Files
orca/src/shared/ws-outbound-backpressure-queue.test.ts
T

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TypeScript

import { describe, expect, it, vi } from 'vitest'
import { createWsOutboundBackpressureQueue } from './ws-outbound-backpressure-queue'
// Deterministic harness: bufferedAmount and the drain timer are both injected,
// so no wall-clock races. `runTimers` fires the single parked drain callback.
function createHarness(overrides?: {
softCapBytes?: number
maxQueuedBytes?: number
maxQueuedFrames?: number
maxDrainFramesPerTurn?: number
writable?: boolean
parkAfterSend?: boolean
throwOnSend?: boolean
}) {
const sent: string[] = []
let bufferedAmount = 0
let writable = overrides?.writable ?? true
const overflow = vi.fn()
let pendingTimer: (() => void) | null = null
let pendingTimerDelay: number | null = null
const softCapBytes = overrides?.softCapBytes ?? 100
const queue = createWsOutboundBackpressureQueue<string>({
send: (frame) => {
sent.push(frame)
if (overrides?.throwOnSend) {
throw new Error('send failed')
}
if (overrides?.parkAfterSend) {
bufferedAmount = softCapBytes + 1
}
},
byteLengthOf: (frame) => frame.length,
getBufferedAmount: () => bufferedAmount,
isWritable: () => writable,
onOverflow: overflow,
softCapBytes,
maxQueuedBytes: overrides?.maxQueuedBytes ?? 1000,
maxQueuedFrames: overrides?.maxQueuedFrames,
maxDrainFramesPerTurn: overrides?.maxDrainFramesPerTurn,
drainPollMs: 10,
setTimer: (cb, delay) => {
pendingTimer = cb
pendingTimerDelay = delay
return 1 as unknown as ReturnType<typeof setTimeout>
},
clearTimer: () => {
pendingTimer = null
pendingTimerDelay = null
}
})
return {
queue,
sent,
overflow,
setBuffered: (value: number) => {
bufferedAmount = value
},
setWritable: (value: boolean) => {
writable = value
},
runTimer: () => {
const cb = pendingTimer
pendingTimer = null
pendingTimerDelay = null
cb?.()
},
hasTimer: () => pendingTimer !== null,
timerDelay: () => pendingTimerDelay
}
}
describe('ws outbound backpressure queue', () => {
it('sends straight through while under the soft cap', () => {
const h = createHarness()
h.queue.enqueue('a')
h.queue.enqueue('b')
expect(h.sent).toEqual(['a', 'b'])
expect(h.hasTimer()).toBe(false)
})
it('turns an immediate send exception into one overflow signal', () => {
const h = createHarness({ throwOnSend: true })
expect(() => h.queue.enqueue('frame')).not.toThrow()
expect(h.queue.enqueue('later')).toBe(false)
expect(h.sent).toEqual(['frame'])
expect(h.overflow).toHaveBeenCalledOnce()
expect(h.queue.evidence()).toEqual({ queuedBytes: 0, queuedFrames: 0, storageSlots: 0 })
expect(h.hasTimer()).toBe(false)
})
it('applies prospective admission to a direct-send frame', () => {
const sent = vi.fn()
const canSend = vi.fn().mockReturnValueOnce(false).mockReturnValue(true)
let pendingTimer: (() => void) | null = null
const queue = createWsOutboundBackpressureQueue<string>({
send: sent,
byteLengthOf: (frame) => frame.length,
getBufferedAmount: () => 0,
isWritable: () => true,
canSend,
onOverflow: vi.fn(),
setTimer: (callback) => {
pendingTimer = callback
return 1 as unknown as ReturnType<typeof setTimeout>
},
clearTimer: () => {
pendingTimer = null
}
})
expect(queue.enqueue('frame')).toBe(true)
expect(canSend).toHaveBeenCalledWith(5, false)
expect(sent).not.toHaveBeenCalled()
expect(queue.queuedBytes()).toBe(5)
const scheduled = pendingTimer as (() => void) | null
scheduled?.()
expect(canSend).toHaveBeenLastCalledWith(5, true)
expect(sent).toHaveBeenCalledWith('frame')
queue.dispose()
})
it('yields after a configured drain quantum while preserving FIFO order', () => {
const h = createHarness({ maxDrainFramesPerTurn: 2 })
h.setBuffered(101)
h.queue.enqueue('a')
h.queue.enqueue('b')
h.queue.enqueue('c')
h.setBuffered(0)
h.runTimer()
expect(h.sent).toEqual(['a', 'b'])
expect(h.hasTimer()).toBe(true)
expect(h.timerDelay()).toBe(0)
h.runTimer()
expect(h.sent).toEqual(['a', 'b', 'c'])
expect(h.hasTimer()).toBe(false)
})
it('rejects an oversized frame before the direct-send fast path', () => {
const send = vi.fn()
const overflow = vi.fn()
const queue = createWsOutboundBackpressureQueue<string>({
send,
byteLengthOf: (frame) => frame.length,
getBufferedAmount: () => 0,
isWritable: () => true,
onOverflow: overflow,
maxFrameBytes: 4
})
expect(queue.enqueue('12345')).toBe(false)
expect(send).not.toHaveBeenCalled()
expect(overflow).toHaveBeenCalledOnce()
})
it('parks frames in order while over the cap and drains on recovery without loss', () => {
const h = createHarness({ softCapBytes: 100 })
h.setBuffered(200) // over cap
h.queue.enqueue('one')
h.queue.enqueue('two')
h.queue.enqueue('three')
// Nothing sent yet; all held in order.
expect(h.sent).toEqual([])
expect(h.queue.queuedBytes()).toBe('one'.length + 'two'.length + 'three'.length)
expect(h.timerDelay()).toBe(10)
// Link recovers; the drain timer flushes everything in FIFO order.
h.setBuffered(0)
h.runTimer()
expect(h.sent).toEqual(['one', 'two', 'three'])
expect(h.queue.queuedBytes()).toBe(0)
})
it('drops a retained backlog and signals once when a drain send throws', () => {
const h = createHarness({ softCapBytes: 10, throwOnSend: true })
h.setBuffered(100)
const first = h.queue.enqueueCancelable('one')
h.queue.enqueue('two')
h.setBuffered(0)
expect(() => h.runTimer()).not.toThrow()
expect(h.queue.enqueue('later')).toBe(false)
expect(h.sent).toEqual(['one'])
expect(h.overflow).toHaveBeenCalledOnce()
expect(h.queue.evidence()).toEqual({ queuedBytes: 0, queuedFrames: 0, storageSlots: 0 })
expect(first.cancel()).toBe(false)
expect(h.hasTimer()).toBe(false)
})
it('keeps ordering when a frame arrives while a backlog is parked', () => {
const h = createHarness({ softCapBytes: 100 })
h.setBuffered(200)
h.queue.enqueue('first')
h.setBuffered(0)
// Even though the wire is now clear, an existing backlog means the new
// frame must queue behind it, not jump the line.
h.queue.enqueue('second')
expect(h.sent).toEqual([])
h.runTimer()
expect(h.sent).toEqual(['first', 'second'])
})
it('cancels a parked frame and releases its queue capacity before drain', () => {
const h = createHarness({ softCapBytes: 10, maxQueuedBytes: 8 })
h.setBuffered(100)
const cancelled = h.queue.enqueueCancelable('first')
expect(cancelled).toMatchObject({ accepted: true, queued: true })
expect(cancelled.cancel()).toBe(true)
expect(cancelled.cancel()).toBe(false)
expect(h.queue.evidence()).toMatchObject({ queuedBytes: 0, queuedFrames: 0 })
h.queue.enqueue('12345678')
h.setBuffered(0)
h.runTimer()
expect(h.sent).toEqual(['12345678'])
})
it('cannot cancel a frame after it has reached the wire', () => {
const h = createHarness()
const direct = h.queue.enqueueCancelable('direct')
expect(direct).toMatchObject({ accepted: true, queued: false })
expect(direct.cancel()).toBe(false)
expect(h.sent).toEqual(['direct'])
})
it('does not retain sent frame slots while a steady backlog keeps the queue busy', () => {
const h = createHarness({ softCapBytes: 10, parkAfterSend: true })
