Unify context implementations

Implements the new context API on top of the existing ReactStack that we
already use for host context and legacy context. Now there is a single
array that we push and pop from.

This makes the interrupt path slightly slower, since when we reset the
unit of work pointer, we have to iterate over the stack (like before)
*and* switch on the type of work (not like before). On the other hand,
this unifies all of the unwinding behavior in the UnwindWork module.

Author: acdlite

packages/react-reconciler/src/ReactFiberContext.js

@@ -48,7 +48,6 @@ export type LegacyContext = {
   processChildContext(fiber: Fiber, parentContext: Object): Object,
   pushContextProvider(workInProgress: Fiber): boolean,
   invalidateContextProvider(workInProgress: Fiber, didChange: boolean): void,
-  resetContext(): void,
   findCurrentUnmaskedContext(fiber: Fiber): Object,
 };
 
@@ -292,12 +291,6 @@ export default function(stack: Stack): LegacyContext {
     }
   }
 
-  function resetContext(): void {
-    previousContext = emptyObject;
-    contextStackCursor.current = emptyObject;
-    didPerformWorkStackCursor.current = false;
-  }
-
   function findCurrentUnmaskedContext(fiber: Fiber): Object {
     // Currently this is only used with renderSubtreeIntoContainer; not sure if it
     // makes sense elsewhere
@@ -336,7 +329,6 @@ export default function(stack: Stack): LegacyContext {
     processChildContext,
     pushContextProvider,
     invalidateContextProvider,
-    resetContext,
     findCurrentUnmaskedContext,
   };
 }

packages/react-reconciler/src/ReactFiberHostContext.js

@@ -108,18 +108,12 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
     pop(contextFiberStackCursor, fiber);
   }
 
-  function resetHostContainer() {
-    contextStackCursor.current = NO_CONTEXT;
-    rootInstanceStackCursor.current = NO_CONTEXT;
-  }
-
   return {
     getHostContext,
     getRootHostContainer,
     popHostContainer,
     popHostContext,
     pushHostContainer,
     pushHostContext,
-    resetHostContainer,
   };
 }

packages/react-reconciler/src/ReactFiberNewContext.js

@@ -9,20 +9,21 @@
 
 import type {Fiber} from './ReactFiber';
 import type {ReactContext} from 'shared/ReactTypes';
+import type {StackCursor, Stack} from './ReactFiberStack';
 
 import warning from 'fbjs/lib/warning';
 
 export type NewContext = {
   pushProvider(providerFiber: Fiber): void,
   popProvider(providerFiber: Fiber): void,
-  resetProviderStack(): void,
 };
 
-export default function() {
-  let changedBitsStack: Array<any> = [];
-  let currentValueStack: Array<any> = [];
-  let stack: Array<Fiber> = [];
-  let index = -1;
+export default function(stack: Stack) {
+  const {createCursor, push, pop} = stack;
+
+  const providerCursor: StackCursor<Fiber | null> = createCursor(null);
+  const valueCursor: StackCursor<mixed> = createCursor(null);
+  const changedBitsCursor: StackCursor<number> = createCursor(0);
 
   let rendererSigil;
   if (__DEV__) {
@@ -32,10 +33,11 @@ export default function() {
 
   function pushProvider(providerFiber: Fiber): void {
     const context: ReactContext<any> = providerFiber.type.context;
-    index += 1;
-    changedBitsStack[index] = context._changedBits;
-    currentValueStack[index] = context._currentValue;
-    stack[index] = providerFiber;
+
+    push(changedBitsCursor, context._changedBits, providerFiber);
+    push(valueCursor, context._currentValue, providerFiber);
+    push(providerCursor, providerFiber, providerFiber);
+
     context._currentValue = providerFiber.pendingProps.value;
     context._changedBits = providerFiber.stateNode;
 
@@ -51,39 +53,20 @@ export default function() {
   }
 
   function popProvider(providerFiber: Fiber): void {
-    if (__DEV__) {
-      warning(index > -1 && providerFiber === stack[index], 'Unexpected pop.');
-    }
-    const changedBits = changedBitsStack[index];
-    const currentValue = currentValueStack[index];
-    changedBitsStack[index] = null;
-    currentValueStack[index] = null;
-    stack[index] = null;
-    index -= 1;
+    const changedBits = changedBitsCursor.current;
+    const currentValue = valueCursor.current;
+
+    pop(providerCursor, providerFiber);
+    pop(valueCursor, providerFiber);
+    pop(changedBitsCursor, providerFiber);
+
     const context: ReactContext<any> = providerFiber.type.context;
     context._currentValue = currentValue;
     context._changedBits = changedBits;
   }
 
