110 lines
4.6 KiB
TypeScript
110 lines
4.6 KiB
TypeScript
import type { FlightRouterState } from '../../../server/app-render/types';
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import type { RouteCacheKey } from './cache-key';
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import { PrefetchPriority } from '../segment-cache';
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export type PrefetchTask = {
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key: RouteCacheKey;
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/**
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* The FlightRouterState at the time the task was initiated. This is needed
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* when falling back to the non-PPR behavior, which only prefetches up to
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* the first loading boundary.
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*/
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treeAtTimeOfPrefetch: FlightRouterState;
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/**
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* Whether to prefetch dynamic data, in addition to static data. This is
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* used by <Link prefetch={true}>.
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*/
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includeDynamicData: boolean;
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/**
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* sortId is an incrementing counter
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*
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* Newer prefetches are prioritized over older ones, so that as new links
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* enter the viewport, they are not starved by older links that are no
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* longer relevant. In the future, we can add additional prioritization
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* heuristics, like removing prefetches once a link leaves the viewport.
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*
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* The sortId is assigned when the prefetch is initiated, and reassigned if
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* the same task is prefetched again (effectively bumping it to the top of
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* the queue).
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*
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* TODO: We can add additional fields here to indicate what kind of prefetch
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* it is. For example, was it initiated by a link? Or was it an imperative
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* call? If it was initiated by a link, we can remove it from the queue when
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* the link leaves the viewport, but if it was an imperative call, then we
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* should keep it in the queue until it's fulfilled.
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*
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* We can also add priority levels. For example, hovering over a link could
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* increase the priority of its prefetch.
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*/
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sortId: number;
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/**
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* The priority of the task. Like sortId, this affects the task's position in
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* the queue, so it must never be updated without resifting the heap.
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*/
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priority: PrefetchPriority;
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/**
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* The phase of the task. Tasks are split into multiple phases so that their
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* priority can be adjusted based on what kind of work they're doing.
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* Concretely, prefetching the route tree is higher priority than prefetching
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* segment data.
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*/
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phase: PrefetchPhase;
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/**
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* Temporary state for tracking the currently running task. This is currently
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* used to track whether a task deferred some work to run background at
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* priority, but we might need it for additional state in the future.
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*/
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hasBackgroundWork: boolean;
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/**
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* True if the prefetch was cancelled.
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*/
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isCanceled: boolean;
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/**
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* The index of the task in the heap's backing array. Used to efficiently
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* change the priority of a task by re-sifting it, which requires knowing
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* where it is in the array. This is only used internally by the heap
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* algorithm. The naive alternative is indexOf every time a task is queued,
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* which has O(n) complexity.
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*
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* We also use this field to check whether a task is currently in the queue.
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*/
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_heapIndex: number;
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};
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/**
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* Prefetch tasks are processed in two phases: first the route tree is fetched,
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* then the segments. We use this to priortize tasks that have not yet fetched
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* the route tree.
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*/
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declare const enum PrefetchPhase {
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RouteTree = 1,
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Segments = 0
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}
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export type PrefetchSubtaskResult<T> = {
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/**
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* A promise that resolves when the network connection is closed.
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*/
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closed: Promise<void>;
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value: T;
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};
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/**
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* Initiates a prefetch task for the given URL. If a prefetch for the same URL
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* is already in progress, this will bump it to the top of the queue.
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*
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* This is not a user-facing function. By the time this is called, the href is
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* expected to be validated and normalized.
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*
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* @param key The RouteCacheKey to prefetch.
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* @param treeAtTimeOfPrefetch The app's current FlightRouterState
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* @param includeDynamicData Whether to prefetch dynamic data, in addition to
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* static data. This is used by <Link prefetch={true}>.
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*/
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export declare function schedulePrefetchTask(key: RouteCacheKey, treeAtTimeOfPrefetch: FlightRouterState, includeDynamicData: boolean, priority: PrefetchPriority): PrefetchTask;
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export declare function cancelPrefetchTask(task: PrefetchTask): void;
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export declare function reschedulePrefetchTask(task: PrefetchTask, treeAtTimeOfPrefetch: FlightRouterState, includeDynamicData: boolean, priority: PrefetchPriority): void;
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/**
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* Notify the scheduler that we've received new data for an in-progress
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* prefetch. The corresponding task will be added back to the queue (unless the
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* task has been canceled in the meantime).
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*/
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export declare function pingPrefetchTask(task: PrefetchTask): void;
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export {};
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