eth/downloader: optimize fetch result concatenation

rizkyikiw42 · rizkyikiw42 · commit 7d0be24267ef · 2025-12-02T17:05:38.000+08:00
diff --git a/eth/downloader/downloader.go b/eth/downloader/downloader.go
@@ -940,7 +940,11 @@ func (d *Downloader) processSnapSyncContent() error {
 				}
 			}
 		} else { // results already piled up, consume before handling pivot move
-			results = append(append([]*fetchResult{oldPivot}, oldTail...), results...)
+			newResults := make([]*fetchResult, 1+len(oldTail)+len(results))
+			newResults[0] = oldPivot
+			copy(newResults[1:], oldTail)
+			copy(newResults[1+len(oldTail):], results)
+			results = newResults
 		}
 		// Split around the pivot block and process the two sides via snap/full sync
 		if !d.committed.Load() {

Original file line number	Diff line number	Diff line change
`@@ -940,7 +940,11 @@ func (d *Downloader) processSnapSyncContent() error {`
`940`	`940`	`}`
`941`	`941`	`}`
`942`	`942`	`} else { // results already piled up, consume before handling pivot move`
`943`		`- results = append(append([]*fetchResult{oldPivot}, oldTail...), results...)`
	`943`	`+ newResults := make([]*fetchResult, 1+len(oldTail)+len(results))`
	`944`	`+ newResults[0] = oldPivot`
	`945`	`+ copy(newResults[1:], oldTail)`
	`946`	`+ copy(newResults[1+len(oldTail):], results)`
	`947`	`+ results = newResults`
`944`	`948`	`}`
`945`	`949`	`// Split around the pivot block and process the two sides via snap/full sync`
`946`	`950`	`if !d.committed.Load() {`