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      1 /*
      2  * Copyright (C) 2015 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.mtp;
     18 
     19 import android.os.ParcelFileDescriptor;
     20 import android.util.Log;
     21 
     22 import java.io.IOException;
     23 import java.util.concurrent.ExecutorService;
     24 import java.util.concurrent.Executors;
     25 import java.util.concurrent.TimeUnit;
     26 
     27 class PipeManager {
     28     /**
     29      * Milliseconds we wait for background thread when pausing.
     30      */
     31     private final static long AWAIT_TERMINATION_TIMEOUT = 2000;
     32 
     33     final ExecutorService mExecutor;
     34     final MtpDatabase mDatabase;
     35 
     36     PipeManager(MtpDatabase database) {
     37         this(database, Executors.newSingleThreadExecutor());
     38     }
     39 
     40     PipeManager(MtpDatabase database, ExecutorService executor) {
     41         this.mDatabase = database;
     42         this.mExecutor = executor;
     43     }
     44 
     45     ParcelFileDescriptor readDocument(MtpManager model, Identifier identifier) throws IOException {
     46         final Task task = new ImportFileTask(model, identifier);
     47         mExecutor.execute(task);
     48         return task.getReadingFileDescriptor();
     49     }
     50 
     51     ParcelFileDescriptor readThumbnail(MtpManager model, Identifier identifier) throws IOException {
     52         final Task task = new GetThumbnailTask(model, identifier);
     53         mExecutor.execute(task);
     54         return task.getReadingFileDescriptor();
     55     }
     56 
     57     private static abstract class Task implements Runnable {
     58         protected final MtpManager mManager;
     59         protected final Identifier mIdentifier;
     60         protected final ParcelFileDescriptor[] mDescriptors;
     61 
     62         Task(MtpManager manager, Identifier identifier) throws IOException {
     63             mManager = manager;
     64             mIdentifier = identifier;
     65             mDescriptors = ParcelFileDescriptor.createReliablePipe();
     66         }
     67 
     68         ParcelFileDescriptor getReadingFileDescriptor() {
     69             return mDescriptors[0];
     70         }
     71     }
     72 
     73     private static class ImportFileTask extends Task {
     74         ImportFileTask(MtpManager model, Identifier identifier) throws IOException {
     75             super(model, identifier);
     76         }
     77 
     78         @Override
     79         public void run() {
     80             try {
     81                 mManager.importFile(
     82                         mIdentifier.mDeviceId, mIdentifier.mObjectHandle, mDescriptors[1]);
     83                 mDescriptors[1].close();
     84             } catch (IOException error) {
     85                 try {
     86                     mDescriptors[1].closeWithError("Failed to stream a file.");
     87                 } catch (IOException closeError) {
     88                     Log.w(MtpDocumentsProvider.TAG, closeError.getMessage());
     89                 }
     90             }
     91         }
     92     }
     93 
     94     private static class GetThumbnailTask extends Task {
     95         GetThumbnailTask(MtpManager model, Identifier identifier) throws IOException {
     96             super(model, identifier);
     97         }
     98 
     99         @Override
    100         public void run() {
    101             try {
    102                 try (final ParcelFileDescriptor.AutoCloseOutputStream stream =
    103                         new ParcelFileDescriptor.AutoCloseOutputStream(mDescriptors[1])) {
    104                     try {
    105                         stream.write(mManager.getThumbnail(
    106                                 mIdentifier.mDeviceId, mIdentifier.mObjectHandle));
    107                     } catch (IOException error) {
    108                         mDescriptors[1].closeWithError("Failed to stream a thumbnail.");
    109                     }
    110                 }
    111             } catch (IOException closeError) {
    112                 Log.w(MtpDocumentsProvider.TAG, closeError.getMessage());
    113             }
    114         }
    115     }
    116 
    117     boolean close() throws InterruptedException {
    118         mExecutor.shutdownNow();
    119         return mExecutor.awaitTermination(AWAIT_TERMINATION_TIMEOUT, TimeUnit.MILLISECONDS);
    120     }
    121 }
    122