DisplayingBitmaps / src / com.example.android.displayingbitmaps / util /

DiskLruCache.java

1
/*
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 * Copyright (C) 2011 The Android Open Source Project
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 *
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 *      http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 */
16
 
17
package com.example.android.displayingbitmaps.util;
18
 
19
import java.io.BufferedInputStream;
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import java.io.BufferedWriter;
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import java.io.Closeable;
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import java.io.EOFException;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.FileNotFoundException;
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import java.io.FileOutputStream;
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import java.io.FileWriter;
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import java.io.FilterOutputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.InputStreamReader;
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import java.io.OutputStream;
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import java.io.OutputStreamWriter;
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import java.io.Reader;
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import java.io.StringWriter;
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import java.io.Writer;
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import java.lang.reflect.Array;
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import java.nio.charset.Charset;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Iterator;
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import java.util.LinkedHashMap;
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import java.util.Map;
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import java.util.concurrent.Callable;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.LinkedBlockingQueue;
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import java.util.concurrent.ThreadPoolExecutor;
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import java.util.concurrent.TimeUnit;
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/**
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 ******************************************************************************
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 * Taken from the JB source code, can be found in:
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 * libcore/luni/src/main/java/libcore/io/DiskLruCache.java
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 * or direct link:
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 * https://android.googlesource.com/platform/libcore/+/android-4.1.1_r1/luni/src/main/java/libcore/io/DiskLruCache.java
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 ******************************************************************************
57
 *
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 * A cache that uses a bounded amount of space on a filesystem. Each cache
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 * entry has a string key and a fixed number of values. Values are byte
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 * sequences, accessible as streams or files. Each value must be between {@code
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 * 0} and {@code Integer.MAX_VALUE} bytes in length.
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 *
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 * <p>The cache stores its data in a directory on the filesystem. This
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 * directory must be exclusive to the cache; the cache may delete or overwrite
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 * files from its directory. It is an error for multiple processes to use the
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 * same cache directory at the same time.
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 *
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 * <p>This cache limits the number of bytes that it will store on the
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 * filesystem. When the number of stored bytes exceeds the limit, the cache will
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 * remove entries in the background until the limit is satisfied. The limit is
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 * not strict: the cache may temporarily exceed it while waiting for files to be
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 * deleted. The limit does not include filesystem overhead or the cache
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 * journal so space-sensitive applications should set a conservative limit.
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 *
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 * <p>Clients call {@link #edit} to create or update the values of an entry. An
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 * entry may have only one editor at one time; if a value is not available to be
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 * edited then {@link #edit} will return null.
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 * <ul>
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 *     <li>When an entry is being <strong>created</strong> it is necessary to
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 *         supply a full set of values; the empty value should be used as a
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 *         placeholder if necessary.
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 *     <li>When an entry is being <strong>edited</strong>, it is not necessary
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 *         to supply data for every value; values default to their previous
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 *         value.
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 * </ul>
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 * Every {@link #edit} call must be matched by a call to {@link Editor#commit}
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 * or {@link Editor#abort}. Committing is atomic: a read observes the full set
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 * of values as they were before or after the commit, but never a mix of values.
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 *
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 * <p>Clients call {@link #get} to read a snapshot of an entry. The read will
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 * observe the value at the time that {@link #get} was called. Updates and
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 * removals after the call do not impact ongoing reads.
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 *
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 * <p>This class is tolerant of some I/O errors. If files are missing from the
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 * filesystem, the corresponding entries will be dropped from the cache. If
96
 * an error occurs while writing a cache value, the edit will fail silently.
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 * Callers should handle other problems by catching {@code IOException} and
98
 * responding appropriately.
99
 */
100
public final class DiskLruCache implements Closeable {
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    static final String JOURNAL_FILE = "journal";
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    static final String JOURNAL_FILE_TMP = "journal.tmp";
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    static final String MAGIC = "libcore.io.DiskLruCache";
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    static final String VERSION_1 = "1";
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    static final long ANY_SEQUENCE_NUMBER = -1;
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    private static final String CLEAN = "CLEAN";
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    private static final String DIRTY = "DIRTY";
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    private static final String REMOVE = "REMOVE";
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    private static final String READ = "READ";
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111
    private static final Charset UTF_8 = Charset.forName("UTF-8");
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    private static final int IO_BUFFER_SIZE = 8 * 1024;
113
 
