feat: #8824, cache refactor (#8851)

* feat: #8824, cache refactor

ability to disable caches
ability to download contents of cache
refactor cache modules to remove duplicated code

* fix: remove duplicate hit/miss tracking

check cacheEnabled in getUncachedKeys

src/cacheCreate.js

@@ -0,0 +1,91 @@
+'use strict';
+
+module.exports = function (opts) {
+	const LRU = require('lru-cache');
+	const pubsub = require('./pubsub');
+
+	const cache = new LRU(opts);
+
+	cache.name = opts.name;
+	cache.hits = 0;
+	cache.misses = 0;
+	cache.enabled = opts.hasOwnProperty('enabled') ? opts.enabled : true;
+
+	const cacheSet = cache.set;
+	const cacheGet = cache.get;
+	const cacheDel = cache.del;
+	const cacheReset = cache.reset;
+
+	cache.set = function (key, value) {
+		if (!cache.enabled) {
+			return;
+		}
+		cacheSet.apply(cache, [key, value]);
+	};
+
+	cache.get = function (key) {
+		if (!cache.enabled) {
+			return undefined;
+		}
+		const data = cacheGet.apply(cache, [key]);
+		if (data === undefined) {
+			cache.misses += 1;
+		} else {
+			cache.hits += 1;
+		}
+		return data;
+	};
+
+	cache.del = function (keys) {
+		if (!Array.isArray(keys)) {
+			keys = [keys];
+		}
+		pubsub.publish(cache.name + ':cache:del', keys);
+		keys.forEach(key => cacheDel.apply(cache, [key]));
+	};
+
+	cache.reset = function () {
+		pubsub.publish(cache.name + ':cache:reset');
+		localReset();
+	};
+
+	function localReset() {
+		cacheReset.apply(cache);
+		cache.hits = 0;
+		cache.misses = 0;
+	}
+
+	pubsub.on(cache.name + ':cache:reset', function () {
+		localReset();
+	});
+
+	pubsub.on(cache.name + ':cache:del', function (keys) {
+		if (Array.isArray(keys)) {
+			keys.forEach(key => cacheDel.apply(cache, [key]));
+		}
+	});
+
+	cache.getUnCachedKeys = function (keys, cachedData) {
+		if (!cache.enabled) {
+			return keys;
+		}
+		let data;
+		let isCached;
+		const unCachedKeys = keys.filter(function (key) {
+			data = cache.get(key);
+			isCached = data !== undefined;
+			if (isCached) {
+				cachedData[key] = data;
+			}
+			return !isCached;
+		});
+
+		var hits = keys.length - unCachedKeys.length;
+		var misses = keys.length - hits;
+		cache.hits += hits;
+		cache.misses += misses;
+		return unCachedKeys;
+	};
+
+	return cache;
+};