关于dubbo:聊聊dubbogo的metricsFilter

序

本文次要钻研一下 dubbo-go 的 metricsFilter

metricsFilter

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

const (metricFilterName = "metrics")
 
var (metricFilterInstance filter.Filter)
 
// must initialized before using the filter and after loading configuration
func init() {extension.SetFilter(metricFilterName, newMetricsFilter)
}
 
// metricFilter will calculate the invocation's duration and the report to the reporters
// If you want to use this filter to collect the metrics,
// Adding this into your configuration file, like:
// filter: "metrics"
// metrics:
//   reporter:
//     - "your reporter" # here you should specify the reporter, for example 'prometheus'
// more info please take a look at dubbo-samples projects
type metricsFilter struct {reporters []metrics.Reporter
}

• metricsFilter 定义了 reporters 属性

newMetricsFilter

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

func newMetricsFilter() filter.Filter {
    if metricFilterInstance == nil {reporterNames := config.GetMetricConfig().Reporters
        reporters := make([]metrics.Reporter, 0, len(reporterNames))
        for _, name := range reporterNames {reporters = append(reporters, extension.GetMetricReporter(name))
        }
        metricFilterInstance = &metricsFilter{reporters: reporters,}
    }
 
    return metricFilterInstance
}

• newMetricsFilter 办法在 metricFilterInstance 为 null 的时候会获取 config.GetMetricConfig().Reporters，而后创立 reporters 及 metricsFilter

Invoke

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

func (p *metricsFilter) Invoke(ctx context.Context, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {start := time.Now()
    res := invoker.Invoke(ctx, invocation)
    end := time.Now()
    duration := end.Sub(start)
    go func() {
        for _, reporter := range p.reporters {reporter.Report(ctx, invoker, invocation, duration, res)
        }
    }()
    return res
}

• Invoke 办法在 invoker.Invoke(ctx, invocation) 前后记录时间，最初算出 duration，然异步遍历 p.reporters，执行 reporter.Report

OnResponse

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

func (p *metricsFilter) OnResponse(ctx context.Context, res protocol.Result, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {return res}

• OnResponse 办法目前间接返回 result

小结

metricsFilter 的 Invoke 办法在 invoker.Invoke(ctx, invocation) 前后记录时间，最初算出 duration，然异步遍历 p.reporters，执行 reporter.Report

doc

• metrics_filter