public void clearAll() {
    final List<EncodedImage> old;
    synchronized (this) {
      old = new ArrayList<>(mMap.values());
      mMap.clear();
    }
    for (int i = 0; i < old.size(); i++) {
      EncodedImage encodedImage = old.get(i);
      if (encodedImage != null) {
        encodedImage.close();
      }
    }
  }
Removes all items from the StagingArea.
imagepipeline/src/main/java/com/facebook/imagepipeline/cache/StagingArea.java