84 lines
2.8 KiB
TypeScript
84 lines
2.8 KiB
TypeScript
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import { useEffect, useState } from 'react'
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import { useApi } from './ApiContext.tsx'
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export type JobStatus = 'queued' | 'running' | 'succeeded' | 'failed'
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// Job is the GET /api/v1/jobs/{id} response. result may be set while the job
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// is running (a partial result); error is set only when it failed.
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export type Job<R> = {
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id: string
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kind: string
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status: JobStatus
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result: R | null
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error: string | null
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}
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export type JobState<R> = {
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// undefined until the first poll answers.
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status: JobStatus | undefined
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// The latest result, partial while the job runs.
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result: R | null
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// The job's failure, or the latest polling request's own failure (cleared
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// by the next poll that answers).
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error: Error | null
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}
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// Polling starts at FIRST_DELAY_MS and doubles up to MAX_DELAY_MS.
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export const FIRST_DELAY_MS = 500
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export const MAX_DELAY_MS = 2000
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const idle = { status: undefined, result: null, error: null }
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function isTerminal(status: JobStatus): boolean {
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return status === 'succeeded' || status === 'failed'
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}
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// useJob polls GET /api/v1/jobs/{jobId} until the job succeeds or fails,
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// backing off from 500 ms to 2 s. A failed poll is exposed as the error and
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// polling continues. Polling stops only at a terminal status, when jobId
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// changes and on unmount. A null jobId polls nothing.
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export function useJob<R>(jobId: string | null): JobState<R> {
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const { apiFetch } = useApi()
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const [state, setState] = useState<{ jobId: string | null; job: JobState<R> }>({ jobId, job: idle })
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useEffect(() => {
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if (jobId === null) return
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let active = true
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let timer: ReturnType<typeof setTimeout> | undefined
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let delay = FIRST_DELAY_MS
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function next() {
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timer = setTimeout(poll, delay)
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delay = Math.min(delay * 2, MAX_DELAY_MS)
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}
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async function poll() {
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try {
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const job = await apiFetch<Job<R>>(`/api/v1/jobs/${encodeURIComponent(jobId!)}`)
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if (!active) return
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const error = job.status === 'failed' ? new Error(job.error ?? `job ${job.id} failed without an error message`) : null
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setState({ jobId, job: { status: job.status, result: job.result, error } })
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if (isTerminal(job.status)) return
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} catch (error) {
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if (!active) return
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// A failed poll is not the job's end: keep the last known status and
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// result, expose the request's error, and poll again.
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setState((prev) => ({
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jobId,
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job: { ...(prev.jobId === jobId ? prev.job : idle), error: error instanceof Error ? error : new Error(String(error)) },
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}))
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}
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next()
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}
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void poll()
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return () => {
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active = false
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clearTimeout(timer)
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}
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}, [apiFetch, jobId])
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// State left from a previous jobId is not this job's.
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return state.jobId === jobId ? state.job : idle
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}
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