关于golang:聊聊dapr的Pipeline

序

本文次要钻研一下dapr的Pipeline

Pipeline

dapr/pkg/middleware/http/http_pipeline.go

import (    "github.com/dapr/dapr/pkg/config"    "github.com/valyala/fasthttp")type Middleware func(h fasthttp.RequestHandler) fasthttp.RequestHandler// HTTPPipeline defines the middleware pipeline to be plugged into Dapr sidecartype Pipeline struct {    Handlers []Middleware}func BuildHTTPPipeline(spec config.PipelineSpec) (Pipeline, error) {    return Pipeline{}, nil}func (p Pipeline) Apply(handler fasthttp.RequestHandler) fasthttp.RequestHandler {    for i := len(p.Handlers) - 1; i >= 0; i-- {        handler = p.Handlers[i](handler)    }    return handler}

Pipeline定义了Handlers属性，是一个Middleware数组；Pipeline定义了Apply办法，它会从后往前挨个执行Middleware函数；Middleware函数接管fasthttp.RequestHandler，返回fasthttp.RequestHandler

实例

dapr/pkg/http/server.go

type server struct {    config      ServerConfig    tracingSpec config.TracingSpec    metricSpec  config.MetricSpec    pipeline    http_middleware.Pipeline    api         API}func (s *server) useComponents(next fasthttp.RequestHandler) fasthttp.RequestHandler {    return s.pipeline.Apply(next)}

server定义了pipeline属性，其useComponents办法接管fasthttp.RequestHandler)，对其执行pipeline.Apply

小结

dapr的Pipeline定义了Handlers属性，是一个Middleware数组；Pipeline定义了Apply办法，它会从后往前挨个执行Middleware函数；Middleware函数接管fasthttp.RequestHandler，返回fasthttp.RequestHandler。

doc

• dapr