Seperate LatencyStatistics from InputReader

Test: atest LatencyStatisticsTest
Change-Id: I22a39cd5bef7fa9180bc1ee1fd9478a2cf872e83

7 files changed, 237 insertions, 79 deletions

diff --git a/include/input/LatencyStatistics.h b/include/input/LatencyStatistics.h
new file mode 100644
index 0000000000..bd86266901
--- /dev/null
+++ b/include/input/LatencyStatistics.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _UI_INPUT_STATISTICS_H
+#define _UI_INPUT_STATISTICS_H
+
+#include <android-base/chrono_utils.h>
+
+#include <stddef.h>
+
+namespace android {
+
+class LatencyStatistics {
+private:
+    /* Minimum sample recorded */
+    float mMin;
+    /* Maximum sample recorded */
+    float mMax;
+    /* Sum of all samples recorded */
+    float mSum;
+    /* Sum of all the squares of samples recorded */
+    float mSum2;
+    /* Count of all samples recorded */
+    size_t mCount;
+    /* The last time statistics were reported */
+    std::chrono::steady_clock::time_point mLastReportTime;
+    /* Statistics Report Frequency */
+    const std::chrono::seconds mReportPeriod;
+
+public:
+    LatencyStatistics(std::chrono::seconds period);
+
+    void addValue(float);
+    void reset();
+    bool shouldReport();
+
+    float getMean();
+    float getMin();
+    float getMax();
+    float getStDev();
+    size_t getCount();
+};
+
+} // namespace android
+
+#endif // _UI_INPUT_STATISTICS_H
diff --git a/libs/input/Android.bp b/libs/input/Android.bp
index 2d788119cd..17138506e5 100644
--- a/libs/input/Android.bp
+++ b/libs/input/Android.bp
@@ -48,6 +48,7 @@ cc_library {
                 "InputTransport.cpp",
                 "InputWindow.cpp",
                 "ISetInputWindowsListener.cpp",
+                "LatencyStatistics.cpp",
                 "VelocityControl.cpp",
                 "VelocityTracker.cpp",
             ],
diff --git a/libs/input/LatencyStatistics.cpp b/libs/input/LatencyStatistics.cpp
new file mode 100644
index 0000000000..e343578e00
--- /dev/null
+++ b/libs/input/LatencyStatistics.cpp
@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <input/LatencyStatistics.h>
+
+#include <android-base/chrono_utils.h>
+
+#include <cmath>
+#include <limits>
+
+namespace android {
+
+LatencyStatistics::LatencyStatistics(std::chrono::seconds period) : mReportPeriod(period) {
+    reset();
+}
+
+/**
+ * Add a raw value to the statistics
+ */
+void LatencyStatistics::addValue(float value) {
+    if (value < mMin) {
+        mMin = value;
+    }
+    if (value > mMax) {
+        mMax = value;
+    }
+    mSum += value;
+    mSum2 += value * value;
+    mCount++;
+}
+
+/**
+ * Get the mean. Should not be called if no samples have been added.
+ */
+float LatencyStatistics::getMean() {
+    return mSum / mCount;
+}
+
+/**
+ * Get the standard deviation. Should not be called if no samples have been added.
+ */
+float LatencyStatistics::getStDev() {
+    float mean = getMean();
+    return sqrt(mSum2 / mCount - mean * mean);
+}
+
+float LatencyStatistics::getMin() {
+    return mMin;
+}
+
+float LatencyStatistics::getMax() {
+    return mMax;
+}
+
+size_t LatencyStatistics::getCount() {
