Don't repeat markdown link validation (#149169)

We currently validate each link in a markdown file individually. This means that if there are multiple links to the same file, we check if that file exists multiple times

With this change, we instead will check that the file exists once and then use this to add diagnostics for all the links to it. This is done by introducing a new `FileLinkMap` which maps file paths to links within that file

extensions/markdown-language-features/src/languageFeatures/diagnostics.ts

@@ -10,8 +10,9 @@ import { TableOfContents } from '../tableOfContents';
 import { Delayer } from '../util/async';
 import { Disposable } from '../util/dispose';
 import { isMarkdownFile } from '../util/file';
+import { Limiter } from '../util/limiter';
 import { MdWorkspaceContents, SkinnyTextDocument } from '../workspaceContents';
-import { InternalHref, LinkDefinitionSet, MdLink, MdLinkProvider } from './documentLinkProvider';
+import { LinkDefinitionSet, MdLink, MdLinkProvider, MdLinkSource } from './documentLinkProvider';
 import { tryFindMdDocumentForLink } from './references';
 
 const localize = nls.loadMessageBundle();
@@ -218,6 +219,48 @@ export class DiagnosticManager extends Disposable {
 	}
 }
 
+interface FileLinksData {
+	readonly path: vscode.Uri;
+
+	readonly links: Array<{
+		readonly source: MdLinkSource;
+		readonly fragment: string;
+	}>;
+}
+
+/**
+ * Map of file paths to markdown links to that file.
+ */
+class FileLinkMap {
+
+	private readonly _filesToLinksMap = new Map<string, FileLinksData>();
+
+	constructor(links: Iterable<MdLink>) {
+		for (const link of links) {
+			if (link.href.kind !== 'internal') {
+				continue;
+			}
+
+			const fileKey = link.href.path.toString();
+			const existingFileEntry = this._filesToLinksMap.get(fileKey);
+			const linkData = { source: link.source, fragment: link.href.fragment };
+			if (existingFileEntry) {
+				existingFileEntry.links.push(linkData);
+			} else {
+				this._filesToLinksMap.set(fileKey, { path: link.href.path, links: [linkData] });
+			}
+		}
+	}
+
+	public get size(): number {
+		return this._filesToLinksMap.size;
+	}
+
+	public entries(): Iterable<FileLinksData> {
+		return this._filesToLinksMap.values();
+	}
+}
+
 export class DiagnosticComputer {
 
 	constructor(
@@ -290,52 +333,47 @@ export class DiagnosticComputer {
 			return [];
 		}
 
-		const tocs = new Map<string, TableOfContents>();
-
-		// TODO: cache links so we don't recompute duplicate hrefs
-		// TODO: parallelize
-
-		const diagnostics: vscode.Diagnostic[] = [];
-		for (const link of links) {
-			if (token.isCancellationRequested) {
-				return [];
-			}
-
-			if (link.href.kind !== 'internal') {
-				continue;
-			}
-
-			const hrefDoc = await tryFindMdDocumentForLink(link.href, this.workspaceContents);
-			if (hrefDoc && hrefDoc.uri.toString() === doc.uri.toString()) {
-				continue;
-			}
-
-			if (!hrefDoc && !await this.workspaceContents.pathExists(link.href.path)) {
-				diagnostics.push(
-					new vscode.Diagnostic(
-						link.source.hrefRange,
-						localize('invalidPathLink', 'File does not exist at path: {0}', (link.href as InternalHref).path.toString(true)),
-						severity));
-			} else if (hrefDoc) {
-				if (link.href.fragment) {
-					// validate fragment looks valid
-					let hrefDocToc = tocs.get(link.href.path.toString());
-					if (!hrefDocToc) {
-						hrefDocToc = await TableOfContents.create(this.engine, hrefDoc);
-						tocs.set(link.href.path.toString(), hrefDocToc);
-					}
-
-					if (!hrefDocToc.lookup(link.href.fragment)) {
-						diagnostics.push(
-							new vscode.Diagnostic(
-								link.source.hrefRange,
-								localize('invalidLinkToHeaderInOtherFile', 'Header does not exist in file: {0}', (link.href as InternalHref).path.fragment),
-								severity));
-					}
-				}
-			}
+		const linkSet = new FileLinkMap(links);
+		if (linkSet.size === 0) {
+			return [];
 		}
 
+		const limiter = new Limiter(10);
+
+		const diagnostics: vscode.Diagnostic[] = [];
+		await Promise.all(
+			Array.from(linkSet.entries()).map(({ path, links }) => {
+				return limiter.queue(async () => {
+					if (token.isCancellationRequested) {
+						return;
+					}
+
+					const hrefDoc = await tryFindMdDocumentForLink({ kind: 'internal', path: path, fragment: '' }, this.workspaceContents);
+					if (hrefDoc && hrefDoc.uri.toString() === doc.uri.toString()) {
+						// We've already validated our own links in `validateOwnHeaderLinks`
+						return;
+					}
+
+					if (!hrefDoc && !await this.workspaceContents.pathExists(path)) {
+						const msg = localize('invalidPathLink', 'File does not exist at path: {0}', path.toString(true));
+						for (const link of links) {
+							diagnostics.push(new vscode.Diagnostic(link.source.hrefRange, msg, severity));
+						}
+					} else if (hrefDoc) {
+						// Validate each of the links to headers in the file
+						const fragmentLinks = links.filter(x => x.fragment);
+						if (fragmentLinks.length) {
+							const toc = await TableOfContents.create(this.engine, hrefDoc);
+							for (const link of fragmentLinks) {
+								if (!toc.lookup(link.fragment)) {
+									const msg = localize('invalidLinkToHeaderInOtherFile', 'Header does not exist in file: {0}', link.fragment);
+									diagnostics.push(new vscode.Diagnostic(link.source.hrefRange, msg, severity));
+								}
+							}
+						}
+					}
+				});
+			}));
 		return diagnostics;
 	}
 }

extensions/markdown-language-features/src/languageFeatures/documentLinkProvider.ts

@@ -87,7 +87,7 @@ function getWorkspaceFolder(document: SkinnyTextDocument) {
 		|| vscode.workspace.workspaceFolders?.[0]?.uri;
 }
 
-interface MdLinkSource {
+export interface MdLinkSource {
 	readonly text: string;
 	readonly resource: vscode.Uri;
 	readonly hrefRange: vscode.Range;