import { HasLoadingBoundary } from '../../../shared/lib/app-router-types'; import { NEXT_DID_POSTPONE_HEADER, NEXT_ROUTER_PREFETCH_HEADER, NEXT_ROUTER_SEGMENT_PREFETCH_HEADER, NEXT_ROUTER_STALE_TIME_HEADER, NEXT_ROUTER_STATE_TREE_HEADER, NEXT_URL, RSC_CONTENT_TYPE_HEADER, RSC_HEADER } from '../app-router-headers'; import { createFetch, createFromNextReadableStream } from '../router-reducer/fetch-server-response'; import { pingPrefetchTask, isPrefetchTaskDirty, startRevalidationCooldown } from './scheduler'; import { getRouteVaryPath, getFulfilledRouteVaryPath, getSegmentVaryPathForRequest, appendLayoutVaryPath, finalizeLayoutVaryPath, finalizePageVaryPath, clonePageVaryPathWithNewSearchParams, finalizeMetadataVaryPath } from './vary-path'; import { getAppBuildId } from '../../app-build-id'; import { createHrefFromUrl } from '../router-reducer/create-href-from-url'; // TODO: Rename this module to avoid confusion with other types of cache keys import { createCacheKey as createPrefetchRequestKey } from './cache-key'; import { doesStaticSegmentAppearInURL, getCacheKeyForDynamicParam, getRenderedPathname, getRenderedSearch, parseDynamicParamFromURLPart } from '../../route-params'; import { createCacheMap, getFromCacheMap, setInCacheMap, setSizeInCacheMap, deleteFromCacheMap, isValueExpired } from './cache-map'; import { appendSegmentRequestKeyPart, convertSegmentPathToStaticExportFilename, createSegmentRequestKeyPart, HEAD_REQUEST_KEY, ROOT_SEGMENT_REQUEST_KEY } from '../../../shared/lib/segment-cache/segment-value-encoding'; import { normalizeFlightData, prepareFlightRouterStateForRequest } from '../../flight-data-helpers'; import { STATIC_STALETIME_MS } from '../router-reducer/reducers/navigate-reducer'; import { pingVisibleLinks } from '../links'; import { PAGE_SEGMENT_KEY } from '../../../shared/lib/segment'; import { FetchStrategy } from './types'; import { createPromiseWithResolvers } from '../../../shared/lib/promise-with-resolvers'; /** * Ensures a minimum stale time of 30s to avoid issues where the server sends a too * short-lived stale time, which would prevent anything from being prefetched. */ export function getStaleTimeMs(staleTimeSeconds) { return Math.max(staleTimeSeconds, 30) * 1000; } /** * Tracks the status of a cache entry as it progresses from no data (Empty), * waiting for server data (Pending), and finished (either Fulfilled or * Rejected depending on the response from the server. */ export var EntryStatus = /*#__PURE__*/ function(EntryStatus) { EntryStatus[EntryStatus["Empty"] = 0] = "Empty"; EntryStatus[EntryStatus["Pending"] = 1] = "Pending"; EntryStatus[EntryStatus["Fulfilled"] = 2] = "Fulfilled"; EntryStatus[EntryStatus["Rejected"] = 3] = "Rejected"; return EntryStatus; }({}); const isOutputExportMode = process.env.NODE_ENV === 'production' && process.env.__NEXT_CONFIG_OUTPUT === 'export'; const MetadataOnlyRequestTree = [ '', {}, null, 'metadata-only' ]; let routeCacheMap = createCacheMap(); let segmentCacheMap = createCacheMap(); // All invalidation listeners for the whole cache are tracked in single set. // Since we don't yet support tag or path-based invalidation, there's no point // tracking them any more granularly than this. Once we add granular // invalidation, that may change, though generally the model is to just notify // the listeners and allow the caller to poll the prefetch cache with a new // prefetch task if desired. let invalidationListeners = null; // Incrementing counter used to track cache invalidations. let currentCacheVersion = 0; export function getCurrentCacheVersion() { return currentCacheVersion; } /** * Used to clear the client prefetch cache when a server action calls * revalidatePath or revalidateTag. Eventually we will support only clearing the * segments that were actually affected, but there's more work to be done on the * server before the client is able to do this correctly. */ export function revalidateEntireCache(nextUrl, tree) { // Increment the current cache version. This does not eagerly evict anything // from the cache, but because all the entries are versioned, and we check // the version when reading from the cache, this effectively causes all // entries to be evicted lazily. We do it lazily because in the future, // actions like revalidateTag or refresh will not evict the entire cache, // but rather some subset of the entries. currentCacheVersion++; // Start a cooldown before re-prefetching to allow CDN cache propagation. startRevalidationCooldown(); // Prefetch all the currently visible links again, to re-fill the cache. pingVisibleLinks(nextUrl, tree); // Similarly, notify all invalidation listeners (i.e. those passed to // `router.prefetch(onInvalidate)`), so they can trigger a new prefetch // if needed. pingInvalidationListeners(nextUrl, tree); } function attachInvalidationListener(task) { // This function is called whenever a prefetch task reads a cache entry. If // the task has an onInvalidate function associated with it — i.e. the one // optionally passed to router.prefetch(onInvalidate) — then we attach that // listener to the every cache entry that the task reads. Then, if an entry // is invalidated, we call the function. if (task.onInvalidate !== null) { if (invalidationListeners === null) { invalidationListeners = new Set([ task ]); } else { invalidationListeners.add(task); } } } function notifyInvalidationListener(task) { const onInvalidate = task.onInvalidate; if (onInvalidate !== null) { // Clear the callback from the task object to guarantee it's not called more // than once. task.onInvalidate = null; // This is a user-space function, so we must wrap in try/catch. try { onInvalidate(); } catch (error) { if (typeof reportError === 'function') { reportError(error); } else { console.error(error); } } } } export function pingInvalidationListeners(nextUrl, tree) { // The rough equivalent of pingVisibleLinks, but for onInvalidate callbacks. // This is called when the Next-Url or the base tree changes, since those // may affect the result of a prefetch task. It's also called after a // cache invalidation. if (invalidationListeners !== null) { const tasks = invalidationListeners; invalidationListeners = null; for (const task of tasks){ if (isPrefetchTaskDirty(task, nextUrl, tree)) { notifyInvalidationListener(task); } } } } export function readRouteCacheEntry(now, key) { const varyPath = getRouteVaryPath(key.pathname, key.search, key.nextUrl); const isRevalidation = false; return getFromCacheMap(now, getCurrentCacheVersion(), routeCacheMap, varyPath, isRevalidation); } export function readSegmentCacheEntry(now, varyPath) { const isRevalidation = false; return getFromCacheMap(now, getCurrentCacheVersion(), segmentCacheMap, varyPath, isRevalidation); } function readRevalidatingSegmentCacheEntry(now, varyPath) { const isRevalidation = true; return getFromCacheMap(now, getCurrentCacheVersion(), segmentCacheMap, varyPath, isRevalidation); } export function waitForSegmentCacheEntry(pendingEntry) { // Because the entry is pending, there's already a in-progress request. // Attach a promise to the entry that will resolve when the server responds. let promiseWithResolvers = pendingEntry.promise; if (promiseWithResolvers === null) { promiseWithResolvers = pendingEntry.promise = createPromiseWithResolvers(); } else { // There's already a promise we can use } return promiseWithResolvers.promise; } /** * Checks if an entry for a route exists in the cache. If so, it returns the * entry, If not, it adds an empty entry to the cache and returns it. */ export function readOrCreateRouteCacheEntry(now, task, key) { attachInvalidationListener(task); const existingEntry = readRouteCacheEntry(now, key); if (existingEntry !== null) { return existingEntry; } // Create a pending entry and add it to the cache. const pendingEntry = { canonicalUrl: null, status: 0, blockedTasks: null, tree: null, metadata: null, // This is initialized to true because we don't know yet whether the route // could be intercepted. It's only set to false once we receive a response // from the server. couldBeIntercepted: true, // Similarly, we don't yet know if the route supports PPR. isPPREnabled: false, renderedSearch: null, // Map-related fields ref: null, size: 0, // Since this is an empty entry, there's no reason to ever evict it. It will // be updated when the data is populated. staleAt: Infinity, version: getCurrentCacheVersion() }; const varyPath = getRouteVaryPath(key.pathname, key.search, key.nextUrl); const isRevalidation = false; setInCacheMap(routeCacheMap, varyPath, pendingEntry, isRevalidation); return pendingEntry; } export function requestOptimisticRouteCacheEntry(now, requestedUrl, nextUrl) { // This function is called during a navigation when there was no matching // route tree in the prefetch cache. Before de-opting to a blocking, // unprefetched navigation, we will first attempt to construct an "optimistic" // route tree by checking the cache for similar routes. // // Check if there's a route with the same pathname, but with different // search params. We can then base our optimistic route tree on this entry. // // Conceptually, we are simulating what would happen if we did perform a // prefetch the requested URL, under the assumption that the server will // not redirect or rewrite the request in a different manner than the // base route tree. This assumption might not hold, in which case we'll have // to recover when we perform the dynamic navigation request. However, this // is what would happen if a route were dynamically rewritten/redirected // in between the prefetch and the navigation. So the logic needs to exist // to handle this case regardless. // Look for a route with the same pathname, but with an empty search string. // TODO: There's nothing inherently special about the empty search string; // it's chosen somewhat arbitrarily, with the rationale that it's the most // likely one to exist. But we should update this to match _any_ search // string. The plan is to generalize this logic alongside other improvements // related to "fallback" cache entries. const requestedSearch = requestedUrl.search; if (requestedSearch === '') { // The caller would have already checked if a route with an empty search // string is in the cache. So we can bail out here. return null; } const urlWithoutSearchParams = new URL(requestedUrl); urlWithoutSearchParams.search = ''; const routeWithNoSearchParams = readRouteCacheEntry(now, createPrefetchRequestKey(urlWithoutSearchParams.href, nextUrl)); if (routeWithNoSearchParams === null || routeWithNoSearchParams.status !== 2) { // Bail out of constructing an optimistic route tree. This will result in // a blocking, unprefetched navigation. return null; } // Now we have a base route tree we can "patch" with our optimistic values. // Optimistically assume that redirects for the requested pathname do // not vary on the search string. Therefore, if the base route was // redirected to a different search string, then the optimistic route // should be redirected to the same search string. Otherwise, we use // the requested search string. const canonicalUrlForRouteWithNoSearchParams = new URL(routeWithNoSearchParams.canonicalUrl, requestedUrl.origin); const optimisticCanonicalSearch = canonicalUrlForRouteWithNoSearchParams.search !== '' ? canonicalUrlForRouteWithNoSearchParams.search : requestedSearch; // Similarly, optimistically assume that rewrites for the requested // pathname do not vary on the search string. Therefore, if the base // route was rewritten to a different search string, then the optimistic // route should be rewritten to the same search string. Otherwise, we use // the requested search string. const optimisticRenderedSearch = routeWithNoSearchParams.renderedSearch !== '' ? routeWithNoSearchParams.renderedSearch : requestedSearch; const optimisticUrl = new URL(routeWithNoSearchParams.canonicalUrl, location.origin); optimisticUrl.search = optimisticCanonicalSearch; const optimisticCanonicalUrl = createHrefFromUrl(optimisticUrl); const optimisticRouteTree = createOptimisticRouteTree(routeWithNoSearchParams.tree, optimisticRenderedSearch); const optimisticMetadataTree = createOptimisticRouteTree(routeWithNoSearchParams.metadata, optimisticRenderedSearch); // Clone the base route tree, and override the relevant fields with our // optimistic values. const optimisticEntry = { canonicalUrl: optimisticCanonicalUrl, status: 2, // This isn't cloned because it's instance-specific blockedTasks: null, tree: optimisticRouteTree, metadata: optimisticMetadataTree, couldBeIntercepted: routeWithNoSearchParams.couldBeIntercepted, isPPREnabled: routeWithNoSearchParams.isPPREnabled, // Override the rendered search with the optimistic value. renderedSearch: optimisticRenderedSearch, // Map-related fields ref: null, size: 0, staleAt: routeWithNoSearchParams.staleAt, version: routeWithNoSearchParams.version }; // Do not insert this entry into the cache. It only exists so we can // perform the current navigation. Just return it to the caller. return optimisticEntry; } function createOptimisticRouteTree(tree, newRenderedSearch) { // Create a new route tree that identical to the original one except for // the rendered search string, which is contained in the vary path. let clonedSlots = null; const originalSlots = tree.slots; if (originalSlots !== null) { clonedSlots = {}; for(const parallelRouteKey in originalSlots){ const childTree = originalSlots[parallelRouteKey]; clonedSlots[parallelRouteKey] = createOptimisticRouteTree(childTree, newRenderedSearch); } } // We only need to clone the vary path if the route is a page. if (tree.isPage) { return { requestKey: tree.requestKey, segment: tree.segment, varyPath: clonePageVaryPathWithNewSearchParams(tree.varyPath, newRenderedSearch), isPage: true, slots: clonedSlots, isRootLayout: tree.isRootLayout, hasLoadingBoundary: tree.hasLoadingBoundary, hasRuntimePrefetch: tree.hasRuntimePrefetch }; } return { requestKey: tree.requestKey, segment: tree.segment, varyPath: tree.varyPath, isPage: false, slots: clonedSlots, isRootLayout: tree.isRootLayout, hasLoadingBoundary: tree.hasLoadingBoundary, hasRuntimePrefetch: tree.hasRuntimePrefetch }; } /** * Checks if an entry for a segment exists in the cache. If so, it returns the * entry, If not, it adds an empty entry to the cache and returns it. */ export function readOrCreateSegmentCacheEntry(now, fetchStrategy, route, tree) { const existingEntry = readSegmentCacheEntry(now, tree.varyPath); if (existingEntry !== null) { return existingEntry; } // Create a pending entry and add it to the cache. const varyPathForRequest = getSegmentVaryPathForRequest(fetchStrategy, tree); const pendingEntry = createDetachedSegmentCacheEntry(route.staleAt); const isRevalidation = false; setInCacheMap(segmentCacheMap, varyPathForRequest, pendingEntry, isRevalidation); return pendingEntry; } export function readOrCreateRevalidatingSegmentEntry(now, fetchStrategy, route, tree) { // This function is called when we've already confirmed that a particular // segment is cached, but we want to perform another request anyway in case it // returns more complete and/or fresher data than we already have. The logic // for deciding whether to replace the existing entry is handled elsewhere; // this function just handles retrieving a cache entry that we can use to // track the revalidation. // // The reason revalidations are stored in the cache is because we need to be // able to dedupe multiple revalidation requests. The reason they have to be // handled specially is because we shouldn't overwrite a "normal" entry if // one exists at the same keypath. So, for each internal cache location, there // is a special "revalidation" slot that is used solely for this purpose. // // You can think of it as if all the revalidation entries were stored in a // separate cache map from the canonical entries, and then transfered to the // canonical cache map once the request is complete — this isn't how it's // actually implemented, since it's more efficient to store them in the same // data structure as the normal entries, but that's how it's modeled // conceptually. // TODO: Once we implement Fallback behavior for params, where an entry is // re-keyed based on response information, we'll need to account for the // possibility that the keypath of the previous entry is more generic than // the keypath of the revalidating entry. In other words, the server could // return a less generic entry upon revalidation. For now, though, this isn't // a concern because the keypath is based solely on the prefetch strategy, // not on data contained in the response. const existingEntry = readRevalidatingSegmentCacheEntry(now, tree.varyPath); if (existingEntry !== null) { return existingEntry; } // Create a pending entry and add it to the cache. const varyPathForRequest = getSegmentVaryPathForRequest(fetchStrategy, tree); const pendingEntry = createDetachedSegmentCacheEntry(route.staleAt); const isRevalidation = true; setInCacheMap(segmentCacheMap, varyPathForRequest, pendingEntry, isRevalidation); return pendingEntry; } export function overwriteRevalidatingSegmentCacheEntry(fetchStrategy, route, tree) { // This function is called when we've already decided to replace an existing // revalidation entry. Create a new entry and write it into the cache, // overwriting the previous value. const varyPathForRequest = getSegmentVaryPathForRequest(fetchStrategy, tree); const pendingEntry = createDetachedSegmentCacheEntry(route.staleAt); const isRevalidation = true; setInCacheMap(segmentCacheMap, varyPathForRequest, pendingEntry, isRevalidation); return pendingEntry; } export function upsertSegmentEntry(now, varyPath, candidateEntry) { // We have a new entry that has not yet been inserted into the cache. Before // we do so, we need to confirm whether it takes precedence over the existing // entry (if one exists). // TODO: We should not upsert an entry if its key was invalidated in the time // since the request was made. We can do that by passing the "owner" entry to // this function and confirming it's the same as `existingEntry`. if (isValueExpired(now, getCurrentCacheVersion(), candidateEntry)) { // The entry is expired. We cannot upsert it. return null; } const existingEntry = readSegmentCacheEntry(now, varyPath); if (existingEntry !== null) { // Don't replace a more specific segment with a less-specific one. A case where this // might happen is if the existing segment was fetched via // ``. if (// We fetched the new segment using a different, less specific fetch strategy // than the segment we already have in the cache, so it can't have more content. candidateEntry.fetchStrategy !== existingEntry.fetchStrategy && !canNewFetchStrategyProvideMoreContent(existingEntry.fetchStrategy, candidateEntry.fetchStrategy) || // The existing entry isn't partial, but the new one is. // (TODO: can this be true if `candidateEntry.fetchStrategy >= existingEntry.fetchStrategy`?) !existingEntry.isPartial && candidateEntry.isPartial) { // We're going to leave revalidating entry in the cache so that it doesn't // get revalidated again unnecessarily. Downgrade the Fulfilled entry to // Rejected and null out the data so it can be garbage collected. We leave // `staleAt` intact to prevent subsequent revalidation attempts only until // the entry expires. const rejectedEntry = candidateEntry; rejectedEntry.status = 3; rejectedEntry.loading = null; rejectedEntry.rsc = null; return null; } // Evict the existing entry from the cache. deleteFromCacheMap(existingEntry); } const isRevalidation = false; setInCacheMap(segmentCacheMap, varyPath, candidateEntry, isRevalidation); return candidateEntry; } export function createDetachedSegmentCacheEntry(staleAt) { const emptyEntry = { status: 0, // Default to assuming the fetch strategy will be PPR. This will be updated // when a fetch is actually initiated. fetchStrategy: FetchStrategy.PPR, rsc: null, loading: null, isPartial: true, promise: null, // Map-related fields ref: null, size: 0, staleAt, version: 0 }; return emptyEntry; } export function upgradeToPendingSegment(emptyEntry, fetchStrategy) { const pendingEntry = emptyEntry; pendingEntry.status = 1; pendingEntry.fetchStrategy = fetchStrategy; if (fetchStrategy === FetchStrategy.Full) { // We can assume the response will contain the full segment data. Set this // to false so we know it's OK to omit this segment from any navigation // requests that may happen while the data is still pending. pendingEntry.isPartial = false; } // Set the version here, since this is right before the request is initiated. // The next time the global cache version is incremented, the entry will // effectively be evicted. This happens before initiating the request, rather // than when receiving the response, because it's guaranteed to happen // before the data is read on the server. pendingEntry.version = getCurrentCacheVersion(); return pendingEntry; } function pingBlockedTasks(entry) { const blockedTasks = entry.blockedTasks; if (blockedTasks !== null) { for (const task of blockedTasks){ pingPrefetchTask(task); } entry.blockedTasks = null; } } function fulfillRouteCacheEntry(entry, tree, metadataVaryPath, staleAt, couldBeIntercepted, canonicalUrl, renderedSearch, isPPREnabled) { // The Head is not actually part of the route tree, but other than that, it's // fetched and cached like a segment. Some functions expect a RouteTree // object, so rather than fork the logic in all those places, we use this // "fake" one. const metadata = { requestKey: HEAD_REQUEST_KEY, segment: HEAD_REQUEST_KEY, varyPath: metadataVaryPath, // The metadata isn't really a "page" (though it isn't really a "segment" // either) but for the purposes of how this field is used, it behaves like // one. If this logic ever gets more complex we can change this to an enum. isPage: true, slots: null, isRootLayout: false, hasLoadingBoundary: HasLoadingBoundary.SubtreeHasNoLoadingBoundary, hasRuntimePrefetch: false }; const fulfilledEntry = entry; fulfilledEntry.status = 2; fulfilledEntry.tree = tree; fulfilledEntry.metadata = metadata; fulfilledEntry.staleAt = staleAt; fulfilledEntry.couldBeIntercepted = couldBeIntercepted; fulfilledEntry.canonicalUrl = canonicalUrl; fulfilledEntry.renderedSearch = renderedSearch; fulfilledEntry.isPPREnabled = isPPREnabled; pingBlockedTasks(entry); return fulfilledEntry; } function fulfillSegmentCacheEntry(segmentCacheEntry, rsc, loading, staleAt, isPartial) { const fulfilledEntry = segmentCacheEntry; fulfilledEntry.status = 2; fulfilledEntry.rsc = rsc; fulfilledEntry.loading = loading; fulfilledEntry.staleAt = staleAt; fulfilledEntry.isPartial = isPartial; // Resolve any listeners that were waiting for this data. if (segmentCacheEntry.promise !== null) { segmentCacheEntry.promise.resolve(fulfilledEntry); // Free the promise for garbage collection. fulfilledEntry.promise = null; } return fulfilledEntry; } function rejectRouteCacheEntry(entry, staleAt) { const rejectedEntry = entry; rejectedEntry.status = 3; rejectedEntry.staleAt = staleAt; pingBlockedTasks(entry); } function rejectSegmentCacheEntry(entry, staleAt) { const rejectedEntry = entry; rejectedEntry.status = 3; rejectedEntry.staleAt = staleAt; if (entry.promise !== null) { // NOTE: We don't currently propagate the reason the prefetch was canceled // but we could by accepting a `reason` argument. entry.promise.resolve(null); entry.promise = null; } } function convertRootTreePrefetchToRouteTree(rootTree, renderedPathname, renderedSearch, acc) { // Remove trailing and leading slashes const pathnameParts = renderedPathname.split('/').filter((p)=>p !