1 files changed, 280 insertions, 0 deletions
diff --git a/java/src/org/kelar/inputmethod/dictionarypack/DictionaryService.java b/java/src/org/kelar/inputmethod/dictionarypack/DictionaryService.java
new file mode 100644
index 000000000..851a1d925
--- /dev/null
+++ b/java/src/org/kelar/inputmethod/dictionarypack/DictionaryService.java
@@ -0,0 +1,280 @@
+/**
+ * Copyright (C) 2011 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 org.kelar.inputmethod.dictionarypack;
+
+import android.app.AlarmManager;
+import android.app.PendingIntent;
+import android.app.Service;
+import android.content.Context;
+import android.content.Intent;
+import android.os.IBinder;
+import android.util.Log;
+import android.widget.Toast;
+
+import org.kelar.inputmethod.latin.BinaryDictionaryFileDumper;
+import org.kelar.inputmethod.latin.R;
+import org.kelar.inputmethod.latin.common.LocaleUtils;
+
+import java.util.Locale;
+import java.util.Random;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+import javax.annotation.Nonnull;
+
+/**
+ * Service that handles background tasks for the dictionary provider.
+ *
+ * This service provides the context for the long-running operations done by the
+ * dictionary provider. Those include:
+ * - Checking for the last update date and scheduling the next update. This runs every
+ *   day around midnight, upon reception of the DATE_CHANGED_INTENT_ACTION broadcast.
+ *   Every four days, it schedules an update of the metadata with the alarm manager.
+ * - Issuing the order to update the metadata. This runs every four days, between 0 and
+ *   6, upon reception of the UPDATE_NOW_INTENT_ACTION broadcast sent by the alarm manager
+ *   as a result of the above action.
+ * - Handling a download that just ended. These come in two flavors:
+ *   - Metadata is finished downloading. We should check whether there are new dictionaries
+ *     available, and download those that we need that have new versions.
+ *   - A dictionary file finished downloading. We should put the file ready for a client IME
+ *     to access, and mark the current state as such.
+ */
+public final class DictionaryService extends Service {
+    private static final String TAG = DictionaryService.class.getSimpleName();
+
+    /**
+     * The package name, to use in the intent actions.
+     */
+    private static final String PACKAGE_NAME = "org.kelar.inputmethod.latin";
+
+    /**
+     * The action of the date changing, used to schedule a periodic freshness check
+     */
+    private static final String DATE_CHANGED_INTENT_ACTION =
+            Intent.ACTION_DATE_CHANGED;
+
+    /**
+     * The action of displaying a toast to warn the user an automatic download is starting.
+     */
+    /* package */ static final String SHOW_DOWNLOAD_TOAST_INTENT_ACTION =
+            PACKAGE_NAME + ".SHOW_DOWNLOAD_TOAST_INTENT_ACTION";
+
+    /**
+     * A locale argument, as a String.
+     */
+    /* package */ static final String LOCALE_INTENT_ARGUMENT = "locale";
+
+    /**
+     * How often, in milliseconds, we want to update the metadata. This is a
+     * floor value; actually, it may happen several hours later, or even more.
+     */
+    private static final long UPDATE_FREQUENCY_MILLIS = TimeUnit.DAYS.toMillis(4);
+
+    /**
+     * We are waked around midnight, local time. We want to wake between midnight and 6 am,
+     * roughly. So use a random time between 0 and this delay.
+     */
+    private static final int MAX_ALARM_DELAY_MILLIS = (int)TimeUnit.HOURS.toMillis(6);
+
+    /**
+     * How long we consider a "very long time". If no update took place in this time,
+     * the content provider will trigger an update in the background.
+     */
+    private static final long VERY_LONG_TIME_MILLIS = TimeUnit.DAYS.toMillis(14);
+
+    /**
+     * After starting a download, how long we wait before considering it may be stuck. After this
+     * period is elapsed, if the keyboard tries to download again, then we cancel and re-register
+     * the request; if it's within this time, we just leave it be.
+     * It's important to note that we do not re-submit the request merely because the time is up.
+     * This is only to decide whether to cancel the old one and re-requesting when the keyboard
+     * fires a new request for the same data.
