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 Go to latest Published: Jul 19, 2021 License: MIT Imports: 16 Imported by: 0

Documentation

Overview

Package log4go provides level-based and highly configurable logging.

Enhanced Logging

This is inspired by the logging functionality in Java. Essentially, you create a Logger object and create output filters for it. You can send whatever you want to the Logger, and it will filter that based on your settings and send it to the outputs. This way, you can put as much debug code in your program as you want, and when you're done you can filter out the mundane messages so only the important ones show up.

Utility functions are provided to make life easier. Here is some example code to get started:

log := log4go.NewLogger() log.AddFilter("stdout", log4go.DEBUG, log4go.NewConsoleLogWriter()) log.AddFilter("log", log4go.FINE, log4go.NewFileLogWriter("example.log", true)) log.Info("The time is now: %s", time.LocalTime().Format("15:04:05 MST 2006/01/02"))

The first two lines can be combined with the utility NewDefaultLogger:

log := log4go.NewDefaultLogger(log4go.DEBUG) log.AddFilter("log", log4go.FINE, log4go.NewFileLogWriter("example.log", true)) log.Info("The time is now: %s", time.LocalTime().Format("15:04:05 MST 2006/01/02"))

Usage notes:

  • The ConsoleLogWriter does not display the source of the message to standard output, but the FileLogWriter does.
  • The utility functions (Info, Debug, Warn, etc) derive their source from the calling function, and this incurs extra overhead.

Changes from 2.0:

  • The external interface has remained mostly stable, but a lot of the internals have been changed, so if you depended on any of this or created your own LogWriter, then you will probably have to update your code. In particular, Logger is now a map and ConsoleLogWriter is now a channel behind-the-scenes, and the LogWrite method no longer has return values.

Future work: (please let me know if you think I should work on any of these particularly)

  • Log file rotation
  • Logging configuration files ala log4j
  • Have the ability to remove filters?
  • Have GetInfoChannel, GetDebugChannel, etc return a chan string that allows for another method of logging
  • Add an XML filter type

Index

Constants

View Source 
const (
	L4G_VERSION = "log4go-v3.0.1"
	L4G_MAJOR   = 3
	L4G_MINOR   = 0
	L4G_BUILD   = 1
)

Version information

View Source 
const (
	FORMAT_DEFAULT = "[%D %T] [%L] (%S) %M"
	FORMAT_SHORT   = "[%t %d] [%L] %M"
	FORMAT_ABBREV  = "[%L] %M"
)

Variables

View Source 
var (
	// LogBufferLength specifies how many log messages a particular log4go
	// logger can buffer at a time before writing them.
	LogBufferLength = 50480
)

***** Variables *****

Functions

func AddFilter 

func AddFilter(name string, lvl Level, writer LogWriter)

Wrapper for (*Logger).AddFilter

func Close 

func Close()

Wrapper for (*Logger).Close (closes and removes all logwriters)

func Crash 

func Crash(args ...interface{})

func Crashf 

func Crashf(format string, args ...interface{})

Logs the given message and crashes the program

func Critical 

func Critical(arg0 interface{}, args ...interface{})

Utility for critical log messages (returns an error for easy function returns) (see Debug() for parameter explanation) These functions will execute a closure exactly once, to build the error message for the return Wrapper for (*Logger).Critical

func CriticalT 

func CriticalT(tag string, arg0 interface{}, args ...interface{})

func Debug 

func Debug(arg0 interface{}, args ...interface{})

Utility for debug log messages When given a string as the first argument, this behaves like Logf but with the DEBUG log level (e.g. the first argument is interpreted as a format for the latter arguments) When given a closure of type func()string, this logs the string returned by the closure iff it will be logged. The closure runs at most one time. When given anything else, the log message will be each of the arguments formatted with %v and separated by spaces (ala Sprint). Wrapper for (*Logger).Debug

func DebugT 

func DebugT(tag string, arg0 interface{}, args ...interface{})

func Error 

func Error(arg0 interface{}, args ...interface{})

Utility for error log messages (returns an error for easy function returns) (see Debug() for parameter explanation) These functions will execute a closure exactly once, to build the error message for the return Wrapper for (*Logger).Error

func ErrorT 

func ErrorT(tag string, arg0 interface{}, args ...interface{})

func Exit 

func Exit(args ...interface{})

Compatibility with `log`

func Exitf 

func Exitf(format string, args ...interface{})

Compatibility with `log`

func Fine 

func Fine(arg0 interface{}, args ...interface{})

