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// Copyright (c) 2017 Uber Technologies, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package log
import (
"bytes"
"fmt"
"log"
"sync"
)
// Logger provides an abstract interface for logging from Reporters.
// Applications can provide their own implementation of this interface to adapt
// reporters logging to whatever logging library they prefer (stdlib log,
// logrus, go-logging, etc).
type Logger interface {
// Error logs a message at error priority
Error(msg string)
// Infof logs a message at info priority
Infof(msg string, args ...interface{})
}
// StdLogger is implementation of the Logger interface that delegates to default `log` package
var StdLogger = &stdLogger{}
type stdLogger struct{}
func (l *stdLogger) Error(msg string) {
log.Printf("ERROR: %s", msg)
}
// Infof logs a message at info priority
func (l *stdLogger) Infof(msg string, args ...interface{}) {
log.Printf(msg, args...)
}
// Debugf logs a message at debug priority
func (l *stdLogger) Debugf(msg string, args ...interface{}) {
log.Printf(fmt.Sprintf("DEBUG: %s", msg), args...)
}
// NullLogger is implementation of the Logger interface that is no-op
var NullLogger = &nullLogger{}
type nullLogger struct{}
func (l *nullLogger) Error(msg string) {}
func (l *nullLogger) Infof(msg string, args ...interface{}) {}
func (l *nullLogger) Debugf(msg string, args ...interface{}) {}
// BytesBufferLogger implements Logger backed by a bytes.Buffer.
type BytesBufferLogger struct {
mux sync.Mutex
buf bytes.Buffer
}
// Error implements Logger.
func (l *BytesBufferLogger) Error(msg string) {
l.mux.Lock()
l.buf.WriteString(fmt.Sprintf("ERROR: %s\n", msg))
l.mux.Unlock()
}
// Infof implements Logger.
func (l *BytesBufferLogger) Infof(msg string, args ...interface{}) {
l.mux.Lock()
l.buf.WriteString("INFO: " + fmt.Sprintf(msg, args...) + "\n")
l.mux.Unlock()
}
// Debugf implements Logger.
func (l *BytesBufferLogger) Debugf(msg string, args ...interface{}) {
l.mux.Lock()
l.buf.WriteString("DEBUG: " + fmt.Sprintf(msg, args...) + "\n")
l.mux.Unlock()
}
// String returns string representation of the underlying buffer.
func (l *BytesBufferLogger) String() string {
l.mux.Lock()
defer l.mux.Unlock()
return l.buf.String()
}
// Flush empties the underlying buffer.
func (l *BytesBufferLogger) Flush() {
l.mux.Lock()
defer l.mux.Unlock()
l.buf.Reset()
}
// DebugLogger is an interface which adds a debug logging level
type DebugLogger interface {
Logger
// Debugf logs a message at debug priority
Debugf(msg string, args ...interface{})
}
// DebugLogAdapter is a log adapter that converts a Logger into a DebugLogger
// If the provided Logger doesn't satisfy the interface, a logger with debug
// disabled is returned
func DebugLogAdapter(logger Logger) DebugLogger {
if logger == nil {
return nil
}
if debugLogger, ok := logger.(DebugLogger); ok {
return debugLogger
}
logger.Infof("debug logging disabled")
return debugDisabledLogAdapter{logger: logger}
}
type debugDisabledLogAdapter struct {
logger Logger
}
func (d debugDisabledLogAdapter) Error(msg string) {
d.logger.Error(msg)
}
func (d debugDisabledLogAdapter) Infof(msg string, args ...interface{}) {
d.logger.Infof(msg, args...)
}
// Debugf is a nop
func (d debugDisabledLogAdapter) Debugf(msg string, args ...interface{}) {
}
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