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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.email.data;
     18 
     19 import com.android.email.Throttle;
     20 import com.android.emailcommon.Logging;
     21 
     22 import android.content.Context;
     23 import android.content.CursorLoader;
     24 import android.database.Cursor;
     25 import android.net.Uri;
     26 import android.os.Handler;
     27 import android.util.Log;
     28 
     29 /**
     30  * A {@link CursorLoader} variant that throttle auto-requery on content changes using
     31  * {@link Throttle}.
     32  */
     33 public class ThrottlingCursorLoader extends CursorLoader {
     34     private final Throttle mThrottle;
     35 
     36     /** Constructor with default timeout */
     37     public ThrottlingCursorLoader(Context context, Uri uri, String[] projection, String selection,
     38             String[] selectionArgs, String sortOrder) {
     39         this(context, uri, projection, selection, selectionArgs, sortOrder,
     40                 Throttle.DEFAULT_MIN_TIMEOUT, Throttle.DEFAULT_MAX_TIMEOUT);
     41     }
     42 
     43     /** Constructor that takes custom timeout */
     44     public ThrottlingCursorLoader(Context context, Uri uri, String[] projection, String selection,
     45             String[] selectionArgs, String sortOrder, int minTimeout, int maxTimeout) {
     46         super(context, uri, projection, selection, selectionArgs, sortOrder);
     47 
     48         Runnable forceLoadRunnable = new Runnable() {
     49             @Override
     50             public void run() {
     51                 callSuperOnContentChanged();
     52             }
     53         };
     54         mThrottle = new Throttle(uri.toString(), forceLoadRunnable, new Handler(),
     55                 minTimeout, maxTimeout);
     56     }
     57 
     58     private void debugLog(String message) {
     59         Log.d(Logging.LOG_TAG, "ThrottlingCursorLoader: [" + getUri() + "] " + message);
     60     }
     61 
     62     @Override
     63     protected void onStartLoading() {
     64         if (Throttle.DEBUG) debugLog("startLoading");
     65         mThrottle.cancelScheduledCallback();
     66         super.onStartLoading();
     67     }
     68 
     69     @Override
     70     protected void onForceLoad() {
     71         if (Throttle.DEBUG) debugLog("forceLoad");
     72         mThrottle.cancelScheduledCallback();
     73         super.onForceLoad();
     74     }
     75 
     76     @Override
     77     protected void onStopLoading() {
     78         if (Throttle.DEBUG) debugLog("stopLoading");
     79         mThrottle.cancelScheduledCallback();
     80         super.onStopLoading();
     81     }
     82 
     83     @Override
     84     public void onCanceled(Cursor cursor) {
     85         if (Throttle.DEBUG) debugLog("onCancelled");
     86         mThrottle.cancelScheduledCallback();
     87         super.onCanceled(cursor);
     88     }
     89 
     90     @Override
     91     protected void onReset() {
     92         if (Throttle.DEBUG) debugLog("onReset");
     93         mThrottle.cancelScheduledCallback();
     94         super.onReset();
     95     }
     96 
     97     @Override
     98     public void onContentChanged() {
     99         if (Throttle.DEBUG) debugLog("onContentChanged");
    100 
    101         mThrottle.onEvent();
    102     }
    103 
    104     private void callSuperOnContentChanged() {
    105         if (Throttle.DEBUG) debugLog("callSuperOnContentChanged");
    106         super.onContentChanged();
    107     }
    108 }
    109