Add a threaded CPU-intensive benchmark to test

In order to understand how simpleperf reports percentages from a whole
system, craft a benchmark set that runs a CPU-intensive thread a number
of times.

Bug: none
Test: run the app
Change-Id: I7c8748f9b5da89be20775a5af60b223d4673023b

startop/apps/test/Android.bp

@@ -17,6 +17,7 @@
 android_app {
     name: "startop_test_app",
     srcs: [
+        "src/CPUIntensive.java",
         "src/EmptyActivity.java",
         "src/LayoutInflationActivity.java",
         "src/ComplexLayoutInflationActivity.java",

startop/apps/test/src/CPUIntensive.java

@@ -0,0 +1,67 @@
+/*
+ * 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.
+ */
+
+/**
+ *  A threaded CPU intensive class for use in benchmarks.
+ */
+
+package com.android.startop.test;
+
+final class CPUIntensive {
+    public static final int THREAD_COUNT = 8;
+    public static final int ARRAY_SIZE = 30000;
+    public static int[][] array = new int[THREAD_COUNT][ARRAY_SIZE];
+
+    static class WorkerThread extends Thread {
+        int mThreadNumber;
+        WorkerThread(int number) {
+            mThreadNumber = number;
+        }
+        public void run() {
+            final int arrayLength = array[mThreadNumber].length;
+            for (int i = 0; i < arrayLength; ++i) {
+                array[mThreadNumber][i] = i * i;
+            }
+            for (int i = 0; i < arrayLength; ++i) {
+                for (int j = 0; j < arrayLength; ++j) {
+                    int swap = array[mThreadNumber][j];
+                    array[mThreadNumber][j] = array[mThreadNumber][(j + i) % arrayLength];
+                    array[mThreadNumber][(j + i) % arrayLength] = swap;
+                }
+            }
+        }
+    };
+
+    public static void doSomeWork(int threadCount) {
+        WorkerThread[] threads = new WorkerThread[threadCount];
+        // Create the threads.
+        for (int i = 0; i < threadCount; ++i) {
+            threads[i] = new WorkerThread(i);
+        }
+        // Start the threads.
+        for (int i = 0; i < threadCount; ++i) {
+            threads[i].start();
+        }
+        // Join the threads.
+        for (int i = 0; i < threadCount; ++i) {
+            try {
+                threads[i].join();
+            } catch (Exception ex) {
+            }
+        }
+    }
+}
+

startop/apps/test/src/SystemServerBenchmarkActivity.java

@@ -26,15 +26,11 @@ import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 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 {
     // Time limit to run benchmarks in seconds
@@ -107,6 +103,22 @@ public class SystemServerBenchmarkActivity extends Activity {
         new Benchmark(benchmarkList, "Empty", () -> {
         });
 
+        new Benchmark(benchmarkList, "CPU Intensive (1 thread)", () -> {
+            CPUIntensive.doSomeWork(1);
+        });
+
+        new Benchmark(benchmarkList, "CPU Intensive (2 thread)", () -> {
+            CPUIntensive.doSomeWork(2);
+        });
+
+        new Benchmark(benchmarkList, "CPU Intensive (4 thread)", () -> {
+            CPUIntensive.doSomeWork(4);
+        });
+
+        new Benchmark(benchmarkList, "CPU Intensive (8 thread)", () -> {
+            CPUIntensive.doSomeWork(8);
+        });
+
         PackageManager pm = getPackageManager();
         new Benchmark(benchmarkList, "getInstalledApplications", () -> {
             pm.getInstalledApplications(PackageManager.MATCH_SYSTEM_ONLY);