Android Open Source - AUIL-for-volley Limited Disc Cache

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License

The source code is released under:

Apache License

Java Source Code

/*******************************************************************************
 * Copyright 2011-2013 Sergey Tarasevich
 *//from  w  w w .j  a  v  a2 s.c  om
 * 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.nostra13.universalimageloader.cache.disc;

import com.nostra13.universalimageloader.cache.disc.naming.FileNameGenerator;
import com.nostra13.universalimageloader.core.DefaultConfigurationFactory;

import java.io.File;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * Abstract disc cache limited by some parameter. If cache exceeds specified limit then file with the most oldest last
 * usage date will be deleted.
 *
 * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
 * @see BaseDiscCache
 * @see FileNameGenerator
 * @since 1.0.0
 */
public abstract class LimitedDiscCache extends BaseDiscCache {

  private static final int INVALID_SIZE = -1;

  private final AtomicInteger cacheSize;

  private final int sizeLimit;

  private final Map<File, Long> lastUsageDates = Collections.synchronizedMap(new HashMap<File, Long>());

  /**
   * @param cacheDir  Directory for file caching. <b>Important:</b> Specify separate folder for cached files. It's
   *                  needed for right cache limit work.
   * @param sizeLimit Cache limit value. If cache exceeds this limit then file with the most oldest last usage date
   *                  will be deleted.
   */
  public LimitedDiscCache(File cacheDir, int sizeLimit) {
    this(cacheDir, DefaultConfigurationFactory.createFileNameGenerator(), sizeLimit);
  }

  /**
   * @param cacheDir          Directory for file caching. <b>Important:</b> Specify separate folder for cached files. It's
   *                          needed for right cache limit work.
   * @param fileNameGenerator Name generator for cached files
   * @param sizeLimit         Cache limit value. If cache exceeds this limit then file with the most oldest last usage date
   *                          will be deleted.
   */
  public LimitedDiscCache(File cacheDir, FileNameGenerator fileNameGenerator, int sizeLimit) {
    super(cacheDir, fileNameGenerator);
    this.sizeLimit = sizeLimit;
    cacheSize = new AtomicInteger();
    calculateCacheSizeAndFillUsageMap();
  }

  private void calculateCacheSizeAndFillUsageMap() {
    new Thread(new Runnable() {
      @Override
      public void run() {
        int size = 0;
        File[] cachedFiles = cacheDir.listFiles();
        if (cachedFiles != null) { // rarely but it can happen, don't know why
          for (File cachedFile : cachedFiles) {
            size += getSize(cachedFile);
            lastUsageDates.put(cachedFile, cachedFile.lastModified());
          }
          cacheSize.set(size);
        }
      }
    }).start();
  }

  @Override
  public void put(String key, File file) {
    int valueSize = getSize(file);
    int curCacheSize = cacheSize.get();

    while (curCacheSize + valueSize > sizeLimit) {
      int freedSize = removeNext();
      if (freedSize == INVALID_SIZE) break; // cache is empty (have nothing to delete)
      curCacheSize = cacheSize.addAndGet(-freedSize);
    }
    cacheSize.addAndGet(valueSize);

    Long currentTime = System.currentTimeMillis();
    file.setLastModified(currentTime);
    lastUsageDates.put(file, currentTime);
  }

  @Override
  public File get(String key) {
    File file = super.get(key);

    Long currentTime = System.currentTimeMillis();
    file.setLastModified(currentTime);
    lastUsageDates.put(file, currentTime);

    return file;
  }

  @Override
  public void clear() {
    lastUsageDates.clear();
    cacheSize.set(0);
    super.clear();
  }

  /** Remove next file and returns it's size */
  private int removeNext() {
    if (lastUsageDates.isEmpty()) {
      return INVALID_SIZE;
    }
    Long oldestUsage = null;
    File mostLongUsedFile = null;
    Set<Entry<File, Long>> entries = lastUsageDates.entrySet();
    synchronized (lastUsageDates) {
      for (Entry<File, Long> entry : entries) {
        if (mostLongUsedFile == null) {
          mostLongUsedFile = entry.getKey();
          oldestUsage = entry.getValue();
        } else {
          Long lastValueUsage = entry.getValue();
          if (lastValueUsage < oldestUsage) {
            oldestUsage = lastValueUsage;
            mostLongUsedFile = entry.getKey();
          }
        }
      }
    }

    int fileSize = 0;
    if (mostLongUsedFile != null) {
      if (mostLongUsedFile.exists()) {
        fileSize = getSize(mostLongUsedFile);
        if (mostLongUsedFile.delete()) {
          lastUsageDates.remove(mostLongUsedFile);
        }
      } else {
        lastUsageDates.remove(mostLongUsedFile);
      }
    }
    return fileSize;
  }

  protected abstract int getSize(File file);
}

Java Source Code List

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