[Scheduler] Profiling features (#16145)

* [Scheduler] Mark user-timing events

Marks when Scheduler starts and stops running a task. Also marks when
a task is initially scheduled, and when Scheduler is waiting for a
callback, which can't be inferred from a sample-based JavaScript CPU
profile alone.

The plan is to use the user-timing events to build a Scheduler profiler
that shows how the lifetime of tasks interact with each other and
with unscheduled main thread work.

The test suite works by printing an text representation of a
Scheduler flamegraph.

* Expose shared array buffer with profiling info

Array contains

- the priority Scheduler is currently running
- the size of the queue
- the id of the currently running task

* Replace user-timing calls with event log

Events are written to an array buffer using a custom instruction format.
For now, this is only meant to be used during page start up, before the
profiler worker has a chance to start up. Once the worker is ready, call
`stopLoggingProfilerEvents` to return the log up to that point, then
send the array buffer to the worker.

Then switch to the sampling based approach.

* Record the current run ID

Each synchronous block of Scheduler work is given a unique run ID. This
is different than a task ID because a single task will have more than
one run if it yields with a continuation.

scripts/rollup/bundles.js

@@ -411,7 +411,13 @@ const bundles = [
 
   /******* React Scheduler (experimental) *******/
   {
-    bundleTypes: [NODE_DEV, NODE_PROD, FB_WWW_DEV, FB_WWW_PROD],
+    bundleTypes: [
+      NODE_DEV,
+      NODE_PROD,
+      FB_WWW_DEV,
+      FB_WWW_PROD,
+      FB_WWW_PROFILING,
+    ],
     moduleType: ISOMORPHIC,
     entry: 'scheduler',
     global: 'Scheduler',

scripts/rollup/validate/eslintrc.cjs.js

@@ -21,6 +21,11 @@ module.exports = {
     process: true,
     setImmediate: true,
     Buffer: true,
+
+    // Scheduler profiling
+    SharedArrayBuffer: true,
+    Int32Array: true,
+    ArrayBuffer: true,
   },
   parserOptions: {
     ecmaVersion: 5,

scripts/rollup/validate/eslintrc.fb.js

@@ -22,6 +22,11 @@ module.exports = {
     // Node.js Server Rendering
     setImmediate: true,
     Buffer: true,
+
+    // Scheduler profiling
+    SharedArrayBuffer: true,
+    Int32Array: true,
+    ArrayBuffer: true,
   },
   parserOptions: {
     ecmaVersion: 5,

scripts/rollup/validate/eslintrc.rn.js

@@ -21,6 +21,11 @@ module.exports = {
     // Fabric. See https://github.com/facebook/react/pull/15490
     // for more information
     nativeFabricUIManager: true,
+
+    // Scheduler profiling
+    SharedArrayBuffer: true,
+    Int32Array: true,
+    ArrayBuffer: true,
   },
   parserOptions: {
     ecmaVersion: 5,

scripts/rollup/validate/eslintrc.umd.js

@@ -24,6 +24,11 @@ module.exports = {
     define: true,
     require: true,
     global: true,
+
+    // Scheduler profiling
+    SharedArrayBuffer: true,
+    Int32Array: true,
+    ArrayBuffer: true,
   },
   parserOptions: {
     ecmaVersion: 5,