From 7b543ac90909e7ef9301aaff3a8f2157cc6a69b1 Mon Sep 17 00:00:00 2001
From: bonny <b.rais@f5.com>
Date: Tue, 24 Sep 2019 10:48:33 -0700
Subject: [PATCH] added remote schema cache. Loaded schemas are stored in the
 cache once they are loaded and resolved. this avoids hundreds of roundtrips
 to remote server for schemas that contain multiple references

---
 openapi3/swagger_loader.go                  | 11 ++++--
 openapi3/swagger_loader_test.go             | 43 ++++++++++++++++++---
 openapi3/testdata/test.refcache.openapi.yml | 15 +++++++
 3 files changed, 60 insertions(+), 9 deletions(-)
 create mode 100644 openapi3/testdata/test.refcache.openapi.yml

diff --git a/openapi3/swagger_loader.go b/openapi3/swagger_loader.go
index d6674622e..d5869518f 100644
--- a/openapi3/swagger_loader.go
+++ b/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
 	}
diff --git a/openapi3/swagger_loader_test.go b/openapi3/swagger_loader_test.go
index 1e1bcaedd..0bf39b566 100644
--- a/openapi3/swagger_loader_test.go
+++ b/openapi3/swagger_loader_test.go
@@ -184,10 +184,10 @@ func TestResolveSchemaExternalRef(t *testing.T) {
 			},
 		},
 	}
-	loader := &openapi3.SwaggerLoader{
-		IsExternalRefsAllowed:  true,
-		LoadSwaggerFromURIFunc: multipleSourceLoader.LoadSwaggerFromURI,
-	}
+	loader := openapi3.NewSwaggerLoader()
+	loader.IsExternalRefsAllowed = true
+	loader.LoadSwaggerFromURIFunc = multipleSourceLoader.LoadSwaggerFromURI
+
 	doc, err := loader.LoadSwaggerFromURI(rootLocation)
 	require.NoError(t, err)
 	err = doc.Validate(loader.Context)
@@ -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["/components.openapi.yml"], "expcting 1 load of referenced schema")
+}
diff --git a/openapi3/testdata/test.refcache.openapi.yml b/openapi3/testdata/test.refcache.openapi.yml
new file mode 100644
index 000000000..7f0744ae0
--- /dev/null
+++ b/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