Rewrite mergeRequestModifiers to operate on pointers rather than copi…

…es. (#224)

client_requests.go

@@ -137,7 +137,7 @@ func sendStructuredRequestParseResponse[ResponseT any](
 	path string,
 	body any,
 	parameters url.Values,
-	requestModifiersPerRequest requestModifiers,
+	requestModifiers requestModifiers,
 ) (*Response[ResponseT], error) {
 	var buf bytes.Buffer
 
@@ -152,7 +152,7 @@ func sendStructuredRequestParseResponse[ResponseT any](
 		path,
 		&buf,
 		parameters,
-		requestModifiersPerRequest,
+		requestModifiers,
 	)
 }
 
@@ -164,7 +164,7 @@ func sendRequestParseResponse[ResponseT any](
 	path string,
 	body io.Reader,
 	parameters url.Values,
-	requestModifiersPerRequest requestModifiers,
+	requestModifiers requestModifiers,
 ) (*Response[ResponseT], error) {
 	// apply the client-level request timeout, if set
 	if client.configuration.RequestTimeout > 0 {
@@ -174,13 +174,10 @@ func sendRequestParseResponse[ResponseT any](
 	}
 
 	// clone the client-level request modifiers to prevent race conditions
-	requestModifiersClient := client.cloneClientRequestModifiers()
+	modifiers := client.cloneClientRequestModifiers()
 
-	// merge the client-level & request-level modifiers, preferring the later
-	modifiers := mergeRequestModifiers(
-		requestModifiersClient,
-		requestModifiersPerRequest,
-	)
+	// merge in the request-level request modifiers
+	mergeRequestModifiers(&modifiers, &requestModifiers)
 
 	req, err := client.newRequest(ctx, method, path, body, parameters, modifiers.headers)
 	if err != nil {
@@ -212,16 +209,13 @@ func sendRequestReturnRawResponse(
 	path string,
 	body io.Reader,
 	parameters url.Values,
-	requestModifiersPerRequest requestModifiers,
+	requestModifiers requestModifiers,
 ) (*http.Response, error) {
 	// clone the client-level request modifiers to prevent race conditions
-	requestModifiersClient := client.cloneClientRequestModifiers()
+	modifiers := client.cloneClientRequestModifiers()
 
-	// merge the client-level & request-level modifiers, preferring the later
-	modifiers := mergeRequestModifiers(
-		requestModifiersClient,
-		requestModifiersPerRequest,
-	)
+	// merge in the request-level request modifiers
+	mergeRequestModifiers(&modifiers, &requestModifiers)
 
 	req, err := client.newRequest(ctx, method, path, body, parameters, modifiers.headers)
 	if err != nil {

request_modifiers.go

@@ -245,47 +245,43 @@ func (m *requestModifiers) additionalQueryParametersOrDefault() url.Values {
 	return m.additionalQueryParameters
 }
 
-// mergeRequestModifiers merges the two objects, preferring the per-request modifiers
-func mergeRequestModifiers(perClient, perRequest requestModifiers) requestModifiers {
-	merged := perClient
-
-	if perRequest.headers.userAgent != "" {
-		merged.headers.userAgent = perRequest.headers.userAgent
+// mergeRequestModifiers merges the values from *rhs into *lhs.
+func mergeRequestModifiers(lhs, rhs *requestModifiers) {
+	if rhs.headers.userAgent != "" {
+		lhs.headers.userAgent = rhs.headers.userAgent
 	}
 
-	if perRequest.headers.token != "" {
-		merged.headers.token = perRequest.headers.token
+	if rhs.headers.token != "" {
+		lhs.headers.token = rhs.headers.token
 	}
 
-	if perRequest.headers.namespace != "" {
-		merged.headers.namespace = perRequest.headers.namespace
+	if rhs.headers.namespace != "" {
+		lhs.headers.namespace = rhs.headers.namespace
 	}
 
-	if len(perRequest.headers.mfaCredentials) != 0 {
-		merged.headers.mfaCredentials = perRequest.headers.mfaCredentials
+	if len(rhs.headers.mfaCredentials) != 0 {
+		lhs.headers.mfaCredentials = rhs.headers.mfaCredentials
 	}
 
-	if perRequest.headers.responseWrappingTTL != 0 {
-		merged.headers.responseWrappingTTL = perRequest.headers.responseWrappingTTL
+	if rhs.headers.responseWrappingTTL != 0 {
+		lhs.headers.responseWrappingTTL = rhs.headers.responseWrappingTTL
 	}
 
