Implement TextClassification system service.

- This service provides the TextClassificationManager access to the
  classification model file.
  See: Icb82b707c9c1b4dcb739f44d888bbc43bc3b03bb
- This service is started at boot time.
  See: Ie4a597bc5c6c4140afbcf7feaa9dd237a3fd5fef

Test: Manually tested. Also see: Ic2a5eceeaec4cd2943c6c753084df46d30511fee
Bug: 32503402
Change-Id: Ic428d00f291e268211866b3fc6b7acbc3eb04e1e

Android.mk

@@ -305,6 +305,7 @@ LOCAL_SRC_FILES += \
 	core/java/android/service/wallpaper/IWallpaperService.aidl \
 	core/java/android/service/chooser/IChooserTargetService.aidl \
 	core/java/android/service/chooser/IChooserTargetResult.aidl \
+	core/java/android/text/ITextClassificationService.aidl \
 	core/java/android/view/accessibility/IAccessibilityInteractionConnection.aidl\
 	core/java/android/view/accessibility/IAccessibilityInteractionConnectionCallback.aidl\
 	core/java/android/view/accessibility/IAccessibilityManager.aidl \

core/java/android/text/ITextClassificationService.aidl

@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2016 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 android.text;
+
+import android.os.ParcelFileDescriptor;
+
+/**
+ * Interface to the text classification service, which grants access to the text classification
+ * LSTM model file.
+ * {@hide}
+ */
+interface ITextClassificationService {
+
+    /**
+     * Request a file descriptor with read-only access to the LSTM model file.
+     * This file descriptor should be closed after the client is done with it.
+     */
+    ParcelFileDescriptor getModelFileFd();
+}

services/core/java/com/android/server/text/TextClassificationService.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2016 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.text;
+
+import android.content.Context;
+import android.os.ParcelFileDescriptor;
+import android.os.RemoteException;
+import android.text.ITextClassificationService;
+import android.util.Slog;
+
+import com.android.server.SystemService;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+/**
+ * Text classification service.
+ * This is used to provide access to the text classification LSTM model file.
+ */
+public class TextClassificationService extends ITextClassificationService.Stub {
+
+    private static final String LOG_TAG = "TextClassificationService";
+
+    public static final class Lifecycle extends SystemService {
+
+        private TextClassificationService mService;
+
+        public Lifecycle(Context context) {
+            super(context);
+            mService = new TextClassificationService();
+        }
+
+        @Override
+        public void onStart() {
+            try {
+                publishBinderService(Context.TEXT_CLASSIFICATION_SERVICE, mService);
+            } catch (Throwable t) {
+                // Starting this service is not critical to the running of this device and should
+                // therefore not crash the device. If it fails, log the error and continue.
+                Slog.e(LOG_TAG, "Could not start the TextClassificationService.", t);
+            }
+        }
+    }
+
+    @Override
+    public synchronized ParcelFileDescriptor getModelFileFd() throws RemoteException {
+        try {
+            return ParcelFileDescriptor.open(
+                    new File("/etc/assistant/smart-selection.model"),
+                    ParcelFileDescriptor.MODE_READ_ONLY);
+        } catch (Throwable t) {
+            Slog.e(LOG_TAG, "Error retrieving an fd to the text classification model file.", t);
+            throw new RemoteException(t.getMessage());
+        }
+    }
+}

services/java/com/android/server/SystemServer.java

@@ -100,6 +100,7 @@ import com.android.server.soundtrigger.SoundTriggerService;
 import com.android.server.statusbar.StatusBarManagerService;
 import com.android.server.storage.DeviceStorageMonitorService;
 import com.android.server.telecom.TelecomLoaderService;
+import com.android.server.text.TextClassificationService;
 import com.android.server.trust.TrustManagerService;
 import com.android.server.tv.TvInputManagerService;
 import com.android.server.tv.TvRemoteService;
@@ -896,6 +897,12 @@ public final class SystemServer {
                 traceEnd();
             }
 
+            if (!disableNonCoreServices) {
+                traceBeginAndSlog("StartTextClassificationService");
+                mSystemServiceManager.startService(TextClassificationService.Lifecycle.class);
+                traceEnd();
+            }
+
             if (!disableNetwork) {
                 traceBeginAndSlog("StartNetworkScoreService");
                 try {