-  function resetProviderStack(): void {
-    for (let i = index; i > -1; i--) {
-      const providerFiber = stack[i];
-      const context: ReactContext<any> = providerFiber.type.context;
-      context._currentValue = context._defaultValue;
-      context._changedBits = 0;
-      changedBitsStack[i] = null;
-      currentValueStack[i] = null;
-      stack[i] = null;
-      if (__DEV__) {
-        context._currentRenderer = null;
-      }
-    }
-    index = -1;
-  }
-
   return {
     pushProvider,
     popProvider,
-    resetProviderStack,
   };
 }

packages/react-reconciler/src/ReactFiberScheduler.js

@@ -157,21 +157,18 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
   config: HostConfig<T, P, I, TI, HI, PI, C, CC, CX, PL>,
 ) {
   const stack = ReactFiberStack();
-  const {reset: resetStack} = stack;
   const hostContext = ReactFiberHostContext(config, stack);
   const legacyContext = ReactFiberLegacyContext(stack);
-  const newContext = ReactFiberNewContext();
+  const newContext = ReactFiberNewContext(stack);
   const {popHostContext, popHostContainer} = hostContext;
   const {
     popTopLevelContextObject: popTopLevelLegacyContextObject,
     popContextProvider: popLegacyContextProvider,
-    resetContext: resetLegacyContext,
   } = legacyContext;
-  const {popProvider, resetProviderStack} = newContext;
+  const {popProvider} = newContext;
   const hydrationContext: HydrationContext<C, CX> = ReactFiberHydrationContext(
     config,
   );
-  const {resetHostContainer} = hostContext;
   const {beginWork} = ReactFiberBeginWork(
     config,
     hostContext,
@@ -188,7 +185,11 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
     newContext,
     hydrationContext,
   );
-  const {throwException, unwindWork} = ReactFiberUnwindWork(
+  const {
+    throwException,
+    unwindWork,
+    unwindInterruptedWork,
+  } = ReactFiberUnwindWork(
     hostContext,
     legacyContext,
     newContext,
@@ -289,15 +290,14 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
     };
   }
 
-  function resetContextStack() {
-    // Reset the stack
-    resetStack();
-    // Reset the cursors
-    resetLegacyContext();
-    resetHostContainer();
-
-    // TODO: Unify new context implementation with other stacks
-    resetProviderStack();
+  function resetStack() {
+    if (nextUnitOfWork !== null) {
+      let interruptedWork = nextUnitOfWork.return;
+      while (interruptedWork !== null) {
+        unwindInterruptedWork(interruptedWork);
+        interruptedWork = interruptedWork.return;
+      }
+    }
 
     if (__DEV__) {
       ReactStrictModeWarnings.discardPendingWarnings();
@@ -841,7 +841,7 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
       nextUnitOfWork === null
     ) {
       // Reset the stack and start working from the root.
-      resetContextStack();
+      resetStack();
       nextRoot = root;
       nextRenderExpirationTime = expirationTime;
       nextUnitOfWork = createWorkInProgress(
@@ -1102,7 +1102,7 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
           ) {
             // This is an interruption. (Used for performance tracking.)
             interruptedBy = fiber;
-            resetContextStack();
+            resetStack();
           }
           if (nextRoot !== root || !isWorking) {
             requestWork(root, expirationTime);

packages/react-reconciler/src/ReactFiberStack.js

@@ -20,7 +20,6 @@ export type Stack = {
   isEmpty(): boolean,
   push<T>(cursor: StackCursor<T>, value: T, fiber: Fiber): void,
   pop<T>(cursor: StackCursor<T>, fiber: Fiber): void,
-  reset(): void,
 };
 
 export default function(): Stack {
@@ -81,23 +80,10 @@ export default function(): Stack {
     cursor.current = value;
   }
 
-  function reset(): void {
-    while (index > -1) {
-      valueStack[index] = null;
-
-      if (__DEV__) {
-        fiberStack[index] = null;
-      }
-
-      index--;
-    }
-  }
-
   return {
     createCursor,
     isEmpty,
     pop,
     push,
-    reset,
   };
 }

packages/react-reconciler/src/ReactFiberUnwindWork.js

@@ -145,8 +145,36 @@ export default function<C, CX>(
         return null;
     }
   }
+
+  function unwindInterruptedWork(interruptedWork: Fiber) {
+    switch (interruptedWork.tag) {
+      case ClassComponent: {
+        popLegacyContextProvider(interruptedWork);
+        break;
+      }
+      case HostRoot: {
+        popHostContainer(interruptedWork);
+        popTopLevelLegacyContextObject(interruptedWork);
+        break;
+      }
+      case HostComponent: {
+        popHostContext(interruptedWork);
+        break;
+      }
+      case HostPortal:
+        popHostContainer(interruptedWork);
+        break;
+      case ContextProvider:
+        popProvider(interruptedWork);
+        break;
+      default:
+        break;
+    }
+  }
+
   return {
     throwException,
     unwindWork,
+    unwindInterruptedWork,
   };
 }

packages/react-reconciler/src/__tests__/ReactIncrementalTriangle-test.internal.js

@@ -542,6 +542,13 @@ ${formatActions(actions)}
         ['c', step(2)],
         ['b', interrupt()],
       );
+
+      simulateMultipleRoots(
+        ['c', toggle(0)],
+        ['c', step(1)],
+        ['b', flush(7)],
+        ['c', toggle(0)],
+      );
     });
 
     it('generative tests', () => {