add hw2

node_modules/chromium-bidi/lib/cjs/utils/Mutex.js

@@ -0,0 +1,68 @@
+"use strict";
+/**
+ * Copyright 2023 Google LLC.
+ * Copyright (c) Microsoft Corporation.
+ * Copyright 2022 The Chromium Authors.
+ *
+ * Licensed 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.
+ */
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.Mutex = void 0;
+/**
+ * Use Mutex class to coordinate local concurrent operations.
+ * Once `acquire` promise resolves, you hold the lock and must
+ * call `release` function returned by `acquire` to release the
+ * lock. Failing to `release` the lock may lead to deadlocks.
+ */
+class Mutex {
+    #locked = false;
+    #acquirers = [];
+    // This is FIFO.
+    acquire() {
+        const state = { resolved: false };
+        if (this.#locked) {
+            return new Promise((resolve) => {
+                this.#acquirers.push(() => resolve(this.#release.bind(this, state)));
+            });
+        }
+        this.#locked = true;
+        return Promise.resolve(this.#release.bind(this, state));
+    }
+    #release(state) {
+        if (state.resolved) {
+            throw new Error('Cannot release more than once.');
+        }
+        state.resolved = true;
+        const resolve = this.#acquirers.shift();
+        if (!resolve) {
+            this.#locked = false;
+            return;
+        }
+        resolve();
+    }
+    async run(action) {
+        const release = await this.acquire();
+        try {
+            // Note we need to await here because we want the await to release AFTER
+            // that await happens. Returning action() will trigger the release
+            // immediately which is counter to what we want.
+            const result = await action();
+            return result;
+        }
+        finally {
+            release();
+        }
+    }
+}
+exports.Mutex = Mutex;
+//# sourceMappingURL=Mutex.js.map