mirror of https://github.com/poanetwork/quorum.git
135 lines
4.4 KiB
Markdown
135 lines
4.4 KiB
Markdown
# XHandler
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[](https://godoc.org/github.com/rs/xhandler) [](https://raw.githubusercontent.com/rs/xhandler/master/LICENSE) [](https://travis-ci.org/rs/xhandler) [](http://gocover.io/github.com/rs/xhandler)
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XHandler is a bridge between [net/context](https://godoc.org/golang.org/x/net/context) and `http.Handler`.
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It lets you enforce `net/context` in your handlers without sacrificing compatibility with existing `http.Handlers` nor imposing a specific router.
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Thanks to `net/context` deadline management, `xhandler` is able to enforce a per request deadline and will cancel the context when the client closes the connection unexpectedly.
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You may create your own `net/context` aware handler pretty much the same way as you would do with http.Handler.
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Read more about xhandler on [Dailymotion engineering blog](http://engineering.dailymotion.com/our-way-to-go/).
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## Installing
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go get -u github.com/rs/xhandler
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## Usage
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```go
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package main
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import (
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"log"
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"net/http"
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"time"
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"github.com/rs/cors"
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"github.com/rs/xhandler"
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"golang.org/x/net/context"
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)
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type myMiddleware struct {
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next xhandler.HandlerC
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}
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func (h myMiddleware) ServeHTTPC(ctx context.Context, w http.ResponseWriter, r *http.Request) {
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ctx = context.WithValue(ctx, "test", "World")
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h.next.ServeHTTPC(ctx, w, r)
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}
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func main() {
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c := xhandler.Chain{}
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// Add close notifier handler so context is cancelled when the client closes
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// the connection
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c.UseC(xhandler.CloseHandler)
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// Add timeout handler
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c.UseC(xhandler.TimeoutHandler(2 * time.Second))
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// Middleware putting something in the context
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c.UseC(func(next xhandler.HandlerC) xhandler.HandlerC {
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return myMiddleware{next: next}
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})
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// Mix it with a non-context-aware middleware handler
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c.Use(cors.Default().Handler)
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// Final handler (using handlerFuncC), reading from the context
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xh := xhandler.HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
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value := ctx.Value("test").(string)
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w.Write([]byte("Hello " + value))
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})
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// Bridge context aware handlers with http.Handler using xhandler.Handle()
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http.Handle("/test", c.Handler(xh))
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if err := http.ListenAndServe(":8080", nil); err != nil {
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log.Fatal(err)
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}
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}
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```
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### Using xmux
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Xhandler comes with an optional context aware [muxer](https://github.com/rs/xmux) forked from [httprouter](https://github.com/julienschmidt/httprouter):
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```go
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package main
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import (
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"fmt"
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"log"
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"net/http"
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"time"
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"github.com/rs/xhandler"
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"github.com/rs/xmux"
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"golang.org/x/net/context"
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)
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func main() {
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c := xhandler.Chain{}
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// Append a context-aware middleware handler
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c.UseC(xhandler.CloseHandler)
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// Another context-aware middleware handler
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c.UseC(xhandler.TimeoutHandler(2 * time.Second))
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mux := xmux.New()
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// Use c.Handler to terminate the chain with your final handler
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mux.GET("/welcome/:name", xhandler.HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, req *http.Request) {
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fmt.Fprintf(w, "Welcome %s!", xmux.Params(ctx).Get("name"))
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}))
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if err := http.ListenAndServe(":8080", c.Handler(mux)); err != nil {
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log.Fatal(err)
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}
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}
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```
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See [xmux](https://github.com/rs/xmux) for more examples.
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## Context Aware Middleware
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Here is a list of `net/context` aware middleware handlers implementing `xhandler.HandlerC` interface.
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Feel free to put up a PR linking your middleware if you have built one:
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| Middleware | Author | Description |
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| ---------- | ------ | ----------- |
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| [xmux](https://github.com/rs/xmux) | [Olivier Poitrey](https://github.com/rs) | HTTP request muxer |
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| [xlog](https://github.com/rs/xlog) | [Olivier Poitrey](https://github.com/rs) | HTTP handler logger |
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| [xstats](https://github.com/rs/xstats) | [Olivier Poitrey](https://github.com/rs) | A generic client for service instrumentation |
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| [xaccess](https://github.com/rs/xaccess) | [Olivier Poitrey](https://github.com/rs) | HTTP handler access logger with [xlog](https://github.com/rs/xlog) and [xstats](https://github.com/rs/xstats) |
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| [cors](https://github.com/rs/cors) | [Olivier Poitrey](https://github.com/rs) | [Cross Origin Resource Sharing](http://www.w3.org/TR/cors/) (CORS) support |
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## Licenses
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All source code is licensed under the [MIT License](https://raw.github.com/rs/xhandler/master/LICENSE).
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