+     */
+    public static final long NO_CANCEL_DOWNLOAD_PERIOD_MILLIS = TimeUnit.SECONDS.toMillis(30);
+
+    /**
+     * An executor that serializes tasks given to it.
+     */
+    private ThreadPoolExecutor mExecutor;
+    private static final int WORKER_THREAD_TIMEOUT_SECONDS = 15;
+
+    @Override
+    public void onCreate() {
+        // By default, a thread pool executor does not timeout its core threads, so it will
+        // never kill them when there isn't any work to do any more. That would mean the service
+        // can never die! By creating it this way and calling allowCoreThreadTimeOut, we allow
+        // the single thread to time out after WORKER_THREAD_TIMEOUT_SECONDS = 15 seconds, allowing
+        // the process to be reclaimed by the system any time after that if it's not doing
+        // anything else.
+        // Executors#newSingleThreadExecutor creates a ThreadPoolExecutor but it returns the
+        // superclass ExecutorService which does not have the #allowCoreThreadTimeOut method,
+        // so we can't use that.
+        mExecutor = new ThreadPoolExecutor(1 /* corePoolSize */, 1 /* maximumPoolSize */,
+                WORKER_THREAD_TIMEOUT_SECONDS /* keepAliveTime */,
+                TimeUnit.SECONDS /* unit for keepAliveTime */,
+                new LinkedBlockingQueue<Runnable>() /* workQueue */);
+        mExecutor.allowCoreThreadTimeOut(true);
+    }
+
+    @Override
+    public void onDestroy() {
+    }
+
+    @Override
+    public IBinder onBind(Intent intent) {
+        // This service cannot be bound
+        return null;
+    }
+
+    /**
+     * Executes an explicit command.
+     *
+     * This is the entry point for arbitrary commands that are executed upon reception of certain
+     * events that should be executed on the context of this service. The supported commands are:
+     * - Check last update time and possibly schedule an update of the data for later.
+     *     This is triggered every day, upon reception of the DATE_CHANGED_INTENT_ACTION broadcast.
+     * - Update data NOW.
+     *     This is normally received upon trigger of the scheduled update.
+     * - Handle a finished download.
+     *     This executes the actions that must be taken after a file (metadata or dictionary data
+     *     has been downloaded (or failed to download).
+     * The commands that can be spun an another thread will be executed serially, in order, on
+     * a worker thread that is created on demand and terminates after a short while if there isn't
+     * any work left to do.
+     */
+    @Override
+    public synchronized int onStartCommand(final Intent intent, final int flags,
+            final int startId) {
+        final DictionaryService self = this;
+        if (SHOW_DOWNLOAD_TOAST_INTENT_ACTION.equals(intent.getAction())) {
+            final String localeString = intent.getStringExtra(LOCALE_INTENT_ARGUMENT);
+            if (localeString == null) {
+                Log.e(TAG, "Received " + intent.getAction() + " without locale; skipped");
+            } else {
+                // This is a UI action, it can't be run in another thread
+                showStartDownloadingToast(
+                        this, LocaleUtils.constructLocaleFromString(localeString));
+            }
+        } else {
+            // If it's a command that does not require UI, arrange for the work to be done on a
+            // separate thread, so that we can return right away. The executor will spawn a thread
+            // if necessary, or reuse a thread that has become idle as appropriate.
+            // DATE_CHANGED or UPDATE_NOW are examples of commands that can be done on another
+            // thread.
+            mExecutor.submit(new Runnable() {
+                @Override
+                public void run() {
+                    dispatchBroadcast(self, intent);
+                    // Since calls to onStartCommand are serialized, the submissions to the executor
+                    // are serialized. That means we are guaranteed to call the stopSelfResult()
+                    // in the same order that we got them, so we don't need to take care of the
+                    // order.
+                    stopSelfResult(startId);
+                }
+            });
+        }
+        return Service.START_REDELIVER_INTENT;
+    }
+
+    static void dispatchBroadcast(final Context context, final Intent intent) {
+        final String action = intent.getAction();
+        if (DATE_CHANGED_INTENT_ACTION.equals(action)) {
+            // This happens when the date of the device changes. This normally happens
+            // at midnight local time, but it may happen if the user changes the date
+            // by hand or something similar happens.
