From 21d58357f2a7dc206522d8d66446decc503786f4 Mon Sep 17 00:00:00 2001
From: mlangkabel <malte.langkabel@gmail.com>
Date: Tue, 28 Aug 2018 13:06:36 +0200
Subject: [PATCH] logic: fixed application crash on windows if JVM tries to
 allocate too much memory by reducing the amount of allocated memory to the
 available size.

---
 src/lib/CMakeLists.txt                        |  2 +
 src/lib/utility/utilityWindows.cpp            | 46 +++++++++++++++++++
 src/lib/utility/utilityWindows.h              | 13 ++++++
 .../parser/java/JavaEnvironmentFactory.cpp    | 18 +++++++-
 4 files changed, 78 insertions(+), 1 deletion(-)
 create mode 100644 src/lib/utility/utilityWindows.cpp
 create mode 100644 src/lib/utility/utilityWindows.h

diff --git a/src/lib/CMakeLists.txt b/src/lib/CMakeLists.txt
index 302a6545..fab08aca 100644
--- a/src/lib/CMakeLists.txt
+++ b/src/lib/CMakeLists.txt
@@ -616,6 +616,8 @@ add_files(
 	utility/utilityMath.h
 	utility/utilityUuid.cpp
 	utility/utilityUuid.h
+	utility/utilityWindows.cpp
+	utility/utilityWindows.h
 	utility/utilityXml.cpp
 	utility/utilityXml.h
 
diff --git a/src/lib/utility/utilityWindows.cpp b/src/lib/utility/utilityWindows.cpp
new file mode 100644
index 00000000..be63770b
--- /dev/null
+++ b/src/lib/utility/utilityWindows.cpp
@@ -0,0 +1,46 @@
+#include "utility/utilityWindows.h"
+
+#ifdef WIN32
+
+#include <Windows.h>
+
+unsigned long utility::getLargestByteSizeOfAllocatableMemory()
+{
+	MEMORY_BASIC_INFORMATION mbi;
+	unsigned long start = 0;
+	bool recording = false;
+	unsigned long freestart = 0, largestFreestart = 0;
+	__int64 free = 0, largestFree = 0;
+
+	while (true)
+	{
+		SIZE_T s = VirtualQuery((LPCVOID)start, &mbi, sizeof(mbi));
+		if (s != sizeof(mbi)) break;
+
+		if (mbi.State == MEM_FREE)
+		{
+			if (!recording) freestart = start;
+
+			free += mbi.RegionSize;
+			recording = true;
+		}
+		else
+		{
+			if (recording)
+			{
+				if (free > largestFree)
+				{
+					largestFree = free;
+					largestFreestart = freestart;
+				}
+			}
+			free = 0;
+			recording = false;
+		}
+		start += mbi.RegionSize;
+	}
+
+	return largestFree;
+}
+
+#endif // WIN32
diff --git a/src/lib/utility/utilityWindows.h b/src/lib/utility/utilityWindows.h
new file mode 100644
index 00000000..c2c0abcb
--- /dev/null
+++ b/src/lib/utility/utilityWindows.h
@@ -0,0 +1,13 @@
+#ifndef UTILITY_WINDOWS_H
+#define UTILITY_WINDOWS_H
+
+#ifdef WIN32
+
+namespace utility
+{
+	unsigned long getLargestByteSizeOfAllocatableMemory();
+}
+
+#endif // WIN32
+
+#endif // UTILITY_WINDOWS_H
diff --git a/src/lib_java/data/parser/java/JavaEnvironmentFactory.cpp b/src/lib_java/data/parser/java/JavaEnvironmentFactory.cpp
index ded0995d..bff5a2fd 100644
--- a/src/lib_java/data/parser/java/JavaEnvironmentFactory.cpp
+++ b/src/lib_java/data/parser/java/JavaEnvironmentFactory.cpp
@@ -8,6 +8,7 @@
 #include "settings/ApplicationSettings.h"
 #include "utility/logging/logging.h"
 #include "utility/utilityLibrary.h"
+#include "utility/utilityWindows.h"
 
 void JavaEnvironmentFactory::createInstance(std::string classPath, std::string& errorString)
 {
@@ -41,7 +42,22 @@ void JavaEnvironmentFactory::createInstance(std::string classPath, std::string&
 
 	s_classPath = classPath;
 
-	const int jvmMaximumMemory = ApplicationSettings::getInstance()->getJavaMaximumMemory();
+	int jvmMaximumMemory = ApplicationSettings::getInstance()->getJavaMaximumMemory();
+
+#ifdef WIN32
+	if (jvmMaximumMemory > 0)
+	{
+		const float underestimationFactor = 0.8f;
+		const int maximumMB = utility::getLargestByteSizeOfAllocatableMemory() / 1024 / 1024 * underestimationFactor;
+		if (jvmMaximumMemory > maximumMB)
+		{
+			LOG_WARNING("Selected amount of maximum JVM memory of " + std::to_string(jvmMaximumMemory) + " MB exceeds maximum allocatable "
+				"memory on system. Correcting selected value to " + std::to_string(maximumMB) + " MB.");
+			jvmMaximumMemory = maximumMB;
+		}
+	}
+#endif // WIN32
+
 	const int optionCount = (jvmMaximumMemory < 0 ? 2 : 3);
 	const std::string maximumMemoryOprionString = "-Xmx" + std::to_string(jvmMaximumMemory) + "m";