DevTools flushes updated passive warning/error info after delay (#20931)

* DevTools flushes updated passive warning/error info after delay
Previously this information was not flushed until the next commit, but this provides a worse user experience if the next commit is really delayed. Instead, the backend now flushes only the warning/error counts after a delay. As a safety, if there are already any pending operations in the queue, we bail.

Co-authored-by: eps1lon <silbermann.sebastian@gmail.com>

packages/react-devtools-shared/src/__tests__/store-test.js

@@ -1075,40 +1075,110 @@ describe('Store', () => {
       `);
     });
 
-    // This is not great, but it seems safer than potentially flushing between commits.
-    // Our logic for determining how to handle e.g. suspended trees or error boundaries
-    // is built on the assumption that we're evaluating the results of a commit, not an in-progress render.
-    it('during passive get counted (but not until the next commit)', () => {
-      function Example() {
-        React.useEffect(() => {
-          console.error('test-only: passive error');
-          console.warn('test-only: passive warning');
-        });
-        return null;
+    describe('during passive effects', () => {
+      function flushPendingBridgeOperations() {
+        jest.runOnlyPendingTimers();
       }
-      const container = document.createElement('div');
-
-      withErrorsOrWarningsIgnored(['test-only:'], () => {
-        act(() => ReactDOM.render(<Example />, container));
-      });
 
-      expect(store).toMatchInlineSnapshot(`
-        [root]
-            <Example>
-      `);
+      // Gross abstraction around pending passive warning/error delay.
+      function flushPendingPassiveErrorAndWarningCounts() {
+        jest.advanceTimersByTime(1000);
+      }
 
-      withErrorsOrWarningsIgnored(['test-only:'], () => {
-        act(() => ReactDOM.render(<Example rerender={1} />, container));
+      it('are counted (after a delay)', () => {
+        function Example() {
+          React.useEffect(() => {
+            console.error('test-only: passive error');
+            console.warn('test-only: passive warning');
+          });
+          return null;
+        }
+        const container = document.createElement('div');
+
+        withErrorsOrWarningsIgnored(['test-only:'], () => {
+          act(() => {
+            ReactDOM.render(<Example />, container);
+          }, false);
+        });
+        flushPendingBridgeOperations();
+        expect(store).toMatchInlineSnapshot(`
+          [root]
+              <Example>
+        `);
+
+        // After a delay, passive effects should be committed as well
+        act(flushPendingPassiveErrorAndWarningCounts, false);
+        expect(store).toMatchInlineSnapshot(`
+          ✕ 1, ⚠ 1
+          [root]
+              <Example> ✕⚠
+        `);
+
+        act(() => ReactDOM.unmountComponentAtNode(container));
+        expect(store).toMatchInlineSnapshot(``);
       });
 
-      expect(store).toMatchInlineSnapshot(`
-        ✕ 1, ⚠ 1
-        [root]
-            <Example> ✕⚠
-      `);
+      it('are flushed early when there is a new commit', () => {
+        function Example() {
+          React.useEffect(() => {
+            console.error('test-only: passive error');
+            console.warn('test-only: passive warning');
+          });
+          return null;
+        }
+
+        function Noop() {
+          return null;
+        }
+
+        const container = document.createElement('div');
+
+        withErrorsOrWarningsIgnored(['test-only:'], () => {
+          act(() => {
+            ReactDOM.render(
+              <>
+                <Example />
+              </>,
+              container,
+            );
+          }, false);
+          flushPendingBridgeOperations();
+          expect(store).toMatchInlineSnapshot(`
+            [root]
+                <Example>
+          `);
+
+          // Before warnings and errors have flushed, flush another commit.
+          act(() => {
+            ReactDOM.render(
+              <>
+                <Example />
+                <Noop />
+              </>,
+              container,
+            );
+          }, false);
+          flushPendingBridgeOperations();
+          expect(store).toMatchInlineSnapshot(`
+            ✕ 1, ⚠ 1
+            [root]
+                <Example> ✕⚠
+                <Noop>
+          `);
+        });
 
-      act(() => ReactDOM.unmountComponentAtNode(container));
-      expect(store).toMatchInlineSnapshot(``);
+        // After a delay, passive effects should be committed as well
+        act(flushPendingPassiveErrorAndWarningCounts, false);
+        expect(store).toMatchInlineSnapshot(`
+          ✕ 2, ⚠ 2
+          [root]
+              <Example> ✕⚠
+              <Noop>
+        `);
+
+        act(() => ReactDOM.unmountComponentAtNode(container));
+        expect(store).toMatchInlineSnapshot(``);
+      });
     });
 
     it('from react get counted', () => {

packages/react-devtools-shared/src/__tests__/utils.js

@@ -14,7 +14,10 @@ import type Store from 'react-devtools-shared/src/devtools/store';
 import type {ProfilingDataFrontend} from 'react-devtools-shared/src/devtools/views/Profiler/types';
 import type {ElementType} from 'react-devtools-shared/src/types';
 
-export function act(callback: Function): void {
+export function act(
+  callback: Function,
+  recursivelyFlush: boolean = true,
+): void {
   const {act: actTestRenderer} = require('react-test-renderer');
   const {act: actDOM} = require('react-dom/test-utils');
 
@@ -24,13 +27,15 @@ export function act(callback: Function): void {
     });
   });
 
