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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 | 3x 4x 4x 105x 102x 102x 105x 6x 6x 6x 12x 12x 6x 3x 105x 105x 129x 129x 129x 129x 99x 30x 30x 6x | import { Channel, ReadAttempt, WriteAttempt, Attempt, Attempted, Thunk } from './channel.js'
export async function* select<Attempts extends Attempt[]>(
...attempts: Attempts
): AsyncGenerator<Attempted<Attempts[number]>> {
while (true) {
const result = await selectNext(...attempts)
Iif (result.done) {
break
}
yield result.value
}
}
export async function selectNext<Attempts extends Attempt[]>(
...attempts: Attempts
): Promise<IteratorResult<Attempted<Attempts[number]>>> {
return selectSync(attempts) ?? await selectAsync(attempts)
}
export function selectAsync<Attempts extends Attempt[]>(
attempts: Attempts
): Promise<IteratorResult<Attempted<Attempts[number]>>> {
return new Promise((resolve, reject) => {
const undos: Thunk[] = []
for (const attempt of attempts) {
if (attempt instanceof Channel) {
undos.push(attempt.pushRead(result => {
undos.forEach(undo => undo())
resolve(result as IteratorResult<Attempted<Attempts[number]>>)
}))
} else Eif (attempt instanceof WriteAttempt) {
undos.push(attempt.channel.pushWrite({ value: attempt.value, enqueued: (err: unknown) => {
undos.forEach(_ => _())
Iif (err) {
reject(err)
return
}
resolve(attempt.perform(attempt.value) as IteratorResult<Attempted<Attempts[number]>>)
}}))
} else if (attempt instanceof ReadAttempt) {
undos.push(attempt.channel.pushRead(result => {
undos.forEach(undo => undo())
resolve(attempt.perform(result) as IteratorResult<Attempted<Attempts[number]>>)
}))
} else {
throw new Error('Invalid attempt.')
}
}
})
}
export function selectSync<Attempts extends Attempt[]>(
attempts: Attempts
): undefined | IteratorResult<Attempted<Attempts[number]>> {
const n = attempts.length
for (let i = 0; i < n; i++) {
const j = i + Math.floor(Math.random() * (n - i))
const attempt = attempts[j] as Attempts[number]
if (attempt instanceof Channel) {
if (attempt.pendingWrites > 0) {
return { value: attempt.consumeWrite() }
}
} else Eif (attempt instanceof WriteAttempt) {
if (attempt.channel.cap === 0 && attempt.channel.pendingReads > 0) {
attempt.channel.consumeRead({ value: attempt.value })
return attempt.perform(attempt.value)
} else Iif (attempt.channel.pendingWrites < attempt.channel.cap) {
attempt.channel.pushWrite({ value: attempt.value })
return attempt.perform(attempt.value)
}
} else if (attempt instanceof ReadAttempt) {
Iif (attempt.channel.pendingWrites > 0) {
const value = attempt.channel.consumeWrite()
return attempt.perform({ value })
}
} else {
throw new Error('Invalid attempt.')
}
attempts[j] = attempts[i]
attempts[i] = attempt
}
return
}
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