log

README

btclog

Package btclog defines a logger interface and provides a default implementation of a subsystem-aware leveled logger implementing the same interface.

Installation

$ go get git.parallelcoin.io/dev/9/btclog

License

Package btclog is licensed under the copyfree ISC License.

Documentation

Overview

Package log defines an interface and default implementation for subsystem logging.

Log level verbosity may be modified at runtime for each individual subsystem logger.

The default implementation in this package must be created by the Backend type. Backends can write to any io.Writer, including multi-writers created by io.MultiWriter. Multi-writers allow log output to be written to many writers, standard output and log files.

Optional logging behavior can be specified by using the LOGFLAGS environment variable and overridden per-Backend by using the WithFlags call option. Multiple LOGFLAGS options can be specified, separated by commas.

The following options are recognized:

longfile: Include the full filepath and line number in all log messages

shortfile: Include the filename and line number in all log messages. Overrides longfile.

Index

• Constants
• type Backend
  • func NewBackend(w io.Writer, opts ...BackendOption) *Backend
  • func (b *Backend) Logger(subsystemTag string) Logger
• type BackendOption
  • func WithFlags(flags uint32) BackendOption
• type Level
  • func LevelFromString(s string) (l Level, ok bool)
  • func (l Level) String() string
• type Logger

Constants

const (

	// of the logging callsite, e.g. /a/b/c/main.go:123.
	Llongfile uint32 = 1 << iota

	// of the logging callsite, e.g. main.go:123.  Overrides Llongfile.
	Lshortfile
)

Flags to modify Backend's behavior.

Types

type Backend

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

func NewBackend

func NewBackend(

	w io.Writer, opts ...BackendOption) *Backend

NewBackend creates a logger backend from a Writer.

func (*Backend) Logger

func (b *Backend) Logger(subsystemTag string) Logger

Logger returns a new logger for a particular subsystem that writes to the Backend b. A tag describes the subsystem and is included in all log messages. The logger uses the info verbosity level by default.

type BackendOption

type BackendOption func(b *Backend)

func WithFlags

func WithFlags(

	flags uint32) BackendOption

WithFlags configures a Backend to use the specified flags rather than using the package's defaults as determined through the LOGFLAGS environment variable.

type Level

type Level uint32

const (
	LevelTrace Level = iota
	LevelDebug
	LevelInfo
	LevelWarn
	LevelError
	LevelCritical
	LevelOff
)

Level constants.

func LevelFromString

func LevelFromString(

	s string) (l Level, ok bool)

LevelFromString returns a level based on the input string s. If the input can't be interpreted as a valid log level, the info level and false is returned.

func (Level) String

func (l Level) String() string

String returns the tag of the logger used in log messages, or "OFF" if the level will not produce any log output.

type Logger

type Logger interface {

	// to log with LevelTrace.
	Tracef(format string, params ...interface{})

	// log with LevelDebug.
	Debugf(format string, params ...interface{})

	// log with LevelInfo.
	Infof(format string, params ...interface{})

	// to log with LevelWarn.
	Warnf(format string, params ...interface{})

	// to log with LevelError.
	Errorf(format string, params ...interface{})

	// log with LevelCritical.
	Criticalf(format string, params ...interface{})

	// and writes to log with LevelTrace.
	Trace(v ...interface{})

	// and writes to log with LevelDebug.
	Debug(v ...interface{})

	// and writes to log with LevelInfo.
	Info(v ...interface{})

	// and writes to log with LevelWarn.
	Warn(v ...interface{})

	// and writes to log with LevelError.
	Error(v ...interface{})

	// and writes to log with LevelCritical.
	Critical(v ...interface{})

	// Level returns the current logging level.
	Level() Level

	// SetLevel changes the logging level to the passed level.
	SetLevel(level Level)
}

var Disabled Logger

Disabled is a Logger that will never output anything.