added remote schema cache. Loaded schemas are stored in the cache onc…

…e they are loaded and resolved.

this avoids hundreds of roundtrips to remote server for schemas that contain multiple references

openapi3/swagger_loader.go

@@ -30,10 +30,11 @@ type SwaggerLoader struct {
 	Context                context.Context
 	LoadSwaggerFromURIFunc func(loader *SwaggerLoader, url *url.URL) (*Swagger, error)
 	visited                map[interface{}]struct{}
+	loadedRemoteSchemas    map[url.URL]*Swagger
 }
 
 func NewSwaggerLoader() *SwaggerLoader {
-	return &SwaggerLoader{}
+	return &SwaggerLoader{loadedRemoteSchemas: map[url.URL]*Swagger{}}
 }
 
 func (swaggerLoader *SwaggerLoader) LoadSwaggerFromURI(location *url.URL) (*Swagger, error) {
@@ -222,9 +223,13 @@ func (swaggerLoader *SwaggerLoader) resolveComponent(swagger *Swagger, ref strin
 			return nil, "", nil, fmt.Errorf("Error while resolving path: %v", err)
 		}
 
-		if swagger, err = swaggerLoader.LoadSwaggerFromURI(resolvedPath); err != nil {
-			return nil, "", nil, fmt.Errorf("Error while resolving reference '%s': %v", ref, err)
+		if swg2, ok := swaggerLoader.loadedRemoteSchemas[*parsedURL]; !ok {
+			if swg2, err = swaggerLoader.LoadSwaggerFromURI(resolvedPath); err != nil {
+				return nil, "", nil, fmt.Errorf("Error while resolving reference '%s': %v", ref, err)
+			}
+			swaggerLoader.loadedRemoteSchemas[*parsedURL] = swg2
 		}
+		swagger = swaggerLoader.loadedRemoteSchemas[*parsedURL]
 		ref = fmt.Sprintf("#%s", fragment)
 		componentPath = resolvedPath
 	}

openapi3/swagger_loader_test.go

@@ -307,10 +307,10 @@ func TestLoadFromRemoteURL(t *testing.T) {
 
 	loader := openapi3.NewSwaggerLoader()
 	loader.IsExternalRefsAllowed = true
-	url, err := url.Parse("http://" + addr + "/test.openapi.json")
+	remote, err := url.Parse("http://" + addr + "/test.openapi.json")
 	require.NoError(t, err)
 
-	swagger, err := loader.LoadSwaggerFromURI(url)
+	swagger, err := loader.LoadSwaggerFromURI(remote)
 	require.NoError(t, err)
 
 	require.Equal(t, "string", swagger.Components.Schemas["TestSchema"].Value.Type)
@@ -423,3 +423,34 @@ func TestLoadYamlFileWithExternalSchemaRef(t *testing.T) {
 
 	require.NotNil(t, swagger.Components.Schemas["AnotherTestSchema"].Value.Type)
 }
+
+type hitCntFS struct {
+	fs   http.Dir
+	hits map[string]int
+}
+
+func (fs hitCntFS) Open(fn string) (http.File, error) {
+	fs.hits[fn] = fs.hits[fn] + 1
+	return fs.fs.Open(fn)
+}
+
+func TestRemoteURLCaching(t *testing.T) {
+
+	sfs := hitCntFS{fs: "testdata", hits: map[string]int{}}
+	fs := http.FileServer(sfs)
+	ts := createTestServer(fs)
+	ts.Start()
+	defer ts.Close()
+
+	loader := openapi3.NewSwaggerLoader()
+	loader.IsExternalRefsAllowed = true
+	remote, err := url.Parse("http://" + addr + "/test.refcache.openapi.yml")
+	require.NoError(t, err)
+
+	_, err = loader.LoadSwaggerFromURI(remote)
+	require.NoError(t, err)
+
+	require.Contains(t, sfs.hits, "/test.refcache.openapi.yml")
+	require.Contains(t, sfs.hits, "/components.openapi.yml")
+	require.Equal(t, 1, sfs.hits["http://localhost:7965/components.openapi.yml"], "expcting 1 load of referenced schema")
+}

openapi3/testdata/test.refcache.openapi.yml

@@ -0,0 +1,15 @@
+---
+openapi: 3.0.0
+info:
+  title: 'OAI Specification w/ refs in YAML. Multiple refs to the same remote schema'
+  version: '1'
+paths: {}
+components:
+  schemas:
+    AnotherTestSchema:
+      type: object
+      properties:
+        ref1:
+          "$ref": http://localhost:7965/components.openapi.yml#/components/schemas/CustomTestSchema
+        ref2:
+          "$ref": http://localhost:7965/components.openapi.yml#/components/schemas/Name