From 2cddb8a8913aa1f5367bd590c123f93c597424b5 Mon Sep 17 00:00:00 2001
From: Makoto Onuki <omakoto@google.com>
Date: Tue, 18 Feb 2020 12:38:21 -0800
Subject: [PATCH] Add WTF when a system server wrapper can't be found

Context.getSystemService() shouldn't return null, but sometimes we observer it.
Add WTFs to investigate it.

Bug: 149406139
Test: Boot with "adb logcat | grep -i wtf" and make sure no wtf is logged
Change-Id: I64c6776cedaeb534d98621db2955d585e6846b8d
---
 .../android/app/SystemServiceRegistry.java    | 42 +++++++++++++++++--
 1 file changed, 38 insertions(+), 4 deletions(-)

diff --git a/core/java/android/app/SystemServiceRegistry.java b/core/java/android/app/SystemServiceRegistry.java
index 50b9d6b47e020..8570c6b5ff48d 100644
--- a/core/java/android/app/SystemServiceRegistry.java
+++ b/core/java/android/app/SystemServiceRegistry.java
@@ -183,6 +183,7 @@ import android.telephony.TelephonyFrameworkInitializer;
 import android.telephony.TelephonyRegistryManager;
 import android.util.ArrayMap;
 import android.util.Log;
+import android.util.Slog;
 import android.view.ContextThemeWrapper;
 import android.view.LayoutInflater;
 import android.view.WindowManager;
@@ -219,6 +220,8 @@ import java.util.Objects;
 public final class SystemServiceRegistry {
     private static final String TAG = "SystemServiceRegistry";
 
+    private static final boolean ENABLE_SERVICE_NOT_FOUND_WTF = true;
+
     // Service registry information.
     // This information is never changed once static initialization has completed.
     private static final Map<Class<?>, String> SYSTEM_SERVICE_NAMES =
@@ -1357,8 +1360,29 @@ public final class SystemServiceRegistry {
      * @hide
      */
     public static Object getSystemService(ContextImpl ctx, String name) {
-        ServiceFetcher<?> fetcher = SYSTEM_SERVICE_FETCHERS.get(name);
-        return fetcher != null ? fetcher.getService(ctx) : null;
+        if (name == null) {
+            return null;
+        }
+        final ServiceFetcher<?> fetcher = SYSTEM_SERVICE_FETCHERS.get(name);
+        if (ENABLE_SERVICE_NOT_FOUND_WTF && fetcher == null) {
+            // This should be a caller bug.
+            Slog.wtf(TAG, "Unknown manager requested: " + name);
+            return null;
+        }
+
+        final Object ret = fetcher.getService(ctx);
+        if (ENABLE_SERVICE_NOT_FOUND_WTF && ret == null) {
+            // Some services do return null in certain situations, so don't do WTF for them.
+            switch (name) {
+                case Context.CONTENT_CAPTURE_MANAGER_SERVICE:
+                case Context.APP_PREDICTION_SERVICE:
+                case Context.INCREMENTAL_SERVICE:
+                    return null;
+            }
+            Slog.wtf(TAG, "Manager wrapper not available: " + name);
+            return null;
+        }
+        return ret;
     }
 
     /**
@@ -1366,7 +1390,15 @@ public final class SystemServiceRegistry {
      * @hide
      */
     public static String getSystemServiceName(Class<?> serviceClass) {
-        return SYSTEM_SERVICE_NAMES.get(serviceClass);
+        if (serviceClass == null) {
+            return null;
+        }
+        final String serviceName = SYSTEM_SERVICE_NAMES.get(serviceClass);
+        if (ENABLE_SERVICE_NOT_FOUND_WTF && serviceName == null) {
+            // This should be a caller bug.
+            Slog.wtf(TAG, "Unknown manager requested: " + serviceClass.getCanonicalName());
+        }
+        return serviceName;
     }
 
     /**
@@ -1663,7 +1695,9 @@ public final class SystemServiceRegistry {
                         try {
                             cache.wait();
                         } catch (InterruptedException e) {
-                            Log.w(TAG, "getService() interrupted");
+                            // This shouldn't normally happen, but if someone interrupts the
+                            // thread, it will.
+                            Slog.wtf(TAG, "getService() interrupted");
                             Thread.currentThread().interrupt();
                             return null;
                         }