next/dist/esm/server/app-render/module-loading/track-module-loading.instance.js

The React Framework

import { CacheSignal } from '../cache-signal';
import { isThenable } from '../../../shared/lib/is-thenable';
/**
 * Tracks all in-flight async imports and chunk loads.
 * Initialized lazily, because we don't want this to error in case it gets pulled into an edge runtime module.
 */ let _moduleLoadingSignal;
function getModuleLoadingSignal() {
    if (!_moduleLoadingSignal) {
        _moduleLoadingSignal = new CacheSignal();
    }
    return _moduleLoadingSignal;
}
export function trackPendingChunkLoad(promise) {
    const moduleLoadingSignal = getModuleLoadingSignal();
    moduleLoadingSignal.trackRead(promise);
}
export function trackPendingImport(exportsOrPromise) {
    const moduleLoadingSignal = getModuleLoadingSignal();
    // requiring an async module returns a promise.
    // if it's sync, there's nothing to track.
    if (isThenable(exportsOrPromise)) {
        // A client reference proxy might look like a promise, but we can only call `.then()` on it, not e.g. `.finally()`.
        // Turn it into a real promise to avoid issues elsewhere.
        const promise = Promise.resolve(exportsOrPromise);
        moduleLoadingSignal.trackRead(promise);
    }
}
/**
 * A top-level dynamic import (or chunk load):
 *
 *   1. delays a prerender (potentially for a task or longer)
 *   2. may reveal more caches that need be filled
 *
 * So if we see one, we want to extend the duration of `cacheSignal` at least until the import/chunk-load is done.
 */ export function trackPendingModules(cacheSignal) {
    const moduleLoadingSignal = getModuleLoadingSignal();
    // We can't just use `cacheSignal.trackRead(moduleLoadingSignal.cacheReady())`,
    // because we might start and finish multiple batches of module loads while waiting for caches,
    // and `moduleLoadingSignal.cacheReady()` would resolve after the first batch.
    // Instead, we'll keep notifying `cacheSignal` of each import/chunk-load.
    const unsubscribe = moduleLoadingSignal.subscribeToReads(cacheSignal);
    // Later, when `cacheSignal` is no longer waiting for any caches (or imports that we've notified it of),
    // we can unsubscribe it.
    cacheSignal.cacheReady().then(unsubscribe);
}

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