Download next.js/packages/next/src/server/app-render/cache-signal.ts from Devendra174/react-code-dataset: direct link, hf CLI and curl.
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https://huggingface.co/datasets/Devendra174/react-code-dataset/resolve/main/next.js/packages/next/src/server/app-render/cache-signal.ts
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4.83 kB
| /** | |
| * This class is used to detect when all cache reads for a given render are settled. | |
| * We do this to allow for cache warming the prerender without having to continue rendering | |
| * the remainder of the page. This feature is really only useful when the cacheComponents flag is on | |
| * and should only be used in codepaths gated with this feature. | |
| */ | |
| import { InvariantError } from '../../shared/lib/invariant-error' | |
| export class CacheSignal { | |
| private count = 0 | |
| private earlyListeners: Array<() => void> = [] | |
| private listeners: Array<() => void> = [] | |
| private tickPending = false | |
| private taskPending = false | |
| private subscribedSignals: Set<CacheSignal> | null = null | |
| constructor() { | |
| if (process.env.NEXT_RUNTIME === 'edge') { | |
| // we rely on `process.nextTick`, which is not supported in edge | |
| throw new InvariantError( | |
| 'CacheSignal cannot be used in the edge runtime, because `cacheComponents` does not support it.' | |
| ) | |
| } | |
| } | |
| private noMorePendingCaches() { | |
| if (!this.tickPending) { | |
| this.tickPending = true | |
| process.nextTick(() => { | |
| this.tickPending = false | |
| if (this.count === 0) { | |
| for (let i = 0; i < this.earlyListeners.length; i++) { | |
| this.earlyListeners[i]() | |
| } | |
| this.earlyListeners.length = 0 | |
| } | |
| }) | |
| } | |
| if (!this.taskPending) { | |
| this.taskPending = true | |
| setTimeout(() => { | |
| this.taskPending = false | |
| if (this.count === 0) { | |
| for (let i = 0; i < this.listeners.length; i++) { | |
| this.listeners[i]() | |
| } | |
| this.listeners.length = 0 | |
| } | |
| }, 0) | |
| } | |
| } | |
| /** | |
| * This promise waits until there are no more in progress cache reads but no later. | |
| * This allows for adding more cache reads after to delay cacheReady. | |
| */ | |
| inputReady() { | |
| return new Promise<void>((resolve) => { | |
| this.earlyListeners.push(resolve) | |
| if (this.count === 0) { | |
| this.noMorePendingCaches() | |
| } | |
| }) | |
| } | |
| /** | |
| * If there are inflight cache reads this Promise can resolve in a microtask however | |
| * if there are no inflight cache reads then we wait at least one task to allow initial | |
| * cache reads to be initiated. | |
| */ | |
| cacheReady() { | |
| return new Promise<void>((resolve) => { | |
| this.listeners.push(resolve) | |
| if (this.count === 0) { | |
| this.noMorePendingCaches() | |
| } | |
| }) | |
| } | |
| beginRead() { | |
| this.count++ | |
| if (this.subscribedSignals !== null) { | |
| for (const subscriber of this.subscribedSignals) { | |
| subscriber.beginRead() | |
| } | |
| } | |
| } | |
| endRead() { | |
| if (this.count === 0) { | |
| throw new InvariantError( | |
| 'CacheSignal got more endRead() calls than beginRead() calls' | |
| ) | |
| } | |
| // If this is the last read we need to wait a task before we can claim the cache is settled. | |
| // The cache read will likely ping a Server Component which can read from the cache again and this | |
| // will play out in a microtask so we need to only resolve pending listeners if we're still at 0 | |
| // after at least one task. | |
| // We only want one task scheduled at a time so when we hit count 1 we don't decrement the counter immediately. | |
| // If intervening reads happen before the scheduled task runs they will never observe count 1 preventing reentrency | |
| this.count-- | |
| if (this.count === 0) { | |
| this.noMorePendingCaches() | |
| } | |
| if (this.subscribedSignals !== null) { | |
| for (const subscriber of this.subscribedSignals) { | |
| subscriber.endRead() | |
| } | |
| } | |
| } | |
| trackRead<T>(promise: Promise<T>) { | |
| this.beginRead() | |
| // `promise.finally()` still rejects, so don't use it here to avoid unhandled rejections | |
| const onFinally = this.endRead.bind(this) | |
| promise.then(onFinally, onFinally) | |
| return promise | |
| } | |
| subscribeToReads(subscriber: CacheSignal): () => void { | |
| if (subscriber === this) { | |
| throw new InvariantError('A CacheSignal cannot subscribe to itself') | |
| } | |
| if (this.subscribedSignals === null) { | |
| this.subscribedSignals = new Set() | |
| } | |
| this.subscribedSignals.add(subscriber) | |
| // we'll notify the subscriber of each endRead() on this signal, | |
| // so we need to give it a corresponding beginRead() for each read we have in flight now. | |
| for (let i = 0; i < this.count; i++) { | |
| subscriber.beginRead() | |
| } | |
| return this.unsubscribeFromReads.bind(this, subscriber) | |
| } | |
| unsubscribeFromReads(subscriber: CacheSignal) { | |
| if (!this.subscribedSignals) { | |
| return | |
| } | |
| this.subscribedSignals.delete(subscriber) | |
| // we don't need to set the set back to `null` if it's empty -- | |
| // if other signals are subscribing to this one, it'll likely get more subscriptions later, | |
| // so we'd have to allocate a fresh set again when that happens. | |
| } | |
| } | |