@dhlx/rwlock-shared/dist/index.js

A simple implementation of a read-write lock with shared read

var l = Object.defineProperty;
var w = (i, t, s) => t in i ? l(i, t, { enumerable: !0, configurable: !0, writable: !0, value: s }) : i[t] = s;
var a = (i, t, s) => w(i, typeof t != "symbol" ? t + "" : t, s);
const n = (i) => new Promise((t) => setTimeout(t, i)), e = class e {
  constructor(t, s = {}) {
    a(this, "state");
    a(this, "timeout", 500);
    this.state = new Int32Array(t), this.timeout = s.timeout || this.timeout;
  }
  /** Acquire a read lock (async). Blocks if a writer is active or waiting. */
  async readLock() {
    for (; ; ) {
      const t = Atomics.load(this.state, e.WRITER), s = Atomics.load(this.state, e.WAITERS);
      if (t === 0 && s === 0) {
        Atomics.add(this.state, e.READERS, 1);
        return;
      }
      await Atomics.waitAsync(this.state, e.WRITER, 0, this.timeout).value, await n(0);
    }
  }
  /** Release a read lock. Wakes a waiting writer if this was the last reader. */
  readUnlock() {
    Atomics.sub(this.state, e.READERS, 1), Atomics.load(this.state, e.WAITERS) > 0 && Atomics.notify(this.state, e.READERS);
  }
  /** Acquire a write lock (async). Blocks until no readers or writers are active. */
  async writeLock() {
    for (Atomics.add(this.state, e.WAITERS, 1); ; ) {
      const t = Atomics.load(this.state, e.READERS);
      if (t === 0 && Atomics.compareExchange(this.state, e.WRITER, 0, 1) === 0)
        break;
      t > 0 ? await Atomics.waitAsync(
        this.state,
        e.READERS,
        0,
        this.timeout
      ).value : await Atomics.waitAsync(
        this.state,
        e.WRITER,
        0,
        this.timeout
      ).value, await n(0);
    }
    Atomics.sub(this.state, e.WAITERS, 1);
  }
  /** Release the write lock. Wakes the next waiter(s) based on priority. */
  writeUnlock() {
    Atomics.store(this.state, e.WRITER, 0), Atomics.load(this.state, e.WAITERS) > 0 ? Atomics.notify(this.state, e.WRITER, 1) : Atomics.notify(this.state, e.WRITER, Number.POSITIVE_INFINITY);
  }
};
// Index constants for clarity
a(e, "READERS", 0), a(e, "WRITER", 1), a(e, "WAITERS", 2);
let c = e;
class E {
  constructor(t, s) {
    a(this, "lock");
    a(this, "dataBuffer");
    a(this, "dataView");
    this.lock = new c(s), this.dataBuffer = t, this.dataView = new DataView(t);
  }
  // 安全读取数据
  async readData() {
    await this.lock.readLock();
    const t = this.deserialize();
    return this.lock.readUnlock(), t;
  }
  // 安全写入数据
  async writeData(t) {
    try {
      await this.lock.writeLock();
      const s = this.deserialize(), r = t(s);
      this.serialize(r);
    } finally {
      this.lock.writeUnlock();
    }
  }
  serialize(t) {
    const s = JSON.stringify(t), o = new TextEncoder().encode(s);
    this.dataView.setUint32(0, o.length), o.forEach((h, d) => this.dataView.setUint8(4 + d, h));
  }
  deserialize() {
    const t = this.dataView.getUint32(0), s = new Uint8Array(this.dataBuffer.slice(4, t + 4)), r = new Uint8Array(s), o = new TextDecoder();
    return o.decode(r) ? JSON.parse(o.decode(r) ?? "{}") : {};
  }
}
function u(i = Int32Array.BYTES_PER_ELEMENT * 3, t = 1024) {
  return {
    lockBuffer: new SharedArrayBuffer(i),
    dataBuffer: new SharedArrayBuffer(t)
  };
}
export {
  c as ReadWriteLock,
  E as SharedData,
  u as createSharedBuffers
};