Remove one allocation by foregoing context.WithValue

context.go

@@ -5,6 +5,7 @@ import (
 	"net"
 	"net/http"
 	"strings"
+	"time"
 )
 
 // URLParam returns the url parameter from a http.Request object.
@@ -92,6 +93,9 @@ type Context struct {
 
 	// methodNotAllowed hint
 	methodNotAllowed bool
+
+	// parentCtx is the parent of this one, for using Context as a context.Context directly
+	parentCtx context.Context
 }
 
 // Reset a routing context to its initial state.
@@ -139,6 +143,29 @@ func (x *Context) RoutePattern() string {
 	return replaceWildcards(routePattern)
 }
 
+type directContext Context
+
+var _ context.Context = (*directContext)(nil)
+
+func (d *directContext) Deadline() (deadline time.Time, ok bool) {
+	return d.parentCtx.Deadline()
+}
+
+func (d *directContext) Done() <-chan struct{} {
+	return d.parentCtx.Done()
+}
+
+func (d *directContext) Err() error {
+	return d.parentCtx.Err()
+}
+
+func (d *directContext) Value(key interface{}) interface{} {
+	if key == RouteCtxKey {
+		return (*Context)(d)
+	}
+	return d.parentCtx.Value(key)
+}
+
 // replaceWildcards takes a route pattern and recursively replaces all
 // occurrences of "/*/" to "/".
 func replaceWildcards(p string) string {

mux.go

@@ -1,7 +1,6 @@
 package chi
 
 import (
-	"context"
 	"fmt"
 	"net/http"
 	"strings"
@@ -78,9 +77,10 @@ func (mx *Mux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	rctx = mx.pool.Get().(*Context)
 	rctx.Reset()
 	rctx.Routes = mx
+	rctx.parentCtx = r.Context()
 
-	// NOTE: r.WithContext() causes 2 allocations and context.WithValue() causes 1 allocation
-	r = r.WithContext(context.WithValue(r.Context(), RouteCtxKey, rctx))
+	// NOTE: r.WithContext() causes 2 allocations
+	r = r.WithContext((*directContext)(rctx))
 
 	// Serve the request and once its done, put the request context back in the sync pool
 	mx.handler.ServeHTTP(w, r)