From 3aa94be38074e92a7a372e4dedec88790363c65c Mon Sep 17 00:00:00 2001 From: Nate Finch Date: Fri, 27 Jun 2014 06:13:39 -0400 Subject: [PATCH] update readme and mention gopkg.in in godoc --- README.md | 135 ++++++++++++++++++++++++-------------------------- lumberjack.go | 8 +++ 2 files changed, 72 insertions(+), 71 deletions(-) diff --git a/README.md b/README.md index 6e5d24e..070560f 100644 --- a/README.md +++ b/README.md @@ -1,32 +1,40 @@ - # lumberjack [![GoDoc](https://godoc.org/github.com/natefinch/lumberjack?status.png)](https://godoc.org/github.com/natefinch/lumberjack) [![Build Status](https://travis-ci.org/natefinch/lumberjack.png)](https://travis-ci.org/natefinch/lumberjack) ### Lumberjack is a Go package for writing logs to rolling files. +Package lumberjack provides a rolling logger. + +Note that this is v2.0 of lumberjack, and should be imported using gopkg.in +thusly: + + import "gopkg.in/natefinch/lumberjack.v2" + +The package name remains simply lumberjack, and the code resides at +https://github.com/natefinch/lumberjack under the v2.0 branch. + Lumberjack is intended to be one part of a logging infrastructure. It is not an all-in-one solution, but instead is a pluggable component at the bottom of the logging stack that simply controls the files to which logs are written. -Lumberjack plays well with any logger that can write to an io.Writer, -including the standard library's log package. +Lumberjack plays well with any logging package that can write to an +io.Writer, including the standard library's log package. Lumberjack assumes that only one process is writing to the output files. Using the same lumberjack configuration from multiple processes on the same machine will result in improper behavior. -#### Example -To use lumberjack with the standard library's log package, just pass it into the -SetOutput function when your application starts. +**Example** + +To use lumberjack with the standard library's log package, just pass it into the SetOutput function when your application starts. Code: ```go log.SetOutput(&lumberjack.Logger{ - Dir: "/var/log/myapp/", - NameFormat: "2006-01-02T15-04-05.000.log", - MaxSize: lumberjack.Gigabyte, + Filename: "/var/log/myapp/foo.log", + MaxSize: 500, // megabytes MaxBackups: 3, MaxAge: 28, }) @@ -34,35 +42,23 @@ log.SetOutput(&lumberjack.Logger{ -## Constants -``` go -const ( - Megabyte = 1024 * 1024 - Gigabyte = 1024 * Megabyte -) -``` - - - ## type Logger ``` go type Logger struct { - // Dir determines the directory in which to store log files. - // It defaults to os.TempDir() if empty. - Dir string `json:"dir" yaml:"dir"` + // Filename is the file to write logs to. Backup log files will be retained + // in the same directory. It uses -lumberjack.log in + // os.TempDir() if empty. + Filename string `json:"filename" yaml:"filename"` - // NameFormat is the time formatting layout used to generate filenames. - // It defaults to "2006-01-02T15-04-05.000.log". - NameFormat string `json:"nameformat" yaml:"nameformat"` + // MaxSize is the maximum size in megabytes of the log file before it gets + // rotated. It defaults to 100 megabytes. + MaxSize int `json:"maxsize" yaml:"maxsize"` - // MaxSize is the maximum size in bytes of the log file before it gets - // rolled. It defaults to 100 megabytes. - MaxSize int64 `json:"maxsize" yaml:"maxsize"` - - // MaxAge is the maximum number of days to retain old log files based on - // FileInfo.ModTime. Note that a day is defined as 24 hours and may not - // exactly correspond to calendar days due to daylight savings, leap - // seconds, etc. The default is not to remove old log files based on age. + // MaxAge is the maximum number of days to retain old log files based on the + // timestamp encoded in their filename. Note that a day is defined as 24 + // hours and may not exactly correspond to calendar days due to daylight + // savings, leap seconds, etc. The default is not to remove old log files + // based on age. MaxAge int `json:"maxage" yaml:"maxage"` // MaxBackups is the maximum number of old log files to retain. The default @@ -70,36 +66,34 @@ type Logger struct { // deleted.) MaxBackups int `json:"maxbackups" yaml:"maxbackups"` - // LocalTime determines if the time used for formatting the filename is the - // computer's local time. The default is to use UTC time. + // LocalTime determines if the time used for formatting the timestamps in + // backup files is the computer's local time. The default is to use UTC + // time. LocalTime bool `json:"localtime" yaml:"localtime"` // contains filtered or unexported fields } ``` -Logger is an io.WriteCloser that writes to a log file in the given directory -with the given NameFormat. NameFormat should include a time formatting -layout in it that produces a valid unique filename for the OS. For more -about time formatting layouts, read a http://golang.org/pkg/time/#pkg-constants. +Logger is an io.WriteCloser that writes to the specified filename. -The date encoded in the filename by NameFormat is used to determine which log -files are most recent in several situations. +Logger opens or creates the logfile on first Write. If the file exists and +is less than MaxSize megabytes, lumberjack will open and append to that file. +If the file exists and its size is >= MaxSize megabytes, the file is renamed +by putting the current time in a timestamp in the name immediately before the +file's extension (or the end of the filename if there's no extension). A new +log file is then created using original filename. -Logger opens or creates a logfile on first Write. It looks for files in the -directory that match its name format, and if the one with the most recent -NameFormat date is less than MaxSize, it will open and append to that file. -If no such file exists, or the file is >= MaxSize, a new file is created -using the current time with NameFormat to generate the filename. - -Whenever a write would cause the current log file exceed MaxSize, a new file -is created using the current time. +Whenever a write would cause the current log file exceed MaxSize megabytes, +the current file is closed, renamed, and a new log file created with the +original name. Thus, the filename you give Logger is always the "current" log +file. ### Cleaning Up Old Log Files -Whenever a new file gets created, old log files may be deleted. The log file -directory is scanned for files that match NameFormat. The most recent files -according to their NameFormat date will be retained, up to a number equal to -MaxBackups (or all of them if MaxBackups is 0). Any files with a last -modified time (based on FileInfo.ModTime) older than MaxAge days are deleted, -regardless of MaxBackups. +Whenever a new logfile gets created, old log files may be deleted. The most +recent files according to the encoded timestamp will be retained, up to a +number equal to MaxBackups (or all of them if MaxBackups is 0). Any files +with an encoded timestamp older than MaxAge days are deleted, regardless of +MaxBackups. Note that the time encoded in the timestamp is the rotation +time, which may differ from the last time that file was written to. If MaxBackups and MaxAge are both 0, no old log files will be deleted. @@ -131,35 +125,34 @@ rotations outside of the normal rotation rules, such as in response to SIGHUP. After rotating, this initiates a cleanup of old log files according to the normal rules. - -#### Example +**Example** Example of how to rotate in response to SIGHUP. Code: + ```go - l := &lumberjack.Logger{} - log.SetOutput(l) - c := make(chan os.Signal, 1) - signal.Notify(c, syscall.SIGHUP) +l := &lumberjack.Logger{} +log.SetOutput(l) +c := make(chan os.Signal, 1) +signal.Notify(c, syscall.SIGHUP) - go func() { - for { - <-c - l.Rotate() - } - }() +go func() { + for { + <-c + l.Rotate() + } +}() ``` - ### func (\*Logger) Write ``` go func (l *Logger) Write(p []byte) (n int, err error) ``` Write implements io.Writer. If a write would cause the log file to be larger -than MaxSize, a new log file is created using the current time formatted with -PathFormat. If the length of the write is greater than MaxSize, an error is -returned. +than MaxSize, the file is closed, renamed to include a timestamp of the +current time, and a new log file is created using the original log file name. +If the length of the write is greater than MaxSize, an error is returned. diff --git a/lumberjack.go b/lumberjack.go index dcc2289..aca3baa 100644 --- a/lumberjack.go +++ b/lumberjack.go @@ -1,5 +1,13 @@ // Package lumberjack provides a rolling logger. // +// Note that this is v2.0 of lumberjack, and should be imported using gopkg.in +// thusly: +// +// import "gopkg.in/natefinch/lumberjack.v2" +// +// The package name remains simply lumberjack, and the code resides at +// https://github.com/natefinch/lumberjack under the v2.0 branch. +// // Lumberjack is intended to be one part of a logging infrastructure. // It is not an all-in-one solution, but instead is a pluggable // component at the bottom of the logging stack that simply controls the files