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scrap/node_modules/next/dist/esm/server/app-render/dynamic-rendering.js
2024-09-24 03:52:46 +00:00

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JavaScript

/**
* The functions provided by this module are used to communicate certain properties
* about the currently running code so that Next.js can make decisions on how to handle
* the current execution in different rendering modes such as pre-rendering, resuming, and SSR.
*
* Today Next.js treats all code as potentially static. Certain APIs may only make sense when dynamically rendering.
* Traditionally this meant deopting the entire render to dynamic however with PPR we can now deopt parts
* of a React tree as dynamic while still keeping other parts static. There are really two different kinds of
* Dynamic indications.
*
* The first is simply an intention to be dynamic. unstable_noStore is an example of this where
* the currently executing code simply declares that the current scope is dynamic but if you use it
* inside unstable_cache it can still be cached. This type of indication can be removed if we ever
* make the default dynamic to begin with because the only way you would ever be static is inside
* a cache scope which this indication does not affect.
*
* The second is an indication that a dynamic data source was read. This is a stronger form of dynamic
* because it means that it is inappropriate to cache this at all. using a dynamic data source inside
* unstable_cache should error. If you want to use some dynamic data inside unstable_cache you should
* read that data outside the cache and pass it in as an argument to the cached function.
*/ // Once postpone is in stable we should switch to importing the postpone export directly
import React from "react";
import { DynamicServerError } from "../../client/components/hooks-server-context";
import { StaticGenBailoutError } from "../../client/components/static-generation-bailout";
import { getPathname } from "../../lib/url";
const hasPostpone = typeof React.unstable_postpone === "function";
export function createPrerenderState(isDebugSkeleton) {
return {
isDebugSkeleton,
dynamicAccesses: []
};
}
/**
* This function communicates that the current scope should be treated as dynamic.
*
* In most cases this function is a no-op but if called during
* a PPR prerender it will postpone the current sub-tree.
*/ export function markCurrentScopeAsDynamic(store, expression) {
const pathname = getPathname(store.urlPathname);
if (store.isUnstableCacheCallback) {
// inside cache scopes marking a scope as dynamic has no effect because the outer cache scope
// creates a cache boundary. This is subtly different from reading a dynamic data source which is
// forbidden inside a cache scope.
return;
} else if (store.dynamicShouldError) {
throw new StaticGenBailoutError(`Route ${pathname} with \`dynamic = "error"\` couldn't be rendered statically because it used \`${expression}\`. See more info here: https://nextjs.org/docs/app/building-your-application/rendering/static-and-dynamic#dynamic-rendering`);
} else if (// We are in a prerender (PPR enabled, during build)
store.prerenderState) {
// We track that we had a dynamic scope that postponed.
// This will be used by the renderer to decide whether
// the prerender requires a resume
postponeWithTracking(store.prerenderState, expression, pathname);
} else {
store.revalidate = 0;
if (store.isStaticGeneration) {
// We aren't prerendering but we are generating a static page. We need to bail out of static generation
const err = new DynamicServerError(`Route ${pathname} 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;
}
}
}
/**
* This function communicates that some dynamic data was read. This typically would refer to accessing
* a Request specific data store such as cookies or headers. This function is not how end-users will
* describe reading from dynamic data sources which are valid to cache and up to the author to make
* a determination of when to do so.
*
* If we are inside a cache scope we error
* Also during a PPR Prerender we postpone
*/ export function trackDynamicDataAccessed(store, expression) {
const pathname = getPathname(store.urlPathname);
if (store.isUnstableCacheCallback) {
throw new Error(`Route ${pathname} used "${expression}" inside a function cached with "unstable_cache(...)". Accessing Dynamic data sources inside a cache scope is not supported. If you need this data inside a cached function use "${expression}" outside of the cached function and pass the required dynamic data in as an argument. See more info here: https://nextjs.org/docs/app/api-reference/functions/unstable_cache`);
} else if (store.dynamicShouldError) {
throw new StaticGenBailoutError(`Route ${pathname} with \`dynamic = "error"\` couldn't be rendered statically because it used \`${expression}\`. See more info here: https://nextjs.org/docs/app/building-your-application/rendering/static-and-dynamic#dynamic-rendering`);
} else if (// We are in a prerender (PPR enabled, during build)
store.prerenderState) {
// We track that we had a dynamic scope that postponed.
