next.js/packages/next/src/server/web/spec-extension/revalidate.ts

import {
  abortAndThrowOnSynchronousRequestDataAccess,
  postponeWithTracking,
} from '../../app-render/dynamic-rendering'
import { isDynamicRoute } from '../../../shared/lib/router/utils'
import {
  NEXT_CACHE_IMPLICIT_TAG_ID,
  NEXT_CACHE_SOFT_TAG_MAX_LENGTH,
} from '../../../lib/constants'
import { workAsyncStorage } from '../../app-render/work-async-storage.external'
import { workUnitAsyncStorage } from '../../app-render/work-unit-async-storage.external'
import { DynamicServerError } from '../../../client/components/hooks-server-context'
import { InvariantError } from '../../../shared/lib/invariant-error'

/**
 * This function allows you to purge [cached data](https://nextjs.org/docs/app/building-your-application/caching) on-demand for a specific cache tag.
 *
 * Read more: [Next.js Docs: `revalidateTag`](https://nextjs.org/docs/app/api-reference/functions/revalidateTag)
 */
export function revalidateTag(tag: string) {
  return revalidate([tag], `revalidateTag ${tag}`)
}

/**
 * This function allows you to purge [cached data](https://nextjs.org/docs/app/building-your-application/caching) on-demand for a specific path.
 *
 * Read more: [Next.js Docs: `unstable_expirePath`](https://nextjs.org/docs/app/api-reference/functions/unstable_expirePath)
 */
export function unstable_expirePath(
  originalPath: string,
  type?: 'layout' | 'page'
) {
  if (originalPath.length > NEXT_CACHE_SOFT_TAG_MAX_LENGTH) {
    console.warn(
      `Warning: expirePath received "${originalPath}" which exceeded max length of ${NEXT_CACHE_SOFT_TAG_MAX_LENGTH}. See more info here https://nextjs.org/docs/app/api-reference/functions/unstable_expirePath`
    )
    return
  }

  let normalizedPath = `${NEXT_CACHE_IMPLICIT_TAG_ID}${originalPath}`

  if (type) {
    normalizedPath += `${normalizedPath.endsWith('/') ? '' : '/'}${type}`
  } else if (isDynamicRoute(originalPath)) {
    console.warn(
      `Warning: a dynamic page path "${originalPath}" was passed to "expirePath", but the "type" parameter is missing. This has no effect by default, see more info here https://nextjs.org/docs/app/api-reference/functions/unstable_expirePath`
    )
  }
  return revalidate([normalizedPath], `unstable_expirePath ${originalPath}`)
}

/**
 * This function allows you to purge [cached data](https://nextjs.org/docs/app/building-your-application/caching) on-demand for a specific cache tag.
 *
 * Read more: [Next.js Docs: `unstable_expireTag`](https://nextjs.org/docs/app/api-reference/functions/unstable_expireTag)
 */
export function unstable_expireTag(...tags: string[]) {
  return revalidate(tags, `unstable_expireTag ${tags.join(', ')}`)
}

/**
 * This function allows you to purge [cached data](https://nextjs.org/docs/app/building-your-application/caching) on-demand for a specific path.
 *
 * Read more: [Next.js Docs: `revalidatePath`](https://nextjs.org/docs/app/api-reference/functions/revalidatePath)
 */
export function revalidatePath(originalPath: string, type?: 'layout' | 'page') {
  if (originalPath.length > NEXT_CACHE_SOFT_TAG_MAX_LENGTH) {
    console.warn(
      `Warning: revalidatePath received "${originalPath}" which exceeded max length of ${NEXT_CACHE_SOFT_TAG_MAX_LENGTH}. See more info here https://nextjs.org/docs/app/api-reference/functions/revalidatePath`
    )
    return
  }

  let normalizedPath = `${NEXT_CACHE_IMPLICIT_TAG_ID}${originalPath}`

  if (type) {
    normalizedPath += `${normalizedPath.endsWith('/') ? '' : '/'}${type}`
  } else if (isDynamicRoute(originalPath)) {
    console.warn(
      `Warning: a dynamic page path "${originalPath}" was passed to "revalidatePath", but the "type" parameter is missing. This has no effect by default, see more info here https://nextjs.org/docs/app/api-reference/functions/revalidatePath`
    )
  }
  return revalidate([normalizedPath], `revalidatePath ${originalPath}`)
}

function revalidate(tags: string[], expression: string) {
  const store = workAsyncStorage.getStore()
  if (!store || !store.incrementalCache) {
    throw new Error(
      `Invariant: static generation store missing in ${expression}`
    )
  }

  const workUnitStore = workUnitAsyncStorage.getStore()
  if (workUnitStore) {
    if (workUnitStore.phase === 'render') {
      throw new Error(
        `Route ${store.route} used "${expression}" during render which is unsupported. To ensure revalidation is performed consistently it must always happen outside of renders and cached functions. See more info here: https://nextjs.org/docs/app/building-your-application/rendering/static-and-dynamic#dynamic-rendering`
      )
    }

    switch (workUnitStore.type) {
      case 'cache':
      case 'private-cache':
        throw new Error(
          `Route ${store.route} used "${expression}" inside a "use cache" which is unsupported. To ensure revalidation is performed consistently it must always happen outside of renders and cached functions. See more info here: https://nextjs.org/docs/app/building-your-application/rendering/static-and-dynamic#dynamic-rendering`
        )
      case 'unstable-cache':
        throw new Error(
          `Route ${store.route} used "${expression}" inside a function cached with "unstable_cache(...)" which is unsupported. To ensure revalidation is performed consistently it must always happen outside of renders and cached functions. See more info here: https://nextjs.org/docs/app/building-your-application/rendering/static-and-dynamic#dynamic-rendering`
        )
      case 'prerender':
        // cacheComponents Prerender
        const error = new Error(
          `Route ${store.route} used ${expression} without first calling \`await connection()\`.`
        )
        return abortAndThrowOnSynchronousRequestDataAccess(
          store.route,
          expression,
          error,
          workUnitStore
        )
      case 'prerender-client':
        throw new InvariantError(
          `${expression} must not be used within a client component. Next.js should be preventing ${expression} from being included in client components statically, but did not in this case.`
        )
      case 'prerender-ppr':
        return postponeWithTracking(
          store.route,
          expression,
          workUnitStore.dynamicTracking
        )
      case 'prerender-legacy':
        workUnitStore.revalidate = 0

        const err = new DynamicServerError(
          `Route ${store.route} couldn't be rendered statically because it used \`${expression}\`. See more info here: https://nextjs.org/docs/messages/dynamic-server-error`
        )
        store.dynamicUsageDescription = expression
        store.dynamicUsageStack = err.stack

        throw err
      case 'request':
        if (process.env.NODE_ENV !== 'production') {
          // TODO: This is most likely incorrect. It would lead to the ISR
          // status being flipped when revalidating a static page with a server
          // action.
          workUnitStore.usedDynamic = true
        }
        break
      default:
        workUnitStore satisfies never
    }
  }

  if (!store.pendingRevalidatedTags) {
    store.pendingRevalidatedTags = []
  }

  for (const tag of tags) {
    if (!store.pendingRevalidatedTags.includes(tag)) {
      store.pendingRevalidatedTags.push(tag)
    }
  }

  // TODO: only revalidate if the path matches
  store.pathWasRevalidated = true
}