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/* * Copyright (C) 2011 The Android Open Source Project */* www . ja v a2s . c o m*/ * 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 in.srain.cube.file; import java.io.*; import java.lang.reflect.Array; import java.nio.charset.Charset; import java.util.*; import java.util.concurrent.*; /** * ***************************************************************************** * Taken from the JB source code, can be found in: * libcore/luni/src/main/java/libcore/io/DiskLruCache.java * or direct link: * https://android.googlesource.com/platform/libcore/+/android-4.1.1_r1/luni/src/main/java/libcore/io/DiskLruCache.java * ***************************************************************************** * <p/> * 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. 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/> * <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/> * <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/> * <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/> * <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/> * <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_TMP = "journal.tmp"; static final String MAGIC = "libcore.io.DiskLruCache"; static final String VERSION_1 = "1"; static final long ANY_SEQUENCE_NUMBER = -1; private static final String CLEAN = "CLEAN"; private static final String DIRTY = "DIRTY"; private static final String REMOVE = "REMOVE"; private static final String READ = "READ"; private static final Charset UTF_8 = Charset.forName("UTF-8"); private static final int IO_BUFFER_SIZE = 8 * 1024; /** * This cache uses a journal file named "journal". A typical journal file * looks like this: * libcore.io.DiskLruCache * 1 * 100 * 2 * <p/> * CLEAN 3400330d1dfc7f3f7f4b8d4d803dfcf6 832 21054 * DIRTY 335c4c6028171cfddfbaae1a9c313c52 * CLEAN 335c4c6028171cfddfbaae1a9c313c52 3934 2342 * REMOVE 335c4c6028171cfddfbaae1a9c313c52 * DIRTY 1ab96a171faeeee38496d8b330771a7a * CLEAN 1ab96a171faeeee38496d8b330771a7a 1600 234 * READ 335c4c6028171cfddfbaae1a9c313c52 * READ 3400330d1dfc7f3f7f4b8d4d803dfcf6 * <p/> * 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. * <p/> * 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. * <p/> * 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 int appVersion; private final 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; /* From java.util.Arrays */ @SuppressWarnings("unchecked") private static <T> T[] copyOfRange(T[] original, int start, int end) { final int originalLength = original.length; // For exception priority compatibility. if (start > end) { throw new IllegalArgumentException(); } if (start < 0 || start > originalLength) { throw new ArrayIndexOutOfBoundsException(); } final int resultLength = end - start; final int copyLength = Math.min(resultLength, originalLength - start); final T[] result = (T[]) Array .newInstance(original.getClass().getComponentType(), resultLength); System.arraycopy(original, start, result, 0, copyLength); return result; } /** * Returns the remainder of 'reader' as a string, closing it when done. */ public 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(); } } /** * Returns the ASCII characters up to but not including the next "\r\n", or * "\n". * * @throws java.io.EOFException if the stream is exhausted before the next newline * character. */ public static String readAsciiLine(InputStream in) throws IOException { // TODO: support UTF-8 here instead StringBuilder result = new StringBuilder(80); while (true) { int c = in.read(); if (c == -1) { throw new EOFException(); } else if (c == '\n') { break; } result.append((char) c); } int length = result.length(); if (length > 0 && result.charAt(length - 1) == '\r') { result.setLength(length - 1); } return result.toString(); } /** * Closes 'closeable', ignoring any checked exceptions. Does nothing if 'closeable' is null. */ public static void closeQuietly(Closeable closeable) { if (closeable != null) { try { closeable.close(); } catch (RuntimeException rethrown) { throw rethrown; } catch (Exception ignored) { } } } /** * Recursively delete everything in {@code dir}. */ // TODO: this should specify paths as Strings rather than as Files public static void deleteContents(File dir) throws IOException { File[] files = dir.listFiles(); if (files == null) { throw new IllegalArgumentException("not a directory: " + dir); } for (File file : files) { if (file.isDirectory()) { deleteContents(file); } if (!file.delete()) { throw new IOException("failed to delete file: " + file); } } } /** * This cache uses a single background thread to evict entries. */ private final ExecutorService executorService = new ThreadPoolExecutor(0, 1, 60L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); private final Callable<Void> cleanupCallable = new Callable<Void>() { @Override 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_TMP); 