fix: protect shared rules across delivery and recovery (#560)

go-gost/x/api/config_transaction_test.go

@@ -0,0 +1,76 @@
+package api
+
+import (
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"github.com/go-gost/x/config"
+)
+
+func assertMutationAvailable(t *testing.T) {
+	t.Helper()
+	done := make(chan struct{})
+	go func() { unlock := config.LockMutation(); unlock(); close(done) }()
+	select {
+	case <-done:
+	case <-time.After(time.Second):
+		t.Fatal("network I/O holds runtime mutation lock")
+	}
+}
+
+func TestConfigTransactionDoesNotLockWhileReadingBody(t *testing.T) {
+	router := gin.New()
+	router.Use(configTransaction())
+	router.POST("/config", func(c *gin.Context) { c.JSON(http.StatusOK, Response{Msg: "OK"}) })
+	reader, writer := io.Pipe()
+	defer reader.Close()
+	defer writer.Close()
+	request := httptest.NewRequest(http.MethodPost, "/config", reader)
+	done := make(chan struct{})
+	go func() { defer close(done); router.ServeHTTP(httptest.NewRecorder(), request) }()
+	if _, err := writer.Write([]byte("{")); err != nil {
+		t.Fatal(err)
+	}
+	assertMutationAvailable(t)
+	writer.Close()
+	select {
+	case <-done:
+	case <-time.After(time.Second):
+		t.Fatal("handler did not finish")
+	}
+}
+
+type blockedResponse struct {
+	header  http.Header
+	started chan struct{}
+	release chan struct{}
+}
+
+func (w *blockedResponse) Header() http.Header { return w.header }
+func (w *blockedResponse) WriteHeader(int)     {}
+func (w *blockedResponse) Write(p []byte) (int, error) {
+	close(w.started)
+	<-w.release
+	return len(p), nil
+}
+
+func TestConfigTransactionReleasesLockBeforeSendingResponse(t *testing.T) {
+	router := gin.New()
+	router.Use(configTransaction())
+	router.POST("/config", func(c *gin.Context) { c.JSON(http.StatusOK, Response{Msg: "OK"}) })
+	writer := &blockedResponse{header: make(http.Header), started: make(chan struct{}), release: make(chan struct{})}
+	defer close(writer.release)
+	request := httptest.NewRequest(http.MethodPost, "/config", strings.NewReader("{}"))
+	go router.ServeHTTP(writer, request)
+	select {
+	case <-writer.started:
+	case <-time.After(time.Second):
+		t.Fatal("response did not start")
+	}
+	assertMutationAvailable(t)
+}