Use waitForDeclaredService to get Lights HAL

We cache the reference to the HAL and use a DeathRecipient to keep track
of whether it's still good.

Adds waitForService and waitForDeclaredService to the ServiceManager
Java implementation because they were missing.

Test: atest LightsManagerTest
Test: atest LightsServiceTest
Bug: 152509747
Bug: 154631113
Bug: 154627432
Bug: 154629168
Change-Id: Ife8471f3a7e47b48bb31015ddf40f1d7fef6240f

7 files changed, 159 insertions, 19 deletions

diff --git a/core/java/android/os/ServiceManager.java b/core/java/android/os/ServiceManager.java
index 74ff310ad3af..b654707a683b 100644
--- a/core/java/android/os/ServiceManager.java
+++ b/core/java/android/os/ServiceManager.java
@@ -16,6 +16,7 @@
 
 package android.os;
 
+import android.annotation.NonNull;
 import android.compat.annotation.UnsupportedAppUsage;
 import android.util.ArrayMap;
 import android.util.Log;
@@ -219,6 +220,44 @@ public final class ServiceManager {
     }
 
     /**
+     * Returns whether the specified service is declared.
+     *
+     * @return true if the service is declared somewhere (eg. VINTF manifest) and
+     * waitForService should always be able to return the service.
+     */
+    public static boolean isDeclared(@NonNull String name) {
+        try {
+            return getIServiceManager().isDeclared(name);
+        } catch (RemoteException e) {
+            Log.e(TAG, "error in isDeclared", e);
+            return false;
+        }
+    }
+
+    /**
+     * Returns the specified service from the service manager.
+     *
+     * If the service is not running, servicemanager will attempt to start it, and this function
+     * will wait for it to be ready.
+     *
+     * @return {@code null} only if there are permission problems or fatal errors.
+     */
+    public static native IBinder waitForService(@NonNull String name);
+
+    /**
+     * Returns the specified service from the service manager, if declared.
+     *
+     * If the service is not running, servicemanager will attempt to start it, and this function
+     * will wait for it to be ready.
+     *
+     * @return {@code null} if the service is not declared in the manifest, or if there are
+     * permission problems, or if there are fatal errors.
+     */
+    public static IBinder waitForDeclaredService(@NonNull String name) {
+        return isDeclared(name) ? waitForService(name) : null;
+    }
+
+    /**
      * Return a list of all currently running services.
      * @return an array of all currently running services, or <code>null</code> in
      * case of an exception
diff --git a/core/java/android/os/ServiceManagerNative.java b/core/java/android/os/ServiceManagerNative.java
index 39ddcb2af3c2..91b56fbbc38e 100644
--- a/core/java/android/os/ServiceManagerNative.java
+++ b/core/java/android/os/ServiceManagerNative.java
@@ -87,7 +87,7 @@ class ServiceManagerProxy implements IServiceManager {
     }
 
     public boolean isDeclared(String name) throws RemoteException {
-        throw new RemoteException();
+        return mServiceManager.isDeclared(name);
     }
 
