| /* |
| * Copyright 2022 Google LLC |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package com.google.android.libraries.mobiledatadownload.file.openers; |
| |
| import android.net.Uri; |
| import com.google.android.libraries.mobiledatadownload.file.OpenContext; |
| import com.google.android.libraries.mobiledatadownload.file.Opener; |
| import com.google.android.libraries.mobiledatadownload.file.SynchronousFileStorage; |
| import com.google.common.collect.Iterables; |
| import java.io.FileNotFoundException; |
| import java.io.IOException; |
| import java.util.ArrayDeque; |
| import java.util.Deque; |
| |
| /** |
| * Calculates the size of a directory by recursively summing the size of all of its children. If the |
| * Uri refers to an empty directory, returns 0. If the Uri refers to a file or does not exist, |
| * throws {@link FileNotFoundException}. |
| * |
| * <p>WARNING: this opener suffers from the following caveats and should be used with caution: |
| * |
| * <ul> |
| * <li>Directory tree traversal is not an atomic operation |
| * <li>There are no special considerations for symlinks, meaning the opener could get caught in a |
| * recursive directory loop (i.e. a directory that contains a symlink to itself) |
| * <li>Fails fast if there is an I/O error while processing a given child Uri |
| * </ul> |
| * |
| * <p>Usage: long size = storage.open(uri, RecursiveSizeOpener.create()); |
| */ |
| public final class RecursiveSizeOpener implements Opener<Long> { |
| private RecursiveSizeOpener() {} |
| |
| public static RecursiveSizeOpener create() { |
| return new RecursiveSizeOpener(); |
| } |
| |
| @Override |
| public Long open(OpenContext context) throws IOException { |
| long totalSize = 0; |
| Deque<Uri> toProcess = new ArrayDeque<>(); |
| SynchronousFileStorage storage = context.storage(); |
| |
| // Stripping the Uri fragment means children filenames don't get encoded by transforms. This is |
| // intentional: we're simply calculating the total file size regardless of the "correct" names. |
| // Children API call throws FNF if the Uri is a file or does not exist. |
| Uri uriWithoutFragment = context.originalUri().buildUpon().fragment(null).build(); |
| Iterables.addAll(toProcess, storage.children(uriWithoutFragment)); |
| |
| // NOTE: breadth-first traversal is an arbitrary implementation choice |
| while (!toProcess.isEmpty()) { |
| Uri uri = toProcess.remove(); |
| if (storage.isDirectory(uri)) { |
| Iterables.addAll(toProcess, storage.children(uri)); |
| } else if (storage.exists(uri)) { |
| totalSize += storage.fileSize(uri); |
| } else { |
| throw new FileNotFoundException(String.format("Child %s could not be opened", uri)); |
| } |
| } |
| |
| return totalSize; |
| } |
| } |