Added logging

vendor/github.com/op/go-logging/backend.go

@@ -0,0 +1,39 @@
+// Copyright 2013, Örjan Persson. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package logging
+
+// defaultBackend is the backend used for all logging calls.
+var defaultBackend LeveledBackend
+
+// Backend is the interface which a log backend need to implement to be able to
+// be used as a logging backend.
+type Backend interface {
+	Log(Level, int, *Record) error
+}
+
+// SetBackend replaces the backend currently set with the given new logging
+// backend.
+func SetBackend(backends ...Backend) LeveledBackend {
+	var backend Backend
+	if len(backends) == 1 {
+		backend = backends[0]
+	} else {
+		backend = MultiLogger(backends...)
+	}
+
+	defaultBackend = AddModuleLevel(backend)
+	return defaultBackend
+}
+
+// SetLevel sets the logging level for the specified module. The module
+// corresponds to the string specified in GetLogger.
+func SetLevel(level Level, module string) {
+	defaultBackend.SetLevel(level, module)
+}
+
+// GetLevel returns the logging level for the specified module.
+func GetLevel(module string) Level {
+	return defaultBackend.GetLevel(module)
+}