log/logger.go

// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements.  See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to You 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 (
	"io"
)

// Level is the log level.
type Level int

// Enums log level constants.
const (
	LevelNil Level = iota
	LevelTrace
	LevelDebug
	LevelInfo
	LevelWarn
	LevelError
	LevelFatal
)

// String turns the LogLevel to string.
func (lv *Level) String() string {
	return LevelStrings[*lv]
}

// LevelStrings is the map from log level to its string representation.
var LevelStrings = map[Level]string{
	LevelTrace: "trace",
	LevelDebug: "debug",
	LevelInfo:  "info",
	LevelWarn:  "warn",
	LevelError: "error",
	LevelFatal: "fatal",
}

// LevelNames is the map from string to log level.
var LevelNames = map[string]Level{
	"trace": LevelTrace,
	"debug": LevelDebug,
	"info":  LevelInfo,
	"warn":  LevelWarn,
	"error": LevelError,
	"fatal": LevelFatal,
}

// LoggerOptions is the log options.
type LoggerOptions struct {
	LogLevel Level
	Pattern  string
	Writer   io.Writer
}

// LoggerOption modifies the LoggerOptions.
type LoggerOption func(*LoggerOptions)

// Field is the user defined log field.
type Field struct {
	Key   string
	Value interface{}
}

// Logger is the underlying logging work for server.
type Logger interface {
	// Trace logs to TRACE log. Arguments are handled in the manner of fmt.Print.
	Trace(args ...interface{})
	// Tracef logs to TRACE log. Arguments are handled in the manner of fmt.Printf.
	Tracef(format string, args ...interface{})
	// Debug logs to DEBUG log. Arguments are handled in the manner of fmt.Print.
	Debug(args ...interface{})
	// Debugf logs to DEBUG log. Arguments are handled in the manner of fmt.Printf.
	Debugf(format string, args ...interface{})
	// Info logs to INFO log. Arguments are handled in the manner of fmt.Print.
	Info(args ...interface{})
	// Infof logs to INFO log. Arguments are handled in the manner of fmt.Printf.
	Infof(format string, args ...interface{})
	// Warn logs to WARNING log. Arguments are handled in the manner of fmt.Print.
	Warn(args ...interface{})
	// Warnf logs to WARNING log. Arguments are handled in the manner of fmt.Printf.
	Warnf(format string, args ...interface{})
	// Error logs to ERROR log. Arguments are handled in the manner of fmt.Print.
	Error(args ...interface{})
	// Errorf logs to ERROR log. Arguments are handled in the manner of fmt.Printf.
	Errorf(format string, args ...interface{})
	// Fatal logs to ERROR log. Arguments are handled in the manner of fmt.Print.
	// All Fatal logs will exit by calling os.Exit(1).
	// Implementations may also call os.Exit() with a non-zero exit code.
	Fatal(args ...interface{})
	// Fatalf logs to ERROR log. Arguments are handled in the manner of fmt.Printf.
	Fatalf(format string, args ...interface{})

	// Sync calls the underlying Core's Sync method, flushing any buffered log entries.
	// Applications should take care to call Sync before exiting.
	Sync() error

	// SetLevel set the output log level.
	SetLevel(output string, level Level)
	// GetLevel get the output log level.
	GetLevel(output string) Level
	// WithFields set some user defined data to logs, such as uid, imei, etc.
	// Fields must be paired.
	// Deprecated: use With instead.
	WithFields(fields ...string) Logger
	// With add user defined fields to Logger. Fields support multiple values.
	With(fields ...Field) Logger
}