+    return mCount;
+}
+
+/**
+ * Reset internal state. The variable 'when' is the time when the data collection started.
+ * Call this to start a new data collection window.
+ */
+void LatencyStatistics::reset() {
+    mMax = std::numeric_limits<float>::lowest();
+    mMin = std::numeric_limits<float>::max();
+    mSum = 0;
+    mSum2 = 0;
+    mCount = 0;
+    mLastReportTime = std::chrono::steady_clock::now();
+}
+
+bool LatencyStatistics::shouldReport() {
+    std::chrono::duration timeSinceReport = std::chrono::steady_clock::now() - mLastReportTime;
+    return mCount != 0 && timeSinceReport > mReportPeriod;
+}
+
+} // namespace android
diff --git a/libs/input/tests/Android.bp b/libs/input/tests/Android.bp
index ade931e01a..c1c35e1b89 100644
--- a/libs/input/tests/Android.bp
+++ b/libs/input/tests/Android.bp
@@ -7,6 +7,7 @@ cc_test {
         "InputEvent_test.cpp",
         "InputPublisherAndConsumer_test.cpp",
         "InputWindow_test.cpp",
+        "LatencyStatistics_test.cpp",
         "TouchVideoFrame_test.cpp",
         "VelocityTracker_test.cpp",
     ],
diff --git a/libs/input/tests/LatencyStatistics_test.cpp b/libs/input/tests/LatencyStatistics_test.cpp
new file mode 100644
index 0000000000..6d1cab4187
--- /dev/null
+++ b/libs/input/tests/LatencyStatistics_test.cpp
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+#include <input/LatencyStatistics.h>
+#include <cmath>
+#include <limits>
+
+namespace android {
+namespace test {
+
+TEST(LatencyStatisticsTest, ResetStats) {
+    LatencyStatistics stats{5min};
+    stats.addValue(5.0);
+    stats.addValue(19.3);
+    stats.addValue(20);
+    stats.reset();
+
+    ASSERT_EQ(stats.getCount(), 0u);
+    ASSERT_EQ(std::isnan(stats.getStDev()), true);
+    ASSERT_EQ(std::isnan(stats.getMean()), true);
+}
+
+TEST(LatencyStatisticsTest, AddStatsValue) {
+    LatencyStatistics stats{5min};
+    stats.addValue(5.0);
+
+    ASSERT_EQ(stats.getMin(), 5.0);
+    ASSERT_EQ(stats.getMax(), 5.0);
+    ASSERT_EQ(stats.getCount(), 1u);
+    ASSERT_EQ(stats.getMean(), 5.0);
+    ASSERT_EQ(stats.getStDev(), 0.0);
+}
+
+TEST(LatencyStatisticsTest, AddMultipleStatsValue) {
+    LatencyStatistics stats{5min};
+    stats.addValue(4.0);
+    stats.addValue(6.0);
+    stats.addValue(8.0);
+    stats.addValue(10.0);
+
+    float stdev = stats.getStDev();
+
+    ASSERT_EQ(stats.getMin(), 4.0);
+    ASSERT_EQ(stats.getMax(), 10.0);
+    ASSERT_EQ(stats.getCount(), 4u);
+    ASSERT_EQ(stats.getMean(), 7.0);
+    ASSERT_EQ(stdev * stdev, 5.0);
+}
+
+TEST(LatencyStatisticsTest, ShouldReportStats) {
+    LatencyStatistics stats{0min};
+    stats.addValue(5.0);
+
+    ASSERT_EQ(stats.shouldReport(), true);
+}
+
+} // namespace test
+} // namespace android
\ No newline at end of file
diff --git a/services/inputflinger/InputReader.cpp b/services/inputflinger/InputReader.cpp
index eee49d5e2a..df5dcafec9 100644
--- a/services/inputflinger/InputReader.cpp
+++ b/services/inputflinger/InputReader.cpp
@@ -85,9 +85,6 @@ static constexpr nsecs_t TOUCH_DATA_TIMEOUT = ms2ns(20);
 // data.
 static constexpr nsecs_t STYLUS_DATA_LATENCY = ms2ns(10);
 
