[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.

.eslintrc.js

@@ -140,6 +140,8 @@ module.exports = {
   ],
 
   globals: {
+    SharedArrayBuffer: true,
+
     spyOnDev: true,
     spyOnDevAndProd: true,
     spyOnProd: true,

packages/react-reconciler/src/__tests__/ReactIncrementalPerf-test.internal.js

@@ -136,6 +136,7 @@ describe('ReactDebugFiberPerf', () => {
     require('shared/ReactFeatureFlags').enableProfilerTimer = false;
     require('shared/ReactFeatureFlags').replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
     require('shared/ReactFeatureFlags').debugRenderPhaseSideEffectsForStrictMode = false;
+    require('scheduler/src/SchedulerFeatureFlags').enableProfiling = false;
 
     // Import after the polyfill is set up:
     React = require('react');

packages/scheduler/npm/umd/scheduler.development.js

@@ -110,6 +110,20 @@
     );
   }
 
+  function unstable_startLoggingProfilingEvents() {
+    return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.Scheduler.unstable_startLoggingProfilingEvents.apply(
+      this,
+      arguments
+    );
+  }
+
+  function unstable_stopLoggingProfilingEvents() {
+    return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.Scheduler.unstable_stopLoggingProfilingEvents.apply(
+      this,
+      arguments
+    );
+  }
+
   return Object.freeze({
     unstable_now: unstable_now,
     unstable_scheduleCallback: unstable_scheduleCallback,
@@ -124,6 +138,8 @@
     unstable_pauseExecution: unstable_pauseExecution,
     unstable_getFirstCallbackNode: unstable_getFirstCallbackNode,
     unstable_forceFrameRate: unstable_forceFrameRate,
+    unstable_startLoggingProfilingEvents: unstable_startLoggingProfilingEvents,
+    unstable_stopLoggingProfilingEvents: unstable_stopLoggingProfilingEvents,
     get unstable_IdlePriority() {
       return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED
         .Scheduler.unstable_IdlePriority;
@@ -144,5 +160,9 @@
       return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED
         .Scheduler.unstable_UserBlockingPriority;
     },
+    get unstable_sharedProfilingBuffer() {
+      return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED
+        .Scheduler.unstable_getFirstCallbackNode;
+    },
   });
 });

packages/scheduler/npm/umd/scheduler.production.min.js

@@ -104,6 +104,20 @@
     );
   }
 
+  function unstable_startLoggingProfilingEvents() {
+    return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.Scheduler.unstable_startLoggingProfilingEvents.apply(
+      this,
+      arguments
+    );
+  }
+
+  function unstable_stopLoggingProfilingEvents() {
+    return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.Scheduler.unstable_stopLoggingProfilingEvents.apply(
+      this,
+      arguments
+    );
+  }
+
   return Object.freeze({
     unstable_now: unstable_now,
     unstable_scheduleCallback: unstable_scheduleCallback,
@@ -118,6 +132,8 @@
     unstable_pauseExecution: unstable_pauseExecution,
     unstable_getFirstCallbackNode: unstable_getFirstCallbackNode,
     unstable_forceFrameRate: unstