Added logging

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

@@ -0,0 +1,65 @@
+// 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
+
+// TODO remove Level stuff from the multi logger. Do one thing.
+
+// multiLogger is a log multiplexer which can be used to utilize multiple log
+// backends at once.
+type multiLogger struct {
+	backends []LeveledBackend
+}
+
+// MultiLogger creates a logger which contain multiple loggers.
+func MultiLogger(backends ...Backend) LeveledBackend {
+	var leveledBackends []LeveledBackend
+	for _, backend := range backends {
+		leveledBackends = append(leveledBackends, AddModuleLevel(backend))
+	}
+	return &multiLogger{leveledBackends}
+}
+
+// Log passes the log record to all backends.
+func (b *multiLogger) Log(level Level, calldepth int, rec *Record) (err error) {
+	for _, backend := range b.backends {
+		if backend.IsEnabledFor(level, rec.Module) {
+			// Shallow copy of the record for the formatted cache on Record and get the
+			// record formatter from the backend.
+			r2 := *rec
+			if e := backend.Log(level, calldepth+1, &r2); e != nil {
+				err = e
+			}
+		}
+	}
+	return
+}
+
+// GetLevel returns the highest level enabled by all backends.
+func (b *multiLogger) GetLevel(module string) Level {
+	var level Level
+	for _, backend := range b.backends {
+		if backendLevel := backend.GetLevel(module); backendLevel > level {
+			level = backendLevel
+		}
+	}
+	return level
+}
+
+// SetLevel propagates the same level to all backends.
+func (b *multiLogger) SetLevel(level Level, module string) {
+	for _, backend := range b.backends {
+		backend.SetLevel(level, module)
+	}
+}
+
+// IsEnabledFor returns true if any of the backends are enabled for it.
+func (b *multiLogger) IsEnabledFor(level Level, module string) bool {
+	for _, backend := range b.backends {
+		if backend.IsEnabledFor(level, module) {
+			return true
+		}
+	}
+	return false
+}