public GlideBuilder setDiskCacheService(ExecutorService service) {
        this.diskCacheService = service;
        return this;
    }
Sets the {@link ExecutorService} implementation to use when retrieving
{@link com.bumptech.glide.load.engine.Resource}s that are currently in cache.

<p>
    Any implementation must order requests based on their {@link Priority} for thumbnail
    requests to work properly.
</p>

@see #setResizeService(ExecutorService)
@see FifoPriorityThreadPoolExecutor

@param service The ExecutorService to use.
@return This builder.
core/src/main/java/com/bumptech/glide/GlideBuilder.java