64 lines
1.8 KiB
TypeScript
64 lines
1.8 KiB
TypeScript
/** @jest-environment node */
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describe('image-processing-limiter', () => {
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afterEach(() => {
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delete process.env.IMAGE_PROCESSING_MAX_CONCURRENT
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})
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test('并发为 2 时同时释放两个任务，名额仍先直接转交给既有等待者', async () => {
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jest.resetModules()
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process.env.IMAGE_PROCESSING_MAX_CONCURRENT = '2'
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const { withImageProcessingSlot } = await import('@/lib/image-processing-limiter')
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const releases: Array<() => void> = []
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const started: number[] = []
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let active = 0
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let peak = 0
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const runTask = (index: number) => withImageProcessingSlot(() => {
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active += 1
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peak = Math.max(peak, active)
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started.push(index)
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return new Promise<void>((resolve) => {
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releases[index] = () => {
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active -= 1
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resolve()
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}
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})
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})
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const firstTask = runTask(0)
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const secondTask = runTask(1)
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const firstQueuedTask = runTask(2)
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const secondQueuedTask = runTask(3)
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await new Promise<void>((resolve) => setImmediate(resolve))
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expect(started).toEqual([0, 1])
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releases[0]()
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releases[1]()
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// 两个 release continuation 已排入微任务后再发起新请求。旧实现会先把
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// active 降到 0，新请求 4 因而抢入，随后等待者 2、3 继续自增到 3。
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const lateTask = Promise.resolve().then(() => runTask(4))
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await new Promise<void>((resolve) => setImmediate(resolve))
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expect(started).toEqual([0, 1, 2, 3])
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expect(peak).toBe(2)
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releases[2]()
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releases[3]()
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await new Promise<void>((resolve) => setImmediate(resolve))
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expect(started).toEqual([0, 1, 2, 3, 4])
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releases[4]()
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await Promise.all([
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firstTask,
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secondTask,
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firstQueuedTask,
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secondQueuedTask,
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lateTask,
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])
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expect(peak).toBe(2)
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})
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})
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