Initial work on memory pressure handling. See #904.

scopehal/AcceleratorBuffer.h

@@ -1,8 +1,8 @@
 /***********************************************************************************************************************
 *                                                                                                                      *
-* libscopehal v0.1                                                                                                     *
+* libscopehal                                                                                                          *
 *                                                                                                                      *
-* Copyright (c) 2012-2022 Andrew D. Zonenberg and contributors                                                         *
+* Copyright (c) 2012-2024 Andrew D. Zonenberg and contributors                                                         *
 * All rights reserved.                                                                                                 *
 *                                                                                                                      *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the     *

scopehal/scopehal.cpp

@@ -987,3 +987,15 @@ const char* ScopehalGetVersion()
 {
 	return SCOPEHAL_VERSION;
 }
+
+/**
+	@brief Called when we run low on memory
+
+	@param level	Indicates if this is a soft or hard memory exhaustion condition
+	@param type		Indicates if we are low on CPU or GPU memory
+ */
+void OnMemoryPressure(MemoryPressureLevel level, MemoryPressureType type)
+{
+	for(auto handler : g_memoryPressureHandlers)
+		handler(level, type);
+}

scopehal/scopehal.h

@@ -272,4 +272,39 @@ uint32_t ColorFromString(const std::string& str, unsigned int alpha = 255);
 
 const char* ScopehalGetVersion();
 
+///@brief Levels of memory pressure
+enum class MemoryPressureLevel
+{
+	///@brief A memory allocation has failed and we need to free memory immediately to continue execution
+	Hard,
+
+	/**
+		@brief Free memory has reached a warning threshold.
+
+		We should trim caches or otherwise try to make space but don't need to be too aggressive about it.
+
+		This level is only available if we have VK_EXT_memory_budget; without this extension we do not know about
+		memory pressure until a hard allocation failure occurs.
+	 */
+	Soft
+};
+
+///@brief Types of memory pressure
+enum class MemoryPressureType
+{
+	///@brief Pinned CPU-side memory
+	Host,
+
+	///@brief GPU-side memory
+	Device
+};
+
+///@brief Memory pressure handler type, called when free memory reaches a warning level or a Vulkan allocation fails
+typedef void (*MemoryPressureHandler)(MemoryPressureLevel level, MemoryPressureType type);
+
+///@brief List of handlers for low memory registered by various subsystems
+std::set<MemoryPressureHandler> g_memoryPressureHandlers;
+
+void OnMemoryPressure(MemoryPressureLevel level, MemoryPressureType type);
+
 #endif