From a47c38631979d4ab4614af3c98ca2808255c0f3a Mon Sep 17 00:00:00 2001
From: LTbinglingfeng <tan13318527080@163.com>
Date: Mon, 15 Jun 2026 15:51:15 +0800
Subject: [PATCH] Avoid counting all logs for tail reads

---
 internal/api/handlers/management/logs.go      | 67 +------------------
 internal/api/handlers/management/logs_test.go | 22 +++++-
 2 files changed, 21 insertions(+), 68 deletions(-)

diff --git a/internal/api/handlers/management/logs.go b/internal/api/handlers/management/logs.go
index 3dfc635a..6d8477ba 100644
--- a/internal/api/handlers/management/logs.go
+++ b/internal/api/handlers/management/logs.go
@@ -101,12 +101,7 @@ func (h *Handler) GetLogs(c *gin.Context) {
 			c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("failed to read log files: %v", errTail)})
 			return
 		}
-		total, errCount := countLogFileLines(files)
-		if errCount != nil {
-			c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("failed to read log files: %v", errCount)})
-			return
-		}
-		writeLogsResponse(c, result.lines, total, result.latest, result.nextCursor, false)
+		writeLogsResponse(c, result.lines, len(result.lines), result.latest, result.nextCursor, false)
 		return
 	}
 
@@ -612,66 +607,6 @@ func readTailLogLines(path string, limit int) (completeLogRead, error) {
 	return readCompleteLogLines(path, start, boundary, limit)
 }
 
-func countLogFileLines(files []string) (int, error) {
-	total := 0
-	for i := range files {
-		count, errCount := countLogLines(files[i])
-		if errCount != nil {
-			if errors.Is(errCount, os.ErrNotExist) {
-				continue
-			}
-			return 0, errCount
-		}
-		total += count
-	}
-	return total, nil
-}
-
-func countLogLines(path string) (int, error) {
-	file, errOpen := os.Open(path)
-	if errOpen != nil {
-		return 0, errOpen
-	}
-	defer func() {
-		_ = file.Close()
-	}()
-	info, errStat := file.Stat()
-	if errStat != nil {
-		return 0, errStat
-	}
-	if info.IsDir() {
-		return 0, fmt.Errorf("invalid log file")
-	}
-
-	buf := make([]byte, 32*1024)
-	count := 0
-	lineLen := 0
-	for {
-		n, errRead := file.Read(buf)
-		for _, b := range buf[:n] {
-			if b == '\n' {
-				count++
-				lineLen = 0
-				continue
-			}
-			lineLen++
-			if lineLen > logScannerMaxBuffer {
-				return 0, fmt.Errorf("log line exceeds %d bytes", logScannerMaxBuffer)
-			}
-		}
-		if errRead == io.EOF {
-			break
-		}
-		if errRead != nil {
-			return 0, errRead
-		}
-	}
-	if lineLen > 0 {
-		count++
-	}
-	return count, nil
-}
-
 func tailStartOffset(path string, boundary int64, limit int) (int64, error) {
 	if limit <= 0 {
 		return 0, nil
diff --git a/internal/api/handlers/management/logs_test.go b/internal/api/handlers/management/logs_test.go
index eb38176c..34a07c7e 100644
--- a/internal/api/handlers/management/logs_test.go
+++ b/internal/api/handlers/management/logs_test.go
@@ -149,8 +149,8 @@ func TestGetLogsTailLimitReturnsRecentLinesWithCursor(t *testing.T) {
 	if !reflect.DeepEqual(resp.Lines, wantLines) {
 		t.Fatalf("lines = %#v, want %#v", resp.Lines, wantLines)
 	}
-	if resp.LineCount != 4 {
-		t.Fatalf("line-count = %d, want full scan count 4", resp.LineCount)
+	if resp.LineCount != len(wantLines) {
+		t.Fatalf("line-count = %d, want returned line count %d", resp.LineCount, len(wantLines))
 	}
 	if resp.NextCursor == "" {
 		t.Fatal("next-cursor is empty")
@@ -161,6 +161,24 @@ func TestGetLogsTailLimitReturnsRecentLinesWithCursor(t *testing.T) {
 	}
 }
 
+func TestGetLogsTailLimitDoesNotScanOlderFilesForLineCount(t *testing.T) {
+	dir := t.TempDir()
+	rotatedPath := filepath.Join(dir, defaultLogFileName+".1")
+	if err := os.WriteFile(rotatedPath, []byte(strings.Repeat("x", logScannerMaxBuffer+1)+"\n"), 0o644); err != nil {
+		t.Fatalf("write rotated log: %v", err)
+	}
+	writeMainLog(t, dir, "[2026-06-15 10:00:00] current\n")
+
+	resp := performGetLogs(t, newLogsTestHandler(dir, true), "/v0/management/logs?limit=1")
+	wantLines := []string{"[2026-06-15 10:00:00] current"}
+	if !reflect.DeepEqual(resp.Lines, wantLines) {
+		t.Fatalf("lines = %#v, want %#v", resp.Lines, wantLines)
+	}
+	if resp.LineCount != len(wantLines) {
+		t.Fatalf("line-count = %d, want returned line count %d", resp.LineCount, len(wantLines))
+	}
+}
+
 func TestGetLogsNoLimitKeepsFullScanBehavior(t *testing.T) {
 	dir := t.TempDir()
 	writeMainLog(t, dir, "complete\npartial")