Method writeAsync

lib/internal/streams/iter/push.js:193–233

* Write chunks asynchronously. * If signal is provided, a write blocked on backpressure will reject * immediately when the signal fires. The cancelled write is removed from * pendingWrites so it does not occupy a slot. The queue itself is NOT put * into an error state - this is per-opera

(chunks, signal)

   * @returns {Promise<void>}
   */
  async writeAsync(chunks, signal) {
    // Check writer state before signal (spec order: state, then signal)
    if (this.#writerState === 'closed') {
      throw new ERR_INVALID_STATE.TypeError('Writer is closed');
    }
    if (this.#writerState === 'closing') {
      throw new ERR_INVALID_STATE.TypeError('Writer is closing');
    }
    if (this.#writerState === 'errored') {
      throw this.#error;
    }
    if (this.#consumerState !== 'active') {
      throw this.#consumerState === 'thrown' && this.#error ?
        this.#error :
        new ERR_INVALID_STATE.TypeError('Stream closed by consumer');
    }

    // Check for pre-aborted signal (after state checks per spec)
    signal?.throwIfAborted();

    // Try sync first
    if (this.writeSync(chunks)) {
      return;
    }

    // Buffer is full
    switch (this.#backpressure) {
      case 'strict':
        if (this.#pendingWrites.length >= this.#highWaterMark) {
          throw new ERR_INVALID_STATE.RangeError(
            'Backpressure violation: too many pending writes. ' +
            'Await each write() call to respect backpressure.');
        }
        return this.#createPendingWrite(chunks, signal);
      case 'block':
        return this.#createPendingWrite(chunks, signal);
      default:
        throw new ERR_INVALID_STATE(
          'Unexpected: writeSync should have handled non-strict policy');
    }
  }

  /**
   * Create a pending write promise, optionally racing against a signal.