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
https://github.com/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 (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 ¶
- Variables
- func CopyStandardLogTo(name string)
- func Error(args ...interface{})
- func ErrorDepth(depth int, args ...interface{})
- func Errorf(format string, args ...interface{})
- func Errorln(args ...interface{})
- func Exit(args ...interface{})
- func ExitDepth(depth int, args ...interface{})
- func Exitf(format string, args ...interface{})
- func Exitln(args ...interface{})
- func Fatal(args ...interface{})
- func FatalDepth(depth int, args ...interface{})
- func Fatalf(format string, args ...interface{})
- func Fatalln(args ...interface{})
- func Flush()
- func GetRateLimit() (time.Duration, int)
- func Info(args ...interface{})
- func InfoDepth(depth int, args ...interface{})
- func Infof(format string, args ...interface{})
- func Infoln(args ...interface{})
- func SetOnFatalFunc(f func([]byte))
- func SetOutput(w io.Writer) io.Writer
- func SetRateLimit(limit time.Duration, burst int) (time.Duration, int)
- func SetVModule(value string) (string, error)
- func VModule() string
- func Warning(args ...interface{})
- func WarningDepth(depth int, args ...interface{})
- func Warningf(format string, args ...interface{})
- func Warningln(args ...interface{})
- type Level
- type OutputStats
- type Verbose
Constants ¶
This section is empty.
Variables ¶
var MaxSize uint64 = 1024 * 1024 * 1800
MaxSize is the maximum size of a log file in bytes.
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 an error message. 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"). Use when wrapping Error()
func Errorf ¶
func Errorf(format string, args ...interface{})
Errorf logs an error message. Arguments are handled in the manner of fmt.Printf; a newline is appended if missing.
func Errorln ¶
func Errorln(args ...interface{})
Errorln logs an error message. Arguments are handled in the manner of fmt.Println; a newline is appended if missing.
func Exit ¶
func Exit(args ...interface{})
Exit logs a fatal message, 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 a fatal message, then calls os.Exit(1). Arguments are handled in the manner of fmt.Printf; a newline is appended if missing.
func Fatal ¶
func Fatal(args ...interface{})
Fatal logs a fatal message, 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. Think carefully before using Fatal, it is usually better to return an error to your caller.
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"). Use when wrapping Fatal().
func Fatalf ¶
func Fatalf(format string, args ...interface{})
Fatalf logs a fatal message, 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. Think carefully before using Fatalf, it is usually better to return an error to your caller.
func Fatalln ¶
func Fatalln(args ...interface{})
Fatalln logs a fatal message, 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 GetRateLimit ¶
GetRateLimit returns the seconds and burst size for the current rate limiter.
If no rate limit it setup, it will return zero values.
func Info ¶
func Info(args ...interface{})
Info logs an informational message. 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"). Use when wrapping Info()
func Infof ¶
func Infof(format string, args ...interface{})
Infof logs an informational message. Arguments are handled in the manner of fmt.Printf; a newline is appended if missing.
func Infoln ¶
func Infoln(args ...interface{})
Infoln logs an informational message. Arguments are handled in the manner of fmt.Println; a newline is appended if missing.
func SetOnFatalFunc ¶
func SetOnFatalFunc(f func([]byte))
SetOnFatalFunc sets a function to be called on glog.Fatal() invocation. It allows to run some logic to report or track the error before os.Exit. It's expected that the passed function doesn't hang (i.e. doing network request) as it will halt the termination.
func SetOutput ¶
SetOutput sets the writer for log output. By default this is os.StdErr. It returns the writer that was previously set.
func SetRateLimit ¶
SetRateLimit sets the rate limit in seconds and burst size.
func SetVModule ¶
SetVModule sets the per-module verbosity level. Syntax: message=2,routing*=1
func Warning ¶
func Warning(args ...interface{})
Warning logs a warning message. 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").
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.
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.
func (*OutputStats) PrevRateLimitedLines ¶
func (s *OutputStats) PrevRateLimitedLines() int64
PrevRateLimitedLines returns the previous number of lines dropped due to rate limiting.
func (*OutputStats) RateLimitedLines ¶
func (s *OutputStats) RateLimitedLines() int64
RateLimitedLines returns the number of lines dropped due to rate limiting.
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 ¶
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.
Source Files