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const key = (directory: string, sessionID: string) => `${directory}\n${sessionID}`
export const SESSION_PREFETCH_TTL = 15_000
type Meta = {
limit: number
cursor?: string
complete: boolean
at: number
}
export function shouldSkipSessionPrefetch(input: { message: boolean; info?: Meta; chunk: number; now?: number }) {
if (input.message) {
if (!input.info) return true
if (input.info.complete) return true
if (input.info.limit > input.chunk) return true
} else {
if (!input.info) return false
}
return (input.now ?? Date.now()) - input.info.at < SESSION_PREFETCH_TTL
}
const cache = new Map<string, Meta>()
const inflight = new Map<string, Promise<Meta | undefined>>()
const rev = new Map<string, number>()
const version = (id: string) => rev.get(id) ?? 0
export function getSessionPrefetch(directory: string, sessionID: string) {
return cache.get(key(directory, sessionID))
}
export function getSessionPrefetchPromise(directory: string, sessionID: string) {
return inflight.get(key(directory, sessionID))
}
export function clearSessionPrefetchInflight() {
inflight.clear()
}
export function isSessionPrefetchCurrent(directory: string, sessionID: string, value: number) {
return version(key(directory, sessionID)) === value
}
export function runSessionPrefetch(input: {
directory: string
sessionID: string
task: (value: number) => Promise<Meta | undefined>
}) {
const id = key(input.directory, input.sessionID)
const pending = inflight.get(id)
if (pending) return pending
const value = version(id)
const promise = input.task(value).finally(() => {
if (inflight.get(id) === promise) inflight.delete(id)
})
inflight.set(id, promise)
return promise
}
export function setSessionPrefetch(input: {
directory: string
sessionID: string
limit: number
cursor?: string
complete: boolean
at?: number
}) {
cache.set(key(input.directory, input.sessionID), {
limit: input.limit,
cursor: input.cursor,
complete: input.complete,
at: input.at ?? Date.now(),
})
}
export function clearSessionPrefetch(directory: string, sessionIDs: Iterable<string>) {
for (const sessionID of sessionIDs) {
if (!sessionID) continue
const id = key(directory, sessionID)
rev.set(id, version(id) + 1)
cache.delete(id)
inflight.delete(id)
}
}
export function clearSessionPrefetchDirectory(directory: string) {
const prefix = `${directory}\n`
const keys = new Set([...cache.keys(), ...inflight.keys()])
for (const id of keys) {
if (!id.startsWith(prefix)) continue
rev.set(id, version(id) + 1)
cache.delete(id)
inflight.delete(id)
}
}
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