NMS: Prototype of nms-data seriously updated

I think it's ready now...

1 files changed, 134 insertions, 53 deletions

diff --git a/web/nms.gathering.org/js/nms-data.js b/web/nms.gathering.org/js/nms-data.js
index 4dda8e4..5f5a2b4 100644
--- a/web/nms.gathering.org/js/nms-data.js
+++ b/web/nms.gathering.org/js/nms-data.js
@@ -11,6 +11,22 @@
 
 
 /*
+ * This will obviously be moved
+ */
+var nmsCore = nmsCore || {
+	stats: {
+		assertErrors:0
+	}
+}
+
+nmsCore.assert = function(cb) {
+	if (!cb) {
+		nmsCore.stats.assertErrors++;
+		throw "Assertion failed";
+	}
+}
+
+/*
  * This file/module/whatever is an attempt to gather all data collection in
  * one place.
  *
@@ -21,7 +37,11 @@
  * and callbacks and whatnot, instead of all the custom stuff that we
  * started out with.
  *
- * Public interfaces:
+ * Sources are identified by a name, which is then available in
+ * nmsData[name] in full. A copy of the previous data set is kept in
+ * nmsData.old[name]. You can use getNow / setNow() to append a 'now='
+ * string.
+ *
  * nmsData.data[name] - actual data
  * nmsData.registerSource() - add a source, will be polled periodicall
  * nmsData.updateSource() - issue a one-off update, outside of whatever
@@ -30,48 +50,107 @@
 
 
 var nmsData = nmsData || {
-	data: {}, // Actual data
-	sources: {},
-
-	// Tracks metdata (hashes/timestamps)
-	poller: {
-		hashes:{}, 
-		time:{}
-	},
-	// setInterval handlers (and more?)
-	pollers: {
-
-	},
+	old: {}, // Single copy of previous data. Automatically populated.
 	stats: {
 		identicalFetches:0,
 		outstandingAjaxRequests:0,
 		ajaxOverflow:0,
+		pollClearsEmpty:0,
 		pollClears:0,
-		pollSets:0
-	}
+		pollSets:0,
+		newSource:0,
+		oldSource:0
+	},
+	/*
+	 * The last time stamp of any data received, regardless of source.
+	 *
+	 * Used as a fallback for blank now, but can also be used to check
+	 * "freshness", I suppose.
+	 */
+	_last: undefined,
+	_now: undefined,
+
+	/*
+	 * These are provided so we can introduce error checking when we
+	 * have time.
+	 * 
+	 * now() represents the data, not the intent. That means that if
+	 * you want to check if we are traveling in time you should not
+	 * check nmsData.now. That will always return a value as long as
+	 * we've had a single piece of data.
+	 */
+	get now() { return this._now || this._last; },
+	set now(val) {
+		if (val == undefined) {
+			this._now = undefined;
+		}
+		// FIXME: Check if now is valid syntax.
+		this._now = now;
+	},
+	/*
+	 * List of sources, name, handler, etc
+	 */
+	_sources: {},
+
+	/*
+	 * Maximum number of AJAX requests in transit before we start
+	 * skipping updates.
+	 */
+	_ajaxThreshold: 5
 };
 
+
+nmsData._dropData = function (name) {
+	nmsCore.assert(name);
+	nmsCore.assert(this[name]);
+	delete this[name];
+	delete this.old[name];
+}
+
+nmsData.removeSource = function (name) {
+	if (this._sources[name] == undefined) {
+		this.stats.pollClearsEmpty++;
+		return true;
+	}
+	if (this._sources[name]['handle']) {
+		this.stats.pollClears++;
+		clearInterval(this._sources[name]['handle']);
+	}
+	delete this._sources[name];
+}
+
 /*
  * Register a source.
  *
- * name: "Local" name. Maps to nmsData.data[name]
- * remotename: The primary attribute to get from the remote source.
+ * name: "Local" name. Maps to nmsData[name]
  * target: URL of the source
  * cb: Optional callback
  * cbdata: Optional callback data
  *
- * Update frequency will (eventually) be handled by parsing max-age from
- * the source. Right now it's hardcoded.
+ * This can be called multiple times to add multiple handlers. There's no
+ * guarantee that they will be run in order, but right now they do.
+ *
+ * Update frequency _might_ be adaptive eventually, but since we only
+ * execute callbacks on change and backend sends cache headers, the browser
+ * will not issue actual HTTP requests.
  *
  * FIXME: Should be unified with nmsTimers() somehow.
  */
-nmsData.registerSource = function(name, remotename, target, cb, cbdata) {
-	if(this.pollers[name]) {
-		clearInterval(this.pollers[name]);
-		this.stats.pollClears++;
+nmsData.registerSource = function(name, target, cb, cbdata) {
+	var cbob = {
+		name: name,
+		cb: cb,
+		cbdata: cbdata
+	};
+	if (this._sources[name] == undefined) {
+		this._sources[name] = { target: target, cbs: [] };
+		this._sources[name]['handle'] = setInterval(function(){nmsData.updateSource(name)}, 1000);
+		this.stats.newSource++;
+	} else {
+		this.stats.oldSource++;
 	}
-	this.sources[name] = { remotename: remotename, target: target, cb: cb, cbdata: cbdata };
-	this.pollers[name] = setInterval(function(){nmsData.updateSource(name)}, 1000);
+	this._sources[name].cbs.push(cbob);
+
 	this.stats.pollSets++;
 }
 
