Handle reentrancy in server renderer

Context stack should be per server renderer instance.

Author: acdlite

packages/react-dom/src/__tests__/ReactServerRendering-test.internal.js

@@ -667,6 +667,59 @@ describe('ReactDOMServer', () => {
       expect(results).toEqual([2, 1, 3, 1]);
     });
 
+    it('renders context API, reentrancy', () => {
+      const Context = React.unstable_createContext(0);
+
+      function Provider(props) {
+        return Context.provide(props.value, props.children);
+      }
+
+      function Consumer(props) {
+        return Context.consume(value => {
+          return 'Result: ' + value;
+        });
+      }
+
+      let reentrantMarkup;
+      function Reentrant() {
+        reentrantMarkup = ReactDOMServer.renderToString(
+          <App value={1} reentrant={false} />,
+        );
+        return null;
+      }
+
+      const Indirection = React.Fragment;
+
+      function App(props) {
+        return (
+          <Provider value={props.value}>
+            {props.reentrant && <Reentrant />}
+            <Provider value={2}>
+              <Consumer />
+            </Provider>
+            <Indirection>
+              <Indirection>
+                <Consumer />
+                <Provider value={3}>
+                  <Consumer />
+                </Provider>
+              </Indirection>
+            </Indirection>
+            <Consumer />
+          </Provider>
+        );
+      }
+
+      const markup = ReactDOMServer.renderToString(
+        <App value={1} reentrant={true} />,
+      );
+      // Extract the numbers rendered by the consumers
+      const results = markup.match(/\d+/g).map(Number);
+      const reentrantResults = reentrantMarkup.match(/\d+/g).map(Number);
+      expect(results).toEqual([2, 1, 3, 1]);
+      expect(reentrantResults).toEqual([2, 1, 3, 1]);
+    });
+
     it('renders components with different batching strategies', () => {
       class StaticComponent extends React.Component {
         render() {

packages/react-dom/src/server/ReactPartialRenderer.js

@@ -123,33 +123,6 @@ if (__DEV__) {
   };
 }
 
-// Context (new API)
-let providerStack: Array<ReactProvider<any>> = []; // Stack of provider objects
-let index = -1;
-
-export function pushProvider<T>(provider: ReactProvider<T>): void {
-  index += 1;
-  providerStack[index] = provider;
-  const context: ReactContext<any> = provider.type.context;
-  context.currentProvider = provider;
-}
-
-export function popProvider<T>(provider: ReactProvider<T>): void {
-  if (__DEV__) {
-    warning(index > -1 && provider === providerStack[index], 'Unexpected pop.');
-  }
-  // $FlowFixMe - Intentionally unsound
-  providerStack[index] = null;
-  index -= 1;
-  const context: ReactContext<any> = provider.type.context;
-  if (index < 0) {
-    context.currentProvider = null;
-  } else {
-    const previousProvider = providerStack[index];
-    context.currentProvider = previousProvider;
-  }
-}
-
 let didWarnDefaultInputValue = false;
 let didWarnDefaultChecked = false;
 let didWarnDefaultSelectValue = false;
@@ -565,6 +538,9 @@ class ReactDOMServerRenderer {
   previousWasTextNode: boolean;
   makeStaticMarkup: boolean;
 
+  providerStack: Array<ReactProvider<any>>;
+  providerIndex: number;
+
   constructor(children: mixed, makeStaticMarkup: boolean) {
     const flatChildren = flattenTopLevelChildren(children);
 
@@ -586,6 +562,37 @@ class ReactDOMServerRenderer {
     this.currentSelectValue = null;
     this.previousWasTextNode = false;
     this.makeStaticMarkup = makeStaticMarkup;
+
+    // Context (new API)
+    this.providerStack = []; // Stack of provider objects
+    this.providerIndex = -1;
+  }
+
+  pushProvider<T>(provider: ReactProvider<T>): void {
+    this.providerIndex += 1;
+    this.providerStack[this.providerIndex] = provider;
+    const context: ReactContext<any> = provider.type.context;
+    context.currentProvider = provider;
+  }
+
+  popProvider<T>(provider: ReactProvider<T>): void {
+    if (__DEV__) {
+      warning(
+        this.providerIndex > -1 &&
+          provider === this.providerStack[this.providerIndex],
+        'Unexpected pop.',
+      );
+    }
+    // $FlowFixMe - Intentionally unsound
+    this.providerStack[this.providerIndex] = null;
+    this.providerIndex -= 1;
+    const context: ReactContext<any> = provider.type.context;
+    if (this.providerIndex < 0) {
+      context.currentProvider = null;
+    } else {
+      const previousProvider = this.providerStack[this.providerIndex];
+      context.currentProvider = previousProvider;
+    }
   }
 
   read(bytes: number): string | null {
@@ -615,7 +622,7 @@ class ReactDOMServerRenderer {
           frame.type.type.$$typeof === REACT_PROVIDER_TYPE
         ) {
           const provider: ReactProvider<any> = (frame.type: any);
-          popProvider(provider);
+          this.popProvider(provider);
         }
         continue;
       }
@@ -743,7 +750,7 @@ class ReactDOMServerRenderer {
               ((frame: any): FrameDev).debugElementStack = [];
             }
 
-            pushProvider(provider);
+            this.pushProvider(provider);
 
             this.stack.push(frame);
             return '';