fix(code-style): polish the logs/logs.go (#5071)

* fix(code-style): polish the logs/logs.go

1. private method statement use lower case
2. remove the meaningless bracket
...
Signed-off-by: NDong Gang <dong.gang@daocloud.io>

* Correct the comment

src/app/backend/resource/logs/logs.go

@@ -19,8 +19,8 @@ import (
 	"strings"
 )
 
-// LINE_INDEX_NOT_FOUND is returned if requested line could not be found
-var LINE_INDEX_NOT_FOUND = -1
+// LineIndexNotFound is returned if requested line could not be found
+var LineIndexNotFound = -1
 
 // DefaultDisplayNumLogLines returns default number of lines in case of invalid request.
 var DefaultDisplayNumLogLines = 100
@@ -154,7 +154,7 @@ type LogTimestamp string
 func (self LogLines) SelectLogs(logSelection *Selection) (LogLines, LogTimestamp, LogTimestamp, Selection, bool) {
 	requestedNumItems := logSelection.OffsetTo - logSelection.OffsetFrom
 	referenceLineIndex := self.getLineIndex(&logSelection.ReferencePoint)
-	if referenceLineIndex == LINE_INDEX_NOT_FOUND || requestedNumItems <= 0 || len(self) == 0 {
+	if referenceLineIndex == LineIndexNotFound || requestedNumItems <= 0 || len(self) == 0 {
 		// Requested reference line could not be found, probably it's already gone or requested no logs. Return no logs.
 		return LogLines{}, "", "", Selection{}, false
 	}
@@ -216,10 +216,10 @@ func (self LogLines) getLineIndex(logLineId *LogLineId) int {
 	if 0 <= offset && offset < linesMatched {
 		return matchingStartedAt + offset
 	}
-	return LINE_INDEX_NOT_FOUND
+	return LineIndexNotFound
 }
 
-// CreateLogLineId returns ID of the line with provided lineIndex.
+// createLogLineId returns ID of the line with provided lineIndex.
 func (self LogLines) createLogLineId(lineIndex int) *LogLineId {
 	logTimestamp := self[lineIndex].Timestamp
 	// determine whether to use negative or positive indexing
@@ -235,7 +235,7 @@ func (self LogLines) createLogLineId(lineIndex int) *LogLineId {
 	}
 	offset := step
 	for ; 0 <= lineIndex-offset && lineIndex-offset < len(self); offset += step {
-		if !(self[lineIndex-offset].Timestamp == logTimestamp) {
+		if self[lineIndex-offset].Timestamp != logTimestamp {
 			break
 		}
 	}