Utility for fine log messages (see Debug() for parameter explanation) Wrapper for (*Logger).Fine

func Finest 

func Finest(arg0 interface{}, args ...interface{})

Utility for finest log messages (see Debug() for parameter explanation) Wrapper for (*Logger).Finest

func FormatLogRecord 

func FormatLogRecord(formatCache *formatCacheType, format string, rec *LogRecord) string

Known format codes: %T - Time (15:04:05 MST) %t - Time (15:04) %D - Date (2006/01/02) %d - Date (01/02/06) %L - Level (FNST, FINE, DEBG, TRAC, WARN, EROR, CRIT) %S - Source %M - Message %c - sec ---- Alternate %G - tag %I - ip %l - logId Ignores unknown formats Recommended: "[%D %T] [%L] (%S) %M"

func GetLevel 

func GetLevel() string

func Info 

func Info(arg0 interface{}, args ...interface{})

Utility for info log messages (see Debug() for parameter explanation) Wrapper for (*Logger).Info

func InfoT 

func InfoT(tag string, arg0 interface{}, args ...interface{})

func IsEnabledFor 

func IsEnabledFor(lvl Level) bool

func LoadConfiguration 

func LoadConfiguration(filename string)

Wrapper for (*Logger).LoadConfiguration

func LoadConfigurationByXml added in v1.7.3 

func LoadConfigurationByXml(xc *XmlLoggerConfig)

func Log 

func Log(lvl Level, source, message string)

Send a log message manually Wrapper for (*Logger).Log

func Logc 

func Logc(lvl Level, closure func() string)

Send a closure log message Wrapper for (*Logger).Logc

func Logf 

func Logf(lvl Level, format string, args ...interface{})

Send a formatted log message easily Wrapper for (*Logger).Logf

func SetLevel 

func SetLevel(lvl int)

func Stderr 

func Stderr(args ...interface{})

Compatibility with `log`

func Stderrf 

func Stderrf(format string, args ...interface{})

Compatibility with `log`

func Stdout 

func Stdout(args ...interface{})

Compatibility with `log`

func Stdoutf 

func Stdoutf(format string, args ...interface{})

Compatibility with `log`

func Trace 

func Trace(arg0 interface{}, args ...interface{})

Utility for trace log messages (see Debug() for parameter explanation) Wrapper for (*Logger).Trace

func TraceT 

func TraceT(tag string, arg0 interface{}, args ...interface{})

func Warn 

func Warn(arg0 interface{}, args ...interface{})

Utility for warn log messages (returns an error for easy function returns) (see Debug() for parameter explanation) These functions will execute a closure exactly once, to build the error message for the return Wrapper for (*Logger).Warn

func WarnT 

func WarnT(tag string, arg0 interface{}, args ...interface{})

Types

type ConsoleLogWriter 

type ConsoleLogWriter struct {
	// contains filtered or unexported fields
}

This is the standard writer that prints to standard output.

func NewConsoleLogWriter 

func NewConsoleLogWriter() *ConsoleLogWriter

This creates a new ConsoleLogWriter

func (*ConsoleLogWriter) Close 

func (c *ConsoleLogWriter) Close()

Close stops the logger from sending messages to standard output. Attempts to send log messages to this logger after a Close have undefined behavior.

func (*ConsoleLogWriter) LogWrite 

func (c *ConsoleLogWriter) LogWrite(rec *LogRecord)

This is the ConsoleLogWriter's output method. This will block if the output buffer is full.

func (*ConsoleLogWriter) SetFormat 

func (c *ConsoleLogWriter) SetFormat(format string)

type FileLogWriter 

type FileLogWriter struct {
	ScribeCategory string
	// contains filtered or unexported fields
}

This log writer sends output to a file

func NewFileLogWriter 

func NewFileLogWriter(fileName string, rotate, daily, hourly bool) *FileLogWriter

NewFileLogWriter creates a new LogWriter which writes to the given file and has rotation enabled if rotate is true.

If rotate is true, any time a new log file is opened, the old one is renamed with a .### extension to preserve it. The various Set* methods can be used to configure log rotation based on lines, size, and daily.

