luci-base: luci.js: introduce generic LuCI.Poll

Introduce a new LuCI.Poll class which is able to repeat any
promise based function and not strictly tied to HTTP request
semantics.

Also rework LuCI.Request.Poll and XHR.Poll as well as
LuCI.start(), LuCI.stop(), LuCI.halt() etc. to redirect to
the new api.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

modules/luci-base/htdocs/luci-static/resources/luci.js

@@ -331,49 +331,94 @@
 			return (this.interceptors.length < oldlen);
 		},
 
-		poll: Class.singleton({
+		poll: {
-			__name__: 'LuCI.Request.Poll',
-
-			queue: [],
-
 			add: function(interval, url, options, callback) {
 				if (isNaN(interval) || interval <= 0)
 					throw new TypeError('Invalid poll interval');
 
+				var ival = interval >>> 0,
+				    opts = Object.assign({}, options, { timeout: ival * 1000 - 5 });
+
+				return Poll.add(function() {
+					return Request.request(url, options).then(function(res) {
+						if (!Poll.active())
+							return;
+
+						try {
+							callback(res, res.json(), res.duration);
+						}
+						catch (err) {
+							callback(res, null, res.duration);
+						}
+					});
+				}, ival);
+			},
+
+			remove: function(entry) { return Poll.remove(entry) },
+			start: function() { return Poll.start() },
+			stop: function() { return Poll.stop() },
+			active: function() { return Poll.active() }
+		}
+	});
+
+	var Poll = Class.singleton({
+		__name__: 'LuCI.Poll',
+
+		queue: [],
+
+		add: function(fn, interval) {
+			if (interval == null || interval <= 0)
+				interval = window.L ? window.L.env.pollinterval : null;
+
+			if (isNaN(interval) || typeof(fn) != 'function')
+				throw new TypeError('Invalid argument to LuCI.Poll.add()');
+
+			for (var i = 0; i < this.queue.length; i++)
+				if (this.queue[i].fn === fn)
+					return false;
+
 			var e = {
-					interval: interval,
+				r: true,
-					url: url,
+				i: interval >>> 0,
-					options: options,
+				fn: fn
-					callback: callback
 			};
 
 			this.queue.push(e);
-				return e;
+
+			if (this.tick != null && !this.active())
+				this.start();
+
+			return true;
 		},
 
 		remove: function(entry) {
-				var oldlen = this.queue.length, i = oldlen;
+			if (typeof(fn) != 'function')
+				throw new TypeError('Invalid argument to LuCI.Poll.remove()');
 
-				while (i--)
+			var len = this.queue.length;
-					if (this.queue[i] === entry) {
-						delete this.queue[i].running;
-						this.queue.splice(i, 1);
-					}
 
-				if (!this.queue.length)
+			for (var i = len; i > 0; i--)
-					this.stop();
+				if (this.queue[i-1].fn === fn)
+					this.queue.splice(i-1, 1);
 
-				return (this.queue.length < oldlen);
+			if (!this.queue.length && this.stop())
+				this.tick = 0;
+
+			return (this.queue.length != len);
 		},
 
 		start: function() {
-				if (!this.queue.length || this.active())
+			if (this.active())
 				return false;
 
 			this.tick = 0;
+
+			if (this.queue.length) {
 				this.timer = window.setInterval(this.step, 1000);
 				this.step();
 				document.dispatchEvent(new CustomEvent('poll-start'));
+			}
+
 			return true;
 		},
 
@@ -389,39 +434,24 @@
 		},
 
 		step: function() {
-				Request.poll.queue.forEach(function(e) {
+			for (var i = 0, e = null; (e = Poll.queue[i]) != null; i++) {
-					if ((Request.poll.tick % e.interval) != 0)
+				if ((Poll.tick % e.i) != 0)
-						return;
+					continue;
 
-					if (e.running)
+				if (!e.r)
-						return;
+					continue;
 
-					var opts = Object.assign({}, e.options,
+				e.r = false;
-						{ timeout: e.interval * 1000 - 5 });
 
-					e.running = true;
+				Promise.resolve(e.fn()).finally((function() { this.r = true }).bind(e));
-					Request.request(e.url, opts)
-						.then(function(res) {
-							if (!e.running || !Request.poll.active())
-								return;
-
-							try {
-								e.callback(res, res.json(), res.duration);
 			}
-							catch (err) {
-								e.callback(res, null, res.duration);
-							}
-						})
-						.finally(function() { delete e.running });
-				});
 
-				Request.poll.tick = (Request.poll.tick + 1) % Math.pow(2, 32);
+			Poll.tick = (Poll.tick + 1) % Math.pow(2, 32);
 		},
 
 		active: function() {
 			return (this.timer != null);
 		}
-		})
 	});
 
 
@@ -635,7 +665,7 @@
 				if (res.status != 403 || res.headers.get('X-LuCI-Login-Required') != 'yes')
 					return;
 
-				Request.poll.stop();
+				Poll.stop();
 
 				L.ui.showModal(_('Session expired'), [
 					E('div', { class: 'alert-message warning' },
@@ -654,7 +684,8 @@
 			});
 
 			originalCBIInit();
-			Request.poll.start();
+
+			Poll.start();
 
 			document.dispatchEvent(new CustomEvent('luci-loaded'));
 		},
@@ -722,9 +753,9 @@
 					});
 		},
 
-		stop: function(entry) { return Request.poll.remove(entry) },
+		stop: function(entry) { return Poll.remove(entry) },
-		halt: function() { return Request.poll.stop() },
+		halt: function() { return Poll.stop() },
-		run: function() { return Request.poll.start() },
+		run: function() { return Poll.start() },
 
 		/* DOM manipulation */
 		dom: Class.singleton({
@@ -965,6 +996,7 @@
 			}
 		}),
 
+		Poll: Poll,
 		Class: Class,
 		Request: Request,