Merge pull request #16 from Bose/write-err-fix

make it easier to find buffer overruns by returning an error with the complete unwritten buffer

example/example.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"log"
 	"os"
 	"runtime"
 	"time"
@@ -82,7 +83,9 @@ func main() {
 		c.JSON(200, "Hello world!")
 	})
 
-	r.Run(":29090")
+	if err := r.Run(":29090"); err != nil {
+		log.Println("Run error: ", err)
+	}
 }
 
 func newSpanFromContext(c *gin.Context, operationName string) opentracing.Span {

logBuffer.go

@@ -97,7 +97,7 @@ func (b *LogBuffer) Write(data []byte) (n int, err error) {
 	newData := bytes.TrimSuffix(data, []byte("\n"))
 
 	if len(newData)+b.Buff.Len() > int(b.MaxSize) {
-		return 0, fmt.Errorf("write failed: buffer MaxSize = %d, current len = %d, attempted to write len = %d", b.MaxSize, b.Buff.Len(), len(newData))
+		return 0, fmt.Errorf("write failed: buffer MaxSize = %d, current len = %d, attempted to write len = %d, data == %s", b.MaxSize, b.Buff.Len(), len(newData), newData)
 	}
 	return b.Buff.Write(append(newData, []byte(",")...))
 }

logBuffer_test.go

@@ -152,6 +152,9 @@ func TestLogBuffer_Write(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			gotN, err := tt.b.Write(tt.data)
+			if err != nil {
+				t.Log("LogBuffer.Write() error == ", err)
+			}
 			if (err != nil) != tt.wantErr {
 				t.Errorf("LogBuffer.Write() error = %v, wantErr %v", err, tt.wantErr)
 				return