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本文主要研究一下dubbo-go-proxy的AccessLogFilter
AccessLogFilter
dubbo-go-proxy/pkg/filter/accesslog/access_log.go
var accessLogWriter = &model.AccessLogWriter{AccessLogDataChan: make(chan model.AccessLogData, constant.LogDataBuffer)}
func init() {
extension.SetFilterFunc(constant.AccessLogFilter, accessLog())
accessLogWriter.Write()
}
// access log filter
func accessLog() context.FilterFunc {
return func(c context.Context) {
alc := config.GetBootstrap().StaticResources.AccessLogConfig
if !alc.Enable {
return
}
start := time.Now()
c.Next()
latency := time.Now().Sub(start)
// build access_log message
accessLogMsg := buildAccessLogMsg(c, latency)
if len(accessLogMsg) > 0 {
accessLogWriter.Writer(model.AccessLogData{AccessLogConfig: alc, AccessLogMsg: accessLogMsg})
}
}
}init方法通过extension.SetFilterFunc注册了名为constant.AccessLogFilter的context.FilterFunc，然后执行accessLogWriter.Write()；accessLog方法返回context.FilterFunc，该func通过buildAccessLogMsg构建accessLogMsg，然后执行accessLogWriter.Writer
buildAccessLogMsg
dubbo-go-proxy/pkg/filter/accesslog/access_log.go
func buildAccessLogMsg(c context.Context, cost time.Duration) string {
req := c.(*http.HttpContext).Request
valueStr := req.URL.Query().Encode()
if len(valueStr) != 0 {
valueStr = strings.ReplaceAll(valueStr, "&", ",")
}
builder := strings.Builder{}
builder.WriteString("[")
builder.WriteString(time.Now().Format(constant.MessageDateLayout))
builder.WriteString("] ")
builder.WriteString(req.RemoteAddr)
builder.WriteString(" -> ")
builder.WriteString(req.Host)
builder.WriteString(" - ")
if len(valueStr) > 0 {
builder.WriteString("request params: [")
builder.WriteString(valueStr)
builder.WriteString("] ")
}
builder.WriteString("cost time [ ")
builder.WriteString(strconv.Itoa(int(cost)) + " ]")
err := c.(*http.HttpContext).Err
if err != nil {
builder.WriteString(fmt.Sprintf("invoke err [ %v", err))
builder.WriteString("] ")
}
resp := c.(*http.HttpContext).TargetResp.Data
rbs, err := getBytes(resp)
if err != nil {
builder.WriteString(fmt.Sprintf(" response can not convert to string"))
builder.WriteString("] ")
} else {
builder.WriteString(fmt.Sprintf(" response [ %+v", string(rbs)))
builder.WriteString("] ")
}
//builder.WriteString("\n")
return builder.String()
}buildAccessLogMsg方法使用strings.Builder构建accesslog，依次打印time、remoteAddr、host、request params、cost time、err、resp
AccessLogWriter
dubbo-go-proxy/pkg/model/log.go
// access log chan
type AccessLogWriter struct {
AccessLogDataChan chan AccessLogData
}
// access log data
type AccessLogData struct {
AccessLogMsg string
AccessLogConfig AccessLogConfig
}
// writer msg into chan
func (alw *AccessLogWriter) Writer(accessLogData AccessLogData) {
select {
case alw.AccessLogDataChan <- accessLogData:
return
default:
logger.Warn("the channel is full and the access logIntoChannel data will be dropped")
return
}
}AccessLogWriter定义了AccessLogDataChan属性，它是一个AccessLogData类型的channel；Writer方法往AccessLogDataChan写入accessLogData
Write
dubbo-go-proxy/pkg/model/log.go
// write log into out put path
func (alw *AccessLogWriter) Write() {
go func() {
for accessLogData := range alw.AccessLogDataChan {
alw.writeLogToFile(accessLogData)
}
}()
}
// write log to file or console
func (alw *AccessLogWriter) writeLogToFile(ald AccessLogData) {
alc := ald.AccessLogConfig
alm := ald.AccessLogMsg
if len(alc.OutPutPath) == 0 || alc.OutPutPath == constant.Console {
logger.Info(alm)
return
}
_ = WriteToFile(alm, alc.OutPutPath)
}Write启动异步线程遍历AccessLogDataChan，执行writeLogToFile
WriteToFile
dubbo-go-proxy/pkg/model/log.go
// write message to access log file
func WriteToFile(accessLogMsg string, filePath string) error {
pd := filepath.Dir(filePath)
if _, err := os.Stat(pd); err != nil {
if os.IsExist(err) {
logger.Warnf("can not open log dir: %s, %v", filePath, err)
}
err = os.MkdirAll(pd, os.ModePerm)
if err != nil {
logger.Warnf("can not create log dir: %s, %v", filePath, err)
return err
}
}
logFile, err := os.OpenFile(filePath, os.O_CREATE|os.O_APPEND|os.O_RDWR, constant.LogFileMode)
if err != nil {
logger.Warnf("can not open the access log file: %s, %v", filePath, err)
return err
}
now := time.Now().Format(constant.FileDateFormat)
fileInfo, err := logFile.Stat()
if err != nil {
logger.Warnf("can not get the info of access log file: %s, %v", filePath, err)
return err
}
last := fileInfo.ModTime().Format(constant.FileDateFormat)
// this is confused.
// for example, if the last = '2020-03-04'
// and today is '2020-03-05'
// we will create one new file to log access data
// By this way, we can split the access log based on days.
if now != last {
err = os.Rename(fileInfo.Name(), fileInfo.Name()+"."+now)
if err != nil {
logger.Warnf("can not rename access log file: %s, %v", fileInfo.Name(), err)
return err
}
logFile, err = os.OpenFile(fileInfo.Name(), os.O_CREATE|os.O_APPEND|os.O_RDWR, constant.LogFileMode)
if err != nil {
logger.Warnf("can not open access log file: %s, %v", fileInfo.Name(), err)
return err
}
}
_, err = logFile.WriteString(accessLogMsg + "\n")
if err != nil {
logger.Warnf("can not write to access log file: %s, v%", fileInfo.Name(), err)
return err
}
return nil
}WriteToFile方法会按日期对log进行分割，最后通过logFile.WriteString写入日志
小结
dubbo-go-proxy的AccessLogFilter通过extension.SetFilterFunc注册了名为constant.AccessLogFilter的context.FilterFunc，该func通过buildAccessLogMsg构建accessLogMsg，然后往AccessLogDataChan写入accessLogData；然后执行accessLogWriter.Write()启动协程遍历AccessLogDataChan，执行writeLogToFile。