Improve notification coalescence algorithm.

Instead of coalescing for 15 seconds after the first change
notification, coalesce until change notifications have been idle for at
least 2 seconds. This avoids long update delays, which is especially
jarring when using notifications on a wearable and the initial
notification didn't yet include the message body.
Also skip coalescence entirely for deletions; update immediately in that
case.

Change-Id: I67bed9a1af7b023020b0fd5429495eb45000e858

src/com/android/email/EmailNotificationController.java

@@ -56,6 +56,7 @@ import com.android.mail.utils.NotificationUtils;
 
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
@@ -213,9 +214,7 @@ public class EmailNotificationController implements NotificationController {
      */
 
     private static final int NOTIFICATION_DELAYED_MESSAGE = 0;
-    private static final long NOTIFICATION_DELAY = 15 * DateUtils.SECOND_IN_MILLIS;
+    private static final long NOTIFICATION_DELAY = 2 * DateUtils.SECOND_IN_MILLIS;
-    // True if we're coalescing notification updates
-    private static boolean sNotificationDelayedMessagePending;
     // True if accounts have changed and we need to refresh everything
     private static boolean sRefreshAllNeeded;
     // Set of accounts we need to regenerate notifications for
@@ -228,28 +227,30 @@ public class EmailNotificationController implements NotificationController {
             sNotificationThread = new NotificationThread();
             sNotificationHandler = new Handler(sNotificationThread.getLooper(),
                     new Handler.Callback() {
-                        @Override
+                @Override
-                        public boolean handleMessage(final android.os.Message message) {
+                public boolean handleMessage(final android.os.Message message) {
-                            /**
+                    /**
-                             * To reduce spamming the notifications, we quiesce updates for a few
+                     * To reduce spamming the notifications, we quiesce updates for a few
-                             * seconds to batch them up, then handle them here.
+                     * seconds to batch them up, then handle them here.
-                             */
+                     */
-                            LogUtils.d(LOG_TAG, "Delayed notification processing");
+                    if (message.arg1 != 0) {
-                            synchronized (sNotificationDelayedMessageLock) {
+                        LogUtils.d(LOG_TAG, "Delayed notification processing");
-                                sNotificationDelayedMessagePending = false;
+                        synchronized (sNotificationDelayedMessageLock) {
-                                final Context context = (Context)message.obj;
+                            final Context context = (Context)message.obj;
-                                if (sRefreshAllNeeded) {
+                            if (sRefreshAllNeeded) {
-                                    sRefreshAllNeeded = false;
+                                sRefreshAllNeeded = false;
-                                    refreshAllNotificationsInternal(context);
+                                refreshAllNotificationsInternal(context);
-                                }
+                            } else {
                                 for (final Long accountId : sRefreshAccountSet) {
                                     refreshNotificationsForAccountInternal(context, accountId);
                                 }
-                                sRefreshAccountSet.clear();
                             }
-                            return true;
+                            sRefreshAccountSet.clear();
                         }
-                    });
+                    }
+                    return true;
+                }
+            });
         }
     }
 
@@ -590,19 +591,32 @@ public class EmailNotificationController implements NotificationController {
         notificationManager.cancel((int) (NOTIFICATION_ID_BASE_SECURITY_CHANGED + account.mId));
     }
 
+    private static void scheduleNotificationUpdateLocked(final Context context,
+            boolean immediate) {
+        ensureHandlerExists();
+        android.os.Message msg = android.os.Message.obtain(sNotificationHandler,
+                NOTIFICATION_DELAYED_MESSAGE, 1, 0, context);
+        boolean isInDelayWindow = sNotificationHandler.hasMessages(NOTIFICATION_DELAYED_MESSAGE);
+
+        sNotificationHandler.removeMessages(NOTIFICATION_DELAYED_MESSAGE);
+        if (!immediate && isInDelayWindow) {
+            // we're in the delay window, restart timer
+            sNotificationHandler.sendMessageDelayed(msg, NOTIFICATION_DELAY);
+        } else {
+            // no refreshes happened in the last delay window; refresh immediately
+            // and send a dummy message to ensure the delay window is respected
+            // when the next update comes in
+            sNotificationHandler.sendMessage(msg);
+            sNotificationHandler.sendEmptyMessageDelayed(NOTIFICATION_DELAYED_MESSAGE,
+                    NOTIFICATION_DELAY);
+        }
+    }
+
     private static void refreshNotificationsForAccount(final Context context,
-            final long accountId) {
+            final long accountId, boolean immediate) {
         synchronized (sNotificationDelayedMessageLock) {
-            if (sNotificationDelayedMessagePending) {
+            sRefreshAccountSet.add(accountId);
-                sRefreshAccountSet.add(accountId);
+            scheduleNotificationUpdateLocked(context, immediate);
-            } else {
-                ensureHandlerExists();
-                sNotificationHandler.sendMessageDelayed(
-                        android.os.Message.obtain(sNotificationHandler,
-                                NOTIFICATION_DELAYED_MESSAGE, context), NOTIFICATION_DELAY);
-                sNotificationDelayedMessagePending = true;
-                refreshNotificationsForAccountInternal(context, accountId);
-            }
         }
     }
 
@@ -722,18 +736,10 @@ public class EmailNotificationController implements NotificationController {
                 account, folder, true /* getAttention */);
     }
 
-    private static void refreshAllNotifications(final Context context) {
+    private static void refreshAllNotifications(final Context context, boolean immediate) {
         synchronized (sNotificationDelayedMessageLock) {
-            if (sNotificationDelayedMessagePending) {
+            sRefreshAllNeeded = true;
-                sRefreshAllNeeded = true;
+            scheduleNotificationUpdateLocked(context, immediate);
-            } else {
-                ensureHandlerExists();
-                sNotificationHandler.sendMessageDelayed(
-                        android.os.Message.obtain(sNotificationHandler,
-                                NOTIFICATION_DELAYED_MESSAGE, context), NOTIFICATION_DELAY);
-                sNotificationDelayedMessagePending = true;
-                refreshAllNotificationsInternal(context);
-            }
         }
     }
 
@@ -757,8 +763,11 @@ public class EmailNotificationController implements NotificationController {
         }
 
         @Override
-        public void onChange(final boolean selfChange) {
+        public void onChange(final boolean selfChange, Uri uri) {
-            refreshNotificationsForAccount(mContext, mAccountId);
+            List<String> segments = uri != null ? uri.getPathSegments() : null;
+            boolean isDelete = segments != null && segments.size() >= 2
+                    ? EmailProvider.NOTIFICATION_OP_DELETE.equals(segments.get(1)) : false;
+            refreshNotificationsForAccount(mContext, mAccountId, isDelete);
         }
     }
 
@@ -774,7 +783,7 @@ public class EmailNotificationController implements NotificationController {
         }
 
         @Override
-        public void onChange(final boolean selfChange) {
+        public void onChange(final boolean selfChange, Uri uri) {
             final ContentResolver resolver = mContext.getContentResolver();
             final Cursor c = resolver.query(Account.CONTENT_URI, EmailContent.ID_PROJECTION,
                 null, null, null);
@@ -811,7 +820,7 @@ public class EmailNotificationController implements NotificationController {
                 sInstance.unregisterMessageNotification(accountId);
             }
 
-            refreshAllNotifications(mContext);
+            refreshAllNotifications(mContext, !removedAccountList.isEmpty());
         }
     }