Initial system server benchmark activity

This adds a simple activity to the Startop Test App for non-scientific
interactive benchmark running for system_server APIs.

Bug: 140743821
Change-Id: I5485152bde4a791035c71d7b3f23e8cff9649292

startop/apps/test/Android.bp

@@ -21,6 +21,7 @@ android_app {
         "src/LayoutInflationActivity.java",
         "src/ComplexLayoutInflationActivity.java",
         "src/FrameLayoutInflationActivity.java",
+        "src/SystemServerBenchmarkActivity.java",
         "src/TextViewInflationActivity.java",
     ],
     platform_apis: true,

startop/apps/test/AndroidManifest.xml

@@ -71,6 +71,19 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+
+        <activity
+            android:label="SystemServer Benchmark"
+            android:name=".SystemServerBenchmarkActivity"
+            android:exported="true" >
+
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
     </application>
 
 </manifest>

startop/apps/test/res/layout/system_server_benchmark_page.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent" >
+
+    <GridLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:columnCount="3"
+        android:id="@+id/benchmark_list">
+
+    <TextView android:text="Benchmark"/>
+    <TextView android:text="Mean (ms)"/>
+    <TextView android:text="Stdev (ms)"/>
+
+    </GridLayout>
+</ScrollView>

startop/apps/test/src/SystemServerBenchmarkActivity.java

@@ -0,0 +1,112 @@
+/*
+ * 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.
+ */
+
+package com.android.startop.test;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.pm.PackageManager;
+import android.os.AsyncTask;
+import android.os.Bundle;
+import android.os.Trace;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Button;
+import android.widget.GridLayout;
+import android.widget.TextView;
+
+import java.util.Arrays;
+
+class Benchmark {
+    public static final int NUM_ITERATIONS = 1000;
+
+    public Benchmark(ViewGroup parent, CharSequence name, Runnable thunk) {
+        Context context = parent.getContext();
+        Button button = new Button(context);
+        TextView mean = new TextView(context);
+        TextView stdev = new TextView(context);
+
+        button.setText(name);
+        mean.setText("");
+        stdev.setText("");
+
+        button.setOnClickListener((_button) -> {
+            mean.setText("Running...");
+            stdev.setText("");
+
+            new AsyncTask() {
+                double resultMean = 0;
+                double resultStdev = 0;
+
+                @Override
+                protected Object doInBackground(Object... _args) {
+                    long[] results = new long[NUM_ITERATIONS];
+
+                    // Run benchmark
+                    for (int i = 0; i < results.length; i++) {
+                        results[i] = -System.nanoTime();
+                        thunk.run();
+                        results[i] += System.nanoTime();
+                    }
+
+                    // Compute mean
+                    long sum = Arrays.stream(results).sum();
+                    resultMean = (double) sum / results.length;
+
+                    // Compute standard deviation
+                    double variance = 0;
+                    for (long i : results) {
+                        double t = (double) i - resultMean;
+                        variance += t * t;
+                    }
+                    variance /= results.length - 1;
+
+                    resultStdev = Math.sqrt(variance);
+
+                    return null;
+                }
+
+                @Override
+                protected void onPostExecute(Object _result) {
+                    mean.setText(String.format("%.3f", resultMean / 1e6));
+                    stdev.setText(String.format("%.3f", resultStdev / 1e6));
+                }
+            }.execute(new Object());
+        });
+
+        parent.addView(button);
+        parent.addView(mean);
+        parent.addView(stdev);
+    }
+}
+
+public class SystemServerBenchmarkActivity extends Activity {
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.system_server_benchmark_page);
+
+        GridLayout benchmarkList = findViewById(R.id.benchmark_list);
+
+        new Benchmark(benchmarkList, "Empty", () -> {
+        });
+
+        PackageManager pm = getPackageManager();
+        new Benchmark(benchmarkList, "getInstalledApplications", () -> {
+            pm.getInstalledApplications(PackageManager.MATCH_SYSTEM_ONLY);
+        });
+    }
+}