[sourcemaps] Improve ignore-listing performance

packages/next/src/server/dev/middleware-webpack.ts

@@ -5,7 +5,9 @@ import { SourceMapConsumer } from 'next/dist/compiled/source-map08'
 import type { StackFrame } from 'next/dist/compiled/stacktrace-parser'
 import { getSourceMapFromFile } from './get-source-map-from-file'
 import {
+  findApplicableSourceMapPayload,
   sourceMapIgnoreListsEverything,
+  type BasicSourceMapPayload,
   type ModernSourceMapPayload,
 } from '../lib/source-maps'
 import { openFileInEditor } from '../../next-devtools/server/launch-editor'
@@ -50,13 +52,13 @@ type SourceAttributes = {
 type Source =
   | {
       type: 'file'
-      sourceMap: ModernSourceMapPayload
+      sourceMap: BasicSourceMapPayload
       ignoredSources: IgnoredSources
       moduleURL: string
     }
   | {
       type: 'bundle'
-      sourceMap: ModernSourceMapPayload
+      sourceMap: BasicSourceMapPayload
       ignoredSources: IgnoredSources
       compilation: webpack.Compilation
       moduleId: string
@@ -284,11 +286,16 @@ async function getSourceMapFromCompilation(
 }
 
 async function getSource(
-  sourceURL: string,
+  frame: {
+    file: string | null
+    lineNumber: number | null
+    column: number | null
+  },
   options: {
     getCompilations: () => webpack.Compilation[]
   }
 ): Promise<Source | undefined> {
+  let sourceURL = frame.file ?? ''
   const { getCompilations } = options
 
   // Rspack is now using file:// URLs for source maps. Remove the rsc prefix to produce the file:/// url.
@@ -308,7 +315,11 @@ async function getSource(
     const sourceMapPayload = nativeSourceMap.payload
     return {
       type: 'file',
-      sourceMap: sourceMapPayload,
+      sourceMap: findApplicableSourceMapPayload(
+        frame.lineNumber ?? 0,
+        frame.column ?? 0,
+        sourceMapPayload
+      )!,
 
       ignoredSources: getIgnoredSources(
         // @ts-expect-error -- TODO: Support IndexSourceMap
@@ -435,7 +446,7 @@ async function getOriginalStackFrame({
   rootDirectory: string
 }): Promise<OriginalStackFrameResponse> {
   const filename = frame.file ?? ''
-  const source = await getSource(filename, {
+  const source = await getSource(frame, {
     getCompilations: () => {
       const compilations: webpack.Compilation[] = []
 
@@ -658,23 +669,31 @@ export function getSourceMapMiddleware(options: {
     let source: Source | undefined
 
     try {
-      source = await getSource(filename, {
-        getCompilations: () => {
-          const compilations: webpack.Compilation[] = []
-
-          for (const stats of [
-            clientStats(),
-            serverStats(),
-            edgeServerStats(),
-          ]) {
-            if (stats?.compilation) {
-              compilations.push(stats.compilation)
+      source = await getSource(
+        {
+          file: filename,
+          // Webpack doesn't use Index Source Maps
+          lineNumber: null,
+          column: null,
+        },
+        {
+          getCompilations: () => {
+            const compilations: webpack.Compilation[] = []
+
+            for (const stats of [
+              clientStats(),
+              serverStats(),
+              edgeServerStats(),
+            ]) {
+              if (stats?.compilation) {
+                compilations.push(stats.compilation)
+              }
             }
-          }
 
-          return compilations
-        },
-      })
+            return compilations
+          },
+        }
+      )
     } catch (error) {
       return middlewareResponse.internalServerError(res, error)
     }

packages/next/src/server/lib/source-maps.ts

@@ -18,7 +18,7 @@ interface IndexSourceMap {
 }
 
 /** https://tc39.es/ecma426/#sec-source-map-format */
-interface BasicSourceMapPayload {
+export interface BasicSourceMapPayload {
   version: number
   // TODO: Move to https://github.com/jridgewell/sourcemaps which is actively maintained
   /** WARNING: `file` is optional. */
@@ -34,17 +34,9 @@ interface BasicSourceMapPayload {
 
 export type ModernSourceMapPayload = BasicSourceMapPayload | IndexSourceMap
 
-// TODO: This should take the BasicSourceMapPayload. Only the relevant section
-// needs to ignore list everything making this check effectively O(1) multiplied
-// by the complexity of finding the section.
 export function sourceMapIgnoreListsEverything(
-  sourceMap: ModernSourceMapPayload
+  sourceMap: BasicSourceMapPayload
 ): boolean {
-  if ('sections' in sourceMap) {
-    return sourceMap.sections.every((section) => {
-      return sourceMapIgnoreListsEverything(section.map)
-    })
-  }
   return (
     sourceMap.ignoreList !== undefined &&
     sourceMap.sources.length === sourceMap.ignoreList.length
@@ -56,26 +48,40 @@ export function sourceMapIgnoreListsEverything(
  * Equal to the input unless an Index Source Map is used.
  */
 export function findApplicableSourceMapPayload(
-  lineNumber: number,
-  columnNumber: number,
+  line: number,
+  column: number,
   payload: ModernSourceMapPayload
 ): BasicSourceMapPayload | undefined {
   if ('sections' in payload) {
+    if (payload.sections.length === 0) {
+      return undefined
+    }
+
     // Sections must not overlap and must be sorted: https://tc39.es/source-map/#section-object
     // Therefore the last section that has an offset less than or equal to the frame is the applicable one.
-    // TODO(veil): Binary search
-    let section: IndexSourceMapSection | undefined = payload.sections[0]
-    for (
-      let i = 0;
-      i < payload.sections.length &&
-      payload.sections[i].offset.line <= lineNumber &&
-      payload.sections[i].offset.column <= columnNumber;
-      i++
-    ) {
-      section = payload.sections[i]
+    const sections = payload.sections
+    let left = 0
+    let right = sections.length - 1
+    let result: IndexSourceMapSection | null = null
+
+    while (left <= right) {
+      // fast Math.floor
+      const middle = ~~((left + right) / 2)
+      const section = sections[middle]
+      const offset = section.offset
+
+      if (
+        offset.line < line ||
+        (offset.line === line && offset.column <= column)
+      ) {
+        result = section
+        left = middle + 1
+      } else {
+        right = middle - 1
+      }
     }
 
-    return section === undefined ? undefined : section.map
+    return result === null ? undefined : result.map
   } else {
     return payload
   }

packages/next/src/server/patch-error-inspect.ts

@@ -208,7 +208,14 @@ function getSourcemappedFrameIfPossible(
     line: frame.lineNumber ?? 1,
   })
 
-  let ignored = sourceMapIgnoreListsEverything(sourceMapPayload)
+  const applicableSourceMap = findApplicableSourceMapPayload(
+    frame.lineNumber ?? 0,
+    frame.column ?? 0,
+    sourceMapPayload
+  )
+  let ignored =
+    applicableSourceMap !== undefined &&
+    sourceMapIgnoreListsEverything(applicableSourceMap)
   if (sourcePosition.source === null) {
     return {
       stack: {
@@ -223,11 +230,6 @@ function getSourcemappedFrameIfPossible(
     }
   }
 
-  const applicableSourceMap = findApplicableSourceMapPayload(
-    frame.lineNumber ?? 0,
-    frame.column ?? 0,
-    sourceMapPayload
-  )
   // TODO(veil): Upstream a method to sourcemap consumer that immediately says if a frame is ignored or not.
   if (applicableSourceMap === undefined) {
     console.error('No applicable source map found in sections for frame', frame)