== ''); const index = 0; const rootSegment = ROOT_SEGMENT_REQUEST_KEY; return convertTreePrefetchToRouteTree(rootTree.tree, rootSegment, null, ROOT_SEGMENT_REQUEST_KEY, pathnameParts, index, renderedSearch, acc); } function convertTreePrefetchToRouteTree(prefetch, segment, partialVaryPath, requestKey, pathnameParts, pathnamePartsIndex, renderedSearch, acc) { // Converts the route tree sent by the server into the format used by the // cache. The cached version of the tree includes additional fields, such as a // cache key for each segment. Since this is frequently accessed, we compute // it once instead of on every access. This same cache key is also used to // request the segment from the server. let slots = null; let isPage; let varyPath; const prefetchSlots = prefetch.slots; if (prefetchSlots !== null) { isPage = false; varyPath = finalizeLayoutVaryPath(requestKey, partialVaryPath); slots = {}; for(let parallelRouteKey in prefetchSlots){ const childPrefetch = prefetchSlots[parallelRouteKey]; const childParamName = childPrefetch.name; const childParamType = childPrefetch.paramType; const childServerSentParamKey = childPrefetch.paramKey; let childDoesAppearInURL; let childSegment; let childPartialVaryPath; if (childParamType !== null) { // This segment is parameterized. Get the param from the pathname. const childParamValue = parseDynamicParamFromURLPart(childParamType, pathnameParts, pathnamePartsIndex); // Assign a cache key to the segment, based on the param value. In the // pre-Segment Cache implementation, the server computes this and sends // it in the body of the response. In the Segment Cache implementation, // the server sends an empty string and we fill it in here. // TODO: We're intentionally not adding the search param to page // segments here; it's tracked separately and added back during a read. // This would clearer if we waited to construct the segment until it's // read from the cache, since that's effectively what we're // doing anyway. const childParamKey = // The server omits this field from the prefetch response when // cacheComponents is enabled. childServerSentParamKey !== null ? childServerSentParamKey : getCacheKeyForDynamicParam(childParamValue, ''); childPartialVaryPath = appendLayoutVaryPath(partialVaryPath, childParamKey); childSegment = [ childParamName, childParamKey, childParamType ]; childDoesAppearInURL = true; } else { // This segment does not have a param. Inherit the partial vary path of // the parent. childPartialVaryPath = partialVaryPath; childSegment = childParamName; childDoesAppearInURL = doesStaticSegmentAppearInURL(childParamName); } // Only increment the index if the segment appears in the URL. If it's a // "virtual" segment, like a route group, it remains the same. const childPathnamePartsIndex = childDoesAppearInURL ? pathnamePartsIndex + 1 : pathnamePartsIndex; const childRequestKeyPart = createSegmentRequestKeyPart(childSegment); const childRequestKey = appendSegmentRequestKeyPart(requestKey, parallelRouteKey, childRequestKeyPart); slots[parallelRouteKey] = convertTreePrefetchToRouteTree(childPrefetch, childSegment, childPartialVaryPath, childRequestKey, pathnameParts, childPathnamePartsIndex, renderedSearch, acc); } } else { if (requestKey.endsWith(PAGE_SEGMENT_KEY)) { // This is a page segment. isPage = true; varyPath = finalizePageVaryPath(requestKey, renderedSearch, partialVaryPath); // The metadata "segment" is not part the route tree, but it has the same // conceptual params as a page segment. Write the vary path into the // accumulator object. If there are multiple parallel pages, we use the // first one. Which page we choose is arbitrary as long as it's // consistently the same one every time every time. See // finalizeMetadataVaryPath for more details. if (acc.metadataVaryPath === null) { acc.metadataVaryPath = finalizeMetadataVaryPath(requestKey, renderedSearch, partialVaryPath); } } else { // This is a layout segment. isPage = false; varyPath = finalizeLayoutVaryPath(requestKey, partialVaryPath); } } return { requestKey, segment, varyPath, // TODO: Cheating the type system here a bit because TypeScript can't tell // that the type of isPage and varyPath are consistent. The fix would be to // create separate constructors and call the appropriate one from each of // the branches above. Just seems a bit overkill only for one field so I'll // leave it as-is for now. If isPage were wrong it would break the behavior // and we'd catch it quickly, anyway. isPage: isPage, slots, isRootLayout: prefetch.isRootLayout, // This field is only relevant to dynamic routes. For a PPR/static route, // there's always some partial loading state we can fetch. hasLoadingBoundary: HasLoadingBoundary.SegmentHasLoadingBoundary, hasRuntimePrefetch: prefetch.hasRuntimePrefetch }; } function convertRootFlightRouterStateToRouteTree(flightRouterState, renderedSearch, acc) { return convertFlightRouterStateToRouteTree(flightRouterState, ROOT_SEGMENT_REQUEST_KEY, null, renderedSearch, acc); } function convertFlightRouterStateToRouteTree(flightRouterState, requestKey, parentPartialVaryPath, renderedSearch, acc) { const originalSegment = flightRouterState[0]; let segment; let partialVaryPath; let isPage; let varyPath; if (Array.isArray(originalSegment)) { isPage = false; const paramCacheKey = originalSegment[1]; partialVaryPath = appendLayoutVaryPath(parentPartialVaryPath, paramCacheKey); varyPath = finalizeLayoutVaryPath(requestKey, partialVaryPath); segment = originalSegment; } else { // This segment does not have a param. Inherit the partial vary path of // the parent. partialVaryPath = parentPartialVaryPath; if (requestKey.endsWith(PAGE_SEGMENT_KEY)) { // This is a page segment. isPage = true; // The navigation implementation expects the search params to be included // in the segment. However, in the case of a static response, the search // params are omitted. So the client needs to add them back in when reading // from the Segment Cache. // // For consistency, we'll do this for dynamic responses, too. // // TODO: We should move search params out of FlightRouterState and handle // them entirely on the client, similar to our plan for dynamic params. segment = PAGE_SEGMENT_KEY; varyPath = finalizePageVaryPath(requestKey, renderedSearch, partialVaryPath); // The metadata "segment" is not part the route tree, but it has the same // conceptual params as a page segment. Write the vary path into the // accumulator object. If there are multiple parallel pages, we use the // first one. Which page we choose is arbitrary as long as it's // consistently the same one every time every time. See // finalizeMetadataVaryPath for more details. if (acc.metadataVaryPath === null) { acc.metadataVaryPath = finalizeMetadataVaryPath(requestKey, renderedSearch, partialVaryPath); } } else { // This is a layout segment. isPage = false; segment = originalSegment; varyPath = finalizeLayoutVaryPath(requestKey, partialVaryPath); } } let slots = null; const parallelRoutes = flightRouterState[1]; for(let parallelRouteKey in parallelRoutes){ const childRouterState = parallelRoutes[parallelRouteKey]; const childSegment = childRouterState[0]; // TODO: Eventually, the param values will not be included in the response // from the server. We'll instead fill them in on the client by parsing // the URL. This is where we'll do that. const childRequestKeyPart = createSegmentRequestKeyPart(childSegment); const childRequestKey = appendSegmentRequestKeyPart(requestKey, parallelRouteKey, childRequestKeyPart); const childTree = convertFlightRouterStateToRouteTree(childRouterState, childRequestKey, partialVaryPath, renderedSearch, acc); if (slots === null) { slots = { [parallelRouteKey]: childTree }; } else { slots[parallelRouteKey] = childTree; } } return { requestKey, segment, varyPath, // TODO: Cheating the type system here a bit because TypeScript can't tell // that the type of isPage and varyPath are consistent. The fix would be to // create separate constructors and call the appropriate one from each of // the branches above. Just seems a bit overkill only for one field so I'll // leave it as-is for now. If isPage were wrong it would break the behavior // and we'd catch it quickly, anyway. isPage: isPage, slots, isRootLayout: flightRouterState[4] === true, hasLoadingBoundary: flightRouterState[5] !== undefined ? flightRouterState[5] : HasLoadingBoundary.SubtreeHasNoLoadingBoundary, // Non-static tree responses are only used by apps that haven't adopted // Cache Components. So this is always false. hasRuntimePrefetch: false }; } export function convertRouteTreeToFlightRouterState(routeTree) { const parallelRoutes = {}; if (routeTree.slots !== null) { for(const parallelRouteKey in routeTree.slots){ parallelRoutes[parallelRouteKey] = convertRouteTreeToFlightRouterState(routeTree.slots[parallelRouteKey]); } } const flightRouterState = [ routeTree.segment, parallelRoutes, null, null, routeTree.isRootLayout ]; return flightRouterState; } export async function fetchRouteOnCacheMiss(entry, task, key) { // This function is allowed to use async/await because it contains the actual // fetch that gets issued on a cache miss. Notice it writes the result to the // cache entry directly, rather than return data that is then written by // the caller. const pathname = key.pathname; const search = key.search; const nextUrl = key.nextUrl; const segmentPath = '/_tree'; const headers = { [RSC_HEADER]: '1', [NEXT_ROUTER_PREFETCH_HEADER]: '1', [NEXT_ROUTER_SEGMENT_PREFETCH_HEADER]: segmentPath }; if (nextUrl !== null) { headers[NEXT_URL] = nextUrl; } try { const url = new URL(pathname + search, location.origin); let response; let urlAfterRedirects; if (isOutputExportMode) { // In output: "export" mode, we can't use headers to request a particular // segment. Instead, we encode the extra request information into the URL. // This is not part of the "public" interface of the app; it's an internal // Next.js implementation detail that the app developer should not need to // concern themselves with. // // For example, to request a segment: // // Path passed to : /path/to/page // Path passed to fetch: /path/to/page/__next-segments/_tree // // (This is not the exact protocol, just an illustration.) // // Before we do that, though, we need to account for redirects. Even in // output: "export" mode, a proxy might redirect the page to a different // location, but we shouldn't assume or expect that they also redirect all // the segment files, too. // // To check whether the page is redirected, previously we perform a range // request of 64 bytes of the HTML document to check if the target page // is part of this app (by checking if build id matches). Only if the target // page is part of this app do we determine the final canonical URL. // // However, as mentioned in https://github.com/vercel/next.js/pull/85903, // some popular static hosting providers (like Cloudflare Pages or Render.com) // do not support range requests, in the worst case, the entire HTML instead // of 64 bytes could be returned, which is wasteful. // // So instead, we drops the check for build id here, and simply perform // a HEAD request to rejects 1xx/4xx/5xx responses, and then determine the // final URL after redirects. // // NOTE: We could embed the route tree into the HTML document, to avoid // a second request. We're not doing that currently because it would make // the HTML document larger and affect normal page loads. const headResponse = await fetch(url, { method: 'HEAD' }); if (headResponse.status < 200 || headResponse.status >= 400) { // The target page responded w/o a successful status code // Could be a WAF serving a 403, or a 5xx from a backend // // Note that we can't use headResponse.ok here, because // Response#ok returns `false` with 3xx responses. rejectRouteCacheEntry(entry, Date.now() + 10 * 1000); return null; } urlAfterRedirects = headResponse.redirected ? new URL(headResponse.url) : url; response = await fetchPrefetchResponse(addSegmentPathToUrlInOutputExportMode(urlAfterRedirects, segmentPath), headers); } else { // "Server" mode. We can use request headers instead of the pathname. // TODO: The eventual plan is to get rid of our custom request headers and // encode everything into the URL, using a similar strategy to the // "output: export" block above. response = await fetchPrefetchResponse(url, headers); urlAfterRedirects = response !== null && response.redirected ? new URL(response.url) : url; } if (!response || !response.ok || // 204 is a Cache miss. Though theoretically this shouldn't happen when // PPR is enabled, because we always respond to route tree requests, even // if it needs to be blockingly generated on demand. response.status === 204 || !response.body) { // Server responded with an error, or with a miss. We should still cache // the response, but we can try again after 10 seconds. rejectRouteCacheEntry(entry, Date.now() + 10 * 1000); return null; } // TODO: The canonical URL is the href without the origin. I think // historically the reason for this is because the initial canonical URL // gets passed as a prop to the top-level React component, which means it // needs to be computed during SSR. If it were to include the origin, it // would need to always be same as location.origin on the client, to prevent // a hydration mismatch. To sidestep this complexity, we omit the origin. // // However, since this is neither a native URL object nor a fully qualified // URL string, we need to be careful about how we use it. To prevent subtle // mistakes, we should create a special type for it, instead of just string. // Or, we should just use a (readonly) URL object instead. The type of the // prop that we pass to seed the initial state does not need to be the same // type as the state itself. const canonicalUrl = createHrefFromUrl(urlAfterRedirects); // Check whether the response varies based on the Next-Url header. const varyHeader = response.headers.get('vary'); const couldBeIntercepted = varyHeader !== null && varyHeader.includes(NEXT_URL); // Track when the network connection closes. const closed = createPromiseWithResolvers(); // This checks whether the response was served from the per-segment cache, // rather than the old prefetching flow. If it fails, it implies that PPR // is disabled on this route. const routeIsPPREnabled = response.headers.get(NEXT_DID_POSTPONE_HEADER) === '2' || // In output: "export" mode, we can't rely on response headers. But if we // receive a well-formed response, we can assume it's a static response, // because all data is static in this mode. isOutputExportMode; if (routeIsPPREnabled) { const prefetchStream = createPrefetchResponseStream(response.body, closed.resolve, function onResponseSizeUpdate(size) { setSizeInCacheMap(entry, size); }); const serverData = await createFromNextReadableStream(prefetchStream, headers); if (serverData.buildId !== getAppBuildId()) { // The server build does not match the client. Treat as a 404. During // an actual navigation, the router will trigger an MPA navigation. // TODO: Consider moving the build ID to a response header so we can check // it before decoding the response, and so there's one way of checking // across all response types. // TODO: We should cache the fact that this is an MPA navigation. rejectRouteCacheEntry(entry, Date.now() + 10 * 1000); return null; } // Get the params that were used to render the target page. These may // be different from the params in the request URL, if the page // was rewritten. const renderedPathname = getRenderedPathname(response); const renderedSearch = getRenderedSearch(response); // Convert the server-sent data into the RouteTree format used by the // client cache. // // During this traversal, we accumulate additional data into this // "accumulator" object. const acc = { metadataVaryPath: null }; const routeTree = convertRootTreePrefetchToRouteTree(serverData, renderedPathname, renderedSearch, acc); const metadataVaryPath = acc.metadataVaryPath; if (metadataVaryPath === null) { rejectRouteCacheEntry(entry, Date.now() + 10 * 1000); return null; } const staleTimeMs = getStaleTimeMs(serverData.staleTime); fulfillRouteCacheEntry(entry, routeTree, metadataVaryPath, Date.now() + staleTimeMs, couldBeIntercepted, canonicalUrl, renderedSearch, routeIsPPREnabled); } else { // PPR is not enabled for this route. The server responds with a // different format (FlightRouterState) that we need to convert. // TODO: We will unify the responses eventually. I'm keeping the types // separate for now because FlightRouterState has so many // overloaded concerns. const prefetchStream = createPrefetchResponseStream(response.body, closed.resolve, function onResponseSizeUpdate(size) { setSizeInCacheMap(entry, size); }); const serverData = await createFromNextReadableStream(prefetchStream, headers); if (serverData.b !