From 484aec6152d8c42281ac3833f27487ce01a8420c Mon Sep 17 00:00:00 2001
From: patak <matias.capeletto@gmail.com>
Date: Fri, 1 Dec 2023 16:17:47 +0100
Subject: [PATCH 1/2] perf: skip computing sourceRoot in injectSourcesContent

---
 packages/vite/src/node/server/sourcemap.ts | 42 +++++++++++++---------
 1 file changed, 26 insertions(+), 16 deletions(-)

diff --git a/packages/vite/src/node/server/sourcemap.ts b/packages/vite/src/node/server/sourcemap.ts
index c8f2c8d88fdacd..06bb063dcd3df4 100644
--- a/packages/vite/src/node/server/sourcemap.ts
+++ b/packages/vite/src/node/server/sourcemap.ts
@@ -19,11 +19,7 @@ interface SourceMapLike {
   sourceRoot?: string
 }
 
-export async function injectSourcesContent(
-  map: SourceMapLike,
-  file: string,
-  logger: Logger,
-): Promise<void> {
+async function computeSourceRoute(map: SourceMapLike, file: string) {
   let sourceRoot: string | undefined
   try {
     // The source root is undefined for virtual modules and permission errors.
@@ -31,27 +27,41 @@ export async function injectSourcesContent(
       path.resolve(path.dirname(file), map.sourceRoot || ''),
     )
   } catch {}
+  return sourceRoot
+}
+
+export async function injectSourcesContent(
+  map: SourceMapLike,
+  file: string,
+  logger: Logger,
+): Promise<void> {
+  let sourceRootPromise: Promise<string | undefined>
 
   const missingSources: string[] = []
   const sourcesContent = map.sourcesContent || []
   await Promise.all(
-    map.sources.map(async (sourcePath, index) => {
-      let content = null
-      if (sourcePath && !virtualSourceRE.test(sourcePath)) {
+    map.sources
+      .filter(
+        (sourcePath, index) =>
+          !sourcesContent[index] &&
+          sourcePath &&
+          !virtualSourceRE.test(sourcePath),
+      )
+      .map(async (sourcePath, index) => {
+        // inject content from source file when sourcesContent is null
+        sourceRootPromise ??= computeSourceRoute(map, file)
+        const sourceRoot = await sourceRootPromise
         sourcePath = decodeURI(sourcePath)
         if (sourceRoot) {
           sourcePath = path.resolve(sourceRoot, sourcePath)
         }
-        // inject content from source file when sourcesContent is null
-        content =
-          sourcesContent[index] ??
-          (await fsp.readFile(sourcePath, 'utf-8').catch(() => {
+        sourcesContent[index] = await fsp
+          .readFile(sourcePath, 'utf-8')
+          .catch(() => {
             missingSources.push(sourcePath)
             return null
-          }))
-      }
-      sourcesContent[index] = content
-    }),
+          })
+      }),
   )
 
   map.sourcesContent = sourcesContent

From 1b2d1e0dbcdbbe29aaac898d001591a128894747 Mon Sep 17 00:00:00 2001
From: patak <matias.capeletto@gmail.com>
Date: Sat, 2 Dec 2023 15:41:29 +0100
Subject: [PATCH 2/2] fix: use flat for

---
 packages/vite/src/node/server/sourcemap.ts | 52 ++++++++++++----------
 1 file changed, 29 insertions(+), 23 deletions(-)

diff --git a/packages/vite/src/node/server/sourcemap.ts b/packages/vite/src/node/server/sourcemap.ts
index 06bb063dcd3df4..eafde8c25b67d1 100644
--- a/packages/vite/src/node/server/sourcemap.ts
+++ b/packages/vite/src/node/server/sourcemap.ts
@@ -39,30 +39,36 @@ export async function injectSourcesContent(
 
   const missingSources: string[] = []
   const sourcesContent = map.sourcesContent || []
-  await Promise.all(
-    map.sources
-      .filter(
-        (sourcePath, index) =>
-          !sourcesContent[index] &&
-          sourcePath &&
-          !virtualSourceRE.test(sourcePath),
+  const sourcesContentPromises: Promise<void>[] = []
+  for (let index = 0; index < map.sources.length; index++) {
+    const sourcePath = map.sources[index]
+    if (
+      !sourcesContent[index] &&
+      sourcePath &&
+      !virtualSourceRE.test(sourcePath)
+    ) {
+      sourcesContentPromises.push(
+        (async () => {
+          // inject content from source file when sourcesContent is null
+          sourceRootPromise ??= computeSourceRoute(map, file)
+          const sourceRoot = await sourceRootPromise
+          let resolvedSourcePath = decodeURI(sourcePath)
+          if (sourceRoot) {
+            resolvedSourcePath = path.resolve(sourceRoot, resolvedSourcePath)
+          }
+
+          sourcesContent[index] = await fsp
+            .readFile(resolvedSourcePath, 'utf-8')
+            .catch(() => {
+              missingSources.push(resolvedSourcePath)
+              return null
+            })
+        })(),
       )
-      .map(async (sourcePath, index) => {
-        // inject content from source file when sourcesContent is null
-        sourceRootPromise ??= computeSourceRoute(map, file)
-        const sourceRoot = await sourceRootPromise
-        sourcePath = decodeURI(sourcePath)
-        if (sourceRoot) {
-          sourcePath = path.resolve(sourceRoot, sourcePath)
-        }
-        sourcesContent[index] = await fsp
-          .readFile(sourcePath, 'utf-8')
-          .catch(() => {
-            missingSources.push(sourcePath)
-            return null
-          })
-      }),
-  )
+    }
+  }
+
+  await Promise.all(sourcesContentPromises)
 
   map.sourcesContent = sourcesContent