mirror of https://github.com/go-gitea/gitea.git
Refactor web route (#24080)
The old code is unnecessarily complex, and has many misuses. Old code "wraps" a lot, wrap wrap wrap, it's difficult to understand which kind of handler is used. The new code uses a general approach, we do not need to write all kinds of handlers into the "wrapper", do not need to wrap them again and again. New code, there are only 2 concepts: 1. HandlerProvider: `func (h any) (handlerProvider func (next) http.Handler)`, it can be used as middleware 2. Use HandlerProvider to get the final HandlerFunc, and use it for `r.Get()` And we can decouple the route package from context package (see the TODO). # FAQ ## Is `reflect` safe? Yes, all handlers are checked during startup, see the `preCheckHandler` comment. If any handler is wrong, developers could know it in the first time. ## Does `reflect` affect performance? No. https://github.com/go-gitea/gitea/pull/24080#discussion_r1164825901 1. This reflect code only runs for each web handler call, handler is far more slower: 10ms-50ms 2. The reflect is pretty fast (comparing to other code): 0.000265ms 3. XORM has more reflect operations alreadypull/24242/head
wxiaoguang
2 years ago
committed by
GitHub
parent
70fc47a22a
commit
b9a97ccd0e
@ -0,0 +1,200 @@
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// Copyright 2023 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package web
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import (
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goctx "context"
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"fmt"
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"net/http"
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"reflect"
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"strings"
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"code.gitea.io/gitea/modules/context"
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"code.gitea.io/gitea/modules/web/routing"
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)
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// ResponseStatusProvider is an interface to check whether the response has been written by the handler
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type ResponseStatusProvider interface {
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Written() bool
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}
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// TODO: decouple this from the context package, let the context package register these providers
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var argTypeProvider = map[reflect.Type]func(req *http.Request) ResponseStatusProvider{
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reflect.TypeOf(&context.APIContext{}): func(req *http.Request) ResponseStatusProvider { return context.GetAPIContext(req) },
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reflect.TypeOf(&context.Context{}): func(req *http.Request) ResponseStatusProvider { return context.GetContext(req) },
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reflect.TypeOf(&context.PrivateContext{}): func(req *http.Request) ResponseStatusProvider { return context.GetPrivateContext(req) },
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}
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// responseWriter is a wrapper of http.ResponseWriter, to check whether the response has been written
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type responseWriter struct {
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respWriter http.ResponseWriter
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status int
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}
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var _ ResponseStatusProvider = (*responseWriter)(nil)
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func (r *responseWriter) Written() bool {
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return r.status > 0
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}
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func (r *responseWriter) Header() http.Header {
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return r.respWriter.Header()
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}
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func (r *responseWriter) Write(bytes []byte) (int, error) {
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if r.status == 0 {
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r.status = http.StatusOK
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}
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return r.respWriter.Write(bytes)
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}
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func (r *responseWriter) WriteHeader(statusCode int) {
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r.status = statusCode
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r.respWriter.WriteHeader(statusCode)
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}
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var (
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httpReqType = reflect.TypeOf((*http.Request)(nil))
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respWriterType = reflect.TypeOf((*http.ResponseWriter)(nil)).Elem()
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cancelFuncType = reflect.TypeOf((*goctx.CancelFunc)(nil)).Elem()
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)
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// preCheckHandler checks whether the handler is valid, developers could get first-time feedback, all mistakes could be found at startup
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func preCheckHandler(fn reflect.Value, argsIn []reflect.Value) {
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hasStatusProvider := false
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for _, argIn := range argsIn {
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if _, hasStatusProvider = argIn.Interface().(ResponseStatusProvider); hasStatusProvider {
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break
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}
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}
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if !hasStatusProvider {
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panic(fmt.Sprintf("handler should have at least one ResponseStatusProvider argument, but got %s", fn.Type()))
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}
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if fn.Type().NumOut() != 0 && fn.Type().NumIn() != 1 {
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panic(fmt.Sprintf("handler should have no return value or only one argument, but got %s", fn.Type()))
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}
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if fn.Type().NumOut() == 1 && fn.Type().Out(0) != cancelFuncType {
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panic(fmt.Sprintf("handler should return a cancel function, but got %s", fn.Type()))
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}
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}
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func prepareHandleArgsIn(resp http.ResponseWriter, req *http.Request, fn reflect.Value) []reflect.Value {
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isPreCheck := req == nil
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argsIn := make([]reflect.Value, fn.Type().NumIn())
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for i := 0; i < fn.Type().NumIn(); i++ {
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argTyp := fn.Type().In(i)
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switch argTyp {
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case respWriterType:
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argsIn[i] = reflect.ValueOf(resp)
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case httpReqType:
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argsIn[i] = reflect.ValueOf(req)
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default:
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if argFn, ok := argTypeProvider[argTyp]; ok {
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if isPreCheck {
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argsIn[i] = reflect.ValueOf(&responseWriter{})
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} else {
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argsIn[i] = reflect.ValueOf(argFn(req))
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}
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} else {
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panic(fmt.Sprintf("unsupported argument type: %s", argTyp))
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}
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}
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}
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return argsIn
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}
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func handleResponse(fn reflect.Value, ret []reflect.Value) goctx.CancelFunc {
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if len(ret) == 1 {