-	if perRequest.headers.replicationForwardingMode != ReplicationForwardNone {
-		merged.headers.replicationForwardingMode = perRequest.headers.replicationForwardingMode
+	if rhs.headers.replicationForwardingMode != ReplicationForwardNone {
+		lhs.headers.replicationForwardingMode = rhs.headers.replicationForwardingMode
 	}
 
-	if len(perRequest.headers.customHeaders) != 0 {
-		merged.headers.customHeaders = perRequest.headers.customHeaders
+	if len(rhs.headers.customHeaders) != 0 {
+		lhs.headers.customHeaders = rhs.headers.customHeaders
 	}
 
-	if len(perRequest.requestCallbacks) != 0 {
-		merged.requestCallbacks = perRequest.requestCallbacks
+	if len(rhs.requestCallbacks) != 0 {
+		lhs.requestCallbacks = rhs.requestCallbacks
 	}
 
-	if len(perRequest.responseCallbacks) != 0 {
-		merged.responseCallbacks = perRequest.responseCallbacks
+	if len(rhs.responseCallbacks) != 0 {
+		lhs.responseCallbacks = rhs.responseCallbacks
 	}
-
-	return merged
 }
 
 func validateToken(token string) error {

request_modifiers_test.go

@@ -88,43 +88,44 @@ func Test_validateCustomHeaders(t *testing.T) {
 	}
 }
 
-func Test_mergeRequestModifiers(t *testing.T) {
+func Test_mergeRequestModifiers_overwrite(t *testing.T) {
 	cases := map[string]struct {
 		name     string
-		a        requestModifiers
-		b        requestModifiers
+		lhs      requestModifiers
+		rhs      requestModifiers
 		expected requestModifiers
 	}{
 		"empty": {
-			a:        requestModifiers{},
-			b:        requestModifiers{},
+			lhs:      requestModifiers{},
+			rhs:      requestModifiers{},
 			expected: requestModifiers{},
 		},
-		"token-a": {
-			a:        requestModifiers{headers: requestHeaders{token: "token-a"}},
-			b:        requestModifiers{},
-			expected: requestModifiers{headers: requestHeaders{token: "token-a"}},
+		"token-in-lhs": {
+			lhs:      requestModifiers{headers: requestHeaders{token: "token-lhs"}},
+			rhs:      requestModifiers{},
+			expected: requestModifiers{headers: requestHeaders{token: "token-lhs"}},
 		},
-		"token-b": {
-			a:        requestModifiers{},
-			b:        requestModifiers{headers: requestHeaders{token: "token-b"}},
-			expected: requestModifiers{headers: requestHeaders{token: "token-b"}},
+		"token-in-rhs": {
+			lhs:      requestModifiers{},
+			rhs:      requestModifiers{headers: requestHeaders{token: "token-rhs"}},
+			expected: requestModifiers{headers: requestHeaders{token: "token-rhs"}},
 		},
-		"token-a-b": {
-			a:        requestModifiers{headers: requestHeaders{token: "token-a"}},
-			b:        requestModifiers{headers: requestHeaders{token: "token-b"}},
-			expected: requestModifiers{headers: requestHeaders{token: "token-b"}},
+		"token-in-both": {
+			lhs:      requestModifiers{headers: requestHeaders{token: "token-lhs"}},
+			rhs:      requestModifiers{headers: requestHeaders{token: "token-rhs"}},
+			expected: requestModifiers{headers: requestHeaders{token: "token-rhs"}},
 		},
-		"token-namespace": {
-			a:        requestModifiers{headers: requestHeaders{token: "token-a"}},
-			b:        requestModifiers{headers: requestHeaders{namespace: "namespace-b"}},
-			expected: requestModifiers{headers: requestHeaders{token: "token-a", namespace: "namespace-b"}},
+		"token-lhs-and-namespace-rhs": {
+			lhs:      requestModifiers{headers: requestHeaders{token: "token-lhs"}},
+			rhs:      requestModifiers{headers: requestHeaders{namespace: "namespace-rhs"}},
+			expected: requestModifiers{headers: requestHeaders{token: "token-lhs", namespace: "namespace-rhs"}},
 		},
 	}
 
 	for name, tc := range cases {
 		t.Run(name, func(t *testing.T) {
-			require.Equal(t, tc.expected, mergeRequestModifiers(tc.a, tc.b))
+			mergeRequestModifiers(&tc.lhs, &tc.rhs)
+			require.Equal(t, tc.expected, tc.lhs)
 		})
 	}
 }