Add a perf test for BatteryStatsHelper

On Bramble, we get these results:

	endToEnd_median: 321.983605
	getStats_median: 258.134786
	getStats_cached_median: 48.506614
	powerCalculation_median: 51.798291

Test: Lock the device to little cores for consistency
  $ ./frameworks/base/libs/hwui/tests/scripts/prep_generic.sh little
  $ atest BatteryStatsPerfTests

Bug: 173446001

Change-Id: I307bcea38c7001d950de1b506c31b64f89629952
diff --git a/tests/BatteryStatsPerfTest/Android.bp b/tests/BatteryStatsPerfTest/Android.bp
new file mode 100644
index 0000000..58ccec7
--- /dev/null
+++ b/tests/BatteryStatsPerfTest/Android.bp
@@ -0,0 +1,25 @@
+// Copyright (C) 2020 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.
+
+android_test {
+    name: "BatteryStatsPerfTests",
+    srcs: ["src/**/*.java"],
+    static_libs: [
+        "androidx.test.rules",
+        "apct-perftests-utils",
+        "truth-prebuilt",
+    ],
+    platform_apis: true,
+    certificate: "platform",
+}
diff --git a/tests/BatteryStatsPerfTest/AndroidManifest.xml b/tests/BatteryStatsPerfTest/AndroidManifest.xml
new file mode 100644
index 0000000..7633d52
--- /dev/null
+++ b/tests/BatteryStatsPerfTest/AndroidManifest.xml
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2020 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.
+-->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+        package="com.android.frameworks.perftests.batterystats">
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
+    <uses-permission android:name="android.permission.BATTERY_STATS"/>
+
+    <application>
+        <uses-library android:name="android.test.runner" />
+    </application>
+
+    <instrumentation android:name="androidx.test.runner.AndroidJUnitRunner"
+                     android:targetPackage="com.android.frameworks.perftests.batterystats"/>
+</manifest>
diff --git a/tests/BatteryStatsPerfTest/AndroidTest.xml b/tests/BatteryStatsPerfTest/AndroidTest.xml
new file mode 100644
index 0000000..2f9e114
--- /dev/null
+++ b/tests/BatteryStatsPerfTest/AndroidTest.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2020 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.
+-->
+<configuration description="Runs BatteryStats service Performance Tests">
+    <target_preparer class="com.android.tradefed.targetprep.TestAppInstallSetup">
+        <option name="test-file-name" value="BatteryStatsPerfTests.apk"/>
+        <option name="cleanup-apks" value="true"/>
+    </target_preparer>
+
+    <option name="test-suite-tag" value="apct"/>
+    <option name="test-tag" value="BatteryStatsPerfTests"/>
+    <test class="com.android.tradefed.testtype.AndroidJUnitTest">
+        <option name="package" value="com.android.frameworks.perftests.batterystats"/>
+        <option name="runner" value="androidx.test.runner.AndroidJUnitRunner"/>
+    </test>
+</configuration>
diff --git a/tests/BatteryStatsPerfTest/src/com/android/internal/os/BatteryStatsHelperPerfTest.java b/tests/BatteryStatsPerfTest/src/com/android/internal/os/BatteryStatsHelperPerfTest.java
new file mode 100644
index 0000000..6266cda
--- /dev/null
+++ b/tests/BatteryStatsPerfTest/src/com/android/internal/os/BatteryStatsHelperPerfTest.java
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+
+package com.android.internal.os;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import android.content.Context;
+import android.os.BatteryStats;
+import android.os.Bundle;
+import android.os.UserHandle;
+import android.perftests.utils.BenchmarkState;
+import android.perftests.utils.PerfStatusReporter;
+
+import androidx.test.InstrumentationRegistry;
+import androidx.test.filters.LargeTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.util.List;
+
+@RunWith(AndroidJUnit4.class)
+@LargeTest
+public class BatteryStatsHelperPerfTest {
+
+    @Rule
+    public final PerfStatusReporter mPerfStatusReporter = new PerfStatusReporter();
+
+    /**
+     * Measures the performance of {@link BatteryStatsHelper#getStats()}, which triggers
+     * a battery stats sync on every iteration.
+     */
+    @Test
+    public void testGetStats_forceUpdate() {
+        final Context context = InstrumentationRegistry.getContext();
+        final BatteryStatsHelper statsHelper = new BatteryStatsHelper(context,
+                true /* collectBatteryBroadcast */);
+        statsHelper.create((Bundle) null);
+        statsHelper.refreshStats(BatteryStats.STATS_SINCE_CHARGED, UserHandle.myUserId());
+
+        final BenchmarkState state = mPerfStatusReporter.getBenchmarkState();
+        while (state.keepRunning()) {
+            state.pauseTiming();
+            statsHelper.clearStats();
+            state.resumeTiming();
+
+            statsHelper.getStats();
+
+            assertThat(statsHelper.getUsageList()).isNotEmpty();
+        }
+    }
+
+    /**
+     * Measures performance of the {@link BatteryStatsHelper#getStats(boolean)}, which does
+     * not trigger a sync and just returns current values.
+     */
+    @Test
+    public void testGetStats_cached() {
+        final Context context = InstrumentationRegistry.getContext();
+        final BatteryStatsHelper statsHelper = new BatteryStatsHelper(context,
+                true /* collectBatteryBroadcast */);
+        statsHelper.create((Bundle) null);
+        statsHelper.refreshStats(BatteryStats.STATS_SINCE_CHARGED, UserHandle.myUserId());
+
+        final BenchmarkState state = mPerfStatusReporter.getBenchmarkState();
+        while (state.keepRunning()) {
+            state.pauseTiming();
+            statsHelper.clearStats();
+            state.resumeTiming();
+
+            statsHelper.getStats(false /* forceUpdate */);
+
+            assertThat(statsHelper.getUsageList()).isNotEmpty();
+        }
+    }
+
+    @Test
+    public void testPowerCalculation() {
+        final Context context = InstrumentationRegistry.getContext();
+        final BatteryStatsHelper statsHelper = new BatteryStatsHelper(context,
+                true /* collectBatteryBroadcast */);
+        statsHelper.create((Bundle) null);
+        statsHelper.getStats();
+
+        final BenchmarkState state = mPerfStatusReporter.getBenchmarkState();
+        while (state.keepRunning()) {
+            // This will use the cached BatteryStatsObject
+            statsHelper.refreshStats(BatteryStats.STATS_SINCE_CHARGED, UserHandle.myUserId());
+
+            assertThat(statsHelper.getUsageList()).isNotEmpty();
+        }
+    }
+
+    @Test
+    public void testEndToEnd() {
+        final Context context = InstrumentationRegistry.getContext();
+        final BenchmarkState state = mPerfStatusReporter.getBenchmarkState();
+        while (state.keepRunning()) {
+            final BatteryStatsHelper statsHelper = new BatteryStatsHelper(context,
+                    true /* collectBatteryBroadcast */);
+            statsHelper.create((Bundle) null);
+            statsHelper.clearStats();
+            statsHelper.refreshStats(BatteryStats.STATS_SINCE_CHARGED, UserHandle.myUserId());
+
+            state.pauseTiming();
+
+            List<BatterySipper> usageList = statsHelper.getUsageList();
+            double power = 0;
+            for (int i = 0; i < usageList.size(); i++) {
+                BatterySipper sipper = usageList.get(i);
+                power += sipper.sumPower();
+            }
+
+            assertThat(power).isGreaterThan(0.0);
+
+            state.resumeTiming();
+        }
+    }
+}