Péter Szilágyi 289b30715d Godeps, vendor: convert dependency management to trash (#3198 )

This commit converts the dependency management from Godeps to the vendor
folder, also switching the tool from godep to trash. Since the upstream tool
lacks a few features proposed via a few PRs, until those PRs are merged in
(if), use github.com/karalabe/trash.

You can update dependencies via trash --update.

All dependencies have been updated to their latest version.

Parts of the build system are reworked to drop old notions of Godeps and
invocation of the go vet command so that it doesn't run against the vendor
folder, as that will just blow up during vetting.

The conversion drops OpenCL (and hence GPU mining support) from ethash and our
codebase. The short reasoning is that there's noone to maintain and having
opencl libs in our deps messes up builds as go install ./... tries to build
them, failing with unsatisfied link errors for the C OpenCL deps.

golang.org/x/net/context is not vendored in. We expect it to be fetched by the
user (i.e. using go get). To keep ci.go builds reproducible the package is
"vendored" in build/_vendor.

2016-10-28 19:05:01 +02:00

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XHandler

XHandler is a bridge between net/context and http.Handler.

It lets you enforce net/context in your handlers without sacrificing compatibility with existing http.Handlers nor imposing a specific router.

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.

You may create your own net/context aware handler pretty much the same way as you would do with http.Handler.

Read more about xhandler on Dailymotion engineering blog.

Installing

go get -u github.com/rs/xhandler

Usage

package main

import (
	"log"
	"net/http"
	"time"

	"github.com/rs/cors"
	"github.com/rs/xhandler"
	"golang.org/x/net/context"
)

type myMiddleware struct {
	next xhandler.HandlerC
}

func (h myMiddleware) ServeHTTPC(ctx context.Context, w http.ResponseWriter, r *http.Request) {
	ctx = context.WithValue(ctx, "test", "World")
	h.next.ServeHTTPC(ctx, w, r)
}

func main() {
	c := xhandler.Chain{}

	// Add close notifier handler so context is cancelled when the client closes
	// the connection
	c.UseC(xhandler.CloseHandler)

	// Add timeout handler
	c.UseC(xhandler.TimeoutHandler(2 * time.Second))

	// Middleware putting something in the context
	c.UseC(func(next xhandler.HandlerC) xhandler.HandlerC {
		return myMiddleware{next: next}
	})

	// Mix it with a non-context-aware middleware handler
	c.Use(cors.Default().Handler)

	// Final handler (using handlerFuncC), reading from the context
	xh := xhandler.HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
		value := ctx.Value("test").(string)
		w.Write([]byte("Hello " + value))
	})

	// Bridge context aware handlers with http.Handler using xhandler.Handle()
	http.Handle("/test", c.Handler(xh))

	if err := http.ListenAndServe(":8080", nil); err != nil {
		log.Fatal(err)
	}
}

Using xmux

Xhandler comes with an optional context aware muxer forked from httprouter:

package main

import (
	"fmt"
	"log"
	"net/http"
	"time"

	"github.com/rs/xhandler"
	"github.com/rs/xmux"
	"golang.org/x/net/context"
)

func main() {
	c := xhandler.Chain{}

	// Append a context-aware middleware handler
	c.UseC(xhandler.CloseHandler)

	// Another context-aware middleware handler
	c.UseC(xhandler.TimeoutHandler(2 * time.Second))

	mux := xmux.New()

	// Use c.Handler to terminate the chain with your final handler
	mux.GET("/welcome/:name", xhandler.HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, req *http.Request) {
		fmt.Fprintf(w, "Welcome %s!", xmux.Params(ctx).Get("name"))
	}))

	if err := http.ListenAndServe(":8080", c.Handler(mux)); err != nil {
		log.Fatal(err)
	}
}

See xmux for more examples.

Context Aware Middleware

Here is a list of net/context aware middleware handlers implementing xhandler.HandlerC interface.

Feel free to put up a PR linking your middleware if you have built one:

Middleware	Author	Description
xmux	Olivier Poitrey	HTTP request muxer
xlog	Olivier Poitrey	HTTP handler logger
xstats	Olivier Poitrey	A generic client for service instrumentation
xaccess	Olivier Poitrey	HTTP handler access logger with xlog and xstats
cors	Olivier Poitrey	Cross Origin Resource Sharing (CORS) support

Licenses

All source code is licensed under the MIT License.

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