sync with coap

sync.js

var setup, outbox = [], relay = [], syncServers = [],
    relayCap = 4, copyFactor = 1, defaultLeisure = 5000/*ms*/,
    outboxInterval, relaysInterval, initInterval;

exports.log = function (json) {
    if (!setup) {doInit();}
    outbox.push([0, json]);
};

function setupTimers() {
    outboxInterval =  outboxInterval ||
        setInterval(sendOutbox, defaultLeisure*(1+Math.random()));
    relaysInterval = relaysInterval ||
        setInterval(sendRelays, defaultLeisure*10*(1+Math.random()))
    initInterval = initInterval ||
        setInterval(doInit, defaultLeisure*defaultLeisure*(1+Math.random()));
};

function doInit() {
    setup = true;
    coap.on("PUT", function(id, json) {
        relay.push([0, json]);
    })
    // additionally one could use telehash discovery
    coap.multicastConfirmable('GET', '/.well-known/core', function(err, message) {
        if (err) throw(err);
        setupTimers();
        // todo implement this API
        message.on("ack", function(endpoint, _reply) {
            syncServers.push(endpoint)
        })
    });
};

function incrementItem(queue, id) {
    for (var i = queue.length - 1; i >= 0; i--) {
        if (queue[i][2] == id) {
            queue[i][0]++;
            if (queue[i][0] >= copyFactor) {
                // trim from the outbox when reaches copyFactor
                queue = queue.splice(i, 1);
            }
        }
    };
};

function sendMessage(queue) {
    return function (entry) {
        var json = entry[1], id = coap.newId();
        entry[2] = id;
        // todo implement this API
        coap.confirmable('PUT', syncServers, id, json, function(err, message) {
            message.on("ack", function(endpoint) {
                incrementItem(queue, id);
            })
        });
    };
}

function sendRelays() {
    if (relay.length > relayCap) {
        sendMessage(relay)(relay[0]);
    }
};

function sendOutbox() {
    outbox.forEach(sendMessage(outbox));
};