Implement #1339: use v8-compile-cache to load typescript

package.json

@@ -164,6 +164,7 @@
     "create-require": "^1.1.0",
     "diff": "^4.0.1",
     "make-error": "^1.1.1",
+    "v8-compile-cache-lib": "^3.0.0",
     "yn": "3.1.1"
   },
   "prettier": {

src/index.ts

@@ -10,6 +10,7 @@ import type * as _ts from 'typescript';
 import type { Transpiler, TranspilerFactory } from './transpilers/types';
 import {
   assign,
+  attemptRequireWithV8CompileCache,
   cachedLookup,
   normalizeSlashes,
   parse,
@@ -568,7 +569,7 @@ export function create(rawOptions: CreateOptions = {}): Service {
     const compiler = require.resolve(name || 'typescript', {
       paths: [relativeToPath, __dirname],
     });
-    const ts: typeof _ts = require(compiler);
+    const ts: typeof _ts = attemptRequireWithV8CompileCache(require, compiler);
     return { compiler, ts };
   }
 

src/util.ts

@@ -90,3 +90,26 @@ export function cachedLookup<T, R>(fn: (arg: T) => R): (arg: T) => R {
     return cache.get(arg)!;
   };
 }
+
+/**
+ * @internal
+ * Require something with v8-compile-cache, which should make subsequent requires faster.
+ * Do lots of error-handling so that, worst case, we require without the cache, and users are not blocked.
+ */
+export function attemptRequireWithV8CompileCache(
+  requireFn: typeof require,
+  specifier: string
+) {
+  try {
+    const v8CC = (
+      require('v8-compile-cache-lib') as typeof import('v8-compile-cache-lib')
+    ).install();
+    try {
+      return requireFn(specifier);
+    } finally {
+      v8CC?.uninstall();
+    }
+  } catch (e) {
+    return requireFn(specifier);
+  }
+}