Home | History | Annotate | Download | only in net 
      1 /*
      2  * Copyright (C) 2014 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.server.net;
     18 
     19 import android.os.Handler;
     20 import android.os.HandlerThread;
     21 import android.text.TextUtils;
     22 import android.util.Log;
     23 
     24 import java.io.BufferedOutputStream;
     25 import java.io.DataOutputStream;
     26 import java.io.FileOutputStream;
     27 import java.io.IOException;
     28 
     29 public class DelayedDiskWrite {
     30     private HandlerThread mDiskWriteHandlerThread;
     31     private Handler mDiskWriteHandler;
     32     /* Tracks multiple writes on the same thread */
     33     private int mWriteSequence = 0;
     34     private final String TAG = "DelayedDiskWrite";
     35 
     36     public interface Writer {
     37         public void onWriteCalled(DataOutputStream out) throws IOException;
     38     }
     39 
     40     public void write(final String filePath, final Writer w) {
     41         write(filePath, w, true);
     42     }
     43 
     44     public void write(final String filePath, final Writer w, final boolean open) {
     45         if (TextUtils.isEmpty(filePath)) {
     46             throw new IllegalArgumentException("empty file path");
     47         }
     48 
     49         /* Do a delayed write to disk on a separate handler thread */
     50         synchronized (this) {
     51             if (++mWriteSequence == 1) {
     52                 mDiskWriteHandlerThread = new HandlerThread("DelayedDiskWriteThread");
     53                 mDiskWriteHandlerThread.start();
     54                 mDiskWriteHandler = new Handler(mDiskWriteHandlerThread.getLooper());
     55             }
     56         }
     57 
     58         mDiskWriteHandler.post(new Runnable() {
     59             @Override
     60             public void run() {
     61                 doWrite(filePath, w, open);
     62             }
     63         });
     64     }
     65 
     66     private void doWrite(String filePath, Writer w, boolean open) {
     67         DataOutputStream out = null;
     68         try {
     69             if (open) {
     70                 out = new DataOutputStream(new BufferedOutputStream(
     71                         new FileOutputStream(filePath)));
     72             }
     73             w.onWriteCalled(out);
     74         } catch (IOException e) {
     75             loge("Error writing data file " + filePath);
     76         } finally {
     77             if (out != null) {
     78                 try {
     79                     out.close();
     80                 } catch (Exception e) {}
     81             }
     82 
     83             // Quit if no more writes sent
     84             synchronized (this) {
     85                 if (--mWriteSequence == 0) {
     86                     mDiskWriteHandler.getLooper().quit();
     87                     mDiskWriteHandler = null;
     88                     mDiskWriteHandlerThread = null;
     89                 }
     90             }
     91         }
     92     }
     93 
     94     private void loge(String s) {
     95         Log.e(TAG, s);
     96     }
     97 }
     98 
     99