decaffeinate

libraries/metrics/prom_wrapper.js

@@ -0,0 +1,148 @@
+/*
+ * decaffeinate suggestions:
+ * DS101: Remove unnecessary use of Array.from
+ * DS102: Remove unnecessary code created because of implicit returns
+ * DS205: Consider reworking code to avoid use of IIFEs
+ * Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
+ */
+const prom = require('prom-client');
+const registry = require('prom-client').register;
+const metrics = new Map();
+
+
+const optsKey = function(opts) {
+	let keys = Object.keys(opts);
+	if (keys.length === 0) { return ''; }
+
+	keys = keys.sort();
+
+	let hash = '';
+	for (let key of Array.from(keys)) {
+		if (hash.length) { hash += ","; }
+		hash += `${key}:${opts[key]}`;
+	}
+
+	return hash;
+};
+
+const extendOpts = function(opts, labelNames) {
+	for (let label of Array.from(labelNames)) {
+		if (!opts[label]) { opts[label] = ''; }
+	}
+	return opts;
+};
+
+const optsAsArgs = function(opts, labelNames) {
+	const args = [];
+	for (let label of Array.from(labelNames)) {
+		args.push(opts[label] || '');
+	}
+	return args;
+};
+
+
+const PromWrapper = {
+	ttlInMinutes: 0,
+	registry,
+
+	metric(type, name) {
+		return metrics.get(name) || new MetricWrapper(type, name);
+	},
+
+	collectDefaultMetrics: prom.collectDefaultMetrics
+};
+
+
+class MetricWrapper {
+	constructor(type, name) {
+		metrics.set(name, this);
+		this.name = name;
+		this.instances = new Map();
+		this.lastAccess = new Date();
+		this.metric = (() => { switch (type) {
+			case "counter":
+				return new prom.Counter({
+					name,
+					help: name,
+					labelNames: ['app','host','status','method', 'path']
+				});
+			case "summary":
+				return new prom.Summary({
+					name,
+					help: name,
+					maxAgeSeconds: 60,
+					ageBuckets: 10,
+					labelNames: ['app', 'host', 'path', 'status_code', 'method', 'collection', 'query']
+				});
+			case "gauge":
+				return new prom.Gauge({
+					name,
+					help: name,
+					labelNames: ['app','host', 'status']
+				});
+		} })();
+	}
+
+	inc(opts, value) {
+		return this._execMethod('inc', opts, value);
+	}
+
+	observe(opts, value) {
+		return this._execMethod('observe', opts, value);
+	}
+
+	set(opts, value) {
+		return this._execMethod('set', opts, value);
+	}
+
+	sweep() {
+		const thresh = new Date(Date.now() - (1000 * 60 * PromWrapper.ttlInMinutes));
+		this.instances.forEach((instance, key) => {
+			if (thresh > instance.time) {
+				if (process.env['DEBUG_METRICS']) {
+					console.log("Sweeping stale metric instance", this.name, {opts: instance.opts}, key);
+				}
+				return this.metric.remove(...Array.from(optsAsArgs(instance.opts, this.metric.labelNames) || []));
+			}
+		});
+
+		if (thresh > this.lastAccess) {
+			if (process.env['DEBUG_METRICS']) {
+				console.log("Sweeping stale metric", this.name, thresh, this.lastAccess);
+			}
+			metrics.delete(this.name);
+			return registry.removeSingleMetric(this.name);
+		}
+	}
+
+	_execMethod(method, opts, value) {
+		opts = extendOpts(opts, this.metric.labelNames);
+		const key = optsKey(opts);
+		if (key !== '') { this.instances.set(key, { time: new Date(), opts }); }
+		this.lastAccess = new Date();
+		return this.metric[method](opts, value);
+	}
+}
+
+
+if (!PromWrapper.sweepRegistered) {
+	if (process.env['DEBUG_METRICS']) {
+		console.log("Registering sweep method");
+	}
+	PromWrapper.sweepRegistered = true;
+	setInterval(
+		function() {
+			if (PromWrapper.ttlInMinutes) {
+				if (process.env['DEBUG_METRICS']) {
+					console.log("Sweeping metrics");
+				}
+				return metrics.forEach((metric, key) => {
+					return metric.sweep();
+				});
+			}
+		},
+	60000);
+}
+
+
+module.exports = PromWrapper;