log4go

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Published: Oct 20, 2015 License: BSD-2-Clause, AGPL-3.0, Apache-2.0 Imports: 13 Imported by: 0

README

Please see http://log4go.googlecode.com/

Installation:
- Run `goinstall log4go.googlecode.com/hg`

Usage:
- Add the following import:
import l4g "log4go.googlecode.com/hg"

Acknowledgements:
- pomack
  For providing awesome patches to bring log4go up to the latest Go spec

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 (
	FINEST level = iota
	FINE
	DEBUG
	TRACE
	INFO
	WARNING
	ERROR
	CRITICAL
)
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 = 32
)

***** 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{}) error

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 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 Error

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

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 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(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 Ignores unknown formats Recommended: "[%D %T] [%L] (%S) %M"

func Info

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

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

func LoadConfiguration

func LoadConfiguration(filename string)

Wrapper for (*Logger).LoadConfiguration

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 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 Warn

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

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

Types

type ConsoleLogWriter

type ConsoleLogWriter chan *LogRecord

This is the standard writer that prints to standard output.

func NewConsoleLogWriter

func NewConsoleLogWriter() ConsoleLogWriter

This creates a new ConsoleLogWriter

func (ConsoleLogWriter) Close

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

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

type FileLogWriter

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

This log writer sends output to a file

func NewFileLogWriter

func NewFileLogWriter(fname string, rotate 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) 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 chan *LogRecord

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 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
}

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) LoadConfiguration

func (log Logger) LoadConfiguration(filename string)

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

func (Logger) Log

func (log Logger) Log(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

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