// This will be used by the renderer to decide whether
// the prerender requires a resume
postponeWithTracking(store.prerenderState, expression, pathname);
} else {
store.revalidate = 0;
if (store.isStaticGeneration) {
// We aren't prerendering but we are generating a static page. We need to bail out of static generation
const err = new DynamicServerError(`Route ${pathname} couldn't be rendered statically because it used \`${expression}\`. See more info here: https://nextjs.org/docs/messages/dynamic-server-error`);
store.dynamicUsageDescription = expression;
store.dynamicUsageStack = err.stack;
throw err;
}
}
}
export function Postpone({ reason, prerenderState, pathname }) {
postponeWithTracking(prerenderState, reason, pathname);
}
// @TODO refactor patch-fetch and this function to better model dynamic semantics. Currently this implementation
// is too explicit about postponing if we are in a prerender and patch-fetch contains a lot of logic for determining
// what makes the fetch "dynamic". It also doesn't handle Non PPR cases so it is isn't as consistent with the other
// dynamic-rendering methods.
export function trackDynamicFetch(store, expression) {
if (store.prerenderState) {
postponeWithTracking(store.prerenderState, expression, store.urlPathname);
}
}
function postponeWithTracking(prerenderState, expression, pathname) {
assertPostpone();
const reason = `Route ${pathname} needs to bail out of prerendering at this point because it used ${expression}. ` + `React throws this special object to indicate where. It should not be caught by ` + `your own try/catch. Learn more: https://nextjs.org/docs/messages/ppr-caught-error`;
prerenderState.dynamicAccesses.push({
// When we aren't debugging, we don't need to create another error for the
// stack trace.
stack: prerenderState.isDebugSkeleton ? new Error().stack : undefined,
expression
});
React.unstable_postpone(reason);
}
export function usedDynamicAPIs(prerenderState) {
return prerenderState.dynamicAccesses.length > 0;
}
export function formatDynamicAPIAccesses(prerenderState) {
return prerenderState.dynamicAccesses.filter((access)=>typeof access.stack === "string" && access.stack.length > 0).map(({ expression, stack })=>{
stack = stack.split("\n")// Remove the "Error: " prefix from the first line of the stack trace as
// well as the first 4 lines of the stack trace which is the distance
// from the user code and the `new Error().stack` call.
.slice(4).filter((line)=>{
// Exclude Next.js internals from the stack trace.
if (line.includes("node_modules/next/")) {
return false;
}
// Exclude anonymous functions from the stack trace.
if (line.includes(" (<anonymous>)")) {
return false;
}
// Exclude Node.js internals from the stack trace.
if (line.includes(" (node:")) {
return false;
}
return true;
}).join("\n");
return `Dynamic API Usage Debug - ${expression}:\n${stack}`;
});
}
function assertPostpone() {
if (!hasPostpone) {
throw new Error(`Invariant: React.unstable_postpone is not defined. This suggests the wrong version of React was loaded. This is a bug in Next.js`);
}
}
/**
* This is a bit of a hack to allow us to abort a render using a Postpone instance instead of an Error which changes React's
* abort semantics slightly.
*/ export function createPostponedAbortSignal(reason) {
assertPostpone();
const controller = new AbortController();
// We get our hands on a postpone instance by calling postpone and catching the throw
try {
React.unstable_postpone(reason);
} catch (x) {
controller.abort(x);
}
return controller.signal;
}
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