Refactor events middleware.

The reason for refactoring was to accommodate
Multiseis / client sequence exports, which will be
served by this endpoint via a specific Content-Type.

In the process, the cache has been fixed and redesigned.

Related to #12.

lib/www/server/api/index.js

@@ -105,7 +105,7 @@ app.map({
 // 	},
 //
 	'/project/:project/event/': {
-		get: [ mw.event.list ],
+		get: [ mw.event.cache.get, mw.event.list, mw.event.cache.save ],
 		post: [ mw.event.post ],
 		put: [ mw.event.put ],
 		delete: [ mw.event.delete ],

lib/www/server/api/middleware/event/cache.js

@@ -0,0 +1,83 @@
+const { listen } = require('../../../ws/db');
+
+// Event responses take a long time as we are querying a view
+// which is the union of other views and non-optimised tables,
+// so to speed things up a bit for the user we cache the
+// results here.
+// We do this by indexing each result by its ETag value and
+// storing the ID of the project it belongs to as well as the
+// timestamp of the request. If the events for a project are
+// modified in any way (addition/deletion/change) we immediately
+// invalidate all cached responses for that project, else we
+// delete them when they're older than maxAge (plus a delay).
+// When the user sends a request with an ETag, we search for
+// the ETag in our cache and return that, if present, instead
+// of hitting the database.
+
+const cache = {};
+const maxAge = 90*60*1000; // 1.5 hours
+setInterval(() => {
+	const now = Date.now();
+	for (const key in cache) {
+		const value = cache[key];
+		if ((now - value.tstamp) > maxAge) {
+// 			console.log("CLEARING", key);
+			delete cache[key];
+		}
+	}
+}, 5*60*1000); // Run every five minutes
+
+listen(["event"], (data) => {
+	for (const key in cache) {
+		const value = cache[key];
+		if (value.pid == data.payload.pid) {
+			delete cache[key];
+		}
+	}
+});
+
+function get (req, res, next) {
+	try {
+// 		console.log(cache);
+		const etag = req.get('if-none-match');
+// 		console.log("ETag", etag);
+		if (etag && cache[etag]) {
+// 			console.log("In cache");
+			if (cache[etag].headers) {
+				for (const header in cache[etag].headers) {
+					const value = cache[etag].headers[header];
+					if (header && value) {
+						res.set(header, value);
+					}
+				}
+			}
+			// 304s have no body
+			// https://tools.ietf.org/html/rfc7232#section-4.1
+			res.status(304).send();
+			next('route');
+		} else {
+// 			console.log("Not in cache");
+			next();
+		}
+	} catch (err) {
+		next(err);
+	}
+}
+
+function save (req, res, next) {
+	const etag = res.getHeader("etag");
+	if (etag) {
+		cache[etag] = {
+			headers: {
+				"Content-Type": res.getHeader("content-type") || "application/json"
+			},
+			pid: req.params.project,
+			tstamp: Date.now()
+		}
+// 		console.log("CACHE", cache);
+	}
+	
+	next();
+}
+
+module.exports = { get, save };

lib/www/server/api/middleware/event/index.js

@@ -4,5 +4,6 @@ module.exports = {
 	get: require('./get'),
 	post: require('./post'),
 	put: require('./put'),
-	delete: require('./delete')
+	delete: require('./delete'),
+	cache: require('./cache')
 }

lib/www/server/api/middleware/event/list.js

@@ -1,44 +0,0 @@
-
-const { event } = require('../../../lib/db');
-const { listen } = require('../../../ws/db');
-
-const cache = {};
-const maxAge = 1.5*60*1000;
-setInterval(() => {
-	const now = Date.now();
-	for (const key in cache) {
-		const value = cache[key];
-		if ((now - value.tstamp) > maxAge) {
-// 			console.log("CLEARING", key);
-			delete cache[key];
-		}
-	}
-}, 90*60*1000);
-
-listen(["event"], (data) => {
-	for (const key in cache) {
-		const value = cache[key];
-		if (value.pid == data.payload.pid) {
-			delete cache[key];
-		}
-	}
-});
-
-module.exports = async function (req, res, next) {
-
-	try {
-// 		console.log(cache);
-		const etag = req.get('if-none-match');
-		if (etag && cache[etag]) {
-			res.status(304).send(cache[etag].response);
-		} else {
-			const response = await event.list(req.params.project, req.query);
-			res.status(200).send(response);
-			cache[res.getHeaders()["etag"]] = {response, pid: req.params.project, tstamp: Date.now()}
-		}
-		next();
-	} catch (err) {
-		next(err);
-	}
-
-};

lib/www/server/api/middleware/event/list/geojson.js

@@ -0,0 +1,23 @@
+
+const { event } = require('../../../../lib/db');
+
+const geojson = async function (req, res, next) {
+	try {
+		const events = await event.list(req.params.project, req.query);
+		const response = events.filter(event => event.geometry).map(event => {
+			const feature = {
+				type: "Feature",
+				geometry: event.geometry,
+				properties: event
+			};
+			delete feature.properties.geometry;
+			return feature;
+		});
+		res.status(200).send(response);
+		next();
+	} catch (err) {
+		next(err);
+	}
+}
+
+module.exports = geojson;

lib/www/server/api/middleware/event/list/index.js

@@ -0,0 +1,25 @@
+const json = require('./json');
+const geojson = require('./geojson');
+// const seis = require('./seis');
+
+module.exports = async function (req, res, next) {
+	try {
+		const handlers = {
+			"application/json": json,
+			"application/geo+json": geojson,
+// 			"application/vnd.seis+json": seis
+		};
+		
+		const mimetype = req.accepts(Object.keys(handlers));
+		
+		if (mimetype) {
+			res.set("Content-Type", mimetype);
+			await handlers[mimetype](req, res, next);
+		} else {
+			res.status(406).send();
+			next();
+		}
+	} catch (err) {
+		next(err);
+	}
+}

lib/www/server/api/middleware/event/list/json.js

@@ -0,0 +1,14 @@
+
+const { event } = require('../../../../lib/db');
+
+const json = async function (req, res, next) {
+	try {
+		const response = await event.list(req.params.project, req.query);
+		res.status(200).send(response);
+		next();
+	} catch (err) {
+		next(err);
+	}
+};
+
+module.exports = json;