From 2b595fb329df6cc4cda6b420f545e4b2249f86b3 Mon Sep 17 00:00:00 2001
From: Brad Hefta-Gaub <brad@highfidelity.io>
Date: Thu, 24 Mar 2016 16:26:28 -0700
Subject: [PATCH] break out thread safe moving average to get around unix build
 hell

---
 interface/src/Application.cpp              |  2 +-
 libraries/gpu/src/gpu/Query.cpp            |  2 +-
 libraries/shared/src/SimpleMovingAverage.h | 29 ++++++++++++++++++++++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/interface/src/Application.cpp b/interface/src/Application.cpp
index 57fbe22577..4a815e453b 100644
--- a/interface/src/Application.cpp
+++ b/interface/src/Application.cpp
@@ -322,7 +322,7 @@ public:
     static std::atomic<int> _maxElapsed;
     static std::atomic<int> _maxElapsedAverage;
     bool _quit { false };
-    MovingAverage<int, HEARTBEAT_SAMPLES> _movingAverage;
+    ThreadSafeMovingAverage<int, HEARTBEAT_SAMPLES> _movingAverage;
 };
 
 std::atomic<uint64_t> DeadlockWatchdogThread::_heartbeat;
diff --git a/libraries/gpu/src/gpu/Query.cpp b/libraries/gpu/src/gpu/Query.cpp
index 51bd16a979..2e28dcd061 100644
--- a/libraries/gpu/src/gpu/Query.cpp
+++ b/libraries/gpu/src/gpu/Query.cpp
@@ -67,5 +67,5 @@ void RangeTimer::end(gpu::Batch& batch) {
 }
 
 double RangeTimer::getAverage() const {
-    return _movingAverage.getAverage();
+    return _movingAverage.average;
 }
\ No newline at end of file
diff --git a/libraries/shared/src/SimpleMovingAverage.h b/libraries/shared/src/SimpleMovingAverage.h
index 44b1daa2e1..debe58da52 100644
--- a/libraries/shared/src/SimpleMovingAverage.h
+++ b/libraries/shared/src/SimpleMovingAverage.h
@@ -44,6 +44,11 @@ private:
 
 template <class T, int MAX_NUM_SAMPLES> class MovingAverage {
 public:
+    const float WEIGHTING = 1.0f / (float)MAX_NUM_SAMPLES;
+    const float ONE_MINUS_WEIGHTING = 1.0f - WEIGHTING;
+    int numSamples{ 0 };
+    T average;
+
     void clear() {
         numSamples = 0;
     }
@@ -60,6 +65,29 @@ public:
         numSamples++;
     }
 
+    T getAverage() const { return average; }
+    T getNumSamples() const { return numSamples; }
+};
+
+template <class T, int MAX_NUM_SAMPLES> class ThreadSafeMovingAverage {
+public:
+    void clear() {
+        numSamples = 0;
+    }
+
+    bool isAverageValid() const { return (numSamples > 0); }
+
+    void addSample(T sample) {
+        if (numSamples > 0) {
+            T lastAverage = average;
+            average = (sample * WEIGHTING) + (lastAverage * ONE_MINUS_WEIGHTING);
+        }
+        else {
+            average = sample;
+        }
+        numSamples++;
+    }
+
     T getAverage() const { return average; }
     T getNumSamples() const { return numSamples; }
 
@@ -70,4 +98,5 @@ private:
     std::atomic<T> average;
 };
 
+
 #endif // hifi_SimpleMovingAverage_h