참고소스 수정본

참고/playwright-main/packages/isomorphic/semaphore.ts

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+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * 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.
+ */
+
+import { ManualPromise } from './manualPromise';
+
+export class Semaphore {
+  private _max: number;
+  private _acquired = 0;
+  private _queue: ManualPromise[] = [];
+
+  constructor(max: number) {
+    this._max = max;
+  }
+
+  setMax(max: number) {
+    this._max = max;
+  }
+
+  acquire(): Promise<void> {
+    const lock = new ManualPromise();
+    this._queue.push(lock);
+    this._flush();
+    return lock;
+  }
+
+  release() {
+    --this._acquired;
+    this._flush();
+  }
+
+  private _flush() {
+    while (this._acquired < this._max && this._queue.length) {
+      ++this._acquired;
+      this._queue.shift()!.resolve();
+    }
+  }
+}