RelicMonitoring - background or external

// Relic integration point

/**
* Create a transactional scope in which instrumentation that will only add
* trace segments to existing transactions will funciton.
*
* @param Agent agent The agent whose tracer should be used to create the
*                    transaction.
* @param Function callback The function to be run within the transaction.
*/
var runInTransaction = function runInTransaction(agent, callback) {
	return agent.tracer.transactionProxy(function () {
		var transaction = agent.getTransaction();
		callback(transaction);
	})();
}

var Q = require("q");
var agent = require("newrelic");
var coinbase = "litecoin";

runInTransaction(agent, function transactionInScope(transaction) {

	var iTX = agent.getTransaction();
	var trace = transaction.getTrace();

	var measurement = transaction.measure('Blockchain/'+coinbase+'/block');

	// Start a timer
	transaction.timer.begin();
	console.log("transaction", transaction);

	// a work unit
	var delay = function (delay) {
		var d = Q.defer();
		setTimeout(
			function() {
				// stupid timeout to cause a little lag
				console.log("metric", metric);

				var metric = transaction
					.metrics
					.getOrCreateMetric('Blockchain/'+coinbase+'/block');

				console.log("metric",metric);

				var stats = measurement.stats;

				if (stats.callCount < 1) {
					console.log("!OK");
					console.log("stats", stats);
				}

				d.resolve();
			}
			, delay);
		return d.promise;
	};

	// setup some work to track
	// simple promise based approach
	Q.when(delay(1000), function () {
		// stop the timer
		trace.root.timer.end();

		console.log("finalTx", transaction);
		console.log("metrics", transaction.metrics);
		console.log("unscoped", transaction.metrics.unscoped);

		// trace first - it was started inside the tx
		trace.end();
		transaction.end();
	}).then(
		function(){
			agent.stop();
		}
	);
});

In general, you should only need line 72 – ending the transaction will also end the trace, which actually recursively closes all its trace segments (this is something of a hack, in that I don't know what would happen inside New Relic's presentation logic if there's a transaction trace with segments that end after the end of the transaction, but I'm reasonably confident it would be nothing good). If you look at https://github.com/newrelic/node-newrelic/blob/master/lib/instrumentation/core/http.js#L24-L32, you can see how we tie a segment's timer to the measurement process.