[DevTools] Use source maps to infer name asynchronously (facebook#34212)

Author: sebmarkbage

packages/react-devtools-shared/src/devtools/views/Components/InspectedElementSuspendedBy.js

@@ -20,6 +20,7 @@ import {withPermissionsCheck} from 'react-devtools-shared/src/frontend/utils/wit
 import StackTraceView from './StackTraceView';
 import OwnerView from './OwnerView';
 import {meta} from '../../../hydration';
+import useInferredName from '../useInferredName';
 
 import type {
   InspectedElement,
@@ -101,21 +102,7 @@ function SuspendedByRow({
 }: RowProps) {
   const [isOpen, setIsOpen] = useState(false);
   const ioInfo = asyncInfo.awaited;
-  let name = ioInfo.name;
-  if (name === '' || name === 'Promise') {
-    // If all we have is a generic name, we can try to infer a better name from
-    // the stack. We only do this if the stack has more than one frame since
-    // otherwise it's likely to just be the name of the component which isn't better.
-    const bestStack = ioInfo.stack || asyncInfo.stack;
-    if (bestStack !== null && bestStack.length > 1) {
-      // TODO: Ideally we'd get the name from the last ignore listed frame before the
-      // first visible frame since this is the same algorithm as the Flight server uses.
-      // Ideally, we'd also get the name from the source mapped entry instead of the
-      // original entry. However, that would require suspending the immediate display
-      // of these rows to first do source mapping before we can show the name.
-      name = bestStack[0][0];
-    }
-  }
+  const name = useInferredName(asyncInfo);
   const description = ioInfo.description;
   const longName = description === '' ? name : name + ' (' + description + ')';
   const shortDescription = getShortDescription(name, description);

packages/react-devtools-shared/src/devtools/views/useInferredName.js

@@ -0,0 +1,78 @@
+import {use, useContext, useDeferredValue} from 'react';
+
+import type {ReactCallSite} from 'shared/ReactTypes';
+
+import type {SourceMappedLocation} from 'react-devtools-shared/src/symbolicateSource';
+
+import type {SerializedAsyncInfo} from 'react-devtools-shared/src/frontend/types';
+
+import FetchFileWithCachingContext from './Components/FetchFileWithCachingContext';
+
+import {symbolicateSourceWithCache} from 'react-devtools-shared/src/symbolicateSource';
+
+export default function useInferredName(
+  asyncInfo: SerializedAsyncInfo,
+): string {
+  const fetchFileWithCaching = useContext(FetchFileWithCachingContext);
+  const name = asyncInfo.awaited.name;
+  let inferNameFromStack = null;
+  if (!name || name === 'Promise') {
+    // If all we have is a generic name, we can try to infer a better name from
+    // the stack. We only do this if the stack has more than one frame since
+    // otherwise it's likely to just be the name of the component which isn't better.
+    const bestStack = asyncInfo.awaited.stack || asyncInfo.stack;
+    if (bestStack !== null && bestStack.length > 1) {
+      inferNameFromStack = bestStack;
+    }
+  }
+  // Start by not source mapping and just taking the first name and upgrade to
+  // the better name asynchronously if we find one. Most of the time it'll just be
+  // the top of the stack.
+  const shouldSourceMap = useDeferredValue(inferNameFromStack !== null, false);
+  if (inferNameFromStack !== null) {
+    if (shouldSourceMap) {
+      let bestMatch = '';
+      for (let i = 0; i < inferNameFromStack.length; i++) {
+        const callSite: ReactCallSite = inferNameFromStack[i];
+        const [virtualFunctionName, virtualURL, virtualLine, virtualColumn] =
+          callSite;
+        const symbolicatedCallSite: null | SourceMappedLocation =
+          fetchFileWithCaching !== null
+            ? use(
+                symbolicateSourceWithCache(
+                  fetchFileWithCaching,
+                  virtualURL,
+                  virtualLine,
+                  virtualColumn,
+                ),
+              )
+            : null;
+        if (symbolicatedCallSite === null) {
+          // If we can't source map, we treat it as first party code. We called whatever was
+          // the previous callsite.
+          if (bestMatch === '') {
+            return virtualFunctionName || name;
+          } else {
+            return bestMatch;
+          }
+        } else if (!symbolicatedCallSite.ignored) {
+          if (bestMatch === '') {
+            // If we had no good stack frames for internal calls, just use the last
+            // first party function name.
+            return symbolicatedCallSite[0] || virtualFunctionName || name;
+          } else {
+            return bestMatch;
+          }
+        } else {
+          // This line was ignore listed, it might be the one we called into from first party.
+          bestMatch = symbolicatedCallSite[0] || virtualFunctionName;
+        }
+      }
+      return name;
+    } else {
+      return inferNameFromStack[0][0];
+    }
+  } else {
+    return name;
+  }
+}