@@ -83,52 +162,55 @@ nmsData.registerSource = function(name, remotename, target, cb, cbdata) {
  * after a comment is posted).
  */
 nmsData.updateSource = function(name) {
-	nmsData.genericUpdater(name,
-		this.sources[name].remotename,
-		this.sources[name].target,
-		this.sources[name].cb,
-		this.sources[name].cbdata);
+	this._genericUpdater(name);
+}
+
+/*
+ * Reset a source, deleting all data, including old.
+ *
+ * Useful if traveling in time, for example.
+ */
+nmsData.resetSource = function(name) {
+	this[name] = {};
+	this.old[name] = {};
+	this.updateSource(name);
 }
 
 /*
- * Updates nmsData.data[name] with data fetched from remote target in
- * variable "remotename". If a callback is provided, it is called with
- * argument meh.
+ * Updates nmsData[name] and nmsData.old[name], issuing any callbacks where
+ * relevant.
  *
- * This also populates nms.pollers[name] with the server-provided hash.
- * Only if a change is detected is the callback issued.
+ * Do not use this directly. Use updateSource().
  *
- * Used by registerSource.
  */
-nmsData.genericUpdater = function(name, remotename, target, cb, meh) {
-	if (this.stats.outstandingAjaxRequests > 5) {
+nmsData._genericUpdater = function(name) {
+	if (this.stats.outstandingAjaxRequests++ > this._ajaxThreshold) {
+		this.stats.outstandingAjaxRequests--;
 		this.stats.ajaxOverflow++;
 		return;
 	}
 	this.stats.outstandingAjaxRequests++;
 	var now = "";
-	/*
-	if (nms.now != false)
-		now = "now=" + nms.now;
+	if (this._now != undefined)
+		now = "now=" + this._now;
 	if (now != "") {
-		if (target.match("\\?"))
+		if (this._sources[name].target.match("\\?"))
 			now = "&" + now;
 		else
 			now = "?" + now;
 	}
-	*/
 	$.ajax({
 		type: "GET",
-		url: target + now,
-		dataType: "text",
+		url: this._sources[name].target + now,
+		dataType: "json",
 		success: function (data, textStatus, jqXHR) {
-			var  indata = JSON.parse(data);
-			if (nmsData.poller.hashes[name] != indata['hash']) {
-				nmsData.data[name] = indata[remotename];
-				nmsData.poller.hashes[name] = indata['hash'];
-				nmsData.poller.time[name] = indata['time'];
-				if (cb != undefined) {
-					cb(meh);
+			nmsData._last = data['time'];
+			if (nmsData[name] == undefined ||  nmsData[name]['hash'] != data['hash']) {
+				nmsData.old[name] = nmsData[name];
+				nmsData[name] = data;
+				for (var i in nmsData._sources[name].cbs) {
+					var tmp = nmsData._sources[name].cbs[i];
+					tmp.cb(tmp.cbdata);
 				}
 			} else {
 				nmsData.stats.identicalFetches++;
@@ -136,7 +218,6 @@ nmsData.genericUpdater = function(name, remotename, target, cb, meh) {
 		},
 		complete: function(jqXHR, textStatus) {
 			nmsData.stats.outstandingAjaxRequests--;
-			//updateAjaxInfo();
 		}
 	});
 };