//timed update
function refresh() {

    if (BLOCKED != 1) {
        BLOCKED = 1;
        $.ajax({
            url: 'update',
            success: function(data) {
                 BLOCKED = 0;
            }
         });
     }

//click function
function load() {
    if (BLOCKED != 1) {
        BLOCKED = 1;
        $.ajax({
            url: '/load'
        });
    } else setTimeout("load()", 500);
}

// global state
var inFlight = false;
var pendingLoad = false;

function checkPendingLoad() {
    if (pendingLoad) {
        pendingLoad = false;
        load();
    }
}

function refresh() {
    if (!inFlight) {
        inflight = true;
        $.ajax({
            url: 'update',
            complete: function(data) {
                 inFlight = false;
                 checkPendingLoad();
            }
         });
     }
}


//click function
function load() {
    if (!inFlight) {
        inFlight = true;
        $.ajax({
            url: '/load',
            complete: function(data) {
                inFlight = false;
                checkPendingLoad();
            }
        });
    } else {
        pendingLoad = true;
    }
}