+            checkTimeAndMaybeSetupUpdateAlarm(context);
+        } else if (DictionaryPackConstants.UPDATE_NOW_INTENT_ACTION.equals(action)) {
+            // Intent to trigger an update now.
+            UpdateHandler.tryUpdate(context);
+        } else if (DictionaryPackConstants.INIT_AND_UPDATE_NOW_INTENT_ACTION.equals(action)) {
+            // Initialize the client Db.
+            final String mClientId = context.getString(R.string.dictionary_pack_client_id);
+            BinaryDictionaryFileDumper.initializeClientRecordHelper(context, mClientId);
+
+            // Updates the metadata and the download the dictionaries.
+            UpdateHandler.tryUpdate(context);
+        } else {
+            UpdateHandler.downloadFinished(context, intent);
+        }
+    }
+
+    /**
+     * Setups an alarm to check for updates if an update is due.
+     */
+    private static void checkTimeAndMaybeSetupUpdateAlarm(final Context context) {
+        // Of all clients, if the one that hasn't been updated for the longest
+        // is still more recent than UPDATE_FREQUENCY_MILLIS, do nothing.
+        if (!isLastUpdateAtLeastThisOld(context, UPDATE_FREQUENCY_MILLIS)) return;
+
+        PrivateLog.log("Date changed - registering alarm");
+        AlarmManager alarmManager = (AlarmManager)context.getSystemService(Context.ALARM_SERVICE);
+
+        // Best effort to wake between midnight and MAX_ALARM_DELAY_MILLIS in the morning.
+        // It doesn't matter too much if this is very inexact.
+        final long now = System.currentTimeMillis();
+        final long alarmTime = now + new Random().nextInt(MAX_ALARM_DELAY_MILLIS);
+        final Intent updateIntent = new Intent(DictionaryPackConstants.UPDATE_NOW_INTENT_ACTION);
+        // Set the package name to ensure the PendingIntent is only delivered to trusted components
+        updateIntent.setPackage(context.getPackageName());
+        int pendingIntentFlags = PendingIntent.FLAG_CANCEL_CURRENT;
+        if (android.os.Build.VERSION.SDK_INT >= 23) {
+            pendingIntentFlags |= PendingIntent.FLAG_IMMUTABLE;
+        }
+        final PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0,
+                updateIntent, pendingIntentFlags);
+
+        // We set the alarm in the type that doesn't forcefully wake the device
+        // from sleep, but fires the next time the device actually wakes for any
+        // other reason.
+        if (null != alarmManager) alarmManager.set(AlarmManager.RTC, alarmTime, pendingIntent);
+    }
+
+    /**
+     * Utility method to decide whether the last update is older than a certain time.
+     *
+     * @return true if at least `time' milliseconds have elapsed since last update, false otherwise.
+     */
+    private static boolean isLastUpdateAtLeastThisOld(final Context context, final long time) {
+        final long now = System.currentTimeMillis();
+        final long lastUpdate = MetadataDbHelper.getOldestUpdateTime(context);
+        PrivateLog.log("Last update was " + lastUpdate);
+        return lastUpdate + time < now;
+    }
+
+    /**
+     * Refreshes data if it hasn't been refreshed in a very long time.
+     *
+     * This will check the last update time, and if it's been more than VERY_LONG_TIME_MILLIS,
+     * update metadata now - and possibly take subsequent update actions.
+     */
+    public static void updateNowIfNotUpdatedInAVeryLongTime(final Context context) {
+        if (!isLastUpdateAtLeastThisOld(context, VERY_LONG_TIME_MILLIS)) return;
+        UpdateHandler.tryUpdate(context);
+    }
+
+    /**
+     * Shows a toast informing the user that an automatic dictionary download is starting.
+     */
+    private static void showStartDownloadingToast(final Context context,
+            @Nonnull final Locale locale) {
+        final String toastText = String.format(
+                context.getString(R.string.toast_downloading_suggestions),
+                locale.getDisplayName());
+        Toast.makeText(context, toastText, Toast.LENGTH_LONG).show();
+    }
+}