114
    /*
115
     * This cache uses a journal file named "journal". A typical journal file
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     * looks like this:
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     *     libcore.io.DiskLruCache
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     *     1
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     *     100
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     *     2
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     *
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     *     CLEAN 3400330d1dfc7f3f7f4b8d4d803dfcf6 832 21054
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     *     DIRTY 335c4c6028171cfddfbaae1a9c313c52
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     *     CLEAN 335c4c6028171cfddfbaae1a9c313c52 3934 2342
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     *     REMOVE 335c4c6028171cfddfbaae1a9c313c52
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     *     DIRTY 1ab96a171faeeee38496d8b330771a7a
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     *     CLEAN 1ab96a171faeeee38496d8b330771a7a 1600 234
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     *     READ 335c4c6028171cfddfbaae1a9c313c52
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     *     READ 3400330d1dfc7f3f7f4b8d4d803dfcf6
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     *
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     * The first five lines of the journal form its header. They are the
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     * constant string "libcore.io.DiskLruCache", the disk cache's version,
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     * the application's version, the value count, and a blank line.
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     *
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     * Each of the subsequent lines in the file is a record of the state of a
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     * cache entry. Each line contains space-separated values: a state, a key,
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     * and optional state-specific values.
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     *   o DIRTY lines track that an entry is actively being created or updated.
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     *     Every successful DIRTY action should be followed by a CLEAN or REMOVE
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     *     action. DIRTY lines without a matching CLEAN or REMOVE indicate that
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     *     temporary files may need to be deleted.
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     *   o CLEAN lines track a cache entry that has been successfully published
143
     *     and may be read. A publish line is followed by the lengths of each of
144
     *     its values.
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     *   o READ lines track accesses for LRU.
146
     *   o REMOVE lines track entries that have been deleted.
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     *
148
     * The journal file is appended to as cache operations occur. The journal may
149
     * occasionally be compacted by dropping redundant lines. A temporary file named
150
     * "journal.tmp" will be used during compaction; that file should be deleted if
151
     * it exists when the cache is opened.
152
     */
153
 
154
    private final File directory;
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    private final File journalFile;
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    private final File journalFileTmp;
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    private final int appVersion;
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    private final long maxSize;
159
    private final int valueCount;
160
    private long size = 0;
161
    private Writer journalWriter;
162
    private final LinkedHashMap<String, Entry> lruEntries
163
            = new LinkedHashMap<String, Entry>(0, 0.75f, true);
164
    private int redundantOpCount;
165
 
166
    /**
167
     * To differentiate between old and current snapshots, each entry is given
168
     * a sequence number each time an edit is committed. A snapshot is stale if
169
     * its sequence number is not equal to its entry's sequence number.
170
     */
171
    private long nextSequenceNumber = 0;
172
 
173
    /* From java.util.Arrays */
174
    @SuppressWarnings("unchecked")
175
    private static <T> T[] copyOfRange(T[] original, int start, int end) {
176
        final int originalLength = original.length; // For exception priority compatibility.
177
        if (start > end) {
178
            throw new IllegalArgumentException();
179
        }
180
        if (start < 0 || start > originalLength) {
181
            throw new ArrayIndexOutOfBoundsException();
182
        }
183
        final int resultLength = end - start;
184
        final int copyLength = Math.min(resultLength, originalLength - start);
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        final T[] result = (T[]) Array
186
                .newInstance(original.getClass().getComponentType(), resultLength);
187
        System.arraycopy(original, start, result, 0, copyLength);
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        return result;
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    }
190
 
191
    /**
192
     * Returns the remainder of 'reader' as a string, closing it when done.
193
     */
194
    public static String readFully(Reader reader) throws IOException {
195
        try {
196
            StringWriter writer = new StringWriter();
197
            char[] buffer = new char[1024];
198
            int count;
199
            while ((count = reader.read(buffer)) != -1) {
200
                writer.write(buffer, 0, count);
201
            }
202
            return writer.toString();
203
        } finally {
204
            reader.close();
205
        }
206
    }
207
 
