::GetJsonResponse(const char *_ecv_array request, OutputBuffer
 		OutputBuffer::ReleaseAll(response);
 		const char *const filterVal = GetKeyValue("key");
 		const char *const flagsVal = GetKeyValue("flags");
+
+		MutexLocker lock(reprap.GetObjectModelReportMutex());				// grab the mutex to prevent PanelDue retrieving the OM at the same time, which can result in running out of buffers
 		response = reprap.GetModelResponse(nullptr, filterVal, flagsVal);
 	}
 #endif

src/Platform/RepRap.cpp

@@ -151,8 +151,6 @@ extern "C" void hsmciIdle(uint32_t stBits, uint32_t dmaBits) noexcept
 
 #endif //end if HAS_HIGH_SPEED_SD && !SAME5x
 
-#if SUPPORT_OBJECT_MODEL
-
 // Object model table and functions
 // Note: if using GCC version 7.3.1 20180622 and lambda functions are used in this table, you must compile this file with option -std=gnu++17.
 // Otherwise the table will be allocate in RAM instead of flash, which wastes too much RAM.
@@ -439,8 +437,6 @@ constexpr uint8_t RepRap::objectModelTableDescriptor[] =
 
 DEFINE_GET_OBJECT_MODEL_TABLE(RepRap)
 
-#endif
-
 // RepRap member functions.
 
 // Do nothing more in the constructor; put what you want in RepRap:Init()
@@ -493,6 +489,8 @@ static void CheckWatchBuffer(unsigned int module) noexcept
 void RepRap::Init() noexcept
 {
 	OutputBuffer::Init();
+	objectModelReportMutex.Create("ModelReport");
+
 	platform = new Platform();
 #if HAS_SBC_INTERFACE
 	sbcInterface = new SbcInterface();				// needs to be allocated early on Duet 2 so as to avoid using any of the last 64K of RAM
@@ -1119,7 +1117,7 @@ bool RepRap::SpinTimeoutImminent() const noexcept
 	return ticksInSpinState >= HighMainTaskTicksInSpinState;
 }
 
-// Get the JSON status response for the web server (or later for the M105 command).
+// Get the JSON status response for the web server or the M408 command.
 // Type 1 is the ordinary JSON status response.
 // Type 2 is the same except that static parameters are also included.
 // Type 3 is the same but instead of static parameters we report print estimation values.
@@ -2297,8 +2295,6 @@ void RepRap::AppendStringArray(OutputBuffer *buf, const char *name, size_t numVa
 	buf->cat(']');
 }
 
-#if SUPPORT_OBJECT_MODEL
-
 // Return a query into the object model, or return nullptr if no buffer available
 // We append a newline to help PanelDue resync after receiving corrupt or incomplete data. DWC ignores it.
 OutputBuffer *RepRap::GetModelResponse(const GCodeBuffer *_ecv_null gb, const char *key, const char *flags) const THROWS(GCodeException)
@@ -2336,8 +2332,6 @@ OutputBuffer *RepRap::GetModelResponse(const GCodeBuffer *_ecv_null gb, const ch
 	return outBuf;
 }
 
-#endif
-
 // Send a beep. We send it to both PanelDue and the web interface.
 void RepRap::Beep(unsigned int freq, unsigned int ms) noexcept
 {

src/Platform/RepRap.h

@@ -115,10 +115,8 @@ class RepRap INHERIT_OBJECT_MODEL
 #endif
 
 	GCodeResult GetFileInfoResponse(const char *filename, OutputBuffer *&response, bool quitEarly) noexcept;
-
-#if SUPPORT_OBJECT_MODEL
 	OutputBuffer *GetModelResponse(const GCodeBuffer *_ecv_null gb, const char *key, const char *flags) const THROWS(GCodeException);
-#endif
+	Mutex& GetObjectModelReportMutex() noexcept { return objectModelReportMutex; }
 
 	void Beep(unsigned int freq, unsigned int ms) noexcept;
 	void SetMessage(const char *msg) noexcept;
@@ -192,6 +190,8 @@ class RepRap INHERIT_OBJECT_MODEL
  	PrintMonitor* printMonitor;
  	FansManager* fansManager;
 
+ 	Mutex objectModelReportMutex;									// mutex used to limit concurrent reporting of object model, which may result in output buffer starvation
+
  	// Recording the first error message encountered in config.g
  	AutoStringHandle configErrorFilename;
  	unsigned int configErrorLine;