     public void registerClientCallback(String name, IBinder service, IClientCallback cb)
diff --git a/core/jni/Android.bp b/core/jni/Android.bp
index 189a0a72e42c..bd7bc4cf4ceb 100644
--- a/core/jni/Android.bp
+++ b/core/jni/Android.bp
@@ -123,6 +123,7 @@ cc_library_shared {
                 "android_os_MessageQueue.cpp",
                 "android_os_Parcel.cpp",
                 "android_os_SELinux.cpp",
+                "android_os_ServiceManager.cpp",
                 "android_os_SharedMemory.cpp",
                 "android_os_storage_StorageManager.cpp",
                 "android_os_UEventObserver.cpp",
diff --git a/core/jni/AndroidRuntime.cpp b/core/jni/AndroidRuntime.cpp
index 4cb2e975a58b..6fcaddf34322 100644
--- a/core/jni/AndroidRuntime.cpp
+++ b/core/jni/AndroidRuntime.cpp
@@ -136,6 +136,7 @@ extern int register_android_os_HwBlob(JNIEnv *env);
 extern int register_android_os_HwParcel(JNIEnv *env);
 extern int register_android_os_HwRemoteBinder(JNIEnv *env);
 extern int register_android_os_NativeHandle(JNIEnv *env);
+extern int register_android_os_ServiceManager(JNIEnv *env);
 extern int register_android_os_MessageQueue(JNIEnv* env);
 extern int register_android_os_Parcel(JNIEnv* env);
 extern int register_android_os_SELinux(JNIEnv* env);
@@ -1461,6 +1462,7 @@ static const RegJNIRec gRegJNI[] = {
         REG_JNI(register_android_os_HwParcel),
         REG_JNI(register_android_os_HwRemoteBinder),
         REG_JNI(register_android_os_NativeHandle),
+        REG_JNI(register_android_os_ServiceManager),
         REG_JNI(register_android_os_storage_StorageManager),
         REG_JNI(register_android_os_VintfObject),
         REG_JNI(register_android_os_VintfRuntimeInfo),
diff --git a/core/jni/android_os_ServiceManager.cpp b/core/jni/android_os_ServiceManager.cpp
new file mode 100644
index 000000000000..c7479492d404
--- /dev/null
+++ b/core/jni/android_os_ServiceManager.cpp
@@ -0,0 +1,71 @@
+/*
+ * 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.
+ */
+
+#define LOG_TAG "ServiceManager"
+//#define LOG_NDEBUG 0
+#include <android-base/logging.h>
+
+#include <binder/IInterface.h>
+#include <binder/IServiceManager.h>
+#include <nativehelper/JNIHelp.h>
+
+#include "android_util_Binder.h"
+#include "core_jni_helpers.h"
+
+namespace android {
+
+// Native because we have a client-side wait in waitForService() and we do not
+// want an unnecessary second copy of it.
+static jobject android_os_ServiceManager_waitForService(
+        JNIEnv *env,
+        jclass /* clazzObj */,
+        jstring serviceNameObj) {
+
+    const jchar* serviceName = env->GetStringCritical(serviceNameObj, nullptr);
+    if (!serviceName) {
+        jniThrowNullPointerException(env, nullptr);
+        return nullptr;
+    }
+    String16 nameCopy = String16(reinterpret_cast<const char16_t *>(serviceName),
+            env->GetStringLength(serviceNameObj));
+    env->ReleaseStringCritical(serviceNameObj, serviceName);
+
+    sp<IBinder> service = defaultServiceManager()->waitForService(nameCopy);
+
+    if (!service) {
+        return nullptr;
+    }
+
+    return javaObjectForIBinder(env, service);
+}
+
+// ----------------------------------------------------------------------------
+
+static const JNINativeMethod method_table[] = {
+     /* name, signature, funcPtr */
+    {
+        "waitForService",
+        "(Ljava/lang/String;)Landroid/os/IBinder;",
+        (void*)android_os_ServiceManager_waitForService
+    },
+};
+
+int register_android_os_ServiceManager(JNIEnv* env) {
+    return RegisterMethodsOrDie(
+            env, "android/os/ServiceManager", method_table, NELEM(method_table));
+}
+
+}; // namespace android
diff --git a/services/core/java/com/android/server/lights/LightsService.java b/services/core/java/com/android/server/lights/LightsService.java
index 3c6e8d29cae0..8888108100e1 100644
--- a/services/core/java/com/android/server/lights/LightsService.java
+++ b/services/core/java/com/android/server/lights/LightsService.java
@@ -25,6 +25,7 @@ import android.hardware.light.ILights;
 import android.hardware.lights.ILightsManager;
 import android.hardware.lights.Light;
 import android.hardware.lights.LightState;
+import android.os.Binder;
 import android.os.Handler;
 import android.os.IBinder;
 import android.os.Looper;
@@ -37,16 +38,17 @@ import android.util.Slog;
 import android.util.SparseArray;
 import android.view.SurfaceControl;
 
+import com.android.internal.BrightnessSynchronizer;
 import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.Preconditions;
-import com.android.internal.BrightnessSynchronizer;
 import com.android.server.SystemService;
 
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.function.Supplier;
 
 public class LightsService extends SystemService {
     static final String TAG = "LightsService";
@@ -55,7 +57,8 @@ public class LightsService extends SystemService {
     private final LightImpl[] mLightsByType = new LightImpl[LightsManager.LIGHT_ID_COUNT];
     private final SparseArray<LightImpl> mLightsById = new SparseArray<>();
 
-    private ILights mVintfLights = null;
+    @Nullable
+    private final Supplier<ILights> mVintfLights;
 
     @VisibleForTesting
     final LightsManagerBinderService mManagerService;
@@ -391,7 +394,7 @@ public class LightsService extends SystemService {
                     lightState.flashOnMs = onMS;
                     lightState.flashOffMs = offMS;
                     lightState.brightnessMode = (byte) brightnessMode;
-                    mVintfLights.setLightState(mHwLight.id, lightState);
+                    mVintfLights.get().setLightState(mHwLight.id, lightState);
                 } else {
                     setLight_native(mHwLight.id, color, mode, onMS, offMS, brightnessMode);
                 }
@@ -435,19 +438,17 @@ public class LightsService extends SystemService {
     }
 
     public LightsService(Context context) {
-        this(context,
-                ILights.Stub.asInterface(
-                        ServiceManager.getService("android.hardware.light.ILights/default")),
-                Looper.myLooper());
+        this(context, new VintfHalCache(), Looper.myLooper());
     }
 