== getAppBuildId()) { // The server build does not match the client. Treat as a 404. During // an actual navigation, the router will trigger an MPA navigation. // TODO: Consider moving the build ID to a response header so we can check // it before decoding the response, and so there's one way of checking // across all response types. // TODO: We should cache the fact that this is an MPA navigation. rejectRouteCacheEntry(entry, Date.now() + 10 * 1000); return null; } writeDynamicTreeResponseIntoCache(Date.now(), task, // The non-PPR response format is what we'd get if we prefetched these segments // using the LoadingBoundary fetch strategy, so mark their cache entries accordingly. FetchStrategy.LoadingBoundary, response, serverData, entry, couldBeIntercepted, canonicalUrl, routeIsPPREnabled); } if (!couldBeIntercepted) { // This route will never be intercepted. So we can use this entry for all // requests to this route, regardless of the Next-Url header. This works // because when reading the cache we always check for a valid // non-intercepted entry first. // Re-key the entry. The `set` implementation handles removing it from // its previous position in the cache. We don't need to do anything to // update the LRU, because the entry is already in it. // TODO: Treat this as an upsert — should check if an entry already // exists at the new keypath, and if so, whether we should keep that // one instead. const fulfilledVaryPath = getFulfilledRouteVaryPath(pathname, search, nextUrl, couldBeIntercepted); const isRevalidation = false; setInCacheMap(routeCacheMap, fulfilledVaryPath, entry, isRevalidation); } // Return a promise that resolves when the network connection closes, so // the scheduler can track the number of concurrent network connections. return { value: null, closed: closed.promise }; } catch (error) { // Either the connection itself failed, or something bad happened while // decoding the response. rejectRouteCacheEntry(entry, Date.now() + 10 * 1000); return null; } } export async function fetchSegmentOnCacheMiss(route, segmentCacheEntry, routeKey, tree) { // This function is allowed to use async/await because it contains the actual // fetch that gets issued on a cache miss. Notice it writes the result to the // cache entry directly, rather than return data that is then written by // the caller. // // Segment fetches are non-blocking so we don't need to ping the scheduler // on completion. // Use the canonical URL to request the segment, not the original URL. These // are usually the same, but the canonical URL will be different if the route // tree response was redirected. To avoid an extra waterfall on every segment // request, we pass the redirected URL instead of the original one. const url = new URL(route.canonicalUrl, location.origin); const nextUrl = routeKey.nextUrl; const requestKey = tree.requestKey; const normalizedRequestKey = requestKey === ROOT_SEGMENT_REQUEST_KEY ? // handling of these requests, we encode the root segment path as // `_index` instead of as an empty string. This should be treated as // an implementation detail and not as a stable part of the protocol. // It just needs to match the equivalent logic that happens when // prerendering the responses. It should not leak outside of Next.js. '/_index' : requestKey; const headers = { [RSC_HEADER]: '1', [NEXT_ROUTER_PREFETCH_HEADER]: '1', [NEXT_ROUTER_SEGMENT_PREFETCH_HEADER]: normalizedRequestKey }; if (nextUrl !== null) { headers[NEXT_URL] = nextUrl; } const requestUrl = isOutputExportMode ? addSegmentPathToUrlInOutputExportMode(url, normalizedRequestKey) : url; try { const response = await fetchPrefetchResponse(requestUrl, headers); if (!response || !response.ok || response.status === 204 || // Cache miss // This checks whether the response was served from the per-segment cache, // rather than the old prefetching flow. If it fails, it implies that PPR // is disabled on this route. Theoretically this should never happen // because we only issue requests for segments once we've verified that // the route supports PPR. response.headers.get(NEXT_DID_POSTPONE_HEADER) !== '2' && // In output: "export" mode, we can't rely on response headers. But if // we receive a well-formed response, we can assume it's a static // response, because all data is static in this mode. !isOutputExportMode || !response.body) { // Server responded with an error, or with a miss. We should still cache // the response, but we can try again after 10 seconds. rejectSegmentCacheEntry(segmentCacheEntry, Date.now() + 10 * 1000); return null; } // Track when the network connection closes. const closed = createPromiseWithResolvers(); // Wrap the original stream in a new stream that never closes. That way the // Flight client doesn't error if there's a hanging promise. const prefetchStream = createPrefetchResponseStream(response.body, closed.resolve, function onResponseSizeUpdate(size) { setSizeInCacheMap(segmentCacheEntry, size); }); const serverData = await createFromNextReadableStream(prefetchStream, headers); if (serverData.buildId !== getAppBuildId()) { // The server build does not match the client. Treat as a 404. During // an actual navigation, the router will trigger an MPA navigation. // TODO: Consider moving the build ID to a response header so we can check // it before decoding the response, and so there's one way of checking // across all response types. rejectSegmentCacheEntry(segmentCacheEntry, Date.now() + 10 * 1000); return null; } return { value: fulfillSegmentCacheEntry(segmentCacheEntry, serverData.rsc, serverData.loading, // TODO: The server does not currently provide per-segment stale time. // So we use the stale time of the route. route.staleAt, serverData.isPartial), // Return a promise that resolves when the network connection closes, so // the scheduler can track the number of concurrent network connections. closed: closed.promise }; } catch (error) { // Either the connection itself failed, or something bad happened while // decoding the response. rejectSegmentCacheEntry(segmentCacheEntry, Date.now() + 10 * 1000); return null; } } export async function fetchSegmentPrefetchesUsingDynamicRequest(task, route, fetchStrategy, dynamicRequestTree, spawnedEntries) { const key = task.key; const url = new URL(route.canonicalUrl, location.origin); const nextUrl = key.nextUrl; if (spawnedEntries.size === 1 && spawnedEntries.has(route.metadata.requestKey)) { // The only thing pending is the head. Instruct the server to // skip over everything else. dynamicRequestTree = MetadataOnlyRequestTree; } const headers = { [RSC_HEADER]: '1', [NEXT_ROUTER_STATE_TREE_HEADER]: prepareFlightRouterStateForRequest(dynamicRequestTree) }; if (nextUrl !== null) { headers[NEXT_URL] = nextUrl; } switch(fetchStrategy){ case FetchStrategy.Full: { break; } case FetchStrategy.PPRRuntime: { headers[NEXT_ROUTER_PREFETCH_HEADER] = '2'; break; } case FetchStrategy.LoadingBoundary: { headers[NEXT_ROUTER_PREFETCH_HEADER] = '1'; break; } default: { fetchStrategy; } } try { const response = await fetchPrefetchResponse(url, headers); if (!response || !response.ok || !response.body) { // Server responded with an error, or with a miss. We should still cache // the response, but we can try again after 10 seconds. rejectSegmentEntriesIfStillPending(spawnedEntries, Date.now() + 10 * 1000); return null; } const renderedSearch = getRenderedSearch(response); if (renderedSearch !== route.renderedSearch) { // The search params that were used to render the target page are // different from the search params in the request URL. This only happens // when there's a dynamic rewrite in between the tree prefetch and the // data prefetch. // TODO: For now, since this is an edge case, we reject the prefetch, but // the proper way to handle this is to evict the stale route tree entry // then fill the cache with the new response. rejectSegmentEntriesIfStillPending(spawnedEntries, Date.now() + 10 * 1000); return null; } // Track when the network connection closes. const closed = createPromiseWithResolvers(); let fulfilledEntries = null; const prefetchStream = createPrefetchResponseStream(response.body, closed.resolve, function onResponseSizeUpdate(totalBytesReceivedSoFar) { // When processing a dynamic response, we don't know how large each // individual segment is, so approximate by assiging each segment // the average of the total response size. if (fulfilledEntries === null) { // Haven't received enough data yet to know which segments // were included. return; } const averageSize = totalBytesReceivedSoFar / fulfilledEntries.length; for (const entry of fulfilledEntries){ setSizeInCacheMap(entry, averageSize); } }); const serverData = await createFromNextReadableStream(prefetchStream, headers); const isResponsePartial = fetchStrategy === FetchStrategy.PPRRuntime ? serverData.rp?.[0] === true : // (even if we did set the prefetch header, we only use this codepath for non-PPR-enabled routes) false; // Aside from writing the data into the cache, this function also returns // the entries that were fulfilled, so we can streamingly update their sizes // in the LRU as more data comes in. fulfilledEntries = writeDynamicRenderResponseIntoCache(Date.now(), task, fetchStrategy, response, serverData, isResponsePartial, route, spawnedEntries); // Return a promise that resolves when the network connection closes, so // the scheduler can track the number of concurrent network connections. return { value: null, closed: closed.promise }; } catch (error) { rejectSegmentEntriesIfStillPending(spawnedEntries, Date.now() + 10 * 1000); return null; } } function writeDynamicTreeResponseIntoCache(now, task, fetchStrategy, response, serverData, entry, couldBeIntercepted, canonicalUrl, routeIsPPREnabled) { // Get the URL that was used to render the target page. This may be different // from the URL in the request URL, if the page was rewritten. const renderedSearch = getRenderedSearch(response); const normalizedFlightDataResult = normalizeFlightData(serverData.f); if (// A string result means navigating to this route will result in an // MPA navigation. typeof normalizedFlightDataResult === 'string' || normalizedFlightDataResult.length !== 1) { rejectRouteCacheEntry(entry, now + 10 * 1000); return; } const flightData = normalizedFlightDataResult[0]; if (!flightData.isRootRender) { // Unexpected response format. rejectRouteCacheEntry(entry, now + 10 * 1000); return; } const flightRouterState = flightData.tree; // For runtime prefetches, stale time is in the payload at rp[1]. // For other responses, fall back to the header. const staleTimeSeconds = typeof serverData.rp?.[1] === 'number' ? serverData.rp[1] : parseInt(response.headers.get(NEXT_ROUTER_STALE_TIME_HEADER) ?? '', 10); const staleTimeMs = !isNaN(staleTimeSeconds) ? getStaleTimeMs(staleTimeSeconds) : STATIC_STALETIME_MS; // If the response contains dynamic holes, then we must conservatively assume // that any individual segment might contain dynamic holes, and also the // head. If it did not contain dynamic holes, then we can assume every segment // and the head is completely static. const isResponsePartial = response.headers.get(NEXT_DID_POSTPONE_HEADER) === '1'; // Convert the server-sent data into the RouteTree format used by the // client cache. // // During this traversal, we accumulate additional data into this // "accumulator" object. const acc = { metadataVaryPath: null }; const routeTree = convertRootFlightRouterStateToRouteTree(flightRouterState, renderedSearch, acc); const metadataVaryPath = acc.metadataVaryPath; if (metadataVaryPath === null) { rejectRouteCacheEntry(entry, now + 10 * 1000); return; } const fulfilledEntry = fulfillRouteCacheEntry(entry, routeTree, metadataVaryPath, now + staleTimeMs, couldBeIntercepted, canonicalUrl, renderedSearch, routeIsPPREnabled); // If the server sent segment data as part of the response, we should write // it into the cache to prevent a second, redundant prefetch request. // // TODO: When `clientSegmentCache` is enabled, the server does not include // segment data when responding to a route tree prefetch request. However, // when `clientSegmentCache` is set to "client-only", and PPR is enabled (or // the page is fully static), the normal check is bypassed and the server // responds with the full page. This is a temporary situation until we can // remove the "client-only" option. Then, we can delete this function call. writeDynamicRenderResponseIntoCache(now, task, fetchStrategy, response, serverData, isResponsePartial, fulfilledEntry, null); } function rejectSegmentEntriesIfStillPending(entries, staleAt) { const fulfilledEntries = []; for (const entry of entries.values()){ if (entry.status === 1) { rejectSegmentCacheEntry(entry, staleAt); } else if (entry.status === 2) { fulfilledEntries.push(entry); } } return fulfilledEntries; } function writeDynamicRenderResponseIntoCache(now, task, fetchStrategy, response, serverData, isResponsePartial, route, spawnedEntries) { if (serverData.b !== getAppBuildId()) { // The server build does not match the client. Treat as a 404. During // an actual navigation, the router will trigger an MPA navigation. // TODO: Consider moving the build ID to a response header so we can check // it before decoding the response, and so there's one way of checking // across all response types. if (spawnedEntries !== null) { rejectSegmentEntriesIfStillPending(spawnedEntries, now + 10 * 1000); } return null; } const flightDatas = normalizeFlightData(serverData.f); if (typeof flightDatas === 'string') { // This means navigating to this route will result in an MPA navigation. // TODO: We should cache this, too, so that the MPA navigation is immediate. return null; } // For runtime prefetches, stale time is in the payload at rp[1]. // For other responses, fall back to the header. const staleTimeSeconds = typeof serverData.rp?.[1] === 'number' ? serverData.rp[1] : parseInt(response.headers.get(NEXT_ROUTER_STALE_TIME_HEADER) ?? '', 10); const staleTimeMs = !isNaN(staleTimeSeconds) ? getStaleTimeMs(staleTimeSeconds) : STATIC_STALETIME_MS; const staleAt = now + staleTimeMs; for (const flightData of flightDatas){ const seedData = flightData.seedData; if (seedData !== null) { // The data sent by the server represents only a subtree of the app. We // need to find the part of the task tree that matches the response. // // segmentPath represents the parent path of subtree. It's a repeating // pattern of parallel route key and segment: // // [string, Segment, string, Segment, string, Segment, ...] const segmentPath = flightData.segmentPath; let tree = route.tree; for(let i = 0; i < segmentPath.length; i += 2){ const parallelRouteKey = segmentPath[i]; if (tree?.slots?.[parallelRouteKey] !== undefined) { tree = tree.slots[parallelRouteKey]; } else { if (spawnedEntries !== null) { rejectSegmentEntriesIfStillPending(spawnedEntries, now + 10 * 1000); } return null; } } writeSeedDataIntoCache(now, task, fetchStrategy, route, tree, staleAt, seedData, isResponsePartial, spawnedEntries); } const head = flightData.head; if (head !