208
    /**
209
     * Returns the ASCII characters up to but not including the next "\r\n", or
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     * "\n".
211
     *
212
     * @throws java.io.EOFException if the stream is exhausted before the next newline
213
     *     character.
214
     */
215
    public static String readAsciiLine(InputStream in) throws IOException {
216
        // TODO: support UTF-8 here instead
217
 
218
        StringBuilder result = new StringBuilder(80);
219
        while (true) {
220
            int c = in.read();
221
            if (c == -1) {
222
                throw new EOFException();
223
            } else if (c == '\n') {
224
                break;
225
            }
226
 
227
            result.append((char) c);
228
        }
229
        int length = result.length();
230
        if (length > 0 && result.charAt(length - 1) == '\r') {
231
            result.setLength(length - 1);
232
        }
233
        return result.toString();
234
    }
235
 
236
    /**
237
     * Closes 'closeable', ignoring any checked exceptions. Does nothing if 'closeable' is null.
238
     */
239
    public static void closeQuietly(Closeable closeable) {
240
        if (closeable != null) {
241
            try {
242
                closeable.close();
243
            } catch (RuntimeException rethrown) {
244
                throw rethrown;
245
            } catch (Exception ignored) {
246
            }
247
        }
248
    }
249
 
250
    /**
251
     * Recursively delete everything in {@code dir}.
252
     */
253
    // TODO: this should specify paths as Strings rather than as Files
254
    public static void deleteContents(File dir) throws IOException {
255
        File[] files = dir.listFiles();
256
        if (files == null) {
257
            throw new IllegalArgumentException("not a directory: " + dir);
258
        }
259
        for (File file : files) {
260
            if (file.isDirectory()) {
261
                deleteContents(file);
262
            }
263
            if (!file.delete()) {
264
                throw new IOException("failed to delete file: " + file);
265
            }
266
        }
267
    }
268
 
269
    /** This cache uses a single background thread to evict entries. */
270
    private final ExecutorService executorService = new ThreadPoolExecutor(0, 1,
271
            60L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>());
272
    private final Callable<Void> cleanupCallable = new Callable<Void>() {
273
        @Override public Void call() throws Exception {
274
            synchronized (DiskLruCache.this) {
275
                if (journalWriter == null) {
276
                    return null; // closed
277
                }
278
                trimToSize();
279
                if (journalRebuildRequired()) {
280
                    rebuildJournal();
281
                    redundantOpCount = 0;
282
                }
283
            }
284
            return null;
285
        }
286
    };
287
 
288
    private DiskLruCache(File directory, int appVersion, int valueCount, long maxSize) {
289
        this.directory = directory;
290
        this.appVersion = appVersion;
291
        this.journalFile = new File(directory, JOURNAL_FILE);
292
        this.journalFileTmp = new File(directory, JOURNAL_FILE_TMP);
293
        this.valueCount = valueCount;
294
        this.maxSize = maxSize;
295
    }
296
 
297
    /**
298
     * Opens the cache in {@code directory}, creating a cache if none exists
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     * there.
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     *
301
     * @param directory a writable directory
302
     * @param appVersion
303
     * @param valueCount the number of values per cache entry. Must be positive.
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     * @param maxSize the maximum number of bytes this cache should use to store
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     * @throws java.io.IOException if reading or writing the cache directory fails
306
     */
307
    public static DiskLruCache open(File directory, int appVersion, int valueCount, long maxSize)
308
            throws IOException {
309
        if (maxSize <= 0) {
310
            throw new IllegalArgumentException("maxSize <= 0");
311
        }
312
        if (valueCount <= 0) {
313
            throw new IllegalArgumentException("valueCount <= 0");
314
        }
315
 
316
        // prefer to pick up where we left off
317
        DiskLruCache cache = new DiskLruCache(directory, appVersion, valueCount, maxSize);
318
        if (cache.journalFile.exists()) {
319
            try {
320
                cache.readJournal();
321
                cache.processJournal();
322
                cache.journalWriter = new BufferedWriter(new FileWriter(cache.journalFile, true),
323
                        IO_BUFFER_SIZE);
324
                return cache;
325
            } catch (IOException journalIsCorrupt) {
326
//                System.logW("DiskLruCache " + directory + " is corrupt: "
327
//                        + journalIsCorrupt.getMessage() + ", removing");
328
                cache.delete();
329
            }
330
        }
331
 
