fix: reduce number of fs.realpath calls

packages/vite/src/node/__tests__/SymlinkResolver.spec.ts

@@ -0,0 +1,159 @@
+import { relative, resolve } from 'node:path'
+import { beforeEach, describe, expect, test, vi } from 'vitest'
+import type { SymlinkResolver } from '../symlinks'
+import { createSymlinkResolver } from '../symlinks'
+
+let resolver: SymlinkResolver
+
+const realpathMock = vi.fn()
+const readlinkMock = vi.fn()
+
+const root = '/dev/root'
+const realpathSync = (p: string) => {
+  return resolver.realpathSync(resolve(root, p))
+}
+
+describe('SymlinkResolver', () => {
+  beforeEach(() => {
+    mockRealPath({})
+    mockReadLink({})
+    resolver = createSymlinkResolver(root, {
+      realpathSync: { native: realpathMock },
+      readlinkSync: readlinkMock
+    })
+  })
+
+  describe('inside project root', () => {
+    test('no symlinks present', () => {
+      const result = realpathSync('foo/bar')
+      expect(result).toMatchInlineSnapshot(`"/dev/root/foo/bar"`)
+      expect(resolver.fsCalls).toMatchInlineSnapshot(`2`)
+      expect(resolver.cacheHits).toMatchInlineSnapshot(`0`)
+
+      // …is cached?
+      expect(realpathSync('foo/bar')).toBe(result)
+      expect(resolver.fsCalls).toMatchInlineSnapshot(`2`)
+      expect(resolver.cacheHits).toMatchInlineSnapshot(`1`)
+    })
+
+    test('given path is a symlink', () => {
+      mockReadLink({ 'foo/bar': './baz' })
+
+      const result = realpathSync('foo/bar')
+      expect(result).toMatchInlineSnapshot(`"/dev/root/foo/baz"`)
+      expect(resolver.fsCalls).toMatchInlineSnapshot(`3`)
+      expect(resolver.cacheHits).toMatchInlineSnapshot(`0`)
+
+      // …is cached?
+      expect(realpathSync('foo/bar')).toBe(result)
+      expect(resolver.fsCalls).toMatchInlineSnapshot(`3`)
+      expect(resolver.cacheHits).toMatchInlineSnapshot(`1`)
+    })
+
+    test('given path is a symlink pointing out of root', () => {
+      mockReadLink({ foo: '/dev/foo' })
+
+      const result = realpathSync('foo')
+      expect(result).toMatchInlineSnapshot(`"/dev/foo"`)
+      expect(resolver.fsCalls).toMatchInlineSnapshot(`4`)
+      expect(resolver.cacheHits).toMatchInlineSnapshot(`0`)
+
+      // …is cached?
+      expect(realpathSync('foo')).toBe(result)
+      expect(resolver.fsCalls).toMatchInlineSnapshot(`4`)
+      expect(resolver.cacheHits).toMatchInlineSnapshot(`1`)
+    })
+
+    test('given path is a symlink within a symlink', () => {
+      mockRealPath({ foo: 'red' })
+      mockReadLink({ 'red/bar': './baz' })
+
+      const result = realpathSync('foo/bar')
+      expect(result).toMatchInlineSnapshot(`"/dev/root/red/baz"`)
+      expect(resolver.fsCalls).toMatchInlineSnapshot(`3`)
+      expect(resolver.cacheHits).toMatchInlineSnapshot(`0`)
+
+      // …is cached?
+      expect(realpathSync('foo/bar')).toBe(result)
+      expect(resolver.fsCalls).toMatchInlineSnapshot(`3`)
+      expect(resolver.cacheHits).toMatchInlineSnapshot(`1`)
+    })
+
+    test('given path has symlink grand parent', () => {
+      mockRealPath({ 'foo/bar': 'red/bar' })
+
+      const result = realpathSync('foo/bar/main.js')
+      expect(result).toMatchInlineSnapshot(`"/dev/root/red/bar/main.js"`)
+      expect(resolver.fsCalls).toMatchInlineSnapshot(`2`)
+      expect(resolver.cacheHits).toMatchInlineSnapshot(`0`)
+
+      // …is cached?
+      expect(realpathSync('foo/bar/main.js')).toBe(result)
+      expect(realpathSync('foo/bar')).toMatchInlineSnapshot(
+        `"/dev/root/red/bar"`
+      )
+      expect(resolver.fsCalls).toMatchInlineSnapshot(`2`)
+      expect(resolver.cacheHits).toMatchInlineSnapshot(`2`)
+    })
+
+    test('given path has two symlink parents', () => {
+      mockRealPath({ 'foo/bar': 'red/blue' })
+
+      const result = realpathSync('foo/bar/main.js')
+      expect(result).toMatchInlineSnapshot(`"/dev/root/red/blue/main.js"`)
+      expect(resolver.fsCalls).toMatchInlineSnapshot(`2`)
+      expect(resolver.cacheHits).toMatchInlineSnapshot(`0`)
+
+      // …is cached?
+      expect(realpathSync('foo/bar/main.js')).toBe(result)
+      expect(realpathSync('foo/bar')).toMatchInlineSnapshot(
+        `"/dev/root/red/blue"`
+      )
+      expect(realpathSync('foo')).toMatchInlineSnapshot(`"/dev/root/red"`)
+      expect(resolver.fsCalls).toMatchInlineSnapshot(`2`)
+      expect(resolver.cacheHits).toMatchInlineSnapshot(`3`)
+    })
+  })
+
+  test('symlink outside project root', () => {
+    // Mock a symlink that points to another symlink.
+    mockReadLink({ '../foo': './bar', '../bar': './baz' })
+
+    const result = realpathSync('../foo')
+    expect(result).toMatchInlineSnapshot(`"/dev/baz"`)
+    expect(resolver.fsCalls).toMatchInlineSnapshot(`4`)
+    expect(resolver.cacheHits).toMatchInlineSnapshot(`0`)
+
+    // …is cached?
+    expect(realpathSync('../foo')).toBe(result)
+    expect(realpathSync('../bar')).toMatchInlineSnapshot(`"/dev/baz"`)
+    expect(realpathSync('../baz')).toMatchInlineSnapshot(`"/dev/baz"`)
+    expect(resolver.fsCalls).toMatchInlineSnapshot(`4`)
+    expect(resolver.cacheHits).toMatchInlineSnapshot(`3`)
+  })
+})
+
+function mockRealPath(pathMap: Record<string, string>) {
+  realpathMock.mockReset()
+  realpathMock.mockImplementation((arg) => {
+    return resolve(root, pathMap[relative(root, arg)] || arg)
+  })
+}
+
+// Thrown by fs.readlinkSync if given a path that's not a symlink.
+const throwInvalid = throwError(-22)
+
+function mockReadLink(linkMap: Record<string, string>) {
+  readlinkMock.mockReset()
+  readlinkMock.mockImplementation((arg) => {
+    return linkMap[relative(root, arg)] || throwInvalid()
+  })
+}
+
+function throwError(errno: number) {
+  return () => {
+    const e: any = new Error()
+    e.errno = errno
+    throw e
+  }
+}

packages/vite/src/node/config.ts

@@ -64,6 +64,8 @@ import type { PackageCache } from './packages'
 import { loadEnv, resolveEnvPrefix } from './env'
 import type { ResolvedSSROptions, SSROptions } from './ssr'
 import { resolveSSROptions } from './ssr'
+import { createSymlinkResolver } from './symlinks'
+import type { SymlinkResolver } from './symlinks'
 
 const debug = createDebugger('vite:config')
 
@@ -348,6 +350,8 @@ export type ResolvedConfig = Readonly<
     createResolver: (options?: Partial<InternalResolveOptions>) => ResolveFn
     optimizeDeps: DepOptimizationOptions
     /** @internal */
+    symlinkResolver: SymlinkResolver
+    /** @internal */
     packageCache: PackageCache
     worker: ResolveWorkerOptions
     appType: AppType
@@ -558,6 +562,7 @@ export async function resolveConfig(
               aliasPlugin({ entries: resolved.resolve.alias }),
               resolvePlugin({
                 ...resolved.resolve,
+                symlinkResolver: resolved.symlinkResolver,
                 root: resolvedRoot,
                 isProduction,
                 isBuild: command === 'build',
@@ -655,6 +660,7 @@ export async function resolveConfig(
     },
     logger,
     packageCache: new Map(),
+    symlinkResolver: createSymlinkResolver(resolvedRoot),
     createResolver,
     optimizeDeps: {
       disabled: 'build',

packages/vite/src/node/index.ts

@@ -51,7 +51,8 @@ export type {
   SSRTarget
 } from './ssr'
 export type { Plugin, HookHandler } from './plugin'
-export type { PackageCache, PackageData } from './packages'
+export type { PackageCache, PackageData, LoadPackageOptions } from './packages'
+export type { SymlinkResolver } from './symlinks'
 export type {
   Logger,
   LogOptions,

packages/vite/src/node/packages.ts

@@ -1,8 +1,9 @@
 import fs from 'node:fs'
 import path from 'node:path'
-import { createDebugger, createFilter, resolveFrom } from './utils'
+import { createDebugger, createFilter, getRealPath, resolveFrom } from './utils'
 import type { ResolvedConfig } from './config'
 import type { Plugin } from './plugin'
+import type { SymlinkResolver } from './symlinks'
 
 const isDebug = process.env.DEBUG
 const debug = createDebugger('vite:resolve-details', {
@@ -45,27 +46,52 @@ export function invalidatePackageData(
   })
 }
 
+/**
+ * Find and load the `package.json` associated with a module id.
+ *
+ * Using the `options.packageCache` argument is highly recommended for
+ * performance. The easiest way is setting it to the `packageCache`
+ * property of the `vite.ResolvedConfig` object.
+ */
 export function resolvePackageData(
   id: string,
   basedir: string,
-  preserveSymlinks = false,
+  options?: LoadPackageOptions
+): PackageData | null
+
+/** @deprecated Use `options` object argument instead */
+export function resolvePackageData(
+  id: string,
+  basedir: string,
+  preserveSymlinks: boolean | undefined,
   packageCache?: PackageCache
+): PackageData | null
+
+export function resolvePackageData(
+  id: string,
+  basedir: string,
+  arg3?: boolean | LoadPackageOptions,
+  arg4?: PackageCache
 ): PackageData | null {
+  const options =
+    typeof arg3 === 'boolean'
+      ? { preserveSymlinks: arg3, packageCache: arg4 }
+      : arg3 || {}
+
   let pkg: PackageData | undefined
   let cacheKey: string | undefined
-  if (packageCache) {
-    cacheKey = `${id}&${basedir}&${preserveSymlinks}`
-    if ((pkg = packageCache.get(cacheKey))) {
+  if (options.packageCache) {
+    cacheKey = `${id}&${basedir}&${options.preserveSymlinks || false}`
+    if ((pkg = options.packageCache.get(cacheKey))) {
       return pkg
     }
   }
+
   let pkgPath: string | undefined
   try {
-    pkgPath = resolveFrom(`${id}/package.json`, basedir, preserveSymlinks)
-    pkg = loadPackageData(pkgPath, true, packageCache)
-    if (packageCache) {
-      packageCache.set(cacheKey!, pkg)
-    }
+    pkgPath = resolveFrom(`${id}/package.json`, basedir, true)
+    pkg = loadPackageData(pkgPath, options)
+    options.packageCache?.set(cacheKey!, pkg)
     return pkg
   } catch (e) {
     if (e instanceof SyntaxError) {
@@ -79,17 +105,49 @@ export function resolvePackageData(
   return null
 }
 
+export type LoadPackageOptions = {
+  preserveSymlinks?: boolean
+  symlinkResolver?: SymlinkResolver
+  packageCache?: PackageCache
+}
+
+/**
+ * Load a `package.json` file into memory.
+ *
+ * Using the `options.packageCache` argument is highly recommended for
+ * performance. The easiest way is setting it to the `packageCache`
+ * property of the `vite.ResolvedConfig` object.
+ */
+export function loadPackageData(
+  pkgPath: string,
+  options?: LoadPackageOptions
+): PackageData
+
+/** @deprecated Use `options` object argument instead */
 export function loadPackageData(
   pkgPath: string,
-  preserveSymlinks?: boolean,
+  preserveSymlinks: boolean | undefined,
   packageCache?: PackageCache
+): PackageData
+
+export function loadPackageData(
+  pkgPath: string,
+  arg2?: boolean | LoadPackageOptions,
+  arg3?: PackageCache
 ): PackageData {
-  if (!preserveSymlinks) {
-    pkgPath = fs.realpathSync.native(pkgPath)
-  }
+  const options =
+    typeof arg2 === 'boolean'
+      ? { preserveSymlinks: arg2, packageCache: arg3 }
+      : arg2 || {}
+
+  pkgPath = getRealPath(
+    pkgPath,
+    options.symlinkResolver,
+    options.preserveSymlinks
+  )
 
   let cached: PackageData | undefined
-  if ((cached = packageCache?.get(pkgPath))) {
+  if ((cached = options.packageCache?.get(pkgPath))) {
     return cached
   }
 
@@ -127,7 +185,7 @@ export function loadPackageData(
     }
   }
 
-  packageCache?.set(pkgPath, pkg)
+  options.packageCache?.set(pkgPath, pkg)
   return pkg
 }
 

packages/vite/src/node/plugins/css.ts

@@ -364,7 +364,12 @@ export function cssPostPlugin(config: ResolvedConfig): Plugin {
         const getContentWithSourcemap = async (content: string) => {
           if (config.css?.devSourcemap) {
             const sourcemap = this.getCombinedSourcemap()
-            await injectSourcesContent(sourcemap, cleanUrl(id), config.logger)
+            await injectSourcesContent(
+              sourcemap,
+              cleanUrl(id),
+              config.logger,
+              config.symlinkResolver
+            )
             return getCodeWithSourcemap('css', content, sourcemap)
           }
           return content

packages/vite/src/node/plugins/index.ts

@@ -63,6 +63,7 @@ export async function resolvePlugins(
       isProduction: config.isProduction,
       isBuild,
       packageCache: config.packageCache,
+      symlinkResolver: config.symlinkResolver,
       ssrConfig: config.ssr,
       asSrc: true,
       getDepsOptimizer: (ssr: boolean) => getDepsOptimizer(config, ssr),