@pengzhanbo/utils - v3.12.0
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    Class Semaphore

    A counting semaphore for async functions that manages available permits. Semaphores are mainly used to limit the number of concurrent async tasks.

    Each acquire operation takes a permit or waits until one is available. Each release operation adds a permit, potentially allowing a waiting task to proceed.

    The semaphore ensures fairness by maintaining a FIFO (First In, First Out) order for acquirers.

    异步函数使用的计数信号量，管理可用许可。 信号量主要用于限制并发异步任务的数量。

    每次 acquire 操作都会获取一个许可，或者等待直到有一个许可可用。 每次 release 操作都会增加一个许可，可能允许等待的任务继续执行。

    信号量通过维护获取者的 FIFO（先进先出）顺序来确保公平性。

    const sema = new Semaphore(2);

    async function task() {
      await sema.acquire();
      try {
        // This code can only be executed by two tasks at the same time
      } finally {
        sema.release();
      }
    }

    task();
    task();
    task(); // This task will wait until one of the previous tasks releases the semaphore.
    Index
    constructor
    capacity
    available
    acquire release tryAcquire

    • Creates an instance of Semaphore.

      创建一个信号量实例。

      Parameters

      • capacity: number

        允许的最大并发操作数。

      Returns Semaphore

      如果 capacity 不是正整数。

      const sema = new Semaphore(3); // Allows up to 3 concurrent operations.
    capacity: number

    The maximum number of concurrent operations allowed.

    允许的最大并发操作数。

    • Acquires a semaphore, blocking if necessary until one is available.

      获取一个信号量，必要时阻塞直到有一个可用。

      Returns Promise<void>

      const sema = new Semaphore(1);

      async function criticalSection() {
        await sema.acquire();
        try {
          // This code section cannot be executed simultaneously
        } finally {
          sema.release();
        }
      }

    • Releases a semaphore, allowing one more operation to proceed.

      释放一个信号量，允许另一个操作继续进行。

      Returns void

      const sema = new Semaphore(1);

      async function task() {
        await sema.acquire();
        try {
          // This code can only be executed by two tasks at the same time
        } finally {
          sema.release(); // Allows another waiting task to proceed.
        }
      }

    • Tries to acquire a permit without waiting.

      尝试立即获取一个许可，不等待。

      Returns (() => void) | undefined

      A function that releases the acquired permit, or undefined when no permit is available (in which case the caller should fall back to acquire). 获取成功时返回释放许可的函数；无可用许可时返回 undefined（调用方应回退到 acquire）。

      Unlike acquire, this method never queues and never allocates a Promise. 与 acquire 不同，此方法不会排队，也不会分配 Promise。

      const release = semaphore.tryAcquire()
      if (release) {
        try { ... } finally { release() }
      }

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