Robert Berry | a1109ef | 2017-07-17 09:56:44 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2017 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.backup; |
| 18 | |
| 19 | import android.util.Slog; |
| 20 | |
| 21 | import com.android.internal.annotations.GuardedBy; |
| 22 | import com.android.server.backup.RefactoredBackupManagerService; |
| 23 | |
| 24 | import java.io.EOFException; |
| 25 | import java.io.File; |
| 26 | import java.io.IOException; |
| 27 | import java.io.RandomAccessFile; |
| 28 | import java.util.HashSet; |
| 29 | import java.util.Set; |
| 30 | |
| 31 | /** |
| 32 | * Records which apps have been backed up on this device, persisting it to disk so that it can be |
| 33 | * read at subsequent boots. This class is threadsafe. |
| 34 | * |
| 35 | * <p>This is used to decide, when restoring a package at install time, whether it has been |
| 36 | * previously backed up on the current device. If it has been previously backed up it should |
| 37 | * restore from the same restore set that the current device has been backing up to. If it has not |
| 38 | * been previously backed up, it should restore from the ancestral restore set (i.e., the restore |
| 39 | * set that the user's previous device was backing up to). |
| 40 | * |
| 41 | * <p>NB: this is always backed by the same files within the state directory supplied at |
| 42 | * construction. |
| 43 | */ |
| 44 | final class ProcessedPackagesJournal { |
| 45 | private static final String TAG = "ProcessedPackagesJournal"; |
| 46 | private static final String JOURNAL_FILE_NAME = "processed"; |
| 47 | private static final boolean DEBUG = RefactoredBackupManagerService.DEBUG || false; |
| 48 | |
| 49 | // using HashSet instead of ArraySet since we expect 100-500 elements range |
| 50 | @GuardedBy("mProcessedPackages") |
| 51 | private final Set<String> mProcessedPackages = new HashSet<>(); |
| 52 | // TODO: at some point consider splitting the bookkeeping to be per-transport |
| 53 | private final File mStateDirectory; |
| 54 | |
| 55 | /** |
| 56 | * Constructs a new journal. |
| 57 | * |
| 58 | * After constructing the object one should call {@link #init()} to load state from disk if |
| 59 | * it has been previously persisted. |
| 60 | * |
| 61 | * @param stateDirectory The directory in which backup state (including journals) is stored. |
| 62 | */ |
| 63 | ProcessedPackagesJournal(File stateDirectory) { |
| 64 | mStateDirectory = stateDirectory; |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * Loads state from disk if it has been previously persisted. |
| 69 | */ |
| 70 | void init() { |
| 71 | synchronized (mProcessedPackages) { |
| 72 | loadFromDisk(); |
| 73 | } |
| 74 | } |
| 75 | |
| 76 | /** |
| 77 | * Returns {@code true} if {@code packageName} has previously been backed up. |
| 78 | */ |
| 79 | boolean hasBeenProcessed(String packageName) { |
| 80 | synchronized (mProcessedPackages) { |
| 81 | return mProcessedPackages.contains(packageName); |
| 82 | } |
| 83 | } |
| 84 | |
| 85 | void addPackage(String packageName) { |
| 86 | synchronized (mProcessedPackages) { |
| 87 | if (!mProcessedPackages.add(packageName)) { |
| 88 | // This package has already been processed - no need to add it to the journal. |
| 89 | return; |
| 90 | } |
| 91 | |
| 92 | File journalFile = new File(mStateDirectory, JOURNAL_FILE_NAME); |
| 93 | |
| 94 | try (RandomAccessFile out = new RandomAccessFile(journalFile, "rws")) { |
| 95 | out.seek(out.length()); |
| 96 | out.writeUTF(packageName); |
| 97 | } catch (IOException e) { |
| 98 | Slog.e(TAG, "Can't log backup of " + packageName + " to " + journalFile); |
| 99 | } |
| 100 | } |
| 101 | } |
| 102 | |
| 103 | /** |
| 104 | * A copy of the current state of the journal. |
| 105 | * |
| 106 | * <p>Used only for dumping out information for logging. {@link #hasBeenProcessed(String)} |
| 107 | * should be used for efficiently checking whether a package has been backed up before by this |
| 108 | * device. |
| 109 | * |
| 110 | * @return The current set of packages that have been backed up previously. |
| 111 | */ |
| 112 | Set<String> getPackagesCopy() { |
| 113 | synchronized (mProcessedPackages) { |
| 114 | return new HashSet<>(mProcessedPackages); |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | void reset() { |
| 119 | synchronized (mProcessedPackages) { |
| 120 | mProcessedPackages.clear(); |
| 121 | File journalFile = new File(mStateDirectory, JOURNAL_FILE_NAME); |
| 122 | journalFile.delete(); |
| 123 | } |
| 124 | } |
| 125 | |
| 126 | private void loadFromDisk() { |
| 127 | File journalFile = new File(mStateDirectory, JOURNAL_FILE_NAME); |
| 128 | |
| 129 | if (!journalFile.exists()) { |
| 130 | return; |
| 131 | } |
| 132 | |
| 133 | try (RandomAccessFile oldJournal = new RandomAccessFile(journalFile, "r")) { |
| 134 | while (true) { |
| 135 | String packageName = oldJournal.readUTF(); |
| 136 | if (DEBUG) { |
| 137 | Slog.v(TAG, " + " + packageName); |
| 138 | } |
| 139 | mProcessedPackages.add(packageName); |
| 140 | } |
| 141 | } catch (EOFException e) { |
| 142 | // Successfully loaded journal file |
| 143 | } catch (IOException e) { |
| 144 | Slog.e(TAG, "Error reading processed packages journal", e); |
| 145 | } |
| 146 | } |
| 147 | } |