@Override
    public BinaryResource getResource(String resourceId, Object debugInfo) throws IOException {
      if (resourceId.equals(mPoisonResourceId)) {
        throw POISON_EXCEPTION;
      }
      return get().getResource(resourceId, debugInfo);
    }
Verify that multiple threads can write to the cache at the same time.
imagepipeline-base/src/test/java/com/facebook/cache/disk/DiskStorageCacheTest.java