golang基础-tailf日志组件使用
发布时间:2020-12-16 09:43:07 所属栏目:大数据 来源:网络整理
导读:git上log日志组件 https://github.com/hpcloud/tail/blob/master/tail.go 我们写个test来测试下这个组件 package main import ( "fmt" "github.com/hpcloud/tail" "time" ) func main() { filename := "E:developkafkakafka_2.12-1.0.0configserve
git上log日志组件 我们写个test来测试下这个组件 package main
import (
"fmt"
"github.com/hpcloud/tail"
"time"
)
func main() {
filename := "E:developkafkakafka_2.12-1.0.0configserver.properties"
tails,err := tail.TailFile(filename,tail.Config{
ReOpen: true,Follow: true,// Location: &tail.SeekInfo{Offset: 0,Whence: 2},
MustExist: false,Poll: true,})
if err != nil {
fmt.Println("tail file err:",err)
return
}
var msg *tail.Line
var ok bool
for true {
msg,ok = <-tails.Lines
if !ok {
fmt.Printf("tail file close reopen,filename:%sn",tails.Filename)
time.Sleep(100 * time.Millisecond)
continue
}
fmt.Println("msg:",msg)
}
}
执行代码会在终端输出如下该文件的信息: PS E:golanggo_prosrcsafly> go run safly.go
msg: &{# Licensed to the Apache Software Foundation (ASF) under one or more 2017-11-18 19:22:49.194689
2 +0800 CST <nil>}
msg: &{# contributor license agreements. See the NOTICE file distributed with 2017-11-18 19:22:49.194
6892 +0800 CST <nil>}
msg: &{# this work for additional information regarding copyright ownership. 2017-11-18 19:22:49.20869
92 +0800 CST <nil>}
msg: &{# The ASF licenses this file to You under the Apache License,Version 2.0 2017-11-18 19:22:49.2
102004 +0800 CST <nil>}
。。。。。。省略
我们看看源码tailf.go的执行流程: func TailFile(filename string,config Config) (*Tail,error) {
if config.ReOpen && !config.Follow {
util.Fatal("cannot set ReOpen without Follow.")
}
t := &Tail{
Filename: filename,Lines: make(chan *Line),Config: config,}
// when Logger was not specified in config,use default logger
if t.Logger == nil {
t.Logger = log.New(os.Stderr,"",log.LstdFlags)
}
if t.Poll {
t.watcher = watch.NewPollingFileWatcher(filename)
} else {
t.watcher = watch.NewInotifyFileWatcher(filename)
}
if t.MustExist {
var err error
t.file,err = OpenFile(t.Filename)
if err != nil {
return nil,err
}
}
go t.tailFileSync()
return t,nil
}
在最后go t.tailFileSync()启动goroutine tail.openReader()
看看做了什么操作? func (tail *Tail) openReader() {
if tail.MaxLineSize > 0 {
// add 2 to account for newline characters
tail.reader = bufio.NewReaderSize(tail.file,tail.MaxLineSize+2)
} else {
tail.reader = bufio.NewReader(tail.file)
}
}
创建reader,然后for读取line,err := tail.readLine() 然后写入chan 中 // Process `line` even if err is EOF.
if err == nil {
cooloff := !tail.sendLine(line)
if cooloff {
// Wait a second before seeking till the end of
// file when rate limit is reached.
msg := ("Too much log activity; waiting a second " +
"before resuming tailing")
tail.Lines <- &Line{msg,time.Now(),errors.New(msg)}
select {
case <-time.After(time.Second):
case <-tail.Dying():
return
}
if err := tail.seekEnd(); err != nil {
tail.Kill(err)
return
}
}
}
tail.Lines <- &Line{msg,time.Now(),errors.New(msg)}中的Lines是在Tail定义的chan type Tail struct { Filename string Lines chan *Line Config file *os.File reader *bufio.Reader watcher watch.FileWatcher changes *watch.FileChanges tomb.Tomb // provides: Done,Kill,Dying lk sync.Mutex } (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |