Pull CPU statistics code out of threadLoop()

This is to prepare for the threadLoop() merge

Change-Id: I118c7d5c6b011b5d5b95ec7d63fb03feb166a9cf

Author: gkasten

services/audioflinger/AudioFlinger.cpp

@@ -1932,6 +1932,46 @@ AudioFlinger::MixerThread::~MixerThread()
     delete mAudioMixer;
 }
 
+class CpuStats {
+public:
+    void sample();
+#ifdef DEBUG_CPU_USAGE
+private:
+    ThreadCpuUsage mCpu;
+#endif
+};
+
+void CpuStats::sample() {
+#ifdef DEBUG_CPU_USAGE
+    const CentralTendencyStatistics& stats = mCpu.statistics();
+    mCpu.sampleAndEnable();
+    unsigned n = stats.n();
+    // mCpu.elapsed() is expensive, so don't call it every loop
+    if ((n & 127) == 1) {
+        long long elapsed = mCpu.elapsed();
+        if (elapsed >= DEBUG_CPU_USAGE * 1000000000LL) {
+            double perLoop = elapsed / (double) n;
+            double perLoop100 = perLoop * 0.01;
+            double mean = stats.mean();
+            double stddev = stats.stddev();
+            double minimum = stats.minimum();
+            double maximum = stats.maximum();
+            mCpu.resetStatistics();
+            ALOGI("CPU usage over past %.1f secs (%u mixer loops at %.1f mean ms per loop):\n  us per mix loop: mean=%.0f stddev=%.0f min=%.0f max=%.0f\n  %% of wall: mean=%.1f stddev=%.1f min=%.1f max=%.1f",
+                    elapsed * .000000001, n, perLoop * .000001,
+                    mean * .001,
+                    stddev * .001,
+                    minimum * .001,
+                    maximum * .001,
+                    mean / perLoop100,
+                    stddev / perLoop100,
+                    minimum / perLoop100,
+                    maximum / perLoop100);
+        }
+    }
+#endif
+};
+
 bool AudioFlinger::MixerThread::threadLoop()
 {
     Vector< sp<Track> > tracksToRemove;
@@ -1950,42 +1990,13 @@ bool AudioFlinger::MixerThread::threadLoop()
     uint32_t sleepTime = idleSleepTime;
     uint32_t sleepTimeShift = 0;
     Vector< sp<EffectChain> > effectChains;
-#ifdef DEBUG_CPU_USAGE
-    ThreadCpuUsage cpu;
-    const CentralTendencyStatistics& stats = cpu.statistics();
-#endif
+    CpuStats cpuStats;
 
     acquireWakeLock();
 
     while (!exitPending())
     {
-#ifdef DEBUG_CPU_USAGE
-        cpu.sampleAndEnable();
-        unsigned n = stats.n();
-        // cpu.elapsed() is expensive, so don't call it every loop
-        if ((n & 127) == 1) {
-            long long elapsed = cpu.elapsed();
-            if (elapsed >= DEBUG_CPU_USAGE * 1000000000LL) {
-                double perLoop = elapsed / (double) n;
-                double perLoop100 = perLoop * 0.01;
-                double mean = stats.mean();
-                double stddev = stats.stddev();
-                double minimum = stats.minimum();
-                double maximum = stats.maximum();
-                cpu.resetStatistics();
-                ALOGI("CPU usage over past %.1f secs (%u mixer loops at %.1f mean ms per loop):\n  us per mix loop: mean=%.0f stddev=%.0f min=%.0f max=%.0f\n  %% of wall: mean=%.1f stddev=%.1f min=%.1f max=%.1f",
-                        elapsed * .000000001, n, perLoop * .000001,
-                        mean * .001,
-                        stddev * .001,
-                        minimum * .001,
-                        maximum * .001,
-                        mean / perLoop100,
-                        stddev / perLoop100,
-                        minimum / perLoop100,
-                        maximum / perLoop100);
-            }
-        }
-#endif
+        cpuStats.sample();
         processConfigEvents();
 
         mixerStatus = MIXER_IDLE;