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nyx/vendor/github.com/pressly/chi/middleware/closenotify17.go
2017-03-12 20:37:53 +01:00

43 lines
1002 B
Go

// +build go1.7,!go1.8
package middleware
import (
"context"
"net/http"
)
// CloseNotify is a middleware that cancels ctx when the underlying
// connection has gone away. It can be used to cancel long operations
// on the server when the client disconnects before the response is ready.
//
// Note: this behaviour is standard in Go 1.8+, so the middleware does nothing
// on 1.8+ and exists just for backwards compatibility.
func CloseNotify(next http.Handler) http.Handler {
fn := func(w http.ResponseWriter, r *http.Request) {
cn, ok := w.(http.CloseNotifier)
if !ok {
panic("chi/middleware: CloseNotify expects http.ResponseWriter to implement http.CloseNotifier interface")
}
closeNotifyCh := cn.CloseNotify()
ctx, cancel := context.WithCancel(r.Context())
defer cancel()
go func() {
select {
case <-ctx.Done():
return
case <-closeNotifyCh:
cancel()
return
}
}()
r = r.WithContext(ctx)
next.ServeHTTP(w, r)
}
return http.HandlerFunc(fn)
}