     @VisibleForTesting
-    LightsService(Context context, ILights service, Looper looper) {
+    LightsService(Context context, Supplier<ILights> service, Looper looper) {
         super(context);
         mH = new Handler(looper);
-        mVintfLights = service;
-        mManagerService = new LightsManagerBinderService();
+        mVintfLights = service.get() != null ? service : null;
+
         populateAvailableLights(context);
+        mManagerService = new LightsManagerBinderService();
     }
 
     private void populateAvailableLights(Context context) {
@@ -467,7 +468,7 @@ public class LightsService extends SystemService {
 
     private void populateAvailableLightsFromAidl(Context context) {
         try {
-            for (HwLight hwLight : mVintfLights.getLights()) {
+            for (HwLight hwLight : mVintfLights.get().getLights()) {
                 mLightsById.put(hwLight.id, new LightImpl(context, hwLight));
             }
         } catch (RemoteException ex) {
@@ -514,6 +515,33 @@ public class LightsService extends SystemService {
         }
     };
 
+    private static class VintfHalCache implements Supplier<ILights>, IBinder.DeathRecipient {
+        @GuardedBy("this")
+        private ILights mInstance = null;
+
+        @Override
+        public synchronized ILights get() {
+            if (mInstance == null) {
+                IBinder binder = Binder.allowBlocking(ServiceManager.waitForDeclaredService(
+                        "android.hardware.light.ILights/default"));
+                if (binder != null) {
+                    mInstance = ILights.Stub.asInterface(binder);
+                    try {
+                        binder.linkToDeath(this, 0);
+                    } catch (RemoteException e) {
+                        Slog.e(TAG, "Unable to register DeathRecipient for " + mInstance);
+                    }
+                }
+            }
+            return mInstance;
+        }
+
+        @Override
+        public synchronized void binderDied() {
+            mInstance = null;
+        }
+    }
+
     static native void setLight_native(int light, int color, int mode,
             int onMS, int offMS, int brightnessMode);
 }
diff --git a/services/tests/servicestests/src/com/android/server/lights/LightsServiceTest.java b/services/tests/servicestests/src/com/android/server/lights/LightsServiceTest.java
index aa923e22444d..d58937ea9cab 100644
--- a/services/tests/servicestests/src/com/android/server/lights/LightsServiceTest.java
+++ b/services/tests/servicestests/src/com/android/server/lights/LightsServiceTest.java
@@ -16,12 +16,11 @@
 
 package com.android.server.lights;
 
-import static android.hardware.lights.LightsRequest.Builder;
-
 import static android.graphics.Color.BLACK;
 import static android.graphics.Color.BLUE;
 import static android.graphics.Color.GREEN;
 import static android.graphics.Color.WHITE;
+import static android.hardware.lights.LightsRequest.Builder;
 
 import static com.google.common.truth.Truth.assertThat;
 
@@ -93,7 +92,7 @@ public class LightsServiceTest {
 
     @Test
     public void testGetLights_filtersSystemLights() {
-        LightsService service = new LightsService(mContext, mHal, Looper.getMainLooper());
+        LightsService service = new LightsService(mContext, () -> mHal, Looper.getMainLooper());
         LightsManager manager = new LightsManager(mContext, service.mManagerService);
 
         // When lights are listed, only the 4 MICROPHONE lights should be visible.
@@ -102,7 +101,7 @@ public class LightsServiceTest {
 
     @Test
     public void testControlMultipleLights() {
-        LightsService service = new LightsService(mContext, mHal, Looper.getMainLooper());
+        LightsService service = new LightsService(mContext, () -> mHal, Looper.getMainLooper());
         LightsManager manager = new LightsManager(mContext, service.mManagerService);
 
         // When the session requests to turn 3/4 lights on:
@@ -124,7 +123,7 @@ public class LightsServiceTest {
 
     @Test
     public void testControlLights_onlyEffectiveForLifetimeOfClient() {
-        LightsService service = new LightsService(mContext, mHal, Looper.getMainLooper());
+        LightsService service = new LightsService(mContext, () -> mHal, Looper.getMainLooper());
         LightsManager manager = new LightsManager(mContext, service.mManagerService);
         Light micLight = manager.getLights().get(0);
 
@@ -145,7 +144,7 @@ public class LightsServiceTest {
 
     @Test
     public void testControlLights_firstCallerWinsContention() {
-        LightsService service = new LightsService(mContext, mHal, Looper.getMainLooper());
+        LightsService service = new LightsService(mContext, () -> mHal, Looper.getMainLooper());
         LightsManager manager = new LightsManager(mContext, service.mManagerService);
         Light micLight = manager.getLights().get(0);
 
@@ -171,7 +170,7 @@ public class LightsServiceTest {
 
     @Test
     public void testClearLight() {
-        LightsService service = new LightsService(mContext, mHal, Looper.getMainLooper());
+        LightsService service = new LightsService(mContext, () -> mHal, Looper.getMainLooper());
         LightsManager manager = new LightsManager(mContext, service.mManagerService);
         Light micLight = manager.getLights().get(0);