gistfile1.txt

    private static final Map<Class<?>, Boolean> SHARABLE_CACHE = PlatformDependent.newConcurrentHashMap();

    // Not using volatile because it's used only for a sanity check.
    boolean added;

    /**
     * Return {@code true} if the implementation is {@link Sharable} and so can be added
     * to different {@link ChannelPipeline}s.
     */
    public boolean isSharable() {
        Class<?> clazz = getClass();
        Boolean sharable = SHARABLE_CACHE.get(clazz);
        if (sharable == null) {
            sharable = clazz.isAnnotationPresent(Sharable.class); 
            SHARABLE_CACHE.put(clazz, sharable);
        }
        return sharable;
    }