332
        // create a new empty cache
333
        directory.mkdirs();
334
        cache = new DiskLruCache(directory, appVersion, valueCount, maxSize);
335
        cache.rebuildJournal();
336
        return cache;
337
    }
338
 
339
    private void readJournal() throws IOException {
340
        InputStream in = new BufferedInputStream(new FileInputStream(journalFile), IO_BUFFER_SIZE);
341
        try {
342
            String magic = readAsciiLine(in);
343
            String version = readAsciiLine(in);
344
            String appVersionString = readAsciiLine(in);
345
            String valueCountString = readAsciiLine(in);
346
            String blank = readAsciiLine(in);
347
            if (!MAGIC.equals(magic)
348
                    || !VERSION_1.equals(version)
349
                    || !Integer.toString(appVersion).equals(appVersionString)
350
                    || !Integer.toString(valueCount).equals(valueCountString)
351
                    || !"".equals(blank)) {
352
                throw new IOException("unexpected journal header: ["
353
                        + magic + ", " + version + ", " + valueCountString + ", " + blank + "]");
354
            }
355
 
356
            while (true) {
357
                try {
358
                    readJournalLine(readAsciiLine(in));
359
                } catch (EOFException endOfJournal) {
360
                    break;
361
                }
362
            }
363
        } finally {
364
            closeQuietly(in);
365
        }
366
    }
367
 
368
    private void readJournalLine(String line) throws IOException {
369
        String[] parts = line.split(" ");
370
        if (parts.length < 2) {
371
            throw new IOException("unexpected journal line: " + line);
372
        }
373
 
374
        String key = parts[1];
375
        if (parts[0].equals(REMOVE) && parts.length == 2) {
376
            lruEntries.remove(key);
377
            return;
378
        }
379
 
380
        Entry entry = lruEntries.get(key);
381
        if (entry == null) {
382
            entry = new Entry(key);
383
            lruEntries.put(key, entry);
384
        }
385
 
386
        if (parts[0].equals(CLEAN) && parts.length == 2 + valueCount) {
387
            entry.readable = true;
388
            entry.currentEditor = null;
389
            entry.setLengths(copyOfRange(parts, 2, parts.length));
390
        } else if (parts[0].equals(DIRTY) && parts.length == 2) {
391
            entry.currentEditor = new Editor(entry);
392
        } else if (parts[0].equals(READ) && parts.length == 2) {
393
            // this work was already done by calling lruEntries.get()
394
        } else {
395
            throw new IOException("unexpected journal line: " + line);
396
        }
397
    }
398
 
399
    /**
400
     * Computes the initial size and collects garbage as a part of opening the
401
     * cache. Dirty entries are assumed to be inconsistent and will be deleted.
402
     */
403
    private void processJournal() throws IOException {
404
        deleteIfExists(journalFileTmp);
405
        for (Iterator<Entry> i = lruEntries.values().iterator(); i.hasNext(); ) {
406
            Entry entry = i.next();
407
            if (entry.currentEditor == null) {
408
                for (int t = 0; t < valueCount; t++) {
409
                    size += entry.lengths[t];
410
                }
411
            } else {
412
                entry.currentEditor = null;
413
                for (int t = 0; t < valueCount; t++) {
414
                    deleteIfExists(entry.getCleanFile(t));
415
                    deleteIfExists(entry.getDirtyFile(t));
416
                }
417
                i.remove();
418
            }
419
        }
420
    }
421
 
422
    /**
423
     * Creates a new journal that omits redundant information. This replaces the
424
     * current journal if it exists.
425
     */
426
    private synchronized void rebuildJournal() throws IOException {
427
        if (journalWriter != null) {
428
            journalWriter.close();
429
        }
430
 
