Bug 1290014 - Add DiskLruCache library. r=ahunt,Grisha
authorSebastian Kaspari <s.kaspari@gmail.com>
Wed, 27 Jul 2016 16:20:00 +0200
changeset 312466 1e8ebfb60a17b01fa25bd8557715a9002faf675f
parent 312465 347ed1510d82b1963573344a70e40f0903309b02
child 312467 7d65390d95e755b5cfd6896e0f564b41e6f47e7f
push id20447
push userkwierso@gmail.com
push dateFri, 02 Sep 2016 20:36:44 +0000
treeherderfx-team@969397f22187 [default view] [failures only]
perfherder[talos] [build metrics] [platform microbench] (compared to previous push)
reviewersahunt, Grisha
bugs1290014, 1108084
milestone51.0a1
Bug 1290014 - Add DiskLruCache library. r=ahunt,Grisha This patch adds the known and widely used disk LRU cache library by Jake Wharton [1]. It's a standalone version of the disk LRU cache found in the AOSP tree. The goal is to use a flat file disk cache to avoid the overhead of storing blobs in a database [2] (and some bugs like bug 1108084). [1] https://github.com/JakeWharton/DiskLruCache [2] https://wiki.mozilla.org/Performance/Avoid_SQLite_In_Your_Next_Firefox_Feature MozReview-Commit-ID: 2ayN7SYVe4W
mobile/android/base/moz.build
mobile/android/thirdparty/com/jakewharton/disklrucache/DiskLruCache.java
mobile/android/thirdparty/com/jakewharton/disklrucache/StrictLineReader.java
mobile/android/thirdparty/com/jakewharton/disklrucache/Util.java
--- a/mobile/android/base/moz.build
+++ b/mobile/android/base/moz.build
@@ -857,16 +857,19 @@ gbjar.extra_jars += [CONFIG['ANDROID_DES
 gbjar.extra_jars += [CONFIG['ANDROID_RECYCLERVIEW_V7_AAR_LIB']]
 gbjar.extra_jars += [CONFIG['ANDROID_CUSTOMTABS_AAR_LIB']]
 
 gbjar.javac_flags += ['-Xlint:all,-deprecation,-fallthrough', '-J-Xmx512m', '-J-Xms128m']
 
 # gecko-thirdparty is a good place to put small independent libraries
 gtjar = add_java_jar('gecko-thirdparty')
 gtjar.sources += [ thirdparty_source_dir + f for f in [
+    'com/jakewharton/disklrucache/DiskLruCache.java',
+    'com/jakewharton/disklrucache/StrictLineReader.java',
+    'com/jakewharton/disklrucache/Util.java',
     'com/keepsafe/switchboard/AsyncConfigLoader.java',
     'com/keepsafe/switchboard/DeviceUuidFactory.java',
     'com/keepsafe/switchboard/Preferences.java',
     'com/keepsafe/switchboard/Switch.java',
     'com/keepsafe/switchboard/SwitchBoard.java',
     'com/squareup/leakcanary/LeakCanary.java',
     'com/squareup/leakcanary/RefWatcher.java',
     'com/squareup/picasso/Action.java',
new file mode 100644
--- /dev/null
+++ b/mobile/android/thirdparty/com/jakewharton/disklrucache/DiskLruCache.java
@@ -0,0 +1,943 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * 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.jakewharton.disklrucache;
+
+import java.io.BufferedWriter;
+import java.io.Closeable;
+import java.io.EOFException;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.FilterOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.concurrent.Callable;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * A cache that uses a bounded amount of space on a filesystem. Each cache
+ * entry has a string key and a fixed number of values. Each key must match
+ * the regex <strong>[a-z0-9_-]{1,120}</strong>. Values are byte sequences,
+ * accessible as streams or files. Each value must be between {@code 0} and
+ * {@code Integer.MAX_VALUE} bytes in length.
+ *
+ * <p>The cache stores its data in a directory on the filesystem. This
+ * directory must be exclusive to the cache; the cache may delete or overwrite
+ * files from its directory. It is an error for multiple processes to use the
+ * same cache directory at the same time.
+ *
+ * <p>This cache limits the number of bytes that it will store on the
+ * filesystem. When the number of stored bytes exceeds the limit, the cache will
+ * remove entries in the background until the limit is satisfied. The limit is
+ * not strict: the cache may temporarily exceed it while waiting for files to be
+ * deleted. The limit does not include filesystem overhead or the cache
+ * journal so space-sensitive applications should set a conservative limit.
+ *
+ * <p>Clients call {@link #edit} to create or update the values of an entry. An
+ * entry may have only one editor at one time; if a value is not available to be
+ * edited then {@link #edit} will return null.
+ * <ul>
+ * <li>When an entry is being <strong>created</strong> it is necessary to
+ * supply a full set of values; the empty value should be used as a
+ * placeholder if necessary.
+ * <li>When an entry is being <strong>edited</strong>, it is not necessary
+ * to supply data for every value; values default to their previous
+ * value.
+ * </ul>
+ * Every {@link #edit} call must be matched by a call to {@link Editor#commit}
+ * or {@link Editor#abort}. Committing is atomic: a read observes the full set
+ * of values as they were before or after the commit, but never a mix of values.
