From badeea7604a01352f0ca0a95f6bbb9f1ce4f227e Mon Sep 17 00:00:00 2001
From: Gunnar Beutner <gunnar@beutner.name>
Date: Tue, 19 Jan 2016 15:25:44 +0100
Subject: [PATCH] Decrease memory usage for the Object class

refs #10963
---
 lib/base/object.cpp     |  6 ++--
 lib/base/objectlock.hpp | 64 +++++++++++++++++++++++++++++++++++++++--
 2 files changed, 66 insertions(+), 4 deletions(-)

diff --git a/lib/base/object.cpp b/lib/base/object.cpp
index 1a6d1c9ab..2d2779a38 100644
--- a/lib/base/object.cpp
+++ b/lib/base/object.cpp
@@ -40,7 +40,7 @@ static Timer::Ptr l_ObjectCountTimer;
  * Default constructor for the Object class.
  */
 Object::Object(void)
-	: m_References(0)
+	: m_References(0), m_Mutex(0)
 #ifdef I2_DEBUG
 	, m_LockOwner(0)
 #endif /* I2_DEBUG */
@@ -50,7 +50,9 @@ Object::Object(void)
  * Destructor for the Object class.
  */
 Object::~Object(void)
-{ }
+{
+	delete reinterpret_cast<boost::recursive_mutex *>(m_Mutex);
+}
 
 /**
  * Returns a string representation for the object.
diff --git a/lib/base/objectlock.hpp b/lib/base/objectlock.hpp
index 87d108fea..2ef73ecf6 100644
--- a/lib/base/objectlock.hpp
+++ b/lib/base/objectlock.hpp
@@ -22,6 +22,9 @@
 
 #include "base/object.hpp"
 
+#define I2MUTEX_UNLOCKED 0
+#define I2MUTEX_LOCKED 1
+
 namespace icinga
 {
 
@@ -53,11 +56,49 @@ public:
 			Lock();
 	}
 
+	inline static void LockMutex(const Object *object)
+	{
+		unsigned int it = 0;
+
+#ifdef _WIN32
+#	ifdef _WIN64
+		while (InterlockedCompareExchange64(&object->m_Mutex, I2MUTEX_LOCKED, I2MUTEX_UNLOCKED) != I2MUTEX_UNLOCKED) {
+#	else /* _WIN64 */
+		while (InterlockedCompareExchange(&object->m_Mutex, I2MUTEX_LOCKED, I2MUTEX_UNLOCKED) != I2MUTEX_UNLOCKED) {
+#	endif /* _WIN64 */
+#else /* _WIN32 */
+		while (!__sync_bool_compare_and_swap(&object->m_Mutex, I2MUTEX_UNLOCKED, I2MUTEX_LOCKED)) {
+#endif /* _WIN32 */
+			if (object->m_Mutex > I2MUTEX_LOCKED) {
+				boost::recursive_mutex *mtx = reinterpret_cast<boost::recursive_mutex *>(object->m_Mutex);
+				mtx->lock();
+
+				return;
+			}
+
+			Spin(it);
+			it++;
+		}
+
+		boost::recursive_mutex *mtx = new boost::recursive_mutex();
+		mtx->lock();
+#ifdef _WIN32
+#	ifdef _WIN64
+		InterlockedCompareExchange64(&object->m_Mutex, reinterpret_cast<LONGLONG>(mtx), I2MUTEX_LOCKED);
+#	else /* _WIN64 */
+		InterlockedCompareExchange(&object->m_Mutex, reinterpret_cast<LONG>(mtx), I2MUTEX_LOCKED);
+#	endif /* _WIN64 */
+#else /* _WIN32 */
+		__sync_bool_compare_and_swap(&object->m_Mutex, I2MUTEX_LOCKED, reinterpret_cast<uintptr_t>(mtx));
+#endif /* _WIN32 */
+	}
+
 	inline void Lock(void)
 	{
 		ASSERT(!m_Locked && m_Object != NULL);
 
-		m_Object->m_Mutex.lock();
+		LockMutex(m_Object);
+
 		m_Locked = true;
 
 #ifdef I2_DEBUG
@@ -69,6 +110,25 @@ public:
 #endif /* I2_DEBUG */
 	}
 
+	inline static void Spin(unsigned int it)
+	{
+		if (it < 8) {
+			/* Do nothing. */
+		}
+#ifdef SPIN_PAUSE
+		else if (it < 16) {
+			SPIN_PAUSE();
+		}
+#endif /* SPIN_PAUSE */
+		else {
+#ifdef _WIN32
+			Sleep(0);
+#else /* _WIN32 */
+			sched_yield();
+#endif /* _WIN32 */
+		}
+	}
+
 	inline void Unlock(void)
 	{
 #ifdef I2_DEBUG
@@ -82,7 +142,7 @@ public:
 #endif /* I2_DEBUG */
 
 		if (m_Locked) {
-			m_Object->m_Mutex.unlock();
+			reinterpret_cast<boost::recursive_mutex *>(m_Object->m_Mutex)->unlock();
 			m_Locked = false;
 		}
 	}
-- 
2.40.0