431
        Writer writer = new BufferedWriter(new FileWriter(journalFileTmp), IO_BUFFER_SIZE);
432
        writer.write(MAGIC);
433
        writer.write("\n");
434
        writer.write(VERSION_1);
435
        writer.write("\n");
436
        writer.write(Integer.toString(appVersion));
437
        writer.write("\n");
438
        writer.write(Integer.toString(valueCount));
439
        writer.write("\n");
440
        writer.write("\n");
441
 
442
        for (Entry entry : lruEntries.values()) {
443
            if (entry.currentEditor != null) {
444
                writer.write(DIRTY + ' ' + entry.key + '\n');
445
            } else {
446
                writer.write(CLEAN + ' ' + entry.key + entry.getLengths() + '\n');
447
            }
448
        }
449
 
450
        writer.close();
451
        journalFileTmp.renameTo(journalFile);
452
        journalWriter = new BufferedWriter(new FileWriter(journalFile, true), IO_BUFFER_SIZE);
453
    }
454
 
455
    private static void deleteIfExists(File file) throws IOException {
456
//        try {
457
//            Libcore.os.remove(file.getPath());
458
//        } catch (ErrnoException errnoException) {
459
//            if (errnoException.errno != OsConstants.ENOENT) {
460
//                throw errnoException.rethrowAsIOException();
461
//            }
462
//        }
463
        if (file.exists() && !file.delete()) {
464
            throw new IOException();
465
        }
466
    }
467
 
468
    /**
469
     * Returns a snapshot of the entry named {@code key}, or null if it doesn't
470
     * exist is not currently readable. If a value is returned, it is moved to
471
     * the head of the LRU queue.
472
     */
473
    public synchronized Snapshot get(String key) throws IOException {
474
        checkNotClosed();
475
        validateKey(key);
476
        Entry entry = lruEntries.get(key);
477
        if (entry == null) {
478
            return null;
479
        }
480
 
481
        if (!entry.readable) {
482
            return null;
483
        }
484
 
485
        /*
486
         * Open all streams eagerly to guarantee that we see a single published
487
         * snapshot. If we opened streams lazily then the streams could come
488
         * from different edits.
489
         */
490
        InputStream[] ins = new InputStream[valueCount];
491
        try {
492
            for (int i = 0; i < valueCount; i++) {
493
                ins[i] = new FileInputStream(entry.getCleanFile(i));
494
            }
495
        } catch (FileNotFoundException e) {
496
            // a file must have been deleted manually!
497
            return null;
498
        }
499
 
500
        redundantOpCount++;
501
        journalWriter.append(READ + ' ' + key + '\n');
502
        if (journalRebuildRequired()) {
503
            executorService.submit(cleanupCallable);
504
        }
505
 
506
        return new Snapshot(key, entry.sequenceNumber, ins);
507
    }
508
 
509
    /**
510
     * Returns an editor for the entry named {@code key}, or null if another
511
     * edit is in progress.
512
     */
513
    public Editor edit(String key) throws IOException {
514
        return edit(key, ANY_SEQUENCE_NUMBER);
515
    }
516
 
517
    private synchronized Editor edit(String key, long expectedSequenceNumber) throws IOException {
518
        checkNotClosed();
519
        validateKey(key);
520
        Entry entry = lruEntries.get(key);
521
        if (expectedSequenceNumber != ANY_SEQUENCE_NUMBER
522
                && (entry == null || entry.sequenceNumber != expectedSequenceNumber)) {
523
            return null; // snapshot is stale
524
        }
525
        if (entry == null) {
526
            entry = new Entry(key);
527
            lruEntries.put(key, entry);
528
        } else if (entry.currentEditor != null) {
529
            return null; // another edit is in progress
530
        }
531
 
532
        Editor editor = new Editor(entry);
533
        entry.currentEditor = editor;
534
 
535
        // flush the journal before creating files to prevent file leaks
536
        journalWriter.write(DIRTY + ' ' + key + '\n');
537
        journalWriter.flush();
538
        return editor;
539
    }
540
 
541
    /**
542
     * Returns the directory where this cache stores its data.
543
     */
544
    public File getDirectory() {
545
        return directory;
546
    }
547
 
548
    /**
549
     * Returns the maximum number of bytes that this cache should use to store
550
     * its data.
551
     */
552
    public long maxSize() {
553
        return maxSize;
554
    }
555
 
