glog

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 Go to latest Published: Jun 4, 2018 License: GPL-3.0, Apache-2.0 Imports: 20 Imported by: 178

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. As a result, flag.Parse must be called before any logging is done. 

-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 or "glob" pattern matching
	and N is a V level. For instance,

-vmodule=gopher.go=3
	sets the V level to 3 in all Go files named "gopher.go".

-vmodule=foo=3
	sets V to 3 in all files of any packages whose import path ends in "foo".

-vmodule=foo/*=3
	sets V to 3 in all files of any packages whose import path contains "foo".

This fork of original golang/glog adds log rotation functionality. Logs are rotated after reaching file size limit or age limit. Additionally limiting total amount of logs is supported (also by both size and age). To keep it simple, log-rotation is configured with package-level variables:

  • MaxSize - maximum file size (in bytes) - default value: 1024 * 1024 * 1800
  • MinSize - minimum file size (in bytes) - default 0 (even empty file can be rotated)
  • MaxTotalSize - maximum size of all files (in bytes) - default 0 (do not remove old files)
  • RotationInterval - how often log should be rotated - default Never
  • MaxAge - maximum age (time.Duration) of log file - default 0 (do not remove old files)
  • Compress - whether to GZIP compress rotated logs - default - false

Default values provide backward-compatibility with golang/glog. If compression is used, all files except the current one are compressed with GZIP.

Rotation works like this:

  • if MaxSize or RotationInterval is reached, and file size is > MinSize, current file became old file, and new file is created as a current log file
  • all log files older than MaxAge are removed
  • if compression is enabled, the old file is compressed
  • size of all log files in log_dir is recalculated (to handle external removals of files, etc)
  • oldest log files are removed until total size of log files doesn't exceed MaxTotalSize-MaxSize

For sanity, this action is executed only when current file is needs to be rotated

Index

Constants

This section is empty.

Variables

View Source 
var Compress bool

Compress determines whether to compress rotated logs with GZIP or not.

View Source 
var DefaultAlsoToStdErr = false

DefaultAlsoToStdErr establishes the default bool toggling whether logging should be written to BOTH file and stderr.

View Source 
var DefaultDisplay = 3

DefaultDisplay establishes the default verbosity Level for display (stderr) logging.

View Source 
var DefaultLogDirName = "log"

DefaultLogDirName establishes the default directory name for debug (V) logs. Log files will be written inside this dir. By default, this directory will be created if it does not exist within the context's chain directory, eg. <datadir>/<chain>/log/.

View Source 
var DefaultToStdErr = false

DefaultToStdErr establishes the default bool toggling whether logging should be directed ONLY to stderr.

View Source 
var DefaultVerbosity = 5

DefaultVerbosity establishes the default verbosity Level for to-file (debug) logging.

View Source 
var MaxAge time.Duration

MaxAge defines the maximum age of the oldest log file. All log files older than MaxAge will be removed.

View Source 
var MaxSize uint64 = 1024 * 1800

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

View Source 
var MaxTotalSize uint64

MaxTotalSize is a maximum size of all log files.

View Source 
var MinSize uint64

MinSize is a minimum file size qualifying for rotation. This variable can be used to avoid rotation of empty or almost emtpy files.

View Source 
var RotationInterval = Never

RotationInterval determines how often log rotation should take place

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 CopyStandardLogTo 

func CopyStandardLogTo(name string)

CopyStandardLogTo arranges for messages written to the Go "log" package's default logs to also appear in the Google logs for the named and lower severities. Subsequent changes to the standard log's default output location or format may break this behavior.

Valid names are "INFO", "WARNING", "ERROR", and "FATAL". If the name is not recognized, CopyStandardLogTo panics.

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 ErrorDepth 

func ErrorDepth(depth int, args ...interface{})

ErrorDepth acts as Error but uses depth to determine which call frame to log. ErrorDepth(0, "msg") is the same as Error("msg").