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if cancelFunc, ok := ret[0].Interface().(goctx.CancelFunc); ok {
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return cancelFunc
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}
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panic(fmt.Sprintf("unsupported return type: %s", ret[0].Type()))
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} else if len(ret) > 1 {
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panic(fmt.Sprintf("unsupported return values: %s", fn.Type()))
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}
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return nil
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}
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func hasResponseBeenWritten(argsIn []reflect.Value) bool {
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for _, argIn := range argsIn {
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if statusProvider, ok := argIn.Interface().(ResponseStatusProvider); ok {
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if statusProvider.Written() {
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return true
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}
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}
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}
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return false
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}
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// toHandlerProvider converts a handler to a handler provider
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// A handler provider is a function that takes a "next" http.Handler, it can be used as a middleware
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func toHandlerProvider(handler any) func(next http.Handler) http.Handler {
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if hp, ok := handler.(func(next http.Handler) http.Handler); ok {
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return hp
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}
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funcInfo := routing.GetFuncInfo(handler)
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fn := reflect.ValueOf(handler)
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if fn.Type().Kind() != reflect.Func {
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panic(fmt.Sprintf("handler must be a function, but got %s", fn.Type()))
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}
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provider := func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(respOrig http.ResponseWriter, req *http.Request) {
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// wrap the response writer to check whether the response has been written
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resp := respOrig
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if _, ok := resp.(ResponseStatusProvider); !ok {
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resp = &responseWriter{respWriter: resp}
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}
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// prepare the arguments for the handler and do pre-check
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argsIn := prepareHandleArgsIn(resp, req, fn)
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if req == nil {
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preCheckHandler(fn, argsIn)
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return // it's doing pre-check, just return
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}
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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ret := fn.Call(argsIn)
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// handle the return value, and defer the cancel function if there is one
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cancelFunc := handleResponse(fn, ret)
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if cancelFunc != nil {
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defer cancelFunc()
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}
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// if the response has not been written, call the next handler
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if next != nil && !hasResponseBeenWritten(argsIn) {
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next.ServeHTTP(resp, req)
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}
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})
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}
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provider(nil).ServeHTTP(nil, nil) // do a pre-check to make sure all arguments and return values are supported
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return provider
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}
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// MiddlewareWithPrefix wraps a handler function at a prefix, and make it as a middleware
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// TODO: this design is incorrect, the asset handler should not be a middleware
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func MiddlewareWithPrefix(pathPrefix string, middleware func(handler http.Handler) http.Handler, handlerFunc http.HandlerFunc) func(next http.Handler) http.Handler {
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funcInfo := routing.GetFuncInfo(handlerFunc)
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handler := http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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handlerFunc(resp, req)
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})
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return func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
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if !strings.HasPrefix(req.URL.Path, pathPrefix) {
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next.ServeHTTP(resp, req)
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return
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}
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if middleware != nil {
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middleware(handler).ServeHTTP(resp, req)
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} else {
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handler.ServeHTTP(resp, req)
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}
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})
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}
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}
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@ -1,116 +0,0 @@
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// Copyright 2021 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package web
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import (
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goctx "context"
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"net/http"
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"strings"
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"code.gitea.io/gitea/modules/context"
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"code.gitea.io/gitea/modules/web/routing"
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)
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// Wrap converts all kinds of routes to standard library one
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func Wrap(handlers ...interface{}) http.HandlerFunc {
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if len(handlers) == 0 {
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panic("No handlers found")
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}
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ourHandlers := make([]wrappedHandlerFunc, 0, len(handlers))
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for _, handler := range handlers {
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ourHandlers = append(ourHandlers, convertHandler(handler))
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}
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return wrapInternal(ourHandlers)
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}
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func wrapInternal(handlers []wrappedHandlerFunc) http.HandlerFunc {
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return func(resp http.ResponseWriter, req *http.Request) {
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var defers []func()
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defer func() {
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for i := len(defers) - 1; i >= 0; i-- {
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defers[i]()
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}
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}()
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for i := 0; i < len(handlers); i++ {
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handler := handlers[i]
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others := handlers[i+1:]
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done, deferrable := handler(resp, req, others...)