+ *
+ * <p>Clients call {@link #get} to read a snapshot of an entry. The read will
+ * observe the value at the time that {@link #get} was called. Updates and
+ * removals after the call do not impact ongoing reads.
+ *
+ * <p>This class is tolerant of some I/O errors. If files are missing from the
+ * filesystem, the corresponding entries will be dropped from the cache. If
+ * an error occurs while writing a cache value, the edit will fail silently.
+ * Callers should handle other problems by catching {@code IOException} and
+ * responding appropriately.
+ */
+public final class DiskLruCache implements Closeable {
+  static final String JOURNAL_FILE = "journal";
+  static final String JOURNAL_FILE_TEMP = "journal.tmp";
+  static final String JOURNAL_FILE_BACKUP = "journal.bkp";
+  static final String MAGIC = "libcore.io.DiskLruCache";
+  static final String VERSION_1 = "1";
+  static final long ANY_SEQUENCE_NUMBER = -1;
+  static final String STRING_KEY_PATTERN = "[a-z0-9_-]{1,120}";
+  static final Pattern LEGAL_KEY_PATTERN = Pattern.compile(STRING_KEY_PATTERN);
+  private static final String CLEAN = "CLEAN";
+  private static final String DIRTY = "DIRTY";
+  private static final String REMOVE = "REMOVE";
+  private static final String READ = "READ";
+
+    /*
+     * This cache uses a journal file named "journal". A typical journal file
+     * looks like this:
+     *     libcore.io.DiskLruCache
+     *     1
+     *     100
+     *     2
+     *
+     *     CLEAN 3400330d1dfc7f3f7f4b8d4d803dfcf6 832 21054
+     *     DIRTY 335c4c6028171cfddfbaae1a9c313c52
+     *     CLEAN 335c4c6028171cfddfbaae1a9c313c52 3934 2342
+     *     REMOVE 335c4c6028171cfddfbaae1a9c313c52
+     *     DIRTY 1ab96a171faeeee38496d8b330771a7a
+     *     CLEAN 1ab96a171faeeee38496d8b330771a7a 1600 234
+     *     READ 335c4c6028171cfddfbaae1a9c313c52
+     *     READ 3400330d1dfc7f3f7f4b8d4d803dfcf6
+     *
+     * The first five lines of the journal form its header. They are the
+     * constant string "libcore.io.DiskLruCache", the disk cache's version,
+     * the application's version, the value count, and a blank line.
+     *
+     * Each of the subsequent lines in the file is a record of the state of a
+     * cache entry. Each line contains space-separated values: a state, a key,
+     * and optional state-specific values.
+     *   o DIRTY lines track that an entry is actively being created or updated.
+     *     Every successful DIRTY action should be followed by a CLEAN or REMOVE
+     *     action. DIRTY lines without a matching CLEAN or REMOVE indicate that
+     *     temporary files may need to be deleted.
+     *   o CLEAN lines track a cache entry that has been successfully published
+     *     and may be read. A publish line is followed by the lengths of each of
+     *     its values.
+     *   o READ lines track accesses for LRU.
+     *   o REMOVE lines track entries that have been deleted.
+     *
+     * The journal file is appended to as cache operations occur. The journal may
+     * occasionally be compacted by dropping redundant lines. A temporary file named
+     * "journal.tmp" will be used during compaction; that file should be deleted if
+     * it exists when the cache is opened.
+     */
+
+  private final File directory;
+  private final File journalFile;
+  private final File journalFileTmp;
+  private final File journalFileBackup;
+  private final int appVersion;
+  private long maxSize;
+  private final int valueCount;
+  private long size = 0;
+  private Writer journalWriter;
+  private final LinkedHashMap<String, Entry> lruEntries =
+      new LinkedHashMap<String, Entry>(0, 0.75f, true);
+  private int redundantOpCount;
+
+  /**
+   * To differentiate between old and current snapshots, each entry is given
+   * a sequence number each time an edit is committed. A snapshot is stale if
+   * its sequence number is not equal to its entry's sequence number.
+   */
+  private long nextSequenceNumber = 0;
+
+  /** This cache uses a single background thread to evict entries. */
+  final ThreadPoolExecutor executorService =
+      new ThreadPoolExecutor(0, 1, 60L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>());
+  private final Callable<Void> cleanupCallable = new Callable<Void>() {
+    public Void call() throws Exception {
+      synchronized (DiskLruCache.this) {
+        if (journalWriter == null) {
+          return null; // Closed.
+        }
+        trimToSize();
+        if (journalRebuildRequired()) {
+          rebuildJournal();
+          redundantOpCount = 0;
+        }
+      }
+      return null;
+    }
+  };
+
+  private DiskLruCache(File directory, int appVersion, int valueCount, long maxSize) {
+    this.directory = directory;
+    this.appVersion = appVersion;
+    this.journalFile = new File(directory, JOURNAL_FILE);
+    this.journalFileTmp = new File(directory, JOURNAL_FILE_TEMP);
+    this.journalFileBackup = new File(directory, JOURNAL_FILE_BACKUP);
+    this.valueCount = valueCount;
+    this.maxSize = maxSize;
+  }
+
+  /**
+   * Opens the cache in {@code directory}, creating a cache if none exists
+   * there.
+   *
+   * @param directory a writable directory
+   * @param valueCount the number of values per cache entry. Must be positive.
