Adding Caching Adapter, allows caching of _Role and _User queries (fixes #168) (#1664)

* Adding Caching Adapter, allows caching of _Role and _User queries.

src/Controllers/CacheController.js

@@ -0,0 +1,75 @@
+import AdaptableController from './AdaptableController';
+import CacheAdapter        from '../Adapters/Cache/CacheAdapter';
+
+const KEY_SEPARATOR_CHAR = ':';
+
+function joinKeys(...keys) {
+  return keys.join(KEY_SEPARATOR_CHAR);
+}
+
+/**
+ * Prefix all calls to the cache via a prefix string, useful when grouping Cache by object type.
+ *
+ * eg "Role" or "Session"
+ */
+export class SubCache {
+  constructor(prefix, cacheController) {
+    this.prefix = prefix;
+    this.cache = cacheController;
+  }
+
+  get(key) {
+    let cacheKey = joinKeys(this.prefix, key);
+    return this.cache.get(cacheKey);
+  }
+
+  put(key, value, ttl) {
+    let cacheKey = joinKeys(this.prefix, key);
+    return this.cache.put(cacheKey, value, ttl);
+  }
+
+  del(key) {
+    let cacheKey = joinKeys(this.prefix, key);
+    return this.cache.del(cacheKey);
+  }
+
+  clear() {
+    return this.cache.clear();
+  }
+}
+
+
+export class CacheController extends AdaptableController {
+
+  constructor(adapter, appId, options = {}) {
+    super(adapter, appId, options);
+
+    this.role = new SubCache('role', this);
+    this.user = new SubCache('user', this);
+  }
+
+  get(key) {
+    let cacheKey = joinKeys(this.appId, key);
+    return this.adapter.get(cacheKey).then(null, () => Promise.resolve(null));
+  }
+
+  put(key, value, ttl) {
+    let cacheKey = joinKeys(this.appId, key);
+    return this.adapter.put(cacheKey, value, ttl);
+  }
+
+  del(key) {
+    let cacheKey = joinKeys(this.appId, key);
+    return this.adapter.del(cacheKey);
+  }
+
+  clear() {
+    return this.adapter.clear();
+  }
+
+  expectedAdapterType() {
+    return CacheAdapter;
+  }
+}
+
+export default CacheController;