== null) { fulfillEntrySpawnedByRuntimePrefetch(now, fetchStrategy, route, head, null, flightData.isHeadPartial, staleAt, route.metadata, spawnedEntries); } } // Any entry that's still pending was intentionally not rendered by the // server, because it was inside the loading boundary. Mark them as rejected // so we know not to fetch them again. // TODO: If PPR is enabled on some routes but not others, then it's possible // that a different page is able to do a per-segment prefetch of one of the // segments we're marking as rejected here. We should mark on the segment // somehow that the reason for the rejection is because of a non-PPR prefetch. // That way a per-segment prefetch knows to disregard the rejection. if (spawnedEntries !== null) { const fulfilledEntries = rejectSegmentEntriesIfStillPending(spawnedEntries, now + 10 * 1000); return fulfilledEntries; } return null; } function writeSeedDataIntoCache(now, task, fetchStrategy, route, tree, staleAt, seedData, isResponsePartial, entriesOwnedByCurrentTask) { // This function is used to write the result of a runtime server request // (CacheNodeSeedData) into the prefetch cache. const rsc = seedData[0]; const loading = seedData[2]; const isPartial = rsc === null || isResponsePartial; fulfillEntrySpawnedByRuntimePrefetch(now, fetchStrategy, route, rsc, loading, isPartial, staleAt, tree, entriesOwnedByCurrentTask); // Recursively write the child data into the cache. const slots = tree.slots; if (slots !== null) { const seedDataChildren = seedData[1]; for(const parallelRouteKey in slots){ const childTree = slots[parallelRouteKey]; const childSeedData = seedDataChildren[parallelRouteKey]; if (childSeedData !== null && childSeedData !== undefined) { writeSeedDataIntoCache(now, task, fetchStrategy, route, childTree, staleAt, childSeedData, isResponsePartial, entriesOwnedByCurrentTask); } } } } function fulfillEntrySpawnedByRuntimePrefetch(now, fetchStrategy, route, rsc, loading, isPartial, staleAt, tree, entriesOwnedByCurrentTask) { // We should only write into cache entries that are owned by us. Or create // a new one and write into that. We must never write over an entry that was // created by a different task, because that causes data races. const ownedEntry = entriesOwnedByCurrentTask !== null ? entriesOwnedByCurrentTask.get(tree.requestKey) : undefined; if (ownedEntry !== undefined) { fulfillSegmentCacheEntry(ownedEntry, rsc, loading, staleAt, isPartial); } else { // There's no matching entry. Attempt to create a new one. const possiblyNewEntry = readOrCreateSegmentCacheEntry(now, fetchStrategy, route, tree); if (possiblyNewEntry.status === 0) { // Confirmed this is a new entry. We can fulfill it. const newEntry = possiblyNewEntry; fulfillSegmentCacheEntry(upgradeToPendingSegment(newEntry, fetchStrategy), rsc, loading, staleAt, isPartial); } else { // There was already an entry in the cache. But we may be able to // replace it with the new one from the server. const newEntry = fulfillSegmentCacheEntry(upgradeToPendingSegment(createDetachedSegmentCacheEntry(staleAt), fetchStrategy), rsc, loading, staleAt, isPartial); upsertSegmentEntry(now, getSegmentVaryPathForRequest(fetchStrategy, tree), newEntry); } } } async function fetchPrefetchResponse(url, headers) { const fetchPriority = 'low'; // When issuing a prefetch request, don't immediately decode the response; we // use the lower level `createFromResponse` API instead because we need to do // some extra processing of the response stream. See // `createPrefetchResponseStream` for more details. const shouldImmediatelyDecode = false; const response = await createFetch(url, headers, fetchPriority, shouldImmediatelyDecode); if (!response.ok) { return null; } // Check the content type if (isOutputExportMode) { // In output: "export" mode, we relaxed about the content type, since it's // not Next.js that's serving the response. If the status is OK, assume the // response is valid. If it's not a valid response, the Flight client won't // be able to decode it, and we'll treat it as a miss. } else { const contentType = response.headers.get('content-type'); const isFlightResponse = contentType && contentType.startsWith(RSC_CONTENT_TYPE_HEADER); if (!isFlightResponse) { return null; } } return response; } function createPrefetchResponseStream(originalFlightStream, onStreamClose, onResponseSizeUpdate) { // When PPR is enabled, prefetch streams may contain references that never // resolve, because that's how we encode dynamic data access. In the decoded // object returned by the Flight client, these are reified into hanging // promises that suspend during render, which is effectively what we want. // The UI resolves when it switches to the dynamic data stream // (via useDeferredValue(dynamic, static)). // // However, the Flight implementation currently errors if the server closes // the response before all the references are resolved. As a cheat to work // around this, we wrap the original stream in a new stream that never closes, // and therefore doesn't error. // // While processing the original stream, we also incrementally update the size // of the cache entry in the LRU. let totalByteLength = 0; const reader = originalFlightStream.getReader(); return new ReadableStream({ async pull (controller) { while(true){ const { done, value } = await reader.read(); if (!done) { // Pass to the target stream and keep consuming the Flight response // from the server. controller.enqueue(value); // Incrementally update the size of the cache entry in the LRU. // NOTE: Since prefetch responses are delivered in a single chunk, // it's not really necessary to do this streamingly, but I'm doing it // anyway in case this changes in the future. totalByteLength += value.byteLength; onResponseSizeUpdate(totalByteLength); continue; } // The server stream has closed. Exit, but intentionally do not close // the target stream. We do notify the caller, though. onStreamClose(); return; } } }); } function addSegmentPathToUrlInOutputExportMode(url, segmentPath) { if (isOutputExportMode) { // In output: "export" mode, we cannot use a header to encode the segment // path. Instead, we append it to the end of the pathname. const staticUrl = new URL(url); const routeDir = staticUrl.pathname.endsWith('/') ? staticUrl.pathname.slice(0, -1) : staticUrl.pathname; const staticExportFilename = convertSegmentPathToStaticExportFilename(segmentPath); staticUrl.pathname = `${routeDir}/${staticExportFilename}`; return staticUrl; } return url; } /** * Checks whether the new fetch strategy is likely to provide more content than the old one. * * Generally, when an app uses dynamic data, a "more specific" fetch strategy is expected to provide more content: * - `LoadingBoundary` only provides static layouts * - `PPR` can provide shells for each segment (even for segments that use dynamic data) * - `PPRRuntime` can additionally include content that uses searchParams, params, or cookies * - `Full` includes all the content, even if it uses dynamic data * * However, it's possible that a more specific fetch strategy *won't* give us more content if: * - a segment is fully static * (then, `PPR`/`PPRRuntime`/`Full` will all yield equivalent results) * - providing searchParams/params/cookies doesn't reveal any more content, e.g. because of an `await connection()` * (then, `PPR` and `PPRRuntime` will yield equivalent results, only `Full` will give us more) * Because of this, when comparing two segments, we should also check if the existing segment is partial. * If it's not partial, then there's no need to prefetch it again, even using a "more specific" strategy. * There's currently no way to know if `PPRRuntime` will yield more data that `PPR`, so we have to assume it will. * * Also note that, in practice, we don't expect to be comparing `LoadingBoundary` to `PPR`/`PPRRuntime`, * because a non-PPR-enabled route wouldn't ever use the latter strategies. It might however use `Full`. */ export function canNewFetchStrategyProvideMoreContent(currentStrategy, newStrategy) { return currentStrategy < newStrategy; } //# sourceMappingURL=cache.js.map