+   * @param maxSize the maximum number of bytes this cache should use to store
+   * @throws IOException if reading or writing the cache directory fails
+   */
+  public static DiskLruCache open(File directory, int appVersion, int valueCount, long maxSize)
+      throws IOException {
+    if (maxSize <= 0) {
+      throw new IllegalArgumentException("maxSize <= 0");
+    }
+    if (valueCount <= 0) {
+      throw new IllegalArgumentException("valueCount <= 0");
+    }
+
+    // If a bkp file exists, use it instead.
+    File backupFile = new File(directory, JOURNAL_FILE_BACKUP);
+    if (backupFile.exists()) {
+      File journalFile = new File(directory, JOURNAL_FILE);
+      // If journal file also exists just delete backup file.
+      if (journalFile.exists()) {
+        backupFile.delete();
+      } else {
+        renameTo(backupFile, journalFile, false);
+      }
+    }
+
+    // Prefer to pick up where we left off.
+    DiskLruCache cache = new DiskLruCache(directory, appVersion, valueCount, maxSize);
+    if (cache.journalFile.exists()) {
+      try {
+        cache.readJournal();
+        cache.processJournal();
+        return cache;
+      } catch (IOException journalIsCorrupt) {
+        System.out
+            .println("DiskLruCache "
+                + directory
+                + " is corrupt: "
+                + journalIsCorrupt.getMessage()
+                + ", removing");
+        cache.delete();
+      }
+    }
+
+    // Create a new empty cache.
+    directory.mkdirs();
+    cache = new DiskLruCache(directory, appVersion, valueCount, maxSize);
+    cache.rebuildJournal();
+    return cache;
+  }
+
+  private void readJournal() throws IOException {
+    StrictLineReader reader = new StrictLineReader(new FileInputStream(journalFile), Util.US_ASCII);
+    try {
+      String magic = reader.readLine();
+      String version = reader.readLine();
+      String appVersionString = reader.readLine();
+      String valueCountString = reader.readLine();
+      String blank = reader.readLine();
+      if (!MAGIC.equals(magic)
+          || !VERSION_1.equals(version)
+          || !Integer.toString(appVersion).equals(appVersionString)
+          || !Integer.toString(valueCount).equals(valueCountString)
+          || !"".equals(blank)) {
+        throw new IOException("unexpected journal header: [" + magic + ", " + version + ", "
+            + valueCountString + ", " + blank + "]");
+      }
+
+      int lineCount = 0;
+      while (true) {
+        try {
+          readJournalLine(reader.readLine());
+          lineCount++;
+        } catch (EOFException endOfJournal) {
+          break;
+        }
+      }
+      redundantOpCount = lineCount - lruEntries.size();
+
+      // If we ended on a truncated line, rebuild the journal before appending to it.
+      if (reader.hasUnterminatedLine()) {
+        rebuildJournal();
+      } else {
+        journalWriter = new BufferedWriter(new OutputStreamWriter(
+            new FileOutputStream(journalFile, true), Util.US_ASCII));
+      }
+    } finally {
+      Util.closeQuietly(reader);
+    }
+  }
+
+  private void readJournalLine(String line) throws IOException {
+    int firstSpace = line.indexOf(' ');
+    if (firstSpace == -1) {
+      throw new IOException("unexpected journal line: " + line);
+    }
+
+    int keyBegin = firstSpace + 1;
+    int secondSpace = line.indexOf(' ', keyBegin);
+    final String key;
+    if (secondSpace == -1) {
+      key = line.substring(keyBegin);
+      if (firstSpace == REMOVE.length() && line.startsWith(REMOVE)) {
+        lruEntries.remove(key);
+        return;
+      }
+    } else {
+      key = line.substring(keyBegin, secondSpace);
+    }
+
+    Entry entry = lruEntries.get(key);
+    if (entry == null) {
+      entry = new Entry(key);
+      lruEntries.put(key, entry);
+    }
+
+    if (secondSpace != -1 && firstSpace == CLEAN.length() && line.startsWith(CLEAN)) {
+      String[] parts = line.substring(secondSpace + 1).split(" ");
+      entry.readable = true;
+      entry.currentEditor = null;
+      entry.setLengths(parts);
+    } else if (secondSpace == -1 && firstSpace == DIRTY.length() && line.startsWith(DIRTY)) {
+      entry.currentEditor = new Editor(entry);
+    } else if (secondSpace == -1 && firstSpace == READ.length() && line.startsWith(READ)) {
+      // This work was already done by calling lruEntries.get().
+    } else {
+      throw new IOException("unexpected journal line: " + line);
+    }
+  }
+
+  /**
+   * Computes the initial size and collects garbage as a part of opening the
+   * cache. Dirty entries are assumed to be inconsistent and will be deleted.
+   */
+  private void processJournal() throws IOException {
+    deleteIfExists(journalFileTmp);
+    for (Iterator<Entry> i = lruEntries.values().iterator(); i.hasNext(); ) {
+      Entry entry = i.next();
+      if (entry.currentEditor == null) {
+        for (int t = 0; t < valueCount; t++) {
+          size += entry.lengths[t];
+        }
+      } else {
+        entry.currentEditor = null;
+        for (int t = 0; t < valueCount; t++) {
+          deleteIfExists(entry.getCleanFile(t));
+          deleteIfExists(entry.getDirtyFile(t));
+        }
+        i.remove();
+      }
+    }
+  }
+
+  /**
+   * Creates a new journal that omits redundant information. This replaces the
+   * current journal if it exists.
