PDF Document Resource

1import {
2  isResourceError,
3  isViewerFormatError,
4  ViewerFormatError,
5  type ViewerFormatErrorMapperOptions,
6} from "@/lib/viewer-errors";
7import type {
8  PdfDocumentProxy,
9  PdfjsModule,
10  PdfPageProxy,
11} from "@/lib/pdf-document-types";
12import type {
13  ViewerContentBytes,
14  ViewerContentDirectUrl,
15  ViewerContentIdentity,
16} from "@/lib/viewer-resource";
17 
18const PDF_CACHE_MAX = 6;
19 
20type PdfDocumentContent = ViewerContentIdentity &
21  ViewerContentDirectUrl &
22  ViewerContentBytes;
23 
24type DocumentCacheEntry = {
25  loadKey: string;
26  promise: Promise<PdfDocumentProxy>;
27  consumers: number;
28  lastUsedAt: number;
29  retainRejected: boolean;
30  status: "pending" | "resolved" | "rejected";
31  document?: PdfDocumentProxy;
32  error?: unknown;
33};
34 
35type PageCacheEntry = {
36  promise: Promise<PdfPageProxy>;
37  retainRejected: boolean;
38  status: "pending" | "resolved" | "rejected";
39  page?: PdfPageProxy;
40  error?: unknown;
41};
42 
43type PdfResourceOptions = {
44  retainRejected?: boolean;
45};
46 
47let pdfjsPromise: Promise<PdfjsModule> | null = null;
48const documentCache = new Map<string, DocumentCacheEntry>();
49const pageCache = new WeakMap<PdfDocumentProxy, Map<number, PageCacheEntry>>();
50const detachedDocumentEntries = new Set<DocumentCacheEntry>();
51let pruneTimer = 0;
52 
53function loadPdfjs(): Promise<PdfjsModule> {
54  if (!pdfjsPromise) {
55    pdfjsPromise = import("pdfjs-dist/legacy/build/pdf.mjs").then((pdfjs) => {
56      const pdfjsModule = pdfjs as unknown as PdfjsModule;
57      if (!pdfjsModule.GlobalWorkerOptions.workerSrc) {
58        pdfjsModule.GlobalWorkerOptions.workerSrc = new URL(
59          "pdfjs-dist/legacy/build/pdf.worker.min.mjs",
60          import.meta.url,
61        ).toString();
62      }
63      return pdfjsModule;
64    });
65  }
66  return pdfjsPromise;
67}
68 
69function scheduleDocumentPrune() {
70  if (typeof window === "undefined" || pruneTimer) return;
71  pruneTimer = window.setTimeout(() => {
72    pruneTimer = 0;
73    pruneDocumentCache();
74  }, 0);
75}
76 
77function pruneDocumentCache() {
78  while (documentCache.size > PDF_CACHE_MAX) {
79    let evictKey: string | null = null;
80    let evictEntry: DocumentCacheEntry | null = null;
81    for (const [key, documentEntry] of documentCache) {
82      if (documentEntry.consumers > 0 || documentEntry.status === "pending") {
83        continue;
84      }
85      if (!evictEntry || documentEntry.lastUsedAt < evictEntry.lastUsedAt) {
86        evictKey = key;
87        evictEntry = documentEntry;
88      }
89    }
90    if (!evictKey || !evictEntry) return;
91// … truncated