h.setBuffered(100)
h.queue.enqueue('frame-0')
h.queue.enqueue('frame-1')
for (let index = 2; index < 256; index += 1) {
h.setBuffered(0)
h.runTimer()
h.queue.enqueue(`frame-${index}`)
expect(h.queue.evidence().storageSlots).toBeLessThanOrEqual(66)
}
expect(h.sent).toHaveLength(254)
expect(h.queue.evidence()).toMatchObject({ queuedFrames: 2 })
})
it('releases aggregate queue claims on drain, disposal, and denied admission', () => {
let claimedBytes = 0
let denyClaims = false
const overflow = vi.fn()
let bufferedAmount = 100
let pendingTimer: (() => void) | null = null
const sent: string[] = []
const queue = createWsOutboundBackpressureQueue<string>({
send: (frame) => sent.push(frame),
byteLengthOf: (frame) => frame.length,
getBufferedAmount: () => bufferedAmount,
isWritable: () => true,
onOverflow: overflow,
softCapBytes: 10,
setTimer: (callback) => {
pendingTimer = callback
return 1 as unknown as ReturnType<typeof setTimeout>
},
clearTimer: () => {
pendingTimer = null
},
claimQueuedBytes: (bytes) => {
if (denyClaims) {
return null
}
claimedBytes += bytes
return () => {
claimedBytes -= bytes
}
}
})
queue.enqueue('one')
expect(claimedBytes).toBe(3)
bufferedAmount = 0
const runTimer = (): void => {
const callback = pendingTimer
pendingTimer = null
callback?.()
}
runTimer()
expect(sent).toEqual(['one'])
expect(claimedBytes).toBe(0)
bufferedAmount = 100
queue.enqueue('two')
expect(claimedBytes).toBe(3)
denyClaims = true
queue.enqueue('denied')
expect(overflow).toHaveBeenCalledOnce()
expect(claimedBytes).toBe(0)
queue.dispose()
expect(claimedBytes).toBe(0)
})
it('signals overflow (and drops backlog) when the hard cap is exceeded', () => {
const h = createHarness({ softCapBytes: 10, maxQueuedBytes: 8 })
h.setBuffered(100) // over soft cap: everything queues
h.queue.enqueue('12345') // 5 bytes queued
expect(h.overflow).not.toHaveBeenCalled()
h.queue.enqueue('67890') // 10 bytes total > 8 -> overflow
expect(h.overflow).toHaveBeenCalledTimes(1)
// After overflow the queue is inert: no sends, no further overflow calls.
h.setBuffered(0)
h.runTimer()
h.queue.enqueue('later')
expect(h.sent).toEqual([])
expect(h.overflow).toHaveBeenCalledTimes(1)
})
it('bounds zero-byte frames independently of the queued-byte cap', () => {
const h = createHarness({ softCapBytes: 10, maxQueuedFrames: 2 })
h.setBuffered(100)
h.queue.enqueue('')
h.queue.enqueue('')
h.queue.enqueue('')
expect(h.overflow).toHaveBeenCalledOnce()
expect(h.queue.evidence()).toMatchObject({ queuedBytes: 0, queuedFrames: 0 })
})
it('fails closed when a caller reports an invalid retained size', () => {
const overflow = vi.fn()
const queue = createWsOutboundBackpressureQueue<string>({
send: vi.fn(),
byteLengthOf: () => Number.NaN,
getBufferedAmount: () => 100,
isWritable: () => true,
onOverflow: overflow,
softCapBytes: 10
})
queue.enqueue('frame')
expect(overflow).toHaveBeenCalledOnce()
expect(queue.evidence()).toMatchObject({ queuedBytes: 0, queuedFrames: 0 })
})
it('drops the backlog if the socket becomes unwritable mid-park', () => {
const h = createHarness({ softCapBytes: 10 })
h.setBuffered(100)
h.queue.enqueue('data')
h.setWritable(false)
h.runTimer()
expect(h.sent).toEqual([])
expect(h.queue.queuedBytes()).toBe(0)
})
it('does not fast-path a frame while the socket is unwritable', () => {
const h = createHarness({ writable: false })
h.queue.enqueue('data')
expect(h.sent).toEqual([])
expect(h.queue.queuedBytes()).toBe('data'.length)
expect(h.hasTimer()).toBe(true)
})
})