+   */
+  private synchronized void rebuildJournal() throws IOException {
+    if (journalWriter != null) {
+      journalWriter.close();
+    }
+
+    Writer writer = new BufferedWriter(
+        new OutputStreamWriter(new FileOutputStream(journalFileTmp), Util.US_ASCII));
+    try {
+      writer.write(MAGIC);
+      writer.write("\n");
+      writer.write(VERSION_1);
+      writer.write("\n");
+      writer.write(Integer.toString(appVersion));
+      writer.write("\n");
+      writer.write(Integer.toString(valueCount));
+      writer.write("\n");
+      writer.write("\n");
+
+      for (Entry entry : lruEntries.values()) {
+        if (entry.currentEditor != null) {
+          writer.write(DIRTY + ' ' + entry.key + '\n');
+        } else {
+          writer.write(CLEAN + ' ' + entry.key + entry.getLengths() + '\n');
+        }
+      }
+    } finally {
+      writer.close();
+    }
+
+    if (journalFile.exists()) {
+      renameTo(journalFile, journalFileBackup, true);
+    }
+    renameTo(journalFileTmp, journalFile, false);
+    journalFileBackup.delete();
+
+    journalWriter = new BufferedWriter(
+        new OutputStreamWriter(new FileOutputStream(journalFile, true), Util.US_ASCII));
+  }
+
+  private static void deleteIfExists(File file) throws IOException {
+    if (file.exists() && !file.delete()) {
+      throw new IOException();
+    }
+  }
+
+  private static void renameTo(File from, File to, boolean deleteDestination) throws IOException {
+    if (deleteDestination) {
+      deleteIfExists(to);
+    }
+    if (!from.renameTo(to)) {
+      throw new IOException();
+    }
+  }
+
+  /**
+   * Returns a snapshot of the entry named {@code key}, or null if it doesn't
+   * exist is not currently readable. If a value is returned, it is moved to
+   * the head of the LRU queue.
+   */
+  public synchronized Snapshot get(String key) throws IOException {
+    checkNotClosed();
+    validateKey(key);
+    Entry entry = lruEntries.get(key);
+    if (entry == null) {
+      return null;
+    }
+
+    if (!entry.readable) {
+      return null;
+    }
+
+    // Open all streams eagerly to guarantee that we see a single published
+    // snapshot. If we opened streams lazily then the streams could come
+    // from different edits.
+    InputStream[] ins = new InputStream[valueCount];
+    try {
+      for (int i = 0; i < valueCount; i++) {
+        ins[i] = new FileInputStream(entry.getCleanFile(i));
+      }
+    } catch (FileNotFoundException e) {
+      // A file must have been deleted manually!
+      for (int i = 0; i < valueCount; i++) {
+        if (ins[i] != null) {
+          Util.closeQuietly(ins[i]);
+        } else {
+          break;
+        }
+      }
+      return null;
+    }
+
+    redundantOpCount++;
+    journalWriter.append(READ + ' ' + key + '\n');
+    if (journalRebuildRequired()) {
+      executorService.submit(cleanupCallable);
+    }
+
+    return new Snapshot(key, entry.sequenceNumber, ins, entry.lengths);
+  }
+
+  /**
+   * Returns an editor for the entry named {@code key}, or null if another
+   * edit is in progress.
+   */
+  public Editor edit(String key) throws IOException {
+    return edit(key, ANY_SEQUENCE_NUMBER);
+  }
+
+  private synchronized Editor edit(String key, long expectedSequenceNumber) throws IOException {
+    checkNotClosed();
+    validateKey(key);
+    Entry entry = lruEntries.get(key);
+    if (expectedSequenceNumber != ANY_SEQUENCE_NUMBER && (entry == null
+        || entry.sequenceNumber != expectedSequenceNumber)) {
+      return null; // Snapshot is stale.
+    }
+    if (entry == null) {
+      entry = new Entry(key);
+      lruEntries.put(key, entry);
+    } else if (entry.currentEditor != null) {
+      return null; // Another edit is in progress.
+    }
+
+    Editor editor = new Editor(entry);
+    entry.currentEditor = editor;
+
+    // Flush the journal before creating files to prevent file leaks.
+    journalWriter.write(DIRTY + ' ' + key + '\n');
+    journalWriter.flush();
+    return editor;
+  }
+
+  /** Returns the directory where this cache stores its data. */
+  public File getDirectory() {
+    return directory;
+  }
+
+  /**
+   * Returns the maximum number of bytes that this cache should use to store
+   * its data.
+   */
+  public synchronized long getMaxSize() {
+    return maxSize;
+  }
+
+  /**
+   * Changes the maximum number of bytes the cache can store and queues a job
+   * to trim the existing store, if necessary.
+   */
+  public synchronized void setMaxSize(long maxSize) {
+    this.maxSize = maxSize;
+    executorService.submit(cleanupCallable);
+  }
+
+  /**
+   * Returns the number of bytes currently being used to store the values in
+   * this cache. This may be greater than the max size if a background
+   * deletion is pending.
