Add memory pressure information to ANR and system server watchdog.

Bug: 146039257
Test: Manually triggered ANR and inspected report.
Change-Id: Ib32f9bca0de6e04455413addab750c7225a0fe73

services/core/java/com/android/server/MemoryPressureUtil.java

@@ -0,0 +1,56 @@
+/*
+ * 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.server;
+
+import android.os.StrictMode;
+import android.util.Slog;
+
+import libcore.io.IoUtils;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.StringWriter;
+
+/**
+ * Utility method for memory pressure (PSI).
+ */
+public final class MemoryPressureUtil {
+    private static final String FILE = "/proc/pressure/memory";
+    private static final String TAG = "MemoryPressure";
+
+    /**
+     * @return a stanza about memory PSI to add to a report.
+     */
+    public static String currentPsiState() {
+        final StrictMode.ThreadPolicy savedPolicy = StrictMode.allowThreadDiskReads();
+        StringWriter contents = new StringWriter();
+        try {
+            if (new File(FILE).exists()) {
+                contents.append("----- Output from /proc/pressure/memory -----\n");
+                contents.append(IoUtils.readFileAsString(FILE));
+                contents.append("----- End output from /proc/pressure/memory -----\n\n");
+            }
+        } catch (IOException e) {
+            Slog.e(TAG, "Could not read " + FILE, e);
+        } finally {
+            StrictMode.setThreadPolicy(savedPolicy);
+        }
+        return contents.toString();
+    }
+
+    private MemoryPressureUtil(){}
+}

services/core/java/com/android/server/Watchdog.java

@@ -610,6 +610,8 @@ public class Watchdog extends Thread {
             if (mPhonePid > 0) pids.add(mPhonePid);
 
             long anrTime = SystemClock.uptimeMillis();
+            StringBuilder report = new StringBuilder();
+            report.append(MemoryPressureUtil.currentPsiState());
             ProcessCpuTracker processCpuTracker = new ProcessCpuTracker(false);
             StringWriter tracesFileException = new StringWriter();
             final File stack = ActivityManagerService.dumpStackTraces(
@@ -621,7 +623,6 @@ public class Watchdog extends Thread {
             SystemClock.sleep(5000);
 
             processCpuTracker.update();
-            StringBuilder report = new StringBuilder();
             report.append(processCpuTracker.printCurrentState(anrTime));
             report.append(tracesFileException.getBuffer());
 

services/core/java/com/android/server/am/ProcessRecord.java

@@ -66,6 +66,7 @@ import com.android.internal.os.BatteryStatsImpl;
 import com.android.internal.os.ProcessCpuTracker;
 import com.android.internal.os.Zygote;
 import com.android.internal.util.FrameworkStatsLog;
+import com.android.server.MemoryPressureUtil;
 import com.android.server.wm.WindowProcessController;
 import com.android.server.wm.WindowProcessListener;
 
@@ -1582,6 +1583,8 @@ class ProcessRecord implements WindowProcessListener {
             info.append("Parent: ").append(parentShortComponentName).append("\n");
         }
 
+        StringBuilder report = new StringBuilder();
+        report.append(MemoryPressureUtil.currentPsiState());
         ProcessCpuTracker processCpuTracker = new ProcessCpuTracker(true);
 
         // don't dump native PIDs for background ANRs unless it is the process of interest
@@ -1614,7 +1617,6 @@ class ProcessRecord implements WindowProcessListener {
                 (isSilentAnr()) ? null : processCpuTracker, (isSilentAnr()) ? null : lastPids,
                 nativePids, tracesFileException);
 
-        StringBuilder report = new StringBuilder();
         if (isMonitorCpuUsage()) {
             mService.updateCpuStatsNow();
             synchronized (mService.mProcessCpuTracker) {