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if deferrable != nil {
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defers = append(defers, deferrable)
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}
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if done {
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return
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}
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}
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}
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}
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// Middle wrap a context function as a chi middleware
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func Middle(f func(ctx *context.Context)) func(next http.Handler) http.Handler {
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funcInfo := routing.GetFuncInfo(f)
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return func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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ctx := context.GetContext(req)
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f(ctx)
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if ctx.Written() {
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return
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}
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next.ServeHTTP(ctx.Resp, ctx.Req)
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})
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}
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}
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// MiddleCancel wrap a context function as a chi middleware
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func MiddleCancel(f func(ctx *context.Context) goctx.CancelFunc) func(netx http.Handler) http.Handler {
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funcInfo := routing.GetFuncInfo(f)
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return func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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ctx := context.GetContext(req)
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cancel := f(ctx)
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if cancel != nil {
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defer cancel()
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}
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if ctx.Written() {
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return
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}
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next.ServeHTTP(ctx.Resp, ctx.Req)
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})
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}
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}
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// MiddleAPI wrap a context function as a chi middleware
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func MiddleAPI(f func(ctx *context.APIContext)) func(next http.Handler) http.Handler {
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funcInfo := routing.GetFuncInfo(f)
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return func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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ctx := context.GetAPIContext(req)
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f(ctx)
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if ctx.Written() {
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return
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}
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next.ServeHTTP(ctx.Resp, ctx.Req)
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})
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}
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}
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// WrapWithPrefix wraps a provided handler function at a prefix
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func WrapWithPrefix(pathPrefix string, handler http.HandlerFunc, friendlyName ...string) func(next http.Handler) http.Handler {
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funcInfo := routing.GetFuncInfo(handler, friendlyName...)
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return func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
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if !strings.HasPrefix(req.URL.Path, pathPrefix) {
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next.ServeHTTP(resp, req)
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return
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}
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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handler(resp, req)
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})
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}
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}
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@ -1,109 +0,0 @@
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// Copyright 2021 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package web
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import (
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goctx "context"
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"fmt"
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"net/http"
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"code.gitea.io/gitea/modules/context"
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"code.gitea.io/gitea/modules/web/routing"
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)
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type wrappedHandlerFunc func(resp http.ResponseWriter, req *http.Request, others ...wrappedHandlerFunc) (done bool, deferrable func())
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func convertHandler(handler interface{}) wrappedHandlerFunc {
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funcInfo := routing.GetFuncInfo(handler)
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switch t := handler.(type) {
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case http.HandlerFunc:
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return func(resp http.ResponseWriter, req *http.Request, others ...wrappedHandlerFunc) (done bool, deferrable func()) {
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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if _, ok := resp.(context.ResponseWriter); !ok {
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resp = context.NewResponse(resp)
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}
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t(resp, req)
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if r, ok := resp.(context.ResponseWriter); ok && r.Status() > 0 {
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done = true
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}
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return done, deferrable
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}
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case func(http.ResponseWriter, *http.Request):
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return func(resp http.ResponseWriter, req *http.Request, others ...wrappedHandlerFunc) (done bool, deferrable func()) {
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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t(resp, req)
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if r, ok := resp.(context.ResponseWriter); ok && r.Status() > 0 {
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done = true
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}
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return done, deferrable
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}
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case func(ctx *context.Context):
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return func(resp http.ResponseWriter, req *http.Request, others ...wrappedHandlerFunc) (done bool, deferrable func()) {
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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ctx := context.GetContext(req)
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t(ctx)
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done = ctx.Written()
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return done, deferrable
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}
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case func(ctx *context.Context) goctx.CancelFunc:
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return func(resp http.ResponseWriter, req *http.Request, others ...wrappedHandlerFunc) (done bool, deferrable func()) {
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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ctx := context.GetContext(req)
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deferrable = t(ctx)
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done = ctx.Written()
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return done, deferrable
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}
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case func(*context.APIContext):
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return func(resp http.ResponseWriter, req *http.Request, others ...wrappedHandlerFunc) (done bool, deferrable func()) {
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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ctx := context.GetAPIContext(req)
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t(ctx)
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done = ctx.Written()
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return done, deferrable
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}
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case func(*context.APIContext) goctx.CancelFunc:
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return func(resp http.ResponseWriter, req *http.Request, others ...wrappedHandlerFunc) (done bool, deferrable func()) {
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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ctx := context.GetAPIContext(req)
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deferrable = t(ctx)
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done = ctx.Written()
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return done, deferrable
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}
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case func(*context.PrivateContext):
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return func(resp http.ResponseWriter, req *http.Request, others ...wrappedHandlerFunc) (done bool, deferrable func()) {
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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ctx := context.GetPrivateContext(req)
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t(ctx)
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done = ctx.Written()
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return done, deferrable
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}
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case func(*context.PrivateContext) goctx.CancelFunc:
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return func(resp http.ResponseWriter, req *http.Request, others ...wrappedHandlerFunc) (done bool, deferrable func()) {
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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ctx := context.GetPrivateContext(req)
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deferrable = t(ctx)
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done = ctx.Written()
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return done, deferrable
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}
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case func(http.Handler) http.Handler:
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return func(resp http.ResponseWriter, req *http.Request, others ...wrappedHandlerFunc) (done bool, deferrable func()) {
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next := http.HandlerFunc(func(http.ResponseWriter, *http.Request) {})
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if len(others) > 0 {
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next = wrapInternal(others)
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}
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routing.UpdateFuncInfo(req.Context(), funcInfo)
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if _, ok := resp.(context.ResponseWriter); !ok {
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resp = context.NewResponse(resp)
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}
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t(next).ServeHTTP(resp, req)
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if r, ok := resp.(context.ResponseWriter); ok && r.Status() > 0 {
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done = true
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}
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return done, deferrable
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}
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default:
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panic(fmt.Sprintf("Unsupported handler type: %#v", t))
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}
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}
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