+   */
+  public synchronized long size() {
+    return size;
+  }
+
+  private synchronized void completeEdit(Editor editor, boolean success) throws IOException {
+    Entry entry = editor.entry;
+    if (entry.currentEditor != editor) {
+      throw new IllegalStateException();
+    }
+
+    // If this edit is creating the entry for the first time, every index must have a value.
+    if (success && !entry.readable) {
+      for (int i = 0; i < valueCount; i++) {
+        if (!editor.written[i]) {
+          editor.abort();
+          throw new IllegalStateException("Newly created entry didn't create value for index " + i);
+        }
+        if (!entry.getDirtyFile(i).exists()) {
+          editor.abort();
+          return;
+        }
+      }
+    }
+
+    for (int i = 0; i < valueCount; i++) {
+      File dirty = entry.getDirtyFile(i);
+      if (success) {
+        if (dirty.exists()) {
+          File clean = entry.getCleanFile(i);
+          dirty.renameTo(clean);
+          long oldLength = entry.lengths[i];
+          long newLength = clean.length();
+          entry.lengths[i] = newLength;
+          size = size - oldLength + newLength;
+        }
+      } else {
+        deleteIfExists(dirty);
+      }
+    }
+
+    redundantOpCount++;
+    entry.currentEditor = null;
+    if (entry.readable | success) {
+      entry.readable = true;
+      journalWriter.write(CLEAN + ' ' + entry.key + entry.getLengths() + '\n');
+      if (success) {
+        entry.sequenceNumber = nextSequenceNumber++;
+      }
+    } else {
+      lruEntries.remove(entry.key);
+      journalWriter.write(REMOVE + ' ' + entry.key + '\n');
+    }
+    journalWriter.flush();
+
+    if (size > maxSize || journalRebuildRequired()) {
+      executorService.submit(cleanupCallable);
+    }
+  }
+
+  /**
+   * We only rebuild the journal when it will halve the size of the journal
+   * and eliminate at least 2000 ops.
+   */
+  private boolean journalRebuildRequired() {
+    final int redundantOpCompactThreshold = 2000;
+    return redundantOpCount >= redundantOpCompactThreshold //
+        && redundantOpCount >= lruEntries.size();
+  }
+
+  /**
+   * Drops the entry for {@code key} if it exists and can be removed. Entries
+   * actively being edited cannot be removed.
+   *
+   * @return true if an entry was removed.
+   */
+  public synchronized boolean remove(String key) throws IOException {
+    checkNotClosed();
+    validateKey(key);
+    Entry entry = lruEntries.get(key);
+    if (entry == null || entry.currentEditor != null) {
+      return false;
+    }
+
+    for (int i = 0; i < valueCount; i++) {
+      File file = entry.getCleanFile(i);
+      if (file.exists() && !file.delete()) {
+        throw new IOException("failed to delete " + file);
+      }
+      size -= entry.lengths[i];
+      entry.lengths[i] = 0;
+    }
+
+    redundantOpCount++;
+    journalWriter.append(REMOVE + ' ' + key + '\n');
+    lruEntries.remove(key);
+
+    if (journalRebuildRequired()) {
+      executorService.submit(cleanupCallable);
+    }
+
+    return true;
+  }
+
+  /** Returns true if this cache has been closed. */
+  public synchronized boolean isClosed() {
+    return journalWriter == null;
+  }
+
+  private void checkNotClosed() {
+    if (journalWriter == null) {
+      throw new IllegalStateException("cache is closed");
+    }
+  }
+
+  /** Force buffered operations to the filesystem. */
+  public synchronized void flush() throws IOException {
+    checkNotClosed();
+    trimToSize();
+    journalWriter.flush();
+  }
+
+  /** Closes this cache. Stored values will remain on the filesystem. */
+  public synchronized void close() throws IOException {
+    if (journalWriter == null) {
+      return; // Already closed.
+    }
+    for (Entry entry : new ArrayList<Entry>(lruEntries.values())) {
+      if (entry.currentEditor != null) {
+        entry.currentEditor.abort();
+      }
+    }
+    trimToSize();
+    journalWriter.close();
+    journalWriter = null;
+  }
+
+  private void trimToSize() throws IOException {
+    while (size > maxSize) {
+      Map.Entry<String, Entry> toEvict = lruEntries.entrySet().iterator().next();
+      remove(toEvict.getKey());
+    }
+  }
+
+  /**
+   * Closes the cache and deletes all of its stored values. This will delete
+   * all files in the cache directory including files that weren't created by
+   * the cache.
+   */
+  public void delete() throws IOException {
+    close();
+    Util.deleteContents(directory);
+  }
+
+  private void validateKey(String key) {
+    Matcher matcher = LEGAL_KEY_PATTERN.matcher(key);
+    if (!matcher.matches()) {
+      throw new IllegalArgumentException("keys must match regex "
+              + STRING_KEY_PATTERN + ": \"" + key + "\"");
+    }
+  }
+
+  private static String inputStreamToString(InputStream in) throws IOException {
+    return Util.readFully(new InputStreamReader(in, Util.UTF_8));
+  }
+
+  /** A snapshot of the values for an entry. */
+  public final class Snapshot implements Closeable {
+    private final String key;
+    private final long sequenceNumber;
+    private final InputStream[] ins;
+    private final long[] lengths;
+
+    private Snapshot(String key, long sequenceNumber, InputStream[] ins, long[] lengths) {
+      this.key = key;
+      this.sequenceNumber = sequenceNumber;
+      this.ins = ins;
+      this.lengths = lengths;
+    }
+
+    /**
+     * Returns an editor for this snapshot's entry, or null if either the
+     * entry has changed since this snapshot was created or if another edit
+     * is in progress.