The standard log-line format is: 

[%D %T] [%L] (%S) %M

func NewXMLLogWriter 

func NewXMLLogWriter(fName string, rotate bool) *FileLogWriter

NewXMLLogWriter is a utility method for creating a FileLogWriter set up to output XML record log messages instead of line-based ones.

func (*FileLogWriter) Close 

func (w *FileLogWriter) Close()

func (*FileLogWriter) LogWrite 

func (w *FileLogWriter) LogWrite(rec *LogRecord)

This is the FileLogWriter's output method

func (*FileLogWriter) Rotate 

func (w *FileLogWriter) Rotate()

Request that the logs rotate

func (*FileLogWriter) SetFormat 

func (w *FileLogWriter) SetFormat(format string) *FileLogWriter

Set the logging format (chainable). Must be called before the first log message is written.

func (*FileLogWriter) SetHeadFoot 

func (w *FileLogWriter) SetHeadFoot(head, foot string) *FileLogWriter

Set the logfile header and footer (chainable). Must be called before the first log message is written. These are formatted similar to the FormatLogRecord (e.g. you can use %D and %T in your header/footer for date and time).

func (*FileLogWriter) SetRotate 

func (w *FileLogWriter) SetRotate(rotate bool) *FileLogWriter

SetRotate changes whether or not the old logs are kept. (chainable) Must be called before the first log message is written. If rotate is false, the files are overwritten; otherwise, they are rotated to another file before the new log is opened.

func (*FileLogWriter) SetRotateDaily 

func (w *FileLogWriter) SetRotateDaily(daily bool) *FileLogWriter

Set rotate daily (chainable). Must be called before the first log message is written.

func (*FileLogWriter) SetRotateHourly 

func (w *FileLogWriter) SetRotateHourly(hourly bool) *FileLogWriter

func (*FileLogWriter) SetRotateLines 

func (w *FileLogWriter) SetRotateLines(maxLines int) *FileLogWriter

Set rotate at linecount (chainable). Must be called before the first log message is written.

func (*FileLogWriter) SetRotateSize 

func (w *FileLogWriter) SetRotateSize(maxsize int) *FileLogWriter

Set rotate at size (chainable). Must be called before the first log message is written.

type Filter 

type Filter struct {
	Level Level
	LogWriter
}

A Filter represents the log level below which no log records are written to the associated LogWriter.

type FormatLogWriter 

type FormatLogWriter struct {
	// contains filtered or unexported fields
}

This is the standard writer that prints to standard output.

func NewFormatLogWriter 

func NewFormatLogWriter(out io.Writer, format string) FormatLogWriter

This creates a new FormatLogWriter

func (FormatLogWriter) Close 

func (w FormatLogWriter) Close()

Close stops the logger from sending messages to standard output. Attempts to send log messages to this logger after a Close have undefined behavior.

func (FormatLogWriter) LogWrite 

func (w FormatLogWriter) LogWrite(rec *LogRecord)

This is the FormatLogWriter's output method. This will block if the output buffer is full.

type Level 

type Level int

These are the integer logging levels used by the logger 

const (
	FINEST Level = iota
	FINE
	DEBUG
	TRACE
	INFO
	WARNING
	ERROR
	CRITICAL
)

func (Level) String 

func (l Level) String() string

type LogRecord 

type LogRecord struct {
	Level   Level     // The log level
	Created time.Time // The time at which the log message was created (nanoseconds)
	Source  string    // The message source
	Message string    // The log message
	// Alternate
	Tag   string // The tag
	Ip    string // clientIp
	LogId string // logId
	Url   string // url
}

A LogRecord contains all of the pertinent information for each message

type LogWriter 

type LogWriter interface {
	// This will be called to log a LogRecord message.
	LogWrite(rec *LogRecord)

	// This should clean up anything lingering about the LogWriter, as it is called before
	// the LogWriter is removed.  LogWrite should not be called after Close.
	Close()
}

This is an interface for anything that should be able to write logs

type Logger 

type Logger map[string]*Filter

A Logger represents a collection of Filters through which log messages are written. 

var (
	Global Logger
)

func NewConsoleLogger 

func NewConsoleLogger(lvl Level) Logger

Create a new logger with a "stdout" filter configured to send log messages at or above lvl to standard output.

DEPRECATED: use NewDefaultLogger instead.

func NewDefaultLogger 

func NewDefaultLogger(lvl Level) Logger

Create a new logger with a "stdout" filter configured to send log messages at or above lvl to standard output.

func NewLogger 

func NewLogger() Logger

Create a new logger.

