feat: a simple LRUCache in frontend

superset-frontend/packages/superset-ui-core/src/utils/index.ts

@@ -26,6 +26,7 @@ export { default as makeSingleton } from './makeSingleton';
 export { default as promiseTimeout } from './promiseTimeout';
 export { default as logging } from './logging';
 export { default as removeDuplicates } from './removeDuplicates';
+export { lruCache } from './lruCache';
 export * from './featureFlags';
 export * from './random';
 export * from './typedMemo';

superset-frontend/packages/superset-ui-core/src/utils/lruCache.ts

@@ -0,0 +1,69 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+class LRUCache<T> {
+  private cache: Map<string, T>;
+
+  readonly capacity: number;
+
+  constructor(capacity: number) {
+    if (capacity < 1) {
+      throw new Error('The capacity in LRU must be greater than 0.');
+    }
+    this.capacity = capacity;
+    this.cache = new Map<string, T>();
+  }
+
+  public has(key: string): boolean {
+    return this.cache.has(key);
+  }
+
+  public get(key: string): T | undefined {
+    if (this.cache.has(key)) {
+      const tmp = this.cache.get(key) as T;
+      this.cache.delete(key);
+      this.cache.set(key, tmp);
+      return tmp;
+    }
+    return undefined;
+  }
+
+  public set(key: string, value: T) {
+    // Prevent runtime errors
+    if (typeof key !== 'string') {
+      throw new TypeError('The LRUCache key must be string.');
+    }
+    if (this.cache.size >= this.capacity) {
+      this.cache.delete(this.cache.keys().next().value);
+    }
+    this.cache.set(key, value);
+  }
+
+  public clear() {
+    this.cache.clear();
+  }
+
+  public get size() {
+    return this.cache.size;
+  }
+}
+
+export function lruCache<T>(capacity = 100) {
+  return new LRUCache<T>(capacity);
+}

superset-frontend/packages/superset-ui-core/test/utils/lruCache.test.ts

@@ -0,0 +1,57 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { lruCache } from '@superset-ui/core';
+
+test('initial LRU', () => {
+  expect(lruCache().capacity).toBe(100);
+  expect(lruCache(10).capacity).toBe(10);
+  expect(lruCache(10).size).toBe(0);
+  expect(() => lruCache(0)).toThrow(Error);
+});
+
+test('LRU operation', () => {
+  const cache = lruCache<string>(3);
+  cache.set('1', 'a');
+  cache.set('2', 'b');
+  cache.set('3', 'c');
+  cache.set('4', 'd');
+  expect(cache.size).toBe(3);
+  expect(cache.has('1')).toBeFalsy();
+  expect(cache.get('1')).toBeUndefined();
+  cache.get('2');
+  cache.set('5', 'e');
+  expect(cache.has('2')).toBeTruthy();
+  expect(cache.has('3')).toBeFalsy();
+  // @ts-ignore
+  expect(() => cache.set(0)).toThrow(TypeError);
+  cache.clear();
+  expect(cache.size).toBe(0);
+  expect(cache.capacity).toBe(3);
+});
+
+test('LRU handle null and undefined', () => {
+  const cache = lruCache();
+  cache.set('a', null);
+  cache.set('b', undefined);
+  expect(cache.has('a')).toBeTruthy();
+  expect(cache.has('b')).toBeTruthy();
+  expect(cache.get('a')).toBeNull();
+  expect(cache.get('b')).toBeUndefined();
+});