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+/** 
+ * @file llsimplestat.h
+ * @brief Runtime statistics accumulation.
+ *
+ * $LicenseInfo:firstyear=2010&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#ifndef LL_SIMPLESTAT_H
+#define LL_SIMPLESTAT_H
+
+// History
+//
+// The original source for this code is the server repositories'
+// llcommon/llstat.h file.  This particular code was added after the
+// viewer/server code schism but before the effort to convert common
+// code to libraries was complete.  Rather than add to merge issues,
+// the needed code was cut'n'pasted into this new header as it isn't
+// too awful a burden.  Post-modularization, we can look at removing
+// this redundancy.
+
+
+/**
+ * @class LLSimpleStatCounter
+ * @brief Just counts events.
+ *
+ * Really not needed but have a pattern in mind in the future.
+ * Interface limits what can be done at that's just fine.
+ *
+ * *TODO:  Update/transfer unit tests
+ * Unit tests:  indra/test/llcommon_llstat_tut.cpp
+ */
+class LLSimpleStatCounter
+{
+public:
+	inline LLSimpleStatCounter()		{ reset(); }
+	// Default destructor and assignment operator are valid
+
+	inline void reset()					{ mCount = 0; }
+
+	inline void merge(const LLSimpleStatCounter & src)
+										{ mCount += src.mCount; }
+	
+	inline U32 operator++()				{ return ++mCount; }
+
+	inline U32 getCount() const			{ return mCount; }
+		
+protected:
+	U32			mCount;
+};
+
+
+/**
+ * @class LLSimpleStatMMM
+ * @brief Templated collector of min, max and mean data for stats.
+ *
+ * Fed a stream of data samples, keeps a running account of the
+ * min, max and mean seen since construction or the last reset()
+ * call.  A freshly-constructed or reset instance returns counts
+ * and values of zero.
+ *
+ * Overflows and underflows (integer, inf or -inf) and NaN's
+ * are the caller's problem.  As is loss of precision when
+ * the running sum's exponent (when parameterized by a floating
+ * point of some type) differs from a given data sample's.
+ *
+ * Unit tests:  indra/test/llcommon_llstat_tut.cpp
+ */
+template <typename VALUE_T = F32>
+class LLSimpleStatMMM
+{
+public:
+	typedef VALUE_T Value;
+	
+public:
+	LLSimpleStatMMM()				{ reset(); }
+	// Default destructor and assignment operator are valid
+
+	/**
+	 * Resets the object returning all counts and derived
+	 * values back to zero.
+	 */
+	void reset()
+		{
+			mCount = 0;
+			mMin = Value(0);
+			mMax = Value(0);
+			mTotal = Value(0);
+		}
+
+	void record(Value v)
+		{
+			if (mCount)
+			{
+				mMin = llmin(mMin, v);
+				mMax = llmax(mMax, v);
+			}
+			else
+			{
+				mMin = v;
+				mMax = v;
+			}
+			mTotal += v;
+			++mCount;
+		}
+
+	void merge(const LLSimpleStatMMM<VALUE_T> & src)
+		{
+			if (! mCount)
+			{
+				*this = src;
+			}
+			else if (src.mCount)
+			{
+				mMin = llmin(mMin, src.mMin);
+				mMax = llmax(mMax, src.mMax);
+				mCount += src.mCount;
+				mTotal += src.mTotal;
+			}
+		}
+	
+	inline U32 getCount() const		{ return mCount; }
+	inline Value getMin() const		{ return mMin; }
+	inline Value getMax() const		{ return mMax; }
+	inline Value getMean() const	{ return mCount ? mTotal / mCount : mTotal; }
+		
+protected:
+	U32			mCount;
+	Value		mMin;
+	Value		mMax;
+	Value		mTotal;
+};
+
+#endif // LL_SIMPLESTAT_H