+     */
+    public Editor edit() throws IOException {
+      return DiskLruCache.this.edit(key, sequenceNumber);
+    }
+
+    /** Returns the unbuffered stream with the value for {@code index}. */
+    public InputStream getInputStream(int index) {
+      return ins[index];
+    }
+
+    /** Returns the string value for {@code index}. */
+    public String getString(int index) throws IOException {
+      return inputStreamToString(getInputStream(index));
+    }
+
+    /** Returns the byte length of the value for {@code index}. */
+    public long getLength(int index) {
+      return lengths[index];
+    }
+
+    public void close() {
+      for (InputStream in : ins) {
+        Util.closeQuietly(in);
+      }
+    }
+  }
+
+  private static final OutputStream NULL_OUTPUT_STREAM = new OutputStream() {
+    @Override
+    public void write(int b) throws IOException {
+      // Eat all writes silently. Nom nom.
+    }
+  };
+
+  /** Edits the values for an entry. */
+  public final class Editor {
+    private final Entry entry;
+    private final boolean[] written;
+    private boolean hasErrors;
+    private boolean committed;
+
+    private Editor(Entry entry) {
+      this.entry = entry;
+      this.written = (entry.readable) ? null : new boolean[valueCount];
+    }
+
+    /**
+     * Returns an unbuffered input stream to read the last committed value,
+     * or null if no value has been committed.
+     */
+    public InputStream newInputStream(int index) throws IOException {
+      synchronized (DiskLruCache.this) {
+        if (entry.currentEditor != this) {
+          throw new IllegalStateException();
+        }
+        if (!entry.readable) {
+          return null;
+        }
+        try {
+          return new FileInputStream(entry.getCleanFile(index));
+        } catch (FileNotFoundException e) {
+          return null;
+        }
+      }
+    }
+
+    /**
+     * Returns the last committed value as a string, or null if no value
+     * has been committed.
+     */
+    public String getString(int index) throws IOException {
+      InputStream in = newInputStream(index);
+      return in != null ? inputStreamToString(in) : null;
+    }
+
+    /**
+     * Returns a new unbuffered output stream to write the value at
+     * {@code index}. If the underlying output stream encounters errors
+     * when writing to the filesystem, this edit will be aborted when
+     * {@link #commit} is called. The returned output stream does not throw
+     * IOExceptions.
+     */
+    public OutputStream newOutputStream(int index) throws IOException {
+      if (index < 0 || index >= valueCount) {
+        throw new IllegalArgumentException("Expected index " + index + " to "
+                + "be greater than 0 and less than the maximum value count "
+                + "of " + valueCount);
+      }
+      synchronized (DiskLruCache.this) {
+        if (entry.currentEditor != this) {
+          throw new IllegalStateException();
+        }
+        if (!entry.readable) {
+          written[index] = true;
+        }
+        File dirtyFile = entry.getDirtyFile(index);
+        FileOutputStream outputStream;
+        try {
+          outputStream = new FileOutputStream(dirtyFile);
+        } catch (FileNotFoundException e) {
+          // Attempt to recreate the cache directory.
+          directory.mkdirs();
+          try {
+            outputStream = new FileOutputStream(dirtyFile);
+          } catch (FileNotFoundException e2) {
+            // We are unable to recover. Silently eat the writes.
+            return NULL_OUTPUT_STREAM;
+          }
+        }
+        return new FaultHidingOutputStream(outputStream);
+      }
+    }
+
+    /** Sets the value at {@code index} to {@code value}. */
+    public void set(int index, String value) throws IOException {
+      Writer writer = null;
+      try {
+        writer = new OutputStreamWriter(newOutputStream(index), Util.UTF_8);
+        writer.write(value);
+      } finally {
+        Util.closeQuietly(writer);
+      }
+    }
+
+    /**
+     * Commits this edit so it is visible to readers.  This releases the
+     * edit lock so another edit may be started on the same key.
+     */
+    public void commit() throws IOException {
+      if (hasErrors) {
+        completeEdit(this, false);
+        remove(entry.key); // The previous entry is stale.
+      } else {
+        completeEdit(this, true);
+      }
+      committed = true;
+    }
+
+    /**
+     * Aborts this edit. This releases the edit lock so another edit may be
+     * started on the same key.