-  // Flush Bridge operations
-  while (jest.getTimerCount() > 0) {
-    actDOM(() => {
-      actTestRenderer(() => {
-        jest.runAllTimers();
+  if (recursivelyFlush) {
+    // Flush Bridge operations
+    while (jest.getTimerCount() > 0) {
+      actDOM(() => {
+        actTestRenderer(() => {
+          jest.runAllTimers();
+        });
       });
-    });
+    }
   }
 }
 

packages/react-devtools-shared/src/backend/renderer.js

@@ -626,6 +626,14 @@ export function attach(
 
     // If this Fiber is currently being inspected, mark it as needing an udpate as well.
     updateMostRecentlyInspectedElementIfNecessary(fiberID);
+
+    // Passive effects may trigger errors or warnings too;
+    // In this case, we should wait until the rest of the passive effects have run,
+    // but we shouldn't wait until the next commit because that might be a long time.
+    // This would also cause "tearing" between an inspected Component and the tree view.
+    // Then again we don't want to flush too soon because this could be an error during async rendering.
+    // Use a debounce technique to ensure that we'll eventually flush.
+    flushPendingErrorsAndWarningsAfterDelay();
   }
 
   // Patching the console enables DevTools to do a few useful things:
@@ -1198,10 +1206,12 @@ export function attach(
     }
   }
 
-  const pendingOperations: Array<number> = [];
+  type OperationsArray = Array<number>;
+
+  const pendingOperations: OperationsArray = [];
   const pendingRealUnmountedIDs: Array<number> = [];
   const pendingSimulatedUnmountedIDs: Array<number> = [];
-  let pendingOperationsQueue: Array<Array<number>> | null = [];
+  let pendingOperationsQueue: Array<OperationsArray> | null = [];
   const pendingStringTable: Map<string, number> = new Map();
   let pendingStringTableLength: number = 0;
   let pendingUnmountedRootID: number | null = null;
@@ -1218,6 +1228,61 @@ export function attach(
     pendingOperations.push(op);
   }
 
+  function flushOrQueueOperations(operations: OperationsArray): void {
+    if (pendingOperationsQueue !== null) {
+      pendingOperationsQueue.push(operations);
+    } else {
+      hook.emit('operations', operations);
+    }
+  }
+
+  let flushPendingErrorsAndWarningsAfterDelayTimeoutID = null;
+
+  function clearPendingErrorsAndWarningsAfterDelay() {
+    if (flushPendingErrorsAndWarningsAfterDelayTimeoutID !== null) {
+      clearTimeout(flushPendingErrorsAndWarningsAfterDelayTimeoutID);
+      flushPendingErrorsAndWarningsAfterDelayTimeoutID = null;
+    }
+  }
+
+  function flushPendingErrorsAndWarningsAfterDelay() {
+    clearPendingErrorsAndWarningsAfterDelay();
+
+    flushPendingErrorsAndWarningsAfterDelayTimeoutID = setTimeout(() => {
+      flushPendingErrorsAndWarningsAfterDelayTimeoutID = null;
+
+      if (pendingOperations.length > 0) {
+        // On the off chance that something else has pushed pending operations,
+        // we should bail on warnings; it's probably not safe to push midway.
+        return;
+      }
+
+      recordPendingErrorsAndWarnings();
+
+      if (pendingOperations.length === 0) {
+        // No warnings or errors to flush; we can bail out early here too.
+        return;
+      }
+
+      // We can create a smaller operations array than flushPendingEvents()
+      // because we only need to flush warning and error counts.
+      // Only a few pieces of fixed information are required up front.
+      const operations: OperationsArray = new Array(
+        3 + pendingOperations.length,
+      );
+      operations[0] = rendererID;
+      operations[1] = currentRootID;
+      operations[2] = 0; // String table size
+      for (let j = 0; j < pendingOperations.length; j++) {
+        operations[3 + j] = pendingOperations[j];
+      }
+
+      flushOrQueueOperations(operations);
+
+      pendingOperations.length = 0;
+    }, 1000);
+  }
+
   function reevaluateErrorsAndWarnings() {
     fibersWithChangedErrorOrWarningCounts.clear();
     fiberToErrorsMap.forEach((countMap, fiberID) => {
@@ -1230,6 +1295,8 @@ export function attach(
   }
 
   function recordPendingErrorsAndWarnings() {
+    clearPendingErrorsAndWarningsAfterDelay();
+
     fibersWithChangedErrorOrWarningCounts.forEach(fiberID => {
       const fiber = idToFiberMap.get(fiberID);
       if (fiber != null) {
@@ -1319,7 +1386,7 @@ export function attach(
     // Which in turn enables fiber props, states, and hooks to be inspected.
     let i = 0;
     operations[i++] = rendererID;
-    operations[i++] = currentRootID; // Use this ID in case the root was unmounted!
+    operations[i++] = currentRootID;
 
     // Now fill in the string table.
     // [stringTableLength, str1Length, ...str1, str2Length, ...str2, ...]
@@ -1366,18 +1433,9 @@ export function attach(
     i += pendingOperations.length;
 
     // Let the frontend know about tree operations.
-    // The first value in this array will identify which root it corresponds to,
-    // so we do no longer need to dispatch a separate root-committed event.
-    if (pendingOperationsQueue !== null) {
-      // Until the frontend has been connected, store the tree operations.
-      // This will let us avoid walking the tree later when the frontend connects,
-      // and it enables the Profiler's reload-and-profile functionality to work as well.
-      pendingOperationsQueue.push(operations);
-    } else {
-      // If we've already connected to the frontend, just pass the operations through.
-      hook.emit('operations', operations);
-    }
+    flushOrQueueOperations(operations);
 
+    // Reset all of the pending state now that we've told the frontend about it.
     pendingOperations.length = 0;
     pendingRealUnmountedIDs.length = 0;
     pendingSimulatedUnmountedIDs.length = 0;