Add ability to poison contexts, preventing reuse

context.go

@@ -76,6 +76,13 @@ type Context struct {
 
 	methodsAllowed   []methodTyp // allowed methods in case of a 405
 	methodNotAllowed bool
+	poisoned         bool // prevents returning to pool
+}
+
+// PreventReuse marks the Context as being unable to be returned to the pool
+// and allowing it to be safely used outside of the running request.
+func (x *Context) PreventReuse() {
+	x.poisoned = true
 }
 
 // Reset a routing context to its initial state.

mux.go

@@ -88,7 +88,10 @@ func (mx *Mux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	// Serve the request and once its done, put the request context back in the sync pool
 	mx.handler.ServeHTTP(w, r)
-	mx.pool.Put(rctx)
+
+	if !rctx.poisoned {
+		mx.pool.Put(rctx)
+	}
 }
 
 // Use appends a middleware handler to the Mux middleware stack.

mux_test.go

@@ -1980,6 +1980,29 @@ func TestServerBaseContext(t *testing.T) {
 	}
 }
 
+func TestServerPoisonedContext(t *testing.T) {
+	r := NewRouter()
+	var firstContext *Context
+	r.Get("/first", func(w http.ResponseWriter, r *http.Request) {
+		firstContext, _ = r.Context().Value(RouteCtxKey).(*Context)
+		firstContext.PreventReuse()
+	})
+	r.Get("/second", func(w http.ResponseWriter, r *http.Request) {
+		context, _ := r.Context().Value(RouteCtxKey).(*Context)
+		if context == firstContext {
+			t.Fatalf("expected to get a fresh context instance for each request")
+		}
+	})
+
+	ts := httptest.NewUnstartedServer(r)
+	ts.Start()
+
+	defer ts.Close()
+
+	testRequest(t, ts, "GET", "/first", nil)
+	testRequest(t, ts, "GET", "/second", nil)
+}
+
 func testRequest(t *testing.T, ts *httptest.Server, method, path string, body io.Reader) (*http.Response, string) {
 	req, err := http.NewRequest(method, ts.URL+path, body)
 	if err != nil {