+     */
+    public void abort() throws IOException {
+      completeEdit(this, false);
+    }
+
+    public void abortUnlessCommitted() {
+      if (!committed) {
+        try {
+          abort();
+        } catch (IOException ignored) {
+        }
+      }
+    }
+
+    private class FaultHidingOutputStream extends FilterOutputStream {
+      private FaultHidingOutputStream(OutputStream out) {
+        super(out);
+      }
+
+      @Override public void write(int oneByte) {
+        try {
+          out.write(oneByte);
+        } catch (IOException e) {
+          hasErrors = true;
+        }
+      }
+
+      @Override public void write(byte[] buffer, int offset, int length) {
+        try {
+          out.write(buffer, offset, length);
+        } catch (IOException e) {
+          hasErrors = true;
+        }
+      }
+
+      @Override public void close() {
+        try {
+          out.close();
+        } catch (IOException e) {
+          hasErrors = true;
+        }
+      }
+
+      @Override public void flush() {
+        try {
+          out.flush();
+        } catch (IOException e) {
+          hasErrors = true;
+        }
+      }
+    }
+  }
+
+  private final class Entry {
+    private final String key;
+
+    /** Lengths of this entry's files. */
+    private final long[] lengths;
+
+    /** True if this entry has ever been published. */
+    private boolean readable;
+
+    /** The ongoing edit or null if this entry is not being edited. */
+    private Editor currentEditor;
+
+    /** The sequence number of the most recently committed edit to this entry. */
+    private long sequenceNumber;
+
+    private Entry(String key) {
+      this.key = key;
+      this.lengths = new long[valueCount];
+    }
+
+    public String getLengths() throws IOException {
+      StringBuilder result = new StringBuilder();
+      for (long size : lengths) {
+        result.append(' ').append(size);
+      }
+      return result.toString();
+    }
+
+    /** Set lengths using decimal numbers like "10123". */
+    private void setLengths(String[] strings) throws IOException {
+      if (strings.length != valueCount) {
+        throw invalidLengths(strings);
+      }
+
+      try {
+        for (int i = 0; i < strings.length; i++) {
+          lengths[i] = Long.parseLong(strings[i]);
+        }
+      } catch (NumberFormatException e) {
+        throw invalidLengths(strings);
+      }
+    }
+
+    private IOException invalidLengths(String[] strings) throws IOException {
+      throw new IOException("unexpected journal line: " + java.util.Arrays.toString(strings));
+    }
+
+    public File getCleanFile(int i) {
+      return new File(directory, key + "." + i);
+    }
+
+    public File getDirtyFile(int i) {
+      return new File(directory, key + "." + i + ".tmp");
+    }
+  }
+}
new file mode 100644
--- /dev/null
+++ b/mobile/android/thirdparty/com/jakewharton/disklrucache/StrictLineReader.java
@@ -0,0 +1,196 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * 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.jakewharton.disklrucache;
+
+import java.io.ByteArrayOutputStream;
+import java.io.Closeable;
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.UnsupportedEncodingException;
+import java.nio.charset.Charset;
+
+/**
+ * Buffers input from an {@link InputStream} for reading lines.
+ *
+ * <p>This class is used for buffered reading of lines. For purposes of this class, a line ends
+ * with "\n" or "\r\n". End of input is reported by throwing {@code EOFException}. Unterminated
+ * line at end of input is invalid and will be ignored, the caller may use {@code
+ * hasUnterminatedLine()} to detect it after catching the {@code EOFException}.
+ *
+ * <p>This class is intended for reading input that strictly consists of lines, such as line-based
+ * cache entries or cache journal. Unlike the {@link java.io.BufferedReader} which in conjunction
+ * with {@link java.io.InputStreamReader} provides similar functionality, this class uses different
+ * end-of-input reporting and a more restrictive definition of a line.
+ *
+ * <p>This class supports only charsets that encode '\r' and '\n' as a single byte with value 13
+ * and 10, respectively, and the representation of no other character contains these values.
+ * We currently check in constructor that the charset is one of US-ASCII, UTF-8 and ISO-8859-1.
+ * The default charset is US_ASCII.
+ */
+class StrictLineReader implements Closeable {
+  private static final byte CR = (byte) '\r';
+  private static final byte LF = (byte) '\n';
+
+  private final InputStream in;
+  private final Charset charset;
+
+  /*
+   * Buffered data is stored in {@code buf}. As long as no exception occurs, 0 <= pos <= end
+   * and the data in the range [pos, end) is buffered for reading. At end of input, if there is
+   * an unterminated line, we set end == -1, otherwise end == pos. If the underlying
+   * {@code InputStream} throws an {@code IOException}, end may remain as either pos or -1.
+   */
+  private byte[] buf;
+  private int pos;
+  private int end;
+
+  /**
+   * Constructs a new {@code LineReader} with the specified charset and the default capacity.
+   *
+   * @param in the {@code InputStream} to read data from.
+   * @param charset the charset used to decode data. Only US-ASCII, UTF-8 and ISO-8859-1 are
+   * supported.
+   * @throws NullPointerException if {@code in} or {@code charset} is null.
+   * @throws IllegalArgumentException if the specified charset is not supported.
+   */
+  public StrictLineReader(InputStream in, Charset charset) {
+    this(in, 8192, charset);
+  }
+
+  /**
+   * Constructs a new {@code LineReader} with the specified capacity and charset.
+   *
+   * @param in the {@code InputStream} to read data from.
+   * @param capacity the capacity of the buffer.
+   * @param charset the charset used to decode data. Only US-ASCII, UTF-8 and ISO-8859-1 are
+   * supported.
+   * @throws NullPointerException if {@code in} or {@code charset} is null.
+   * @throws IllegalArgumentException if {@code capacity} is negative or zero
+   * or the specified charset is not supported.
