I recently added UI for the Profiler's commit and post-commit durations to the DevTools, but I made two pretty silly oversights:
1. I used the commit hook (called after mutation+layout effects) to read both the layout and passive effect durations. This is silly because passive effects may not have flushed yet git at this point.
2. I didn't reset the values on the HostRoot node, so they accumulated with each commit.
This commitR addresses both issues:
1. First it adds a new DevTools hook, onPostCommitRoot*, to be called after passive effects get flushed. This gives DevTools the opportunity to read passive effect durations (if the build of React being profiled supports it).
2. Second the work loop resets these durations (on the HostRoot) after calling the post-commit hook so address the accumulation problem.
I've also added a unit test to guard against this regressing in the future.
* Doing this in flushPassiveEffectsImpl seemed simplest, since there are so many places we flush passive effects. Is there any potential problem with this though?
* import * as React from "react";
This is the correct way to import React from an ES module since the ES
module will not have a default export. Only named exports.
* import * as ReactDOM from "react-dom"
Brian Vaughn
Sebastian Markbåge
Dan Abramov