Shallow freeze resolver value

Reviewed By: alunyov

Differential Revision: D51049743

fbshipit-source-id: 5c8926e84e3eb355d4eb5972dbcb556d8a6fa022

packages/react-relay/__tests__/RelayResolverModel-test.js

@@ -58,13 +58,15 @@ function logFn(event: LogEvent): void {
 beforeEach(() => {
   RelayFeatureFlags.ENABLE_RELAY_RESOLVERS = true;
   RelayFeatureFlags.ENABLE_CLIENT_EDGES = true;
+  RelayFeatureFlags.ENABLE_SHALLOW_FREEZE_RESOLVER_VALUES = true;
   logEvents = [];
   resetStore(logFn);
 });
 
 afterEach(() => {
   RelayFeatureFlags.ENABLE_RELAY_RESOLVERS = false;
   RelayFeatureFlags.ENABLE_CLIENT_EDGES = false;
+  RelayFeatureFlags.ENABLE_SHALLOW_FREEZE_RESOLVER_VALUES = false;
 });
 
 function createEnvironment() {
@@ -539,8 +541,7 @@ describe.each([
       setIsHuman(true);
       jest.runAllImmediates();
     });
-    // TODO: Should be 0. Relay should not mutate the value here.
-    expect(renderer.toJSON()).toEqual('human:100');
+    expect(renderer.toJSON()).toEqual('human:0');
 
     TestRenderer.act(() => {
       renderer.unmount();
@@ -568,10 +569,9 @@ describe.each([
     );
     expect(renderer.toJSON()).toEqual('robot:0');
 
-    // TODO: should not throw on mutating the inner of the resolver value
     expect(() => {
       chargeBattery();
-    }).toThrow();
+    }).not.toThrow();
 
     TestRenderer.act(() => {
       renderer.unmount();

packages/relay-runtime/store/ResolverCache.js

@@ -26,6 +26,8 @@ import type {
 
 const recycleNodesInto = require('../util/recycleNodesInto');
 const {RELAY_LIVE_RESOLVER} = require('../util/RelayConcreteNode');
+const RelayFeatureFlags = require('../util/RelayFeatureFlags');
+const shallowFreeze = require('../util/shallowFreeze');
 const {generateClientID} = require('./ClientID');
 const RelayModernRecord = require('./RelayModernRecord');
 const {
@@ -172,6 +174,9 @@ class RecordResolverCache implements ResolverCache {
       linkedRecord = RelayModernRecord.create(linkedID, '__RELAY_RESOLVER__');
 
       const evaluationResult = evaluate();
+      if (RelayFeatureFlags.ENABLE_SHALLOW_FREEZE_RESOLVER_VALUES) {
+        shallowFreeze(evaluationResult.resolverResult);
+      }
       RelayModernRecord.setValue(
         linkedRecord,
         RELAY_RESOLVER_VALUE_KEY,

packages/relay-runtime/store/experimental-live-resolvers/LiveResolverCache.js

@@ -36,6 +36,8 @@ import type {LiveState} from 'relay-runtime';
 
 const recycleNodesInto = require('../../util/recycleNodesInto');
 const {RELAY_LIVE_RESOLVER} = require('../../util/RelayConcreteNode');
+const RelayFeatureFlags = require('../../util/RelayFeatureFlags');
+const shallowFreeze = require('../../util/shallowFreeze');
 const {generateClientID, generateClientObjectClientID} = require('../ClientID');
 const RelayModernRecord = require('../RelayModernRecord');
 const {createNormalizationSelector} = require('../RelayModernSelector');
@@ -620,12 +622,18 @@ class LiveResolverCache implements ResolverCache {
         nextOutputTypeRecordIDs,
       );
 
+      if (RelayFeatureFlags.ENABLE_SHALLOW_FREEZE_RESOLVER_VALUES) {
+        shallowFreeze(resolverValue);
+      }
       RelayModernRecord.setValue(
         resolverRecord,
         RELAY_RESOLVER_VALUE_KEY,
         resolverValue,
       );
     } else {
+      if (RelayFeatureFlags.ENABLE_SHALLOW_FREEZE_RESOLVER_VALUES) {
+        shallowFreeze(value);
+      }
       // For "classic" resolvers (or if the value is nullish), we are just setting their
       // value as is.
       RelayModernRecord.setValue(

packages/relay-runtime/util/RelayFeatureFlags.js

@@ -28,6 +28,7 @@ export type FeatureFlags = {
   STRING_INTERN_LEVEL: number,
   LOG_MISSING_RECORDS_IN_PROD: boolean,
   ENABLE_RELAY_OPERATION_TRACKER_SUSPENSE: boolean,
+  ENABLE_SHALLOW_FREEZE_RESOLVER_VALUES: boolean,
 
   // Configure RelayStoreSubscriptions to mark a subscription as affected by an
   // update if there are any overlapping IDs other than ROOT_ID or VIWER_ID,
@@ -63,6 +64,7 @@ const RelayFeatureFlags: FeatureFlags = {
   ENABLE_OPERATION_TRACKER_OPTIMISTIC_UPDATES: false,
   ENABLE_RELAY_OPERATION_TRACKER_SUSPENSE: false,
   ENABLE_FIELD_ERROR_HANDLING: false,
+  ENABLE_SHALLOW_FREEZE_RESOLVER_VALUES: false,
 };
 
 module.exports = RelayFeatureFlags;

packages/relay-runtime/util/shallowFreeze.js

@@ -0,0 +1,23 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
+ * @format
+ * @oncall relay
+ */
+
+'use strict';
+
+// Shallow freeze to prevent Relay from mutating the value in recycleNodesInto or deepFreezing the value
+module.exports = function shallowFreeze(value: mixed) {
+  if (
+    typeof value === 'object' &&
+    value != null &&
+    (Array.isArray(value) || value.constructor === Object)
+  ) {
+    Object.freeze(value);
+  }
+};