diff options
Diffstat (limited to 'vendor/github.com/nxadm/tail/tail.go')
| -rw-r--r-- | vendor/github.com/nxadm/tail/tail.go | 73 |
1 files changed, 44 insertions, 29 deletions
diff --git a/vendor/github.com/nxadm/tail/tail.go b/vendor/github.com/nxadm/tail/tail.go index 58d3c4b95..37ea4411e 100644 --- a/vendor/github.com/nxadm/tail/tail.go +++ b/vendor/github.com/nxadm/tail/tail.go @@ -1,6 +1,12 @@ +// Copyright (c) 2019 FOSS contributors of https://github.com/nxadm/tail // Copyright (c) 2015 HPE Software Inc. All rights reserved. // Copyright (c) 2013 ActiveState Software Inc. All rights reserved. +//nxadm/tail provides a Go library that emulates the features of the BSD `tail` +//program. The library comes with full support for truncation/move detection as +//it is designed to work with log rotation tools. The library works on all +//operating systems supported by Go, including POSIX systems like Linux and +//*BSD, and MS Windows. Go 1.9 is the oldest compiler release supported. package tail import ( @@ -22,26 +28,31 @@ import ( ) var ( + // ErrStop is returned when the tail of a file has been marked to be stopped. ErrStop = errors.New("tail should now stop") ) type Line struct { - Text string - Num int - SeekInfo SeekInfo - Time time.Time - Err error // Error from tail + Text string // The contents of the file + Num int // The line number + SeekInfo SeekInfo // SeekInfo + Time time.Time // Present time + Err error // Error from tail } -// NewLine returns a Line with present time. +// Deprecated: this function is no longer used internally and it has little of no +// use in the API. As such, it will be removed from the API in a future major +// release. +// +// NewLine returns a * pointer to a Line struct. func NewLine(text string, lineNum int) *Line { return &Line{text, lineNum, SeekInfo{}, time.Now(), nil} } -// SeekInfo represents arguments to `io.Seek` +// SeekInfo represents arguments to io.Seek. See: https://golang.org/pkg/io/#SectionReader.Seek type SeekInfo struct { Offset int64 - Whence int // io.Seek* + Whence int } type logger interface { @@ -59,26 +70,28 @@ type logger interface { // Config is used to specify how a file must be tailed. type Config struct { // File-specifc - Location *SeekInfo // Seek to this location before tailing - ReOpen bool // Reopen recreated files (tail -F) - MustExist bool // Fail early if the file does not exist - Poll bool // Poll for file changes instead of using inotify - Pipe bool // Is a named pipe (mkfifo) - RateLimiter *ratelimiter.LeakyBucket + Location *SeekInfo // Tail from this location. If nil, start at the beginning of the file + ReOpen bool // Reopen recreated files (tail -F) + MustExist bool // Fail early if the file does not exist + Poll bool // Poll for file changes instead of using the default inotify + Pipe bool // The file is a named pipe (mkfifo) // Generic IO Follow bool // Continue looking for new lines (tail -f) MaxLineSize int // If non-zero, split longer lines into multiple lines - // Logger, when nil, is set to tail.DefaultLogger - // To disable logging: set field to tail.DiscardingLogger + // Optionally, use a ratelimiter (e.g. created by the ratelimiter/NewLeakyBucket function) + RateLimiter *ratelimiter.LeakyBucket + + // Optionally use a Logger. When nil, the Logger is set to tail.DefaultLogger. + // To disable logging, set it to tail.DiscardingLogger Logger logger } type Tail struct { - Filename string - Lines chan *Line - Config + Filename string // The filename + Lines chan *Line // A consumable channel of *Line + Config // Tail.Configuration file *os.File reader *bufio.Reader @@ -93,16 +106,17 @@ type Tail struct { } var ( - // DefaultLogger is used when Config.Logger == nil + // DefaultLogger logs to os.Stderr and it is used when Config.Logger == nil DefaultLogger = log.New(os.Stderr, "", log.LstdFlags) // DiscardingLogger can be used to disable logging output DiscardingLogger = log.New(ioutil.Discard, "", 0) ) -// TailFile begins tailing the file. Output stream is made available -// via the `Tail.Lines` channel. To handle errors during tailing, -// invoke the `Wait` or `Err` method after finishing reading from the -// `Lines` channel. +// TailFile begins tailing the file. And returns a pointer to a Tail struct +// and an error. An output stream is made available via the Tail.Lines +// channel (e.g. to be looped and printed). To handle errors during tailing, +// after finishing reading from the Lines channel, invoke the `Wait` or `Err` +// method on the returned *Tail. func TailFile(filename string, config Config) (*Tail, error) { if config.ReOpen && !config.Follow { util.Fatal("cannot set ReOpen without Follow.") @@ -138,10 +152,9 @@ func TailFile(filename string, config Config) (*Tail, error) { return t, nil } -// Tell returns the file's current position, like stdio's ftell(). -// But this value is not very accurate. -// One line from the chan(tail.Lines) may have been read, -// so it may have lost one line. +// Tell returns the file's current position, like stdio's ftell() and an error. +// Beware that this value may not be completely accurate because one line from +// the chan(tail.Lines) may have been read already. func (tail *Tail) Tell() (offset int64, err error) { if tail.file == nil { return @@ -167,7 +180,8 @@ func (tail *Tail) Stop() error { return tail.Wait() } -// StopAtEOF stops tailing as soon as the end of the file is reached. +// StopAtEOF stops tailing as soon as the end of the file is reached. The function +// returns an error, func (tail *Tail) StopAtEOF() error { tail.Kill(errStopAtEOF) return tail.Wait() @@ -435,6 +449,7 @@ func (tail *Tail) sendLine(line string) bool { // Cleanup removes inotify watches added by the tail package. This function is // meant to be invoked from a process's exit handler. Linux kernel may not // automatically remove inotify watches after the process exits. +// If you plan to re-read a file, don't call Cleanup in between. func (tail *Tail) Cleanup() { watch.Cleanup(tail.Filename) } |