From 13439c8d79a0b625e244dd3d730c257e44103ee5 Mon Sep 17 00:00:00 2001
From: Yoshiyuki Kurauchi <ahochauwaaaaa@gmail.com>
Date: Thu, 20 Aug 2020 22:15:59 +0900
Subject: [PATCH] add package-wide logger

---
 internal/logger/logger.go | 80 +++++++++++++++++++++++++++++++++++++++
 logger.go                 | 37 ++++++++++++++++++
 2 files changed, 117 insertions(+)
 create mode 100644 internal/logger/logger.go
 create mode 100644 logger.go

diff --git a/internal/logger/logger.go b/internal/logger/logger.go
new file mode 100644
index 00000000..a3de1913
--- /dev/null
+++ b/internal/logger/logger.go
@@ -0,0 +1,80 @@
+// Copyright 2019-2020 go-pfcp authors. All rights reserved.
+// Use of this source code is governed by a MIT-style license that can be
+// found in the LICENSE file.
+
+// Package logger provides a logging functionalities for go-pfcp.
+//
+// This is hidden here to be able to be imported from each package of go-pfcp.
+package logger
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"sync"
+)
+
+var (
+	logger = log.New(os.Stderr, "", log.LstdFlags)
+	logMu  sync.Mutex
+)
+
+// SetLogger replaces the standard logger with arbitrary *log.Logger.
+//
+// DON'T CALL THIS. Use the func in pfcp package instead.
+//
+// This package prints just informational logs from goroutines working background
+// that might help developers test the program but can be ignored safely. More
+// important ones that needs any action by caller would be returned as errors.
+func SetLogger(l *log.Logger) {
+	if l == nil {
+		log.Println("Don't pass nil to SetLogger: use DisableLogging instead.")
+	}
+
+	setLogger(l)
+}
+
+// EnableLogging enables the logging from the package.
+//
+// DON'T CALL THIS. Use the func in pfcp package instead.
+//
+// If l is nil, it uses default logger provided by the package.
+// Logging is enabled by default.
+//
+// See also: SetLogger.
+func EnableLogging(l *log.Logger) {
+	logMu.Lock()
+	defer logMu.Unlock()
+
+	setLogger(l)
+}
+
+// DisableLogging disables the logging from the package.
+//
+// DON'T CALL THIS. Use the func in pfcp package instead.
+//
+// Logging is enabled by default.
+func DisableLogging() {
+	logMu.Lock()
+	defer logMu.Unlock()
+
+	logger.SetOutput(ioutil.Discard)
+}
+
+func setLogger(l *log.Logger) {
+	if l == nil {
+		l = log.New(os.Stderr, "", log.LstdFlags)
+	}
+
+	logMu.Lock()
+	defer logMu.Unlock()
+
+	logger = l
+}
+
+func Logf(format string, v ...interface{}) {
+	logMu.Lock()
+	defer logMu.Unlock()
+
+	logger.Printf(format, v...)
+}
diff --git a/logger.go b/logger.go
new file mode 100644
index 00000000..d0c1441b
--- /dev/null
+++ b/logger.go
@@ -0,0 +1,37 @@
+// Copyright 2019-2020 go-pfcp authors. All rights reserved.
+// Use of this source code is governed by a MIT-style license that can be
+// found in the LICENSE file.
+
+package pfcp
+
+import (
+	"log"
+
+	"github.com/wmnsk/go-pfcp/internal/logger"
+)
+
+// SetLogger replaces the standard logger with arbitrary *log.Logger.
+//
+// This package prints just informational logs from goroutines working background
+// that might help developers test the program but can be ignored safely. More
+// important ones that need any action by the caller would be returned as errors.
+func SetLogger(l *log.Logger) {
+	logger.SetLogger(l)
+}
+
+// EnableLogging enables the logging from the package.
+//
+// If l is nil, it uses default logger provided by the package.
+// Logging is enabled by default.
+//
+// See also: SetLogger.
+func EnableLogging(l *log.Logger) {
+	logger.EnableLogging(l)
+}
+
+// DisableLogging disables the logging from the package.
+//
+// Logging is enabled by default.
+func DisableLogging() {
+	logger.DisableLogging()
+}