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 appVersion * @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"); } // 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(); cache.journalWriter = new BufferedWriter(new FileWriter(cache.journalFile, true), IO_BUFFER_SIZE); return cache; } catch (IOException journalIsCorrupt) { // System.logW("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 { InputStream in = new BufferedInputStream(new FileInputStream(journalFile), IO_BUFFER_SIZE); try { String magic = readAsciiLine(in); String version = readAsciiLine(in); String appVersionString = readAsciiLine(in); String valueCountString = readAsciiLine(in); String blank = readAsciiLine(in); 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 + "]"); } while (true) { try { readJournalLine(readAsciiLine(in)); } catch (EOFException endOfJournal) { break; } } } finally { closeQuietly(in); } } private void readJournalLine(String line) throws IOException { String[] parts = line.split(" "); if (parts.length < 2) { throw new IOException("unexpected journal line: " + line); } String key = parts[1]; if (parts[0].equals(REMOVE) && parts.length == 2) { lruEntries.remove(key); return; } Entry entry = lruEntries.get(key); if (entry == null) { entry = new Entry(key); lruEntries.put(key, entry); } if (parts[0].equals(CLEAN) && parts.length == 2 + valueCount) { entry.readable = true; entry.currentEditor = null; entry.setLengths(copyOfRange(parts, 2, parts.length)); } else if (parts[0].equals(DIRTY) && parts.length == 2) { entry.currentEditor = new Editor(entry); } else if (parts[0].equals(READ) && parts.length == 2) { // 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 FileWriter(journalFileTmp), IO_BUFFER_SIZE); 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'); } } writer.close(); journalFileTmp.renameTo(journalFile); journalWriter = new BufferedWriter(new FileWriter(journalFile, true), IO_BUFFER_SIZE); } private static void deleteIfExists(File file) throws IOException { if (file.exists() && !file.delete()) { 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! return null; } redundantOpCount++; journalWriter.append(READ + ' ' + key + '\n'); if (journalRebuildRequired()) { executorService.submit(cleanupCallable); } return new Snapshot(key, entry.sequenceNumber, ins); } /** * 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 long maxSize() { return maxSize; } /** * 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 (!entry.getDirtyFile(i).exists()) { editor.abort(); throw new IllegalStateException("edit didn't create file " + i); } } } 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'); } 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 REDUNDANT_OP_COMPACT_THRESHOLD = 2000; return redundantOpCount >= REDUNDANT_OP_COMPACT_THRESHOLD && 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.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 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.eldest(); final 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(); deleteContents(directory); } private void validateKey(String key) { if (key.contains(" ") || key.contains("\n") || key.contains("\r")) { throw new IllegalArgumentException( "keys must not contain spaces or newlines: \"" + key + "\""); } } private static String inputStreamToString(InputStream in) throws IOException { return readFully(new InputStreamReader(in, 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 Snapshot(String key, long sequenceNumber, InputStream[] ins) { this.key = key; this.sequenceNumber = sequenceNumber; this.ins = ins; } /** * 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); } public boolean has(int index) { return index < ins.length; } /** * 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)); } @Override public void close() { for (InputStream in : ins) { closeQuietly(in); } } } /** * Edits the values for an entry. */ public final class Editor { private final Entry entry; private boolean hasErrors; private Editor(Entry entry) { this.entry = entry; } /** * 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; } return new FileInputStream(entry.getCleanFile(index)); } } /** * 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; } public boolean has(int index) { File file = entry.getCleanFile(index); return file.exists(); } /** * 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 { synchronized (DiskLruCache.this) { if (entry.currentEditor != this) { throw new IllegalStateException(); } return new FaultHidingOutputStream(new FileOutputStream(entry.getDirtyFile(index))); } } /** * 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), UTF_8); writer.write(value); } finally { 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); } } /** * 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); } 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: " + 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"); } } }