DEPRECATED: Use make(Logger) instead.

func (Logger) AddFilter 

func (log Logger) AddFilter(name string, lvl Level, writer LogWriter) Logger

Add a new LogWriter to the Logger which will only log messages at lvl or higher. This function should not be called from multiple goroutines. Returns the logger for chaining.

func (Logger) Close 

func (log Logger) Close()

Closes all log writers in preparation for exiting the program or a reconfiguration of logging. Calling this is not really imperative, unless you want to guarantee that all log messages are written. Close removes all filters (and thus all LogWriters) from the logger.

func (Logger) Critical 

func (log Logger) Critical(arg0 interface{}, args ...interface{}) error

Critical logs a message at the critical log level and returns the formatted error, See Warn for an explanation of the performance and Debug for an explanation of the parameters.

func (Logger) Debug 

func (log Logger) Debug(arg0 interface{}, args ...interface{})

Debug is a utility method for debug log messages. The behavior of Debug depends on the first argument:

  • arg0 is a string When given a string as the first argument, this behaves like Logf but with the DEBUG log level: the first argument is interpreted as a format for the latter arguments.
  • arg0 is a func()string When given a closure of type func()string, this logs the string returned by the closure iff it will be logged. The closure runs at most one time.
  • arg0 is interface{} When given anything else, the log message will be each of the arguments formatted with %v and separated by spaces (ala Sprint).

func (Logger) Error 

func (log Logger) Error(arg0 interface{}, args ...interface{}) error

Error logs a message at the error log level and returns the formatted error, See Warn for an explanation of the performance and Debug for an explanation of the parameters.

func (Logger) Fine 

func (log Logger) Fine(arg0 interface{}, args ...interface{})

Fine logs a message at the fine log level. See Debug for an explanation of the arguments.

func (Logger) Finest 

func (log Logger) Finest(arg0 interface{}, args ...interface{})

Finest logs a message at the finest log level. See Debug for an explanation of the arguments.

func (Logger) Info 

func (log Logger) Info(arg0 interface{}, args ...interface{})

Info logs a message at the info log level. See Debug for an explanation of the arguments.

func (Logger) IntLogfTagUrl added in v1.7.0 

func (log Logger) IntLogfTagUrl(tag, clientIp, logId, url string, lvl Level, format string, args ...interface{})

func (Logger) IsEnabledFor 

func (log Logger) IsEnabledFor(lvl Level) bool

func (Logger) LoadConfiguration 

func (log Logger) LoadConfiguration(filename string)

Load XML configuration; see examples/example.xml for documentation

func (Logger) LoadConfigurationByXml added in v1.7.3 

func (log Logger) LoadConfigurationByXml(xc *XmlLoggerConfig)

func (Logger) Log 

func (log Logger) Log(lvl Level, source, message string)

Send a log message with manual level, source, and message.

func (Logger) LogWithTag 

func (log Logger) LogWithTag(tag string, lvl Level, source, message string)

Send a log message with manual level, source, and message.

func (Logger) Logc 

func (log Logger) Logc(lvl Level, closure func() string)

Logc logs a string returned by the closure at the given log level, using the caller as its source. If no log message would be written, the closure is never called.

func (Logger) Logf 

func (log Logger) Logf(lvl Level, format string, args ...interface{})

Logf logs a formatted log message at the given log level, using the caller as its source.

func (Logger) Trace 

func (log Logger) Trace(arg0 interface{}, args ...interface{})

Trace logs a message at the trace log level. See Debug for an explanation of the arguments.

func (Logger) Warn 

func (log Logger) Warn(arg0 interface{}, args ...interface{}) error

Warn logs a message at the warning log level and returns the formatted error. At the warning level and higher, there is no performance benefit if the message is not actually logged, because all formats are processed and all closures are executed to format the error message. See Debug for further explanation of the arguments.

type SocketLogWriter 

type SocketLogWriter chan *LogRecord

This log writer sends output to a socket

func NewSocketLogWriter 

func NewSocketLogWriter(proto, hostport string) SocketLogWriter

func (SocketLogWriter) Close 

func (w SocketLogWriter) Close()

func (SocketLogWriter) LogWrite 

func (w SocketLogWriter) LogWrite(rec *LogRecord)

This is the SocketLogWriter's output method

type XmlFilter added in v1.7.3 

type XmlFilter struct {
	Enabled  string        `xml:"enabled,attr"`
	Tag      string        `xml:"tag"`
	Level    string        `xml:"level"`
	Type     string        `xml:"type"`
	Property []XmlProperty `xml:"property"`
}

type XmlLoggerConfig added in v1.7.3 

type XmlLoggerConfig struct {
	ScribeCategory string      `xml:"scribeCategory"`
	Filter         []XmlFilter `xml:"filter"`
}

type XmlProperty added in v1.7.3 

type XmlProperty struct {
	Name  string `xml:"name,attr"`
	Value string `xml:",chardata"`
}

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