聊聊dubbogo的AccessLogFilter

序

本文次要钻研一下 dubbo-go 的 AccessLogFilter

AccessLogFilter

dubbo-go-v1.4.2/filter/filter_impl/access_log_filter.go

type AccessLogFilter struct {logChan chan AccessLogData}

• AccessLogFilter 定义了 AccessLogData 类型的 chan

Invoke

dubbo-go-v1.4.2/filter/filter_impl/access_log_filter.go

func (ef *AccessLogFilter) Invoke(ctx context.Context, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {accessLog := invoker.GetUrl().GetParam(constant.ACCESS_LOG_KEY, "")
    if len(accessLog) > 0 {accessLogData := AccessLogData{data: ef.buildAccessLogData(invoker, invocation), accessLog: accessLog}
        ef.logIntoChannel(accessLogData)
    }
    return invoker.Invoke(ctx, invocation)
}

• Invoke 办法首先通过 invoker.GetUrl().GetParam 获取 constant.ACCESS_LOG_KEY 配置，若 accessLog 有值，则通过 ef.buildAccessLogData 构建 accessLogData，而后执行 ef.logIntoChannel(accessLogData)，最初执行 invoker.Invoke(ctx, invocation)

logIntoChannel

dubbo-go-v1.4.2/filter/filter_impl/access_log_filter.go

func (ef *AccessLogFilter) logIntoChannel(accessLogData AccessLogData) {
    select {
    case ef.logChan <- accessLogData:
        return
    default:
        logger.Warn("The channel is full and the access logIntoChannel data will be dropped")
        return
    }
}

• logIntoChannel 办法通过 select 办法将 accessLogData 写入 ef.logChan

buildAccessLogData

dubbo-go-v1.4.2/filter/filter_impl/access_log_filter.go

func (ef *AccessLogFilter) buildAccessLogData(_ protocol.Invoker, invocation protocol.Invocation) map[string]string {dataMap := make(map[string]string, 16)
    attachments := invocation.Attachments()
    dataMap[constant.INTERFACE_KEY] = attachments[constant.INTERFACE_KEY]
    dataMap[constant.METHOD_KEY] = invocation.MethodName()
    dataMap[constant.VERSION_KEY] = attachments[constant.VERSION_KEY]
    dataMap[constant.GROUP_KEY] = attachments[constant.GROUP_KEY]
    dataMap[constant.TIMESTAMP_KEY] = time.Now().Format(MessageDateLayout)
    dataMap[constant.LOCAL_ADDR], _ = attachments[constant.LOCAL_ADDR]
    dataMap[constant.REMOTE_ADDR], _ = attachments[constant.REMOTE_ADDR]

    if len(invocation.Arguments()) > 0 {builder := strings.Builder{}
        // todo(after the paramTypes were set to the invocation. we should change this implementation)
        typeBuilder := strings.Builder{}

        builder.WriteString(reflect.ValueOf(invocation.Arguments()[0]).String())
        typeBuilder.WriteString(reflect.TypeOf(invocation.Arguments()[0]).Name())
        for idx := 1; idx < len(invocation.Arguments()); idx++ {arg := invocation.Arguments()[idx]
            builder.WriteString(",")
            builder.WriteString(reflect.ValueOf(arg).String())

            typeBuilder.WriteString(",")
            typeBuilder.WriteString(reflect.TypeOf(arg).Name())
        }
        dataMap[Arguments] = builder.String()
        dataMap[Types] = typeBuilder.String()}

    return dataMap
}

• buildAccessLogData 办法提取 invocation.Attachments() 的数据来构建 dataMap

writeLogToFile

dubbo-go-v1.4.2/filter/filter_impl/access_log_filter.go

func (ef *AccessLogFilter) writeLogToFile(data AccessLogData) {
    accessLog := data.accessLog
    if isDefault(accessLog) {logger.Info(data.toLogMessage())
        return
    }

    logFile, err := ef.openLogFile(accessLog)
    if err != nil {logger.Warnf("Can not open the access log file: %s, %v", accessLog, err)
        return
    }
    logger.Debugf("Append log to %s", accessLog)
    message := data.toLogMessage()
    message = message + "\n"
    _, err = logFile.WriteString(message)
    if err != nil {logger.Warnf("Can not write the log into access log file: %s, %v", accessLog, err)
    }
}

• writeLogToFile 办法通过 logFile.WriteString(message) 将 log 写到文件

GetAccessLogFilter

dubbo-go-v1.4.2/filter/filter_impl/access_log_filter.go

func GetAccessLogFilter() filter.Filter {accessLogFilter := &AccessLogFilter{logChan: make(chan AccessLogData, LogMaxBuffer)}
    go func() {
        for accessLogData := range accessLogFilter.logChan {accessLogFilter.writeLogToFile(accessLogData)
        }
    }()
    return accessLogFilter
}

• GetAccessLogFilter 办法会创立 AccessLogFilter，同时异步遍历 accessLogFilter.logChan 执行 accessLogFilter.writeLogToFile(accessLogData)

小结

AccessLogFilter 定义了 AccessLogData 类型的 chan；Invoke 办法首先通过 invoker.GetUrl().GetParam 获取 constant.ACCESS_LOG_KEY 配置，若 accessLog 有值，则通过 ef.buildAccessLogData 构建 accessLogData，而后执行 ef.logIntoChannel(accessLogData)，最初执行 invoker.Invoke(ctx, invocation)

doc

• access_log_filter