| import { strict as assert } from "node:assert"; |
| import { test } from "node:test"; |
| import { Semaphore } from "./semaphore.js"; |
|
|
| test("acquires up to the permit count without waiting, then queues", async () => { |
| const sem = new Semaphore(2); |
| await sem.acquire(); |
| await sem.acquire(); |
| assert.equal(sem.availablePermits, 0); |
|
|
| let third = "pending"; |
| const pending = sem.acquire().then(() => { |
| third = "acquired"; |
| }); |
| await Promise.resolve(); |
| assert.equal(third, "pending"); |
| assert.equal(sem.queueLength, 1); |
|
|
| sem.release(); |
| await pending; |
| assert.equal(third, "acquired"); |
| assert.equal(sem.queueLength, 0); |
| }); |
|
|
| test("releases hand permits to waiters in FIFO order", async () => { |
| const sem = new Semaphore(1); |
| await sem.acquire(); |
|
|
| const order: number[] = []; |
| const a = sem.acquire().then(() => order.push(1)); |
| const b = sem.acquire().then(() => order.push(2)); |
| await Promise.resolve(); |
| assert.equal(sem.queueLength, 2); |
|
|
| sem.release(); |
| await a; |
| sem.release(); |
| await b; |
| assert.deepEqual(order, [1, 2]); |
| }); |
|
|
| test("releasing with no waiters restores a permit", async () => { |
| const sem = new Semaphore(1); |
| await sem.acquire(); |
| assert.equal(sem.availablePermits, 0); |
| sem.release(); |
| assert.equal(sem.availablePermits, 1); |
| |
| await sem.acquire(); |
| assert.equal(sem.availablePermits, 0); |
| }); |
|
|
| test("a permit count of zero disables limiting (always immediate, never queues)", async () => { |
| const sem = new Semaphore(0); |
| await sem.acquire(); |
| await sem.acquire(); |
| await sem.acquire(); |
| assert.equal(sem.queueLength, 0); |
| sem.release(); |
| }); |
|
|
