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      1 /*
      2  * Copyright (C) 2007 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 android.webkit;
     18 
     19 import android.content.Context;
     20 import android.os.Handler;
     21 import android.os.Looper;
     22 import android.os.Message;
     23 import android.os.Process;
     24 import android.util.Log;
     25 
     26 abstract class WebSyncManager implements Runnable {
     27     // message code for sync message
     28     private static final int SYNC_MESSAGE = 101;
     29     // time delay in millisec for a sync (now) message
     30     private static int SYNC_NOW_INTERVAL = 100; // 100 millisec
     31     // time delay in millisec for a sync (later) message
     32     private static int SYNC_LATER_INTERVAL = 5 * 60 * 1000; // 5 minutes
     33     // thread for syncing
     34     private Thread mSyncThread;
     35     // Name of thread
     36     private String mThreadName;
     37     // handler of the sync thread
     38     protected Handler mHandler;
     39     // database for the persistent storage
     40     protected WebViewDatabase mDataBase;
     41     // Ref count for calls to start/stop sync
     42     private int mStartSyncRefCount;
     43     // log tag
     44     protected static final String LOGTAG = "websync";
     45 
     46     private class SyncHandler extends Handler {
     47         @Override
     48         public void handleMessage(Message msg) {
     49             if (msg.what == SYNC_MESSAGE) {
     50                 if (DebugFlags.WEB_SYNC_MANAGER) {
     51                     Log.v(LOGTAG, "*** WebSyncManager sync ***");
     52                 }
     53                 syncFromRamToFlash();
     54 
     55                 // send a delayed message to request sync later
     56                 Message newmsg = obtainMessage(SYNC_MESSAGE);
     57                 sendMessageDelayed(newmsg, SYNC_LATER_INTERVAL);
     58             }
     59         }
     60     }
     61 
     62     protected WebSyncManager(Context context, String name) {
     63         mThreadName = name;
     64         if (context != null) {
     65             mDataBase = WebViewDatabase.getInstance(context);
     66             mSyncThread = new Thread(this);
     67             mSyncThread.setName(mThreadName);
     68             mSyncThread.start();
     69         } else {
     70             throw new IllegalStateException(
     71                     "WebSyncManager can't be created without context");
     72         }
     73     }
     74 
     75     protected Object clone() throws CloneNotSupportedException {
     76         throw new CloneNotSupportedException("doesn't implement Cloneable");
     77     }
     78 
     79     public void run() {
     80         // prepare Looper for sync handler
     81         Looper.prepare();
     82         mHandler = new SyncHandler();
     83         onSyncInit();
     84         // lower the priority after onSyncInit() is done
     85        Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
     86 
     87         Message msg = mHandler.obtainMessage(SYNC_MESSAGE);
     88         mHandler.sendMessageDelayed(msg, SYNC_LATER_INTERVAL);
     89 
     90         Looper.loop();
     91     }
     92 
     93     /**
     94      * sync() forces sync manager to sync now
     95      */
     96     public void sync() {
     97         if (DebugFlags.WEB_SYNC_MANAGER) {
     98             Log.v(LOGTAG, "*** WebSyncManager sync ***");
     99         }
    100         if (mHandler == null) {
    101             return;
    102         }
    103         mHandler.removeMessages(SYNC_MESSAGE);
    104         Message msg = mHandler.obtainMessage(SYNC_MESSAGE);
    105         mHandler.sendMessageDelayed(msg, SYNC_NOW_INTERVAL);
    106     }
    107 
    108     /**
    109      * resetSync() resets sync manager's timer
    110      */
    111     public void resetSync() {
    112         if (DebugFlags.WEB_SYNC_MANAGER) {
    113             Log.v(LOGTAG, "*** WebSyncManager resetSync ***");
    114         }
    115         if (mHandler == null) {
    116             return;
    117         }
    118         mHandler.removeMessages(SYNC_MESSAGE);
    119         Message msg = mHandler.obtainMessage(SYNC_MESSAGE);
    120         mHandler.sendMessageDelayed(msg, SYNC_LATER_INTERVAL);
    121     }
    122 
    123     /**
    124      * startSync() requests sync manager to start sync
    125      */
    126     public void startSync() {
    127         if (DebugFlags.WEB_SYNC_MANAGER) {
    128             Log.v(LOGTAG, "***  WebSyncManager startSync ***, Ref count:" +
    129                     mStartSyncRefCount);
    130         }
    131         if (mHandler == null) {
    132             return;
    133         }
    134         if (++mStartSyncRefCount == 1) {
    135             Message msg = mHandler.obtainMessage(SYNC_MESSAGE);
    136             mHandler.sendMessageDelayed(msg, SYNC_LATER_INTERVAL);
    137         }
    138     }
    139 
    140     /**
    141      * stopSync() requests sync manager to stop sync. remove any SYNC_MESSAGE in
    142      * the queue to break the sync loop
    143      */
    144     public void stopSync() {
    145         if (DebugFlags.WEB_SYNC_MANAGER) {
    146             Log.v(LOGTAG, "*** WebSyncManager stopSync ***, Ref count:" +
    147                     mStartSyncRefCount);
    148         }
    149         if (mHandler == null) {
    150             return;
    151         }
    152         if (--mStartSyncRefCount == 0) {
    153             mHandler.removeMessages(SYNC_MESSAGE);
    154         }
    155     }
    156 
    157     protected void onSyncInit() {
    158     }
    159 
    160     abstract void syncFromRamToFlash();
    161 }
    162