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 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 the functions Info, Warning, Error, Fatal, plus formatting variants such as Infof. It also provides V-style loggingcontrolled 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 Debug(args ...interface{})
- func Debugf(format string, args ...interface{})
- func Error(args ...interface{})
- func ErrorDepth(depth int, args ...interface{})
- func Errorf(format string, args ...interface{})
- func Errorln(args ...interface{})
- func Fatal(args ...interface{})
- func FatalDepth(depth int, args ...interface{})
- func Fatalf(format string, args ...interface{})
- func Fatalln(args ...interface{})
- func Info(args ...interface{})
- func InfoDepth(depth int, args ...interface{})
- func Infof(format string, args ...interface{})
- func Infoln(args ...interface{})
- func Init()
- func NewLogger(subdir string, resetLogDir bool) *loggingT
- func Trace(args ...interface{})
- func Tracef(format string, args ...interface{})
- func Warning(args ...interface{})
- func WarningDepth(depth int, args ...interface{})
- func Warningf(format string, args ...interface{})
- func Warningln(args ...interface{})
- type Level
- type LogDir
- type LoggingT
- type OutputStats
- type Verbose
Constants ¶
This section is empty.
Variables ¶
var G *loggingT
A global logger defined for convenience. Note that you need to call glog.Init() anytime you call flag.Parse() so it can pick up the new arguments.
TODO: This interface is a bit of a mess. Should be that it gets the flags automatically on flag.Parse() and you never have to call Init.
var GlogFlags struct { AlsoToStderr bool // The -alsologtostderr flag. LogDir string // A symlink pointing to the current logdir. Symlink string // contains filtered or unexported fields }
GlogFlags stores the commandline flags related to the golog library.
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 Debugf ¶
func Debugf(format string, args ...interface{})
Debugf is a convenience method to log at v=1.
func Error ¶
func Error(args ...interface{})
Error logs to the ERROR log. 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 log. 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 log. 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 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 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 Init ¶
func Init()
You must call this after calling flag.Parse() to initialize glog with the new commandline arguments.
func Tracef ¶
func Tracef(format string, args ...interface{})
Tracef is a convenience method to log at v=2.
func Warning ¶
func Warning(args ...interface{})
Warning logs to the WARNING log. 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.
type Verbose ¶
type Verbose struct {
// contains filtered or unexported fields
}
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