1 /* 2 * Copyright (C) 2016 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.documentsui.archives; 18 19 import android.content.ContentResolver; 20 import android.content.Context; 21 import android.net.Uri; 22 import android.util.Log; 23 24 import androidx.annotation.GuardedBy; 25 26 import java.io.IOException; 27 import java.util.concurrent.ExecutorService; 28 import java.util.concurrent.Executors; 29 30 import org.apache.commons.compress.archivers.ArchiveException; 31 import org.apache.commons.compress.compressors.CompressorException; 32 33 /** 34 * Loads an instance of Archive lazily. 35 */ 36 public class Loader { 37 private static final String TAG = "Loader"; 38 39 public static final int STATUS_OPENING = 0; 40 public static final int STATUS_OPENED = 1; 41 public static final int STATUS_FAILED = 2; 42 public static final int STATUS_CLOSING = 3; 43 public static final int STATUS_CLOSED = 4; 44 45 private final Context mContext; 46 private final Uri mArchiveUri; 47 private final int mAccessMode; 48 private final Uri mNotificationUri; 49 private final ExecutorService mExecutor = Executors.newSingleThreadExecutor(); 50 private final Object mLock = new Object(); 51 @GuardedBy("mLock") 52 private int mStatus = STATUS_OPENING; 53 @GuardedBy("mLock") 54 private int mRefCount = 0; 55 private Archive mArchive = null; 56 Loader(Context context, Uri archiveUri, int accessMode, Uri notificationUri)57 Loader(Context context, Uri archiveUri, int accessMode, Uri notificationUri) { 58 this.mContext = context; 59 this.mArchiveUri = archiveUri; 60 this.mAccessMode = accessMode; 61 this.mNotificationUri = notificationUri; 62 63 // Start loading the archive immediately in the background. 64 mExecutor.submit(this::get); 65 } 66 get()67 synchronized Archive get() { 68 synchronized (mLock) { 69 if (mStatus == STATUS_OPENED) { 70 return mArchive; 71 } 72 } 73 74 synchronized (mLock) { 75 if (mStatus != STATUS_OPENING) { 76 throw new IllegalStateException( 77 "Trying to perform an operation on an archive which is invalidated."); 78 } 79 } 80 81 try { 82 if (ReadableArchive.supportsAccessMode(mAccessMode)) { 83 final ContentResolver contentResolver = mContext.getContentResolver(); 84 final String archiveMimeType = contentResolver.getType(mArchiveUri); 85 mArchive = ReadableArchive.createForParcelFileDescriptor( 86 mContext, 87 contentResolver.openFileDescriptor( 88 mArchiveUri, "r", null /* signal */), 89 mArchiveUri, archiveMimeType, mAccessMode, mNotificationUri); 90 } else if (WriteableArchive.supportsAccessMode(mAccessMode)) { 91 mArchive = WriteableArchive.createForParcelFileDescriptor( 92 mContext, 93 mContext.getContentResolver().openFileDescriptor( 94 mArchiveUri, "w", null /* signal */), 95 mArchiveUri, mAccessMode, mNotificationUri); 96 } else { 97 throw new IllegalStateException("Access mode not supported."); 98 } 99 synchronized (mLock) { 100 if (mRefCount == 0) { 101 mArchive.close(); 102 mStatus = STATUS_CLOSED; 103 } else { 104 mStatus = STATUS_OPENED; 105 } 106 } 107 } catch (IOException | RuntimeException | ArchiveException | CompressorException e) { 108 Log.e(TAG, "Failed to open the archive.", e); 109 synchronized (mLock) { 110 mStatus = STATUS_FAILED; 111 } 112 throw new IllegalStateException("Failed to open the archive.", e); 113 } finally { 114 synchronized (mLock) { 115 // Only notify when there might be someone listening. 116 if (mRefCount > 0) { 117 // Notify observers that the root directory is loaded (or failed) 118 // so clients reload it. 119 mContext.getContentResolver().notifyChange( 120 ArchivesProvider.buildUriForArchive(mArchiveUri, mAccessMode), 121 null /* observer */, false /* syncToNetwork */); 122 } 123 } 124 } 125 126 return mArchive; 127 } 128 getStatus()129 int getStatus() { 130 synchronized (mLock) { 131 return mStatus; 132 } 133 } 134 acquire()135 void acquire() { 136 synchronized (mLock) { 137 mRefCount++; 138 } 139 } 140 release()141 void release() { 142 synchronized (mLock) { 143 mRefCount--; 144 if (mRefCount == 0) { 145 assert(mStatus == STATUS_OPENING 146 || mStatus == STATUS_OPENED 147 || mStatus == STATUS_FAILED); 148 149 switch (mStatus) { 150 case STATUS_OPENED: 151 try { 152 mArchive.close(); 153 mStatus = STATUS_CLOSED; 154 } catch (IOException e) { 155 Log.e(TAG, "Failed to close the archive on release.", e); 156 } 157 break; 158 case STATUS_FAILED: 159 mStatus = STATUS_CLOSED; 160 break; 161 case STATUS_OPENING: 162 mStatus = STATUS_CLOSING; 163 // ::get() will close the archive once opened. 164 break; 165 } 166 } 167 } 168 } 169 } 170