+   */
+  public StrictLineReader(InputStream in, int capacity, Charset charset) {
+    if (in == null || charset == null) {
+      throw new NullPointerException();
+    }
+    if (capacity < 0) {
+      throw new IllegalArgumentException("capacity <= 0");
+    }
+    if (!(charset.equals(Util.US_ASCII))) {
+      throw new IllegalArgumentException("Unsupported encoding");
+    }
+
+    this.in = in;
+    this.charset = charset;
+    buf = new byte[capacity];
+  }
+
+  /**
+   * Closes the reader by closing the underlying {@code InputStream} and
+   * marking this reader as closed.
+   *
+   * @throws IOException for errors when closing the underlying {@code InputStream}.
+   */
+  public void close() throws IOException {
+    synchronized (in) {
+      if (buf != null) {
+        buf = null;
+        in.close();
+      }
+    }
+  }
+
+  /**
+   * Reads the next line. A line ends with {@code "\n"} or {@code "\r\n"},
+   * this end of line marker is not included in the result.
+   *
+   * @return the next line from the input.
+   * @throws IOException for underlying {@code InputStream} errors.
+   * @throws EOFException for the end of source stream.
+   */
+  public String readLine() throws IOException {
+    synchronized (in) {
+      if (buf == null) {
+        throw new IOException("LineReader is closed");
+      }
+
+      // Read more data if we are at the end of the buffered data.
+      // Though it's an error to read after an exception, we will let {@code fillBuf()}
+      // throw again if that happens; thus we need to handle end == -1 as well as end == pos.
+      if (pos >= end) {
+        fillBuf();
+      }
+      // Try to find LF in the buffered data and return the line if successful.
+      for (int i = pos; i != end; ++i) {
+        if (buf[i] == LF) {
+          int lineEnd = (i != pos && buf[i - 1] == CR) ? i - 1 : i;
+          String res = new String(buf, pos, lineEnd - pos, charset.name());
+          pos = i + 1;
+          return res;
+        }
+      }
+
+      // Let's anticipate up to 80 characters on top of those already read.
+      ByteArrayOutputStream out = new ByteArrayOutputStream(end - pos + 80) {
+        @Override
+        public String toString() {
+          int length = (count > 0 && buf[count - 1] == CR) ? count - 1 : count;
+          try {
+            return new String(buf, 0, length, charset.name());
+          } catch (UnsupportedEncodingException e) {
+            throw new AssertionError(e); // Since we control the charset this will never happen.
+          }
+        }
+      };
+
+      while (true) {
+        out.write(buf, pos, end - pos);
+        // Mark unterminated line in case fillBuf throws EOFException or IOException.
+        end = -1;
+        fillBuf();
+        // Try to find LF in the buffered data and return the line if successful.
+        for (int i = pos; i != end; ++i) {
+          if (buf[i] == LF) {
+            if (i != pos) {
+              out.write(buf, pos, i - pos);
+            }
+            pos = i + 1;
+            return out.toString();
+          }
+        }
+      }
+    }
+  }
+
+  public boolean hasUnterminatedLine() {
+    return end == -1;
+  }
+
+  /**
+   * Reads new input data into the buffer. Call only with pos == end or end == -1,
+   * depending on the desired outcome if the function throws.
+   */
+  private void fillBuf() throws IOException {
+    int result = in.read(buf, 0, buf.length);
+    if (result == -1) {
+      throw new EOFException();
+    }
+    pos = 0;
+    end = result;
+  }
+}
+
new file mode 100644
--- /dev/null
+++ b/mobile/android/thirdparty/com/jakewharton/disklrucache/Util.java
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * 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.jakewharton.disklrucache;
+
+import java.io.Closeable;
+import java.io.File;
+import java.io.IOException;
+import java.io.Reader;
+import java.io.StringWriter;
+import java.nio.charset.Charset;
+
+/** Junk drawer of utility methods. */
+final class Util {
+  static final Charset US_ASCII = Charset.forName("US-ASCII");
+  static final Charset UTF_8 = Charset.forName("UTF-8");
+
+  private Util() {
+  }
+
+  static String readFully(Reader reader) throws IOException {
+    try {
+      StringWriter writer = new StringWriter();
+      char[] buffer = new char[1024];
+      int count;
+      while ((count = reader.read(buffer)) != -1) {
+        writer.write(buffer, 0, count);
+      }
+      return writer.toString();
+    } finally {
+      reader.close();
+    }
+  }
+
+  /**
+   * Deletes the contents of {@code dir}. Throws an IOException if any file
+   * could not be deleted, or if {@code dir} is not a readable directory.
+   */
+  static void deleteContents(File dir) throws IOException {
+    File[] files = dir.listFiles();
+    if (files == null) {
+      throw new IOException("not a readable directory: " + dir);
+    }
+    for (File file : files) {
+      if (file.isDirectory()) {
+        deleteContents(file);
+      }
+      if (!file.delete()) {
+        throw new IOException("failed to delete file: " + file);
+      }
+    }
+  }
+
+  static void closeQuietly(/*Auto*/Closeable closeable) {
+    if (closeable != null) {
+      try {
+        closeable.close();
+      } catch (RuntimeException rethrown) {
+        throw rethrown;
+      } catch (Exception ignored) {
+      }
+    }
+  }
+}