Future-proof clearing providers for future react-dom versions

lib/renderer.js

@@ -67,30 +67,40 @@ class PartialRenderer extends ReactDOMServerRenderer {
 	}
 
 	/*
-	 * `.destroy()` and `.clearProviders()` methods are added here to fix bug in ReactDOM 16.7.0.
+	 * `.destroy()` and `.clearProviders()` methods are added here to fix bug in
+	 * ReactDOM 16.7.0-16.8.2.
 	 * See https://github.com/facebook/react/issues/14705
-	 * This bug will have worse effects with this extension of the class, as contexts are added
-	 * to the context stack without adding to the frame stack, so leftover context values
-	 * crossing over into other threads will be much more common.
-	 * These prototype methods are removed again at bottom of this script if `.clearProviders()`
-	 * prototype method exists already on ReactDOMServerRenderer.
-	 * TODO Alter this depending on outcome of ReactDOM issue and how it is fixed.
+	 * This bug will have worse effects with this extension of the class, as
+	 * contexts are added to the context stack without adding to the frame
+	 * stack, so leftover context values crossing over into other threads will
+	 * be much more common.
+	 * `.destroy()` prototype method is removed again at bottom of this script
+	 * if `.clearProviders()` prototype method exists already on
+	 * ReactDOMServerRenderer.
+	 *
+	 * TODO Alter this when updating to ReactDOM > 16.8.2 which includes
+	 * commit fixing this lands in stable release.
+	 * https://github.com/facebook/react/commit/ab7a67b1dc0e44bf74545ccf51a8c143b3af7402
 	 */
 	destroy() {
 		if (!this.exhausted) this.clearProviders();
 		super.destroy();
 	}
 
 	clearProviders() {
-		while (this.contextIndex > -1) {
-			if (isDev) {
-				this.popProvider(this.contextProviderStack[this.contextIndex]);
-			} else {
-				this.popProvider();
-			}
+		// Restore any remaining providers on the stack to previous values
+		for (let index = this.contextIndex; index >= 0; index--) {
+			const context = this.contextStack[index];
+			const previousValue = this.contextValueStack[index];
+			context[this.threadID] = previousValue;
 		}
 	}
 
+	resetProviders() {
+		this.clearProviders();
+		this.contextIndex = -1;
+	}
+
 	/*
 	 * Read async
 	 */
@@ -370,7 +380,7 @@ class PartialRenderer extends ReactDOMServerRenderer {
 		this.cycle();
 
 		// Clear contexts added in `.restoreStack()`
-		this.clearProviders();
+		this.resetProviders();
 	}
 
 	restoreStack(stackState, element) {
@@ -437,7 +447,7 @@ class PartialRenderer extends ReactDOMServerRenderer {
 		if (!boundaryFrame) {
 			// Clear current render cycle state
 			this.stack.length = 1;
-			this.clearProviders();
+			this.resetProviders();
 
 			// Restore stack and render fallback.
 			// NB Render cycle already in progress, so no need to call `.read()` again.
@@ -595,8 +605,12 @@ function abort(promise) {
 	if (typeof promise.abort === 'function') promise.abort();
 }
 
-// If ReactDOM is version which already has `.clearProviders()` method,
-// remove the version added in the subclass (see comments above on methods)
+/*
+ * If ReactDOM is version which already has `.clearProviders()` method on
+ * `PartialRenderer` class, remove `.destroy()` and `.clearProviders()` methods
+ * overrides in this subclass.
+ * (see comments above on `.destroy()` method)
+ */
 if (ReactDOMServerRenderer.prototype.clearProviders) {
 	delete PartialRenderer.prototype.clearProviders;
 	delete PartialRenderer.prototype.destroy;