Stats are now generated only when needed and at most every 10s.

src/api.js

@@ -531,59 +531,7 @@ Api.fn.server = {
 // Extra methods not really bound to an object.
 Api.fn.xo = {
 	'getStats': function () {
-		// @todo Keep up-to-date stats in this.xo to avoid unecessary
+		return this.xo.stats;
-		// (and possibly heavy) computing.
-
-		var xo = this.xo;
-		var xobjs = xo.xobjs;
-		return Q.all([
-			xobjs.host.get(),
-			xobjs.host_metrics.get().then(function (metrics) {
-				return _.indexBy(metrics, 'id');
-			}),
-			xobjs.VM.get({
-				'is_a_template': false,
-				'is_control_domain': false,
-			}),
-			xobjs.VM_metrics.get().then(function (metrics) {
-				return _.indexBy(metrics, 'id');
-			}),
-			xobjs.SR.count(),
-		]).spread(function (hosts, host_metrics, vms, vms_metrics, n_srs) {
-			var running_vms = _.where(vms, {
-				'power_state': 'Running',
-			});
-
-			var n_cpus = 0;
-			var total_memory = 0;
-			_.each(hosts, function (host) {
-				n_cpus += host.host_CPUs.length;
-				total_memory += +host_metrics[host.metrics].memory_total;
-			});
-
-			var n_vifs = 0;
-			var n_vcpus = 0;
-			var used_memory = 0;
-			_.each(vms, function (vm) {
-				var metrics = vms_metrics[vm.metrics];
-
-				n_vifs += vm.VIFs.length;
-				n_vcpus += +metrics.VCPUs_number;
-				used_memory += +metrics.memory_actual;
-			});
-
-			return {
-				'hosts': hosts.length,
-				'vms': vms.length,
-				'running_vms': running_vms.length,
-				'used_memory': used_memory,
-				'total_memory': total_memory,
-				'vcpus': n_vcpus,
-				'cpus': n_cpus,
-				'vifs': n_vifs,
-				'srs': n_srs,
-			};
-		});
 	},
 
 	'getSessionId': function (req) {

src/xo.js

@@ -165,10 +165,67 @@ function Xo()
 	}
 
 	// Connections to Xen pools/servers.
-	this.connections = {};
+	//this.connections = {};
+
+	// We will keep up-to-date stats in this object
+	this.stats = {};
 }
 require('util').inherits(Xo, require('events').EventEmitter);
 
+Xo.prototype.computeStats = _.throttle(function () {
+	var xo = this;
+	var xobjs = xo.xobjs;
+
+	return Q.all([
+		xobjs.host.get(),
+		xobjs.host_metrics.get().then(function (metrics) {
+			return _.indexBy(metrics, 'id');
+		}),
+		xobjs.VM.get({
+			'is_a_template': false,
+			'is_control_domain': false,
+		}),
+		xobjs.VM_metrics.get().then(function (metrics) {
+			return _.indexBy(metrics, 'id');
+		}),
+		xobjs.SR.count(),
+	]).spread(function (hosts, host_metrics, vms, vms_metrics, n_srs) {
+		var running_vms = _.where(vms, {
+			'power_state': 'Running',
+		});
+
+		var n_cpus = 0;
+		var total_memory = 0;
+		_.each(hosts, function (host) {
+			n_cpus += host.host_CPUs.length;
+			total_memory += +host_metrics[host.metrics].memory_total;
+		});
+
+		var n_vifs = 0;
+		var n_vcpus = 0;
+		var used_memory = 0;
+		_.each(vms, function (vm) {
+			var metrics = vms_metrics[vm.metrics];
+
+			n_vifs += vm.VIFs.length;
+			n_vcpus += +metrics.VCPUs_number;
+			used_memory += +metrics.memory_actual;
+		});
+
+		xo.stats = {
+			'hosts': hosts.length,
+			'vms': vms.length,
+			'running_vms': running_vms.length,
+			'used_memory': used_memory,
+			'total_memory': total_memory,
+			'vcpus': n_vcpus,
+			'cpus': n_cpus,
+			'vifs': n_vifs,
+			'srs': n_srs,
+		};
+	});
+}, 5000);
+
 Xo.prototype.start = function (cfg) {
 	var xo = this;
 	var redis = require('then-redis').createClient(cfg.get('redis', 'uri'));
@@ -255,6 +312,7 @@ Xo.prototype.start = function (cfg) {
 				});
 			});
 		})).then(function () {
+			xo.computeStats();
 			return xapi.call('event.register', ['*']);
 		}).then(function () {
 			return function loop() {
@@ -270,6 +328,8 @@ Xo.prototype.start = function (cfg) {
 
 						// @todo Handle operation types.
 						collection.add(event.snapshot, {'replace': true});
+
+						xo.computeStats();
 					}
 
 					return loop();