-// How often to report input event statistics
-static constexpr nsecs_t STATISTICS_REPORT_FREQUENCY = seconds_to_nanoseconds(5 * 60);
-
 // --- Static Functions ---
 
 template<typename T>
@@ -4314,16 +4311,14 @@ void TouchInputMapper::clearStylusDataPendingFlags() {
 }
 
 void TouchInputMapper::reportEventForStatistics(nsecs_t evdevTime) {
-    nsecs_t now = systemTime(CLOCK_MONOTONIC);
-    nsecs_t latency = now - evdevTime;
-    mStatistics.addValue(nanoseconds_to_microseconds(latency));
-    nsecs_t timeSinceLastReport = now - mStatistics.lastReportTime;
-    if (timeSinceLastReport > STATISTICS_REPORT_FREQUENCY) {
-        android::util::stats_write(android::util::TOUCH_EVENT_REPORTED,
-                mStatistics.min, mStatistics.max,
-                mStatistics.mean(), mStatistics.stdev(), mStatistics.count);
-        mStatistics.reset(now);
-    }
+    if (mStatistics.shouldReport()) {
+        android::util::stats_write(android::util::TOUCH_EVENT_REPORTED, mStatistics.getMin(),
+                                   mStatistics.getMax(), mStatistics.getMean(),
+                                   mStatistics.getStDev(), mStatistics.getCount());
+        mStatistics.reset();
+    }
+    nsecs_t latency = nanoseconds_to_microseconds(systemTime(CLOCK_MONOTONIC) - evdevTime);
+    mStatistics.addValue(latency);
 }
 
 void TouchInputMapper::process(const RawEvent* rawEvent) {
diff --git a/services/inputflinger/InputReader.h b/services/inputflinger/InputReader.h
index 0c08e7da38..33763b6cdf 100644
--- a/services/inputflinger/InputReader.h
+++ b/services/inputflinger/InputReader.h
@@ -24,14 +24,15 @@
 
 #include <input/DisplayViewport.h>
 #include <input/Input.h>
+#include <input/LatencyStatistics.h>
 #include <input/VelocityControl.h>
 #include <input/VelocityTracker.h>
 #include <ui/DisplayInfo.h>
-#include <utils/KeyedVector.h>
+#include <utils/BitSet.h>
 #include <utils/Condition.h>
+#include <utils/KeyedVector.h>
 #include <utils/Mutex.h>
 #include <utils/Timers.h>
-#include <utils/BitSet.h>
 
 #include <optional>
 #include <stddef.h>
@@ -569,69 +570,6 @@ struct CookedPointerData {
     }
 };
 
-/**
- * Basic statistics information.
- * Keep track of min, max, average, and standard deviation of the received samples.
- * Used to report latency information about input events.
- */
-struct LatencyStatistics {
-    float min;
-    float max;
-    // Sum of all samples
-    float sum;
-    // Sum of squares of all samples
-    float sum2;
-    // The number of samples
-    size_t count;
-    // The last time statistics were reported.
-    nsecs_t lastReportTime;
-
-    LatencyStatistics() {
-        reset(systemTime(SYSTEM_TIME_MONOTONIC));
-    }
-
-    inline void addValue(float x) {
-        if (x < min) {
-            min = x;
-        }
-        if (x > max) {
-            max = x;
-        }
-        sum += x;
-        sum2 += x * x;
-        count++;
-    }
-
-    // Get the average value. Should not be called if no samples have been added.
-    inline float mean() {
-        if (count == 0) {
-            return 0;
-        }
-        return sum / count;
-    }
-
-    // Get the standard deviation. Should not be called if no samples have been added.
-    inline float stdev() {
-        if (count == 0) {
-            return 0;
-        }
-        float average = mean();
-        return sqrt(sum2 / count - average * average);
-    }
-
-    /**
-     * Reset internal state. The variable 'when' is the time when the data collection started.
-     * Call this to start a new data collection window.
-     */
-    inline void reset(nsecs_t when) {
-        max = 0;
-        min = std::numeric_limits<float>::max();
-        sum = 0;
-        sum2 = 0;
-        count = 0;
-        lastReportTime = when;
-    }
-};
 
 /* Keeps track of the state of single-touch protocol. */
 class SingleTouchMotionAccumulator {
@@ -1571,8 +1509,10 @@ private:
     VelocityControl mWheelXVelocityControl;
     VelocityControl mWheelYVelocityControl;
 
+    static constexpr std::chrono::duration STATS_REPORT_PERIOD = 5min;
+
     // Latency statistics for touch events
-    struct LatencyStatistics mStatistics;
+    LatencyStatistics mStatistics{STATS_REPORT_PERIOD};
 
     std::optional<DisplayViewport> findViewport();