/**
     * Grant a send credit
     */
    public void grantSendCredit() {
        sendCredits.incrementAndGet();
    }

    /**
     * Grant a receive credit
     */
    public void grantReceiveCredit() {
        receiveCredits.incrementAndGet();
    }

    /**
     * Get number of available send credits
     *
     * @return available send credits
     */