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 Exit 

func Exit(args ...interface{})

Exit logs to the FATAL, ERROR, WARNING, and INFO logs, then calls os.Exit(1). Arguments are handled in the manner of fmt.Print; a newline is appended if missing.

func ExitDepth 

func ExitDepth(depth int, args ...interface{})

ExitDepth acts as Exit but uses depth to determine which call frame to log. ExitDepth(0, "msg") is the same as Exit("msg").

func Exitf 

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

Exitf logs to the FATAL, ERROR, WARNING, and INFO logs, then calls os.Exit(1). Arguments are handled in the manner of fmt.Printf; a newline is appended if missing.

func Exitln 

func Exitln(args ...interface{})

Exitln logs to the FATAL, ERROR, WARNING, and INFO logs, then calls os.Exit(1).

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 FatalDepth 

func FatalDepth(depth int, args ...interface{})

FatalDepth acts as Fatal but uses depth to determine which call frame to log. FatalDepth(0, "msg") is the same as Fatal("msg").

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 GetLogDir 

func GetLogDir() string

func GetLogDirs 

func GetLogDirs() []string

func GetVModule 

func GetVModule() *moduleSpec

GetVModule returns the global verbosity pattern flag.

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 InfoDepth 

func InfoDepth(depth int, args ...interface{})

InfoDepth acts as Info but uses depth to determine which call frame to log. InfoDepth(0, "msg") is the same as Info("msg").

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 Separator 

func Separator(iterable string) string

Separator creates a line, ie ---------------------------------

func SetAlsoToStderr 

func SetAlsoToStderr(to bool)

SetAlsoToStderr sets global output option for logging to both FS and stderr.

func SetD 

func SetD(v int)

func SetLogDir 

func SetLogDir(str string)

func SetToStderr 

func SetToStderr(toStderr bool)

SetToStderr sets the global output style

func SetV 

func SetV(v int)

SetV sets the global verbosity level

func SetVTraceThreshold 

func SetVTraceThreshold(v int)

SetVTraceThreshold sets the current verbosity trace threshold for logging.

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 WarningDepth 

func WarningDepth(depth int, args ...interface{})

WarningDepth acts as Warning but uses depth to determine which call frame to log. WarningDepth(0, "msg") is the same as Warning("msg").

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 Displayable 

type Displayable bool

func D 

func D(level Level) Displayable

func (Displayable) Errorf 

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

func (Displayable) Errorln 

func (d Displayable) Errorln(args ...interface{})

func (Displayable) Infof 

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

func (Displayable) Infoln 

func (d Displayable) Infoln(args ...interface{})

func (Displayable) Warnf 

func (d Displayable) Warnf(format string, args ...interface{})

func (Displayable) Warnln 

func (d Displayable) Warnln(args ...interface{})

type Interval 

type Interval uint8

Interval is a type for rotation interval specification 

const (
	Never Interval = iota
	Hourly
	Daily
	Weekly
	Monthly
)

These constants identify the interval for log rotation.

func ParseInterval 

func ParseInterval(str string) (Interval, error)

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 GetDisplayable 

func GetDisplayable() *Level

func GetVTraceThreshold 

func GetVTraceThreshold() *Level

GetVTraceThreshold gets the current verbosity trace threshold for logging.

func GetVerbosity added in v1.4.0 

func GetVerbosity() *Level

GetVerbosity returns the global verbosity level flag.

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 TraceLocation 

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

traceLocation represents the setting of the -log_backtrace_at flag.

func GetTraceLocation 

func GetTraceLocation() *TraceLocation

GetTraceLocation returns the global TraceLocation flag.

func (*TraceLocation) Get 

func (t *TraceLocation) Get() interface{}

Get is part of the (Go 1.2) flag.Getter interface. It always returns nil for this flag type since the struct is not exported

func (*TraceLocation) Set 

func (t *TraceLocation) Set(value string) error

Syntax: -log_backtrace_at=gopherflakes.go:234 Note that unlike vmodule the file extension is included here.

func (*TraceLocation) String 

func (t *TraceLocation) String() string

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) Error 

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

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

func (Verbose) Errorf 

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

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

func (Verbose) Errorln 

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

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

func (Verbose) Info 

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

INFO 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.

func (Verbose) Warn 

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

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

func (Verbose) Warnf 

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

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

func (Verbose) Warnln 

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

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

Source Files

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