modules/http: keep history of last 120 datapoints

* the http module collects stats snapshots on one
  central location and then streams it to clients
* history of last 120 datapoints (at least 2min)
  is kept for convenience

modules/http/http.lua

@@ -90,7 +90,8 @@ for _, pg in ipairs(pages) do
 end
 
 -- Export built-in prometheus interface
-for k, v in pairs(require('prometheus')) do
+local prometheus = require('prometheus')
+for k, v in pairs(prometheus.endpoints) do
 	M.endpoints[k] = v
 end
 
@@ -304,10 +305,16 @@ function M.interface(host, port, endpoints, crtfile, keyfile)
 	end
 end
 
+-- @function Init module
+function M.init()
+	cq:wrap(prometheus.init)
+end
+
 -- @function Cleanup module
 function M.deinit()
 	if M.ev then event.cancel(M.ev) end
 	M.servers = {}
+	prometheus.deinit()
 end
 
 -- @function Configure module

modules/http/prometheus.lua

 local cqueues = require('cqueues')
+local snapshots, snapshots_count = {}, 120
 
 -- Load dependent modules
 if not stats then modules.load('stats') end
@@ -10,14 +11,20 @@ local function getstats()
 	return t
 end
 
+local function snapshot_end(h, ws)
+	snapshots_count = false
+end
+
 -- Function to sort frequency list
-local function stream_stats(h, ws)
+local function snapshot_start(h, ws)
 	local ok, prev = true, getstats()
-	while ok do
+	while snapshots_count do
+		local is_empty = true
 		-- Get current snapshot
 		local cur, stats_dt = getstats(), {}
 		for k,v in pairs(cur) do
 			stats_dt[k] = v - (prev[k] or 0)
+			is_empty = is_empty and stats_dt[k] == 0
 		end
 		prev = cur
 		-- Calculate upstreams and geotag them if possible
@@ -37,8 +44,38 @@ local function stream_stats(h, ws)
 			end
 		end
 		-- Publish stats updates periodically
-		local push = tojson({stats=stats_dt,upstreams=upstreams or {}})
-		ok = ws:send(push)
+		if not is_empty then
+			local update = {time=os.time(), stats=stats_dt, upstreams=upstreams or {}}
+			table.insert(snapshots, update)
+			if #snapshots > snapshots_count then
+				table.remove(snapshots, 1)
+			end
+		end
+		cqueues.sleep(1)
+	end
+end
+
+-- Function to sort frequency list
+local function stream_stats(h, ws)
+	-- Initially, stream history
+	local ok, last = true, nil
+	local batch = {}
+	for i, s in ipairs(snapshots) do
+		table.insert(batch, s)
+		if #batch == 20 or i + 1 == #snapshots then
+			ok = ws:send(tojson(batch))
+			batch = {}
+		end
+	end
+	-- Publish stats updates periodically
+	while ok do
+		-- Get last snapshot
+		local id = #snapshots - 1
+		if id > 0 and snapshots[id].time ~= last then
+			local push = tojson(snapshots[id])
+			last = snapshots[id].time
+			ok = ws:send(push)
+		end
 		cqueues.sleep(1)
 	end
 end
@@ -79,7 +116,11 @@ end
 
 -- Export endpoints
 return {
-	['/stats']     = {'application/json', getstats, stream_stats},
-	['/frequent']  = {'application/json', function () return stats.frequent() end},
-	['/metrics']   = {'text/plain; version=0.0.4', serve_prometheus},
+	init = snapshot_start,
+	deinit = snapshot_end,
+	endpoints = {
+		['/stats']     = {'application/json', getstats, stream_stats},
+		['/frequent']  = {'application/json', function () return stats.frequent() end},
+		['/metrics']   = {'text/plain; version=0.0.4', serve_prometheus},
+	}
 }
\ No newline at end of file

modules/http/static/kresd.js

@@ -59,11 +59,6 @@ $(function() {
 		renderer: 'multi',
 		series: series,
 	});
-	var x_axis = new Rickshaw.Graph.Axis.Time( {
-		graph: graph,
-		ticksTreatment: 'glow',
-		element: document.querySelector("#x_axis"),
-	} );
 	var y_axis = new Rickshaw.Graph.Axis.Y( {
 		graph: graph,
 		orientation: 'left',
@@ -139,20 +134,22 @@ $(function() {
 	}
 
 	/* Realtime updates over WebSockets */
-	function pushMetrics(resp) {
-		var now = Date.now() / 1000;
+	function pushMetrics(resp, now, buffer) {
 		for (var lb in resp) {
 			var val = resp[lb];
 			/* Push new datapoints */
 			if (lb in data) {
 				data[lb].push({x: now, y:val});
-				if (data[lb].length > 100) {
+				if (data[lb].length > 120) {
 					data[lb].shift();
 				}
 			}
 
 		}
-		graph.update();
+		/* Buffer graph  changes. */
+		if (!buffer) {
+			graph.update();
+		}
 	}
 
 	var age = 0;
@@ -173,7 +170,7 @@ $(function() {
 		/* Update bubbles and prune the oldest */
 		for (var key in resp) {
 			var val = resp[key];
-			if (!val.data) {
+			if (!val.data || !val.location || val.location.longitude == null) {
 				continue;
 			}
 			var sum = val.data.reduce(function(a, b) { return a + b; });
@@ -215,10 +212,21 @@ $(function() {
 
 	/* WebSocket endpoints */
 	var wsStats = (secure ? 'wss://' : 'ws://') + location.host + '/stats';
-    var ws = new Socket(wsStats);
-    ws.onmessage = function(evt) {
-      var data = $.parseJSON(evt.data);
-      pushMetrics(data.stats);
-      pushUpstreams(data.upstreams);
-    };
+	var ws = new Socket(wsStats);
+	ws.onmessage = function(evt) {
+		var data = JSON.parse(evt.data);
+		if (data[0]) {
+			if (data.length > 0) {
+				pushUpstreams(data[data.length - 1].upstreams);
+			}
+			for (var i in data) {
+				pushMetrics(data[i].stats, data[i].time, true);
+			}
+			graph.update();
+		} else {
+			pushMetrics(data.stats, data.time);
+			pushUpstreams(data.upstreams);
+		}
+
+	};
 });
\ No newline at end of file

modules/http/static/main.tpl

@@ -50,7 +50,6 @@
 			<div id="chart_container">
 				<div id="y_axis"></div>
 				<div id="chart"></div>
-				<div id="x_axis"></div>
 			</div>
 			<form id="legend_container">
 				<div id="legend"></div>