glog

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Published: May 17, 2017 License: Apache-2.0 Imports: 20 Imported by: 109

README

glog
====

Leveled execution logs for Go.

This is an efficient pure Go implementation of leveled logs in the
manner of the open source C++ package
	http://code.google.com/p/google-glog

By binding methods to booleans it is possible to use the log package
without paying the expense of evaluating the arguments to the log.
Through the -vmodule flag, the package also provides fine-grained
control over logging at the file level.

The comment from glog.go introduces the ideas:

	Package glog implements logging analogous to the Google-internal
	C++ INFO/ERROR/V setup.  It provides functions Info, Warning,
	Error, Fatal, plus formatting variants such as Infof. It
	also provides V-style logging controlled by the -v and
	-vmodule=file=2 flags.
	
	Basic examples:
	
		glog.Info("Prepare to repel boarders")
	
		glog.Fatalf("Initialization failed: %s", err)
	
	See the documentation for the V function for an explanation
	of these examples:
	
		if glog.V(2) {
			glog.Info("Starting transaction...")
		}
	
		glog.V(2).Infoln("Processed", nItems, "elements")


The repository contains an open source version of the log package
used inside Google. The master copy of the source lives inside
Google, not here. The code in this repo is for export only and is not itself
under development. Feature requests will be ignored.

Send bug reports to golang-nuts@googlegroups.com.

Documentation

Overview

Package glog implements logging analogous to the Google-internal C++ INFO/ERROR/V setup. It provides functions Info, Warning, Error, Fatal, plus formatting variants such as Infof. It also provides V-style logging controlled by the -v and -vmodule=file=2 flags.

Basic examples:

glog.Info("Prepare to repel boarders")

glog.Fatalf("Initialization failed: %s", err)

See the documentation for the V function for an explanation of these examples:

if glog.V(2) {
    glog.Info("Starting transaction...")
}

glog.V(2).Infoln("Processed", nItems, "elements")

Log output is buffered and written periodically using Flush. Programs should call Flush before exiting to guarantee all log output is written.

By default, all log statements write to files in a temporary directory. This package provides several flags that modify this behavior.

-logtostderr=false
    Logs are written to standard error instead of to files.
-alsologtostderr=false
    Logs are written to standard error as well as to files.
-stderrthreshold=ERROR
    Log events at or above this severity are logged to standard
    error as well as to files.
-log_dir=""
    Log files will be written to this directory instead of the
    default temporary directory.

Other flags provide aids to debugging.

-log_backtrace_at=""
    When set to a file and line number holding a logging statement,
    such as
        -log_backtrace_at=gopherflakes.go:234
    a stack trace will be written to the Info log whenever execution
    hits that statement. (Unlike with -vmodule, the ".go" must be
    present.)
-v=0
    Enable V-leveled logging at the specified level.
-vmodule=""
    The syntax of the argument is a comma-separated list of pattern=N,
    where pattern is a literal file name (minus the ".go" suffix) or
    "glob" pattern and N is a V level. For instance,
        -vmodule=gopher*=3
    sets the V level to 3 in all Go files whose names begin "gopher".

Index

Constants

This section is empty.

Variables

View Source
var MaxSize uint64 = 1024 * 1024 * 1800

MaxSize is the maximum size of a log file in bytes.

View Source
var Stats struct {
	Info, Warning, Error OutputStats
}

Stats tracks the number of lines of output and number of bytes per severity level. Values must be read with atomic.LoadInt64.

Functions

func Error

func Error(args ...interface{})

Error logs to the ERROR, WARNING, and INFO logs. Arguments are handled in the manner of fmt.Print; a newline is appended if missing.

func Errorf

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

Errorf logs to the ERROR, WARNING, and INFO logs. Arguments are handled in the manner of fmt.Printf; a newline is appended if missing.

func Errorln

func Errorln(args ...interface{})

Errorln logs to the ERROR, WARNING, and INFO logs. Arguments are handled in the manner of fmt.Println; a newline is appended if missing.

func Fatal

func Fatal(args ...interface{})

Fatal logs to the FATAL, ERROR, WARNING, and INFO logs, including a stack trace of all running goroutines, then calls os.Exit(255). Arguments are handled in the manner of fmt.Print; a newline is appended if missing.

func Fatalf

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

Fatalf logs to the FATAL, ERROR, WARNING, and INFO logs, including a stack trace of all running goroutines, then calls os.Exit(255). Arguments are handled in the manner of fmt.Printf; a newline is appended if missing.

