move source into src dir

src/classes/caching/memory_cache.js

@@ -0,0 +1,45 @@
+import { Readable } from 'stream';
+import { KeyTimeout } from './key_timeout.js';
+
+function streamToBuffer(stream) {
+  const chunks = [];
+  return new Promise((resolve, reject) => {
+    stream.on('data', (chunk) => chunks.push(Buffer.from(chunk)));
+    stream.on('error', (err) => reject(err));
+    stream.on('end', () => resolve(Buffer.concat(chunks)));
+  });
+}
+
+export class MemoryCache {
+  constructor(options = {}) {
+    this.ttl = options.ttl;
+    this.keyTimeout = new KeyTimeout();
+    this.cache = {};
+  }
+
+  get(key) {
+    const cachedValue = this.cache[key];
+    if (cachedValue) {
+      return {
+        bodyStream: Readable.from(cachedValue.bodyBuffer),
+        metaData: cachedValue.metaData,
+      };
+    }
+
+    return undefined;
+  }
+
+  remove(key) {
+    this.keyTimeout.clearTimeout(key);
+    delete this.cache[key];
+  }
+
+  async set(key, bodyStream, metaData) {
+    const bodyBuffer = await streamToBuffer(bodyStream);
+    this.cache[key] = { bodyBuffer, metaData };
+
+    if (typeof this.ttl === 'number') {
+      this.keyTimeout.updateTimeout(key, this.ttl, () => this.remove(key));
+    }
+  }
+}