556
    /**
557
     * Returns the number of bytes currently being used to store the values in
558
     * this cache. This may be greater than the max size if a background
559
     * deletion is pending.
560
     */
561
    public synchronized long size() {
562
        return size;
563
    }
564
 
565
    private synchronized void completeEdit(Editor editor, boolean success) throws IOException {
566
        Entry entry = editor.entry;
567
        if (entry.currentEditor != editor) {
568
            throw new IllegalStateException();
569
        }
570
 
571
        // if this edit is creating the entry for the first time, every index must have a value
572
        if (success && !entry.readable) {
573
            for (int i = 0; i < valueCount; i++) {
574
                if (!entry.getDirtyFile(i).exists()) {
575
                    editor.abort();
576
                    throw new IllegalStateException("edit didn't create file " + i);
577
                }
578
            }
579
        }
580
 
581
        for (int i = 0; i < valueCount; i++) {
582
            File dirty = entry.getDirtyFile(i);
583
            if (success) {
584
                if (dirty.exists()) {
585
                    File clean = entry.getCleanFile(i);
586
                    dirty.renameTo(clean);
587
                    long oldLength = entry.lengths[i];
588
                    long newLength = clean.length();
589
                    entry.lengths[i] = newLength;
590
                    size = size - oldLength + newLength;
591
                }
592
            } else {
593
                deleteIfExists(dirty);
594
            }
595
        }
596
 
597
        redundantOpCount++;
598
        entry.currentEditor = null;
599
        if (entry.readable | success) {
600
            entry.readable = true;
601
            journalWriter.write(CLEAN + ' ' + entry.key + entry.getLengths() + '\n');
602
            if (success) {
603
                entry.sequenceNumber = nextSequenceNumber++;
604
            }
605
        } else {
606
            lruEntries.remove(entry.key);
607
            journalWriter.write(REMOVE + ' ' + entry.key + '\n');
608
        }
609
 
610
        if (size > maxSize || journalRebuildRequired()) {
611
            executorService.submit(cleanupCallable);
612
        }
613
    }
614
 
615
    /**
616
     * We only rebuild the journal when it will halve the size of the journal
617
     * and eliminate at least 2000 ops.
618
     */
619
    private boolean journalRebuildRequired() {
620
        final int REDUNDANT_OP_COMPACT_THRESHOLD = 2000;
621
        return redundantOpCount >= REDUNDANT_OP_COMPACT_THRESHOLD
622
                && redundantOpCount >= lruEntries.size();
623
    }
624
 
625
    /**
626
     * Drops the entry for {@code key} if it exists and can be removed. Entries
627
     * actively being edited cannot be removed.
628
     *
629
     * @return true if an entry was removed.
630
     */
631
    public synchronized boolean remove(String key) throws IOException {
632
        checkNotClosed();
633
        validateKey(key);
634
        Entry entry = lruEntries.get(key);
635
        if (entry == null || entry.currentEditor != null) {
636
            return false;
637
        }
638
 
639
        for (int i = 0; i < valueCount; i++) {
640
            File file = entry.getCleanFile(i);
641
            if (!file.delete()) {
642
                throw new IOException("failed to delete " + file);
643
            }
644
            size -= entry.lengths[i];
645
            entry.lengths[i] = 0;
646
        }
647
 
648
        redundantOpCount++;
649
        journalWriter.append(REMOVE + ' ' + key + '\n');
650
        lruEntries.remove(key);
651
 
652
        if (journalRebuildRequired()) {
653
            executorService.submit(cleanupCallable);
654
        }
655
 
656
        return true;
657
    }
658
 
659
    /**
660
     * Returns true if this cache has been closed.
661
     */
662
    public boolean isClosed() {
663
        return journalWriter == null;
664
    }
665
 
666
    private void checkNotClosed() {
667
        if (journalWriter == null) {
668
            throw new IllegalStateException("cache is closed");
669
        }
670
    }
671
 
672
    /**
673
     * Force buffered operations to the filesystem.
674
     */
675
    public synchronized void flush() throws IOException {
676
        checkNotClosed();
677
        trimToSize();
678
        journalWriter.flush();
679
    }
680
 
