{"files":[{"path":"packages\/react-dom\/src\/server\/ReactPartialRenderer.js","status":"M"}],"patch":"diff --git a\/packages\/react-dom\/src\/server\/ReactPartialRenderer.js b\/packages\/react-dom\/src\/server\/ReactPartialRenderer.js\nindex f33ffd239e..d3ca7a8c1c 100644\n--- a\/packages\/react-dom\/src\/server\/ReactPartialRenderer.js\n+++ b\/packages\/react-dom\/src\/server\/ReactPartialRenderer.js\n@@ -641,8 +641,10 @@ class ReactDOMServerRenderer {\n previousWasTextNode: boolean;\n makeStaticMarkup: boolean;\n \n- providerStack: Array>;\n- providerIndex: number;\n+ contextIndex: number;\n+ contextStack: Array>;\n+ contextValueStack: Array;\n+ contextProviderStack: ?Array>; \/\/ DEV-only\n \n constructor(children: mixed, makeStaticMarkup: boolean) {\n const flatChildren = flattenTopLevelChildren(children);\n@@ -667,46 +669,65 @@ class ReactDOMServerRenderer {\n this.makeStaticMarkup = makeStaticMarkup;\n \n \/\/ Context (new API)\n- this.providerStack = []; \/\/ Stack of provider objects\n- this.providerIndex = -1;\n+ this.contextIndex = -1;\n+ this.contextStack = [];\n+ this.contextValueStack = [];\n+ if (__DEV__) {\n+ this.contextProviderStack = [];\n+ }\n }\n \n+ \/**\n+ * Note: We use just two stacks regardless of how many context providers you have.\n+ * Providers are always popped in the reverse order to how they were pushed\n+ * so we always know on the way down which provider you'll encounter next on the way up.\n+ * On the way down, we push the current provider, and its context value *before*\n+ * we mutated it, onto the stacks. Therefore, on the way up, we always know which\n+ * provider needs to be \"restored\" to which value.\n+ * https:\/\/github.com\/facebook\/react\/pull\/12985#issuecomment-396301248\n+ *\/\n+\n pushProvider(provider: ReactProvider): void {\n- this.providerIndex += 1;\n- this.providerStack[this.providerIndex] = provider;\n+ const index = ++this.contextIndex;\n const context: ReactContext = provider.type._context;\n+ const previousValue = context._currentValue;\n+\n+ \/\/ Remember which value to restore this context to on our way up.\n+ this.contextStack[index] = context;\n+ this.contextValueStack[index] = previousValue;\n+ if (__DEV__) {\n+ \/\/ Only used for push\/pop mismatch warnings.\n+ (this.contextProviderStack: any)[index] = provider;\n+ }\n+\n+ \/\/ Mutate the current value.\n context._currentValue = provider.props.value;\n }\n \n popProvider(provider: ReactProvider): void {\n+ const index = this.contextIndex;\n if (__DEV__) {\n warning(\n- this.providerIndex > -1 &&\n- provider === this.providerStack[this.providerIndex],\n+ index > -1 && provider === (this.contextProviderStack: any)[index],\n 'Unexpected pop.',\n );\n }\n- this.providerStack[this.providerIndex] = null;\n- this.providerIndex -= 1;\n- const context: ReactContext = provider.type._context;\n \n- \/\/ Find the closest parent provider of the same type and use its value.\n- \/\/ TODO: it would be nice to avoid this being O(N).\n- let contextPriorProvider = null;\n- for (let i = this.providerIndex; i >= 0; i--) {\n- \/\/ We assume this Flow type is correct because of the index check above\n- \/\/ and because pushProvider() enforces the correct type.\n- const priorProvider: ReactProvider = (this.providerStack[i]: any);\n- if (priorProvider.type === provider.type) {\n- contextPriorProvider = priorProvider;\n- break;\n- }\n- }\n- if (contextPriorProvider !== null) {\n- context._currentValue = contextPriorProvider.props.value;\n- } else {\n- context._currentValue = context._defaultValue;\n+ const context: ReactContext = this.contextStack[index];\n+ const previousValue = this.contextValueStack[index];\n+\n+ \/\/ \"Hide\" these null assignments from Flow by using `any`\n+ \/\/ because conceptually they are deletions--as long as we\n+ \/\/ promise to never access values beyond `this.contextIndex`.\n+ this.contextStack[index] = (null: any);\n+ this.contextValueStack[index] = (null: any);\n+ if (__DEV__) {\n+ (this.contextProviderStack: any)[index] = (null: any);\n }\n+ this.contextIndex--;\n+\n+ \/\/ Restore to the previous value we stored as we were walking down.\n+ context._currentValue = previousValue;\n }\n \n read(bytes: number): string | null {\n","commit":{"revision":"ec60457bcd22d06c404a44839c14beda88081ac7","authorEmail":"dan.abramov@gmail.com","shortRevision":"ec60457bcd","authoredAt":"2018-06-11T20:52:39+01:00","subject":"Popping context is O(1) in SSR (#13019)","authorName":"Dan Abramov"},"parents":["30bc8ef79295c71f5a4fc459c5bbd4b271f6f390"],"body":""}

dillon1000/react

Files changed