From 975c406ddb02ea083d859e81a86dcd8a3854217a Mon Sep 17 00:00:00 2001
From: David Bariod <davidriod@googlemail.com>
Date: Sat, 27 Oct 2018 15:21:30 +0200
Subject: [PATCH] Use a sync.Once to init the reportCaller data

---
 entry.go       | 30 +++++++++++++++++++-----------
 logrus_test.go |  4 ++--
 2 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/entry.go b/entry.go
index df37550..5f40c58 100644
--- a/entry.go
+++ b/entry.go
@@ -11,16 +11,23 @@ import (
 	"time"
 )
 
-var bufferPool *sync.Pool
+var (
+	bufferPool *sync.Pool
 
-// qualified package name, cached at first use
-var LogrusPackage string
+	// qualified package name, cached at first use
+	logrusPackage string
 
-// Positions in the call stack when tracing to report the calling method
-var minimumCallerDepth int
+	// Positions in the call stack when tracing to report the calling method
+	minimumCallerDepth int
 
-const maximumCallerDepth int = 25
-const knownLogrusFrames int = 4
+	// Used for caller information initialisation
+	callerInitOnce sync.Once
+)
+
+const (
+	maximumCallerDepth int = 25
+	knownLogrusFrames  int = 4
+)
 
 func init() {
 	bufferPool = &sync.Pool{
@@ -143,19 +150,20 @@ func getCaller() (method string) {
 	depth := runtime.Callers(minimumCallerDepth, pcs)
 
 	// cache this package's fully-qualified name
-	if LogrusPackage == "" {
-		LogrusPackage = getPackageName(runtime.FuncForPC(pcs[0]).Name())
+	callerInitOnce.Do(func() {
+		logrusPackage = getPackageName(runtime.FuncForPC(pcs[0]).Name())
 
 		// now that we have the cache, we can skip a minimum count of known-logrus functions
+		// XXX this is dubious, the number of frames may vary store an entry in a logger interface
 		minimumCallerDepth = knownLogrusFrames
-	}
+	})
 
 	for i := 0; i < depth; i++ {
 		fullFuncName := runtime.FuncForPC(pcs[i]).Name()
 		pkg := getPackageName(fullFuncName)
 
 		// If the caller isn't part of this package, we're done
-		if pkg != LogrusPackage {
+		if pkg != logrusPackage {
 			return fullFuncName
 		}
 	}
diff --git a/logrus_test.go b/logrus_test.go
index d829369..2fe3653 100644
--- a/logrus_test.go
+++ b/logrus_test.go
@@ -92,7 +92,7 @@ func logSomething(t *testing.T, message string) Fields {
 	logger.ReportCaller = true
 
 	// override the filter to allow reporting of functions within the logrus package
-	LogrusPackage = "bogusForTesting"
+	logrusPackage = "bogusForTesting"
 
 	entry := logger.WithFields(Fields{
 		"foo": "bar",
@@ -104,7 +104,7 @@ func logSomething(t *testing.T, message string) Fields {
 	assert.Nil(t, err)
 
 	// now clear the override so as not to mess with other usage
-	LogrusPackage = ""
+	logrusPackage = ""
 	return fields
 }