681
    /**
682
     * Closes this cache. Stored values will remain on the filesystem.
683
     */
684
    public synchronized void close() throws IOException {
685
        if (journalWriter == null) {
686
            return; // already closed
687
        }
688
        for (Entry entry : new ArrayList<Entry>(lruEntries.values())) {
689
            if (entry.currentEditor != null) {
690
                entry.currentEditor.abort();
691
            }
692
        }
693
        trimToSize();
694
        journalWriter.close();
695
        journalWriter = null;
696
    }
697
 
698
    private void trimToSize() throws IOException {
699
        while (size > maxSize) {
700
//            Map.Entry<String, Entry> toEvict = lruEntries.eldest();
701
            final Map.Entry<String, Entry> toEvict = lruEntries.entrySet().iterator().next();
702
            remove(toEvict.getKey());
703
        }
704
    }
705
 
706
    /**
707
     * Closes the cache and deletes all of its stored values. This will delete
708
     * all files in the cache directory including files that weren't created by
709
     * the cache.
710
     */
711
    public void delete() throws IOException {
712
        close();
713
        deleteContents(directory);
714
    }
715
 
716
    private void validateKey(String key) {
717
        if (key.contains(" ") || key.contains("\n") || key.contains("\r")) {
718
            throw new IllegalArgumentException(
719
                    "keys must not contain spaces or newlines: \"" + key + "\"");
720
        }
721
    }
722
 
723
    private static String inputStreamToString(InputStream in) throws IOException {
724
        return readFully(new InputStreamReader(in, UTF_8));
725
    }
726
 
727
    /**
728
     * A snapshot of the values for an entry.
729
     */
730
    public final class Snapshot implements Closeable {
731
        private final String key;
732
        private final long sequenceNumber;
733
        private final InputStream[] ins;
734
 
735
        private Snapshot(String key, long sequenceNumber, InputStream[] ins) {
736
            this.key = key;
737
            this.sequenceNumber = sequenceNumber;
738
            this.ins = ins;
739
        }
740
 
741
        /**
742
         * Returns an editor for this snapshot's entry, or null if either the
743
         * entry has changed since this snapshot was created or if another edit
744
         * is in progress.
745
         */
746
        public Editor edit() throws IOException {
747
            return DiskLruCache.this.edit(key, sequenceNumber);
748
        }
749
 
750
        /**
751
         * Returns the unbuffered stream with the value for {@code index}.
752
         */
753
        public InputStream getInputStream(int index) {
754
            return ins[index];
755
        }
756
 
757
        /**
758
         * Returns the string value for {@code index}.
759
         */
760
        public String getString(int index) throws IOException {
761
            return inputStreamToString(getInputStream(index));
762
        }
763
 
764
        @Override public void close() {
765
            for (InputStream in : ins) {
766
                closeQuietly(in);
767
            }
768
        }
769
    }
770
 
771
    /**
772
     * Edits the values for an entry.
773
     */
774
    public final class Editor {
775
        private final Entry entry;
776
        private boolean hasErrors;
777
 
778
        private Editor(Entry entry) {
779
            this.entry = entry;
780
        }
781
 
782
        /**
783
         * Returns an unbuffered input stream to read the last committed value,
784
         * or null if no value has been committed.
785
         */
786
        public InputStream newInputStream(int index) throws IOException {
787
            synchronized (DiskLruCache.this) {
788
                if (entry.currentEditor != this) {
789
                    throw new IllegalStateException();
790
                }
791
                if (!entry.readable) {
792
                    return null;
793
                }
794
                return new FileInputStream(entry.getCleanFile(index));
795
            }
796
        }
797
 
798
        /**
799
         * Returns the last committed value as a string, or null if no value
800
         * has been committed.
801
         */
802
        public String getString(int index) throws IOException {
803
            InputStream in = newInputStream(index);
804
            return in != null ? inputStreamToString(in) : null;
805
        }
806
 
807
        /**
808
         * Returns a new unbuffered output stream to write the value at
809
         * {@code index}. If the underlying output stream encounters errors
810
         * when writing to the filesystem, this edit will be aborted when
811
         * {@link #commit} is called. The returned output stream does not throw
812
         * IOExceptions.
813
         */
814
        public OutputStream newOutputStream(int index) throws IOException {
815
            synchronized (DiskLruCache.this) {
816
                if (entry.currentEditor != this) {
817
                    throw new IllegalStateException();
818
                }
819
                return new FaultHidingOutputStream(new FileOutputStream(entry.getDirtyFile(index)));
820
            }
821
        }
822
 
823
        /**
824
         * Sets the value at {@code index} to {@code value}.
825
         */
826
        public void set(int index, String value) throws IOException {
827
            Writer writer = null;
828
            try {
829
                writer = new OutputStreamWriter(newOutputStream(index), UTF_8);
830
                writer.write(value);
831
            } finally {
832
                closeQuietly(writer);
833
            }
834
        }
835
 
836
        /**
837
         * Commits this edit so it is visible to readers.  This releases the
838
         * edit lock so another edit may be started on the same key.
839
         */
840
        public void commit() throws IOException {
841
            if (hasErrors) {
842
                completeEdit(this, false);
843
                remove(entry.key); // the previous entry is stale
844
            } else {
845
                completeEdit(this, true);
846
            }
847
        }
848
 
849
        /**
850
         * Aborts this edit. This releases the edit lock so another edit may be
851
         * started on the same key.
852
         */
853
        public void abort() throws IOException {
854
            completeEdit(this, false);
855
        }
856
 
857
        private class FaultHidingOutputStream extends FilterOutputStream {
858
            private FaultHidingOutputStream(OutputStream out) {
859
                super(out);
860
            }
861
 
862
            @Override public void write(int oneByte) {
863
                try {
864
                    out.write(oneByte);
865
                } catch (IOException e) {
866
                    hasErrors = true;
867
                }
868
            }
869
 
870
            @Override public void write(byte[] buffer, int offset, int length) {
871
                try {
872
                    out.write(buffer, offset, length);
873
                } catch (IOException e) {
874
                    hasErrors = true;
875
                }
876
            }
877
 
878
            @Override public void close() {
879
                try {
880
                    out.close();
881
                } catch (IOException e) {
882
                    hasErrors = true;
883
                }
884
            }
885
 
886
            @Override public void flush() {
887
                try {
888
                    out.flush();
889
                } catch (IOException e) {
890
                    hasErrors = true;
891
                }
892
            }
893
        }
894
    }
895
 
896
    private final class Entry {
897
        private final String key;
898
 
899
        /** Lengths of this entry's files. */
900
        private final long[] lengths;
901
 
902
        /** True if this entry has ever been published */
903
        private boolean readable;
904
 
905
        /** The ongoing edit or null if this entry is not being edited. */
906
        private Editor currentEditor;
907
 
908
        /** The sequence number of the most recently committed edit to this entry. */
909
        private long sequenceNumber;
910
 
911
        private Entry(String key) {
912
            this.key = key;
913
            this.lengths = new long[valueCount];
914
        }
915
 
916
        public String getLengths() throws IOException {
917
            StringBuilder result = new StringBuilder();
918
            for (long size : lengths) {
919
                result.append(' ').append(size);
920
            }
921
            return result.toString();
922
        }
923
 
924
        /**
925
         * Set lengths using decimal numbers like "10123".
926
         */
927
        private void setLengths(String[] strings) throws IOException {
928
            if (strings.length != valueCount) {
929
                throw invalidLengths(strings);
930
            }
931
 
932
            try {
933
                for (int i = 0; i < strings.length; i++) {
934
                    lengths[i] = Long.parseLong(strings[i]);
935
                }
936
            } catch (NumberFormatException e) {
937
                throw invalidLengths(strings);
938
            }
939
        }
940
 
941
        private IOException invalidLengths(String[] strings) throws IOException {
942
            throw new IOException("unexpected journal line: " + Arrays.toString(strings));
943
        }
944
 
945
        public File getCleanFile(int i) {
946
            return new File(directory, key + "." + i);
947
        }
948
 
949
        public File getDirtyFile(int i) {
950
            return new File(directory, key + "." + i + ".tmp");
951
        }
952
    }
953
}