feat: scan free dev server (#8319)

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

@@ -62,6 +62,13 @@ export interface DepOptimizationOptions {
    * vite project root. This will overwrite default entries inference.
    */
   entries?: string | string[]
+  /**
+   * Enable esbuild based scan phase, to get back to the optimized deps discovery
+   * strategy used in Vite v2
+   * @default false
+   * @experimental
+   */
+  devScan?: boolean
   /**
    * Force optimize listed dependencies (must be resolvable import paths,
    * cannot be globs).

packages/vite/src/node/optimizer/optimizer.ts

@@ -46,6 +46,8 @@ export async function initDepsOptimizer(
   const { logger } = config
   const isBuild = config.command === 'build'
 
+  const scan = config.command !== 'build' && config.optimizeDeps.devScan
+
   const sessionTimestamp = Date.now().toString()
 
   const cachedMetadata = loadCachedDepOptimizationMetadata(config)
@@ -100,7 +102,7 @@ export async function initDepsOptimizer(
   // If there wasn't a cache or it is outdated, we need to prepare a first run
   let firstRunCalled = !!cachedMetadata
   if (!cachedMetadata) {
-    if (isBuild) {
+    if (!scan) {
       // Initialize discovered deps with manually added optimizeDeps.include info
       const discovered = await initialProjectDependencies(
         config,
@@ -460,9 +462,14 @@ export async function initDepsOptimizer(
       exportsData: extractExportsData(resolved, config)
     })
 
-    // Debounced rerun, let other missing dependencies be discovered before
-    // the running next optimizeDeps
-    if (!isBuild) {
+    // Until the first optimize run is called, avoid triggering processing
+    // We'll wait until the user codebase is eagerly processed by Vite so
+    // we can get a list of every missing dependency before giving to the
+    // browser a dependency that may be outdated, thus avoiding full page reloads
+
+    if (scan || firstRunCalled) {
+      // Debounced rerun, let other missing dependencies be discovered before
+      // the running next optimizeDeps
       debouncedProcessing()
     }
 

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

@@ -49,7 +49,10 @@ import {
   optimizedDepNeedsInterop
 } from '../optimizer'
 import { checkPublicFile } from './asset'
-import { ERR_OUTDATED_OPTIMIZED_DEP } from './optimizedDeps'
+import {
+  ERR_OUTDATED_OPTIMIZED_DEP,
+  delayDepsOptimizerUntil
+} from './optimizedDeps'
 import { isCSSRequest, isDirectCSSRequest } from './css'
 
 const isDebug = !!process.env.DEBUG
@@ -183,7 +186,7 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
       let s: MagicString | undefined
       const str = () => s || (s = new MagicString(source))
       const importedUrls = new Set<string>()
-      const staticImportedUrls = new Set<string>()
+      const staticImportedUrls = new Set<{ url: string; id: string }>()
       const acceptedUrls = new Set<{
         url: string
         start: number
@@ -462,7 +465,7 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
           importedUrls.add(urlWithoutBase)
           if (!isDynamicImport) {
             // for pre-transforming
-            staticImportedUrls.add(urlWithoutBase)
+            staticImportedUrls.add({ url: urlWithoutBase, id: resolvedId })
           }
         } else if (!importer.startsWith(clientDir) && !ssr) {
           // check @vite-ignore which suppresses dynamic import warning
@@ -601,20 +604,24 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
         )
 
       // pre-transform known direct imports
+      // TODO: we should also crawl dynamic imports
       if (config.server.preTransformRequests && staticImportedUrls.size) {
-        staticImportedUrls.forEach((url) => {
+        staticImportedUrls.forEach(({ url, id }) => {
           url = unwrapId(removeImportQuery(url)).replace(
             NULL_BYTE_PLACEHOLDER,
             '\0'
           )
-          transformRequest(url, server, { ssr }).catch((e) => {
+          const request = transformRequest(url, server, { ssr }).catch((e) => {
             if (e?.code === ERR_OUTDATED_OPTIMIZED_DEP) {
               // This are expected errors
               return
             }
             // Unexpected error, log the issue but avoid an unhandled exception
             config.logger.error(e.message)
           })
+          if (!config.optimizeDeps.devScan) {
+            delayDepsOptimizerUntil(config, id, () => request)
+          }
         })
       }
 

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

@@ -16,7 +16,7 @@ const debug = createDebugger('vite:optimize-deps')
 const runOptimizerIfIdleAfterMs = 100
 
 interface RunProcessingInfo {
-  ids: { id: string; done: () => Promise<void> }[]
+  ids: { id: string; done: () => Promise<any> }[]
   seenIds: Set<string>
   workersSources: Set<string>
   waitingOn: string | undefined
@@ -51,10 +51,10 @@ export function registerWorkersSource(config: ResolvedConfig, id: string) {
   }
 }
 
-function delayDepsOptimizerUntil(
+export function delayDepsOptimizerUntil(
   config: ResolvedConfig,
   id: string,
-  done: () => Promise<void>
+  done: () => Promise<any>
 ) {
   const info = getRunProcessingInfo(config)
   if (
@@ -98,6 +98,22 @@ export function optimizedDepsPlugin(config: ResolvedConfig): Plugin {
   return {
     name: 'vite:optimized-deps',
 
+    buildStart() {
+      if (!config.isWorker) {
+        initRunProcessingInfo(config)
+      }
+    },
+
+    async resolveId(id) {
+      if (getDepsOptimizer(config)?.isOptimizedDepFile(id)) {
+        return id
+      }
+    },
+
+    // this.load({ id }) isn't implemented in PluginContainer
+    // The logic to register an id to wait until it is processed
+    // is in importAnalysis, see call to delayDepsOptimizerUntil
+
     async load(id) {
       const depsOptimizer = getDepsOptimizer(config)
       if (depsOptimizer?.isOptimizedDepFile(id)) {