func Fatalln

func Fatalln(args ...interface{})

Fatalln logs to the FATAL, ERROR, WARNING, and INFO logs, including a stack trace of all running goroutines, then calls os.Exit(255). Arguments are handled in the manner of fmt.Println; a newline is appended if missing.

func Flush

func Flush()

Flush flushes all pending log I/O.

func Info

func Info(args ...interface{})

Info logs to the INFO log. Arguments are handled in the manner of fmt.Print; a newline is appended if missing.

func Infof

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

Infof logs to the INFO log. Arguments are handled in the manner of fmt.Printf; a newline is appended if missing.

func Infoln

func Infoln(args ...interface{})

Infoln logs to the INFO log. Arguments are handled in the manner of fmt.Println; a newline is appended if missing.

func SetAlsoToStderr

func SetAlsoToStderr(value bool)

Programatic Method to set logging to stderr and files

func SetLogDir

func SetLogDir(value string)

Programmatically set logDir value

func SetLogDirCleanup

func SetLogDirCleanup(seconds int)

Programmatically set logDirCleanup value

func SetLogstashType

func SetLogstashType(value string)

Programatic Method to set logstash type

func SetLogstashURL

func SetLogstashURL(value string)

Programatic Method to set the logstash url

func SetStderrThreshold

func SetStderrThreshold(value string) error

Programatic Method to set stderr threshold

func SetToStderr

func SetToStderr(value bool)

Programatic Method to set logging to stderr instead of file

func SetTraceLocation

func SetTraceLocation(value string) error

func SetVModule

func SetVModule(value string) error

Programatic Method to set vmodule

func SetVerbosity

func SetVerbosity(value int)

Programatic Method to set logging verbosity

func Warning

func Warning(args ...interface{})

Warning logs to the WARNING and INFO logs. Arguments are handled in the manner of fmt.Print; a newline is appended if missing.

func Warningf

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

Warningf logs to the WARNING and INFO logs. Arguments are handled in the manner of fmt.Printf; a newline is appended if missing.

func Warningln

func Warningln(args ...interface{})

Warningln logs to the WARNING and INFO logs. Arguments are handled in the manner of fmt.Println; a newline is appended if missing.

Types

type Level

type Level int32

Level specifies a level of verbosity for V logs. *Level implements flag.Value; the -v flag is of type Level and should be modified only through the flag.Value interface.

func GetVerbosity

func GetVerbosity() Level

Programatic Method to set logging verbosity

func (*Level) Get

func (l *Level) Get() interface{}

Get is part of the flag.Value interface.

func (*Level) Set

func (l *Level) Set(value string) error

Set is part of the flag.Value interface.

func (*Level) String

func (l *Level) String() string

String is part of the flag.Value interface.

type OutputStats

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

OutputStats tracks the number of output lines and bytes written.

func (*OutputStats) Bytes

func (s *OutputStats) Bytes() int64

Bytes returns the number of bytes written.

func (*OutputStats) Lines

func (s *OutputStats) Lines() int64

Lines returns the number of lines written.

type Verbose

type Verbose bool

Verbose is a boolean type that implements Infof (like Printf) etc. See the documentation of V for more information.

func V

func V(level Level) Verbose

V reports whether verbosity at the call site is at least the requested level. The returned value is a boolean of type Verbose, which implements Info, Infoln and Infof. These methods will write to the Info log if called. Thus, one may write either

if glog.V(2) { glog.Info("log this") }

or

glog.V(2).Info("log this")

The second form is shorter but the first is cheaper if logging is off because it does not evaluate its arguments.

Whether an individual call to V generates a log record depends on the setting of the -v and --vmodule flags; both are off by default. If the level in the call to V is at least the value of -v, or of -vmodule for the source file containing the call, the V call will log.

func (Verbose) Info

func (v Verbose) Info(args ...interface{})

Info is equivalent to the global Info function, guarded by the value of v. See the documentation of V for usage.

func (Verbose) Infof

func (v Verbose) Infof(format string, args ...interface{})

Infof is equivalent to the global Infof function, guarded by the value of v. See the documentation of V for usage.

func (Verbose) Infoln

func (v Verbose) Infoln(args ...interface{})

Infoln is equivalent to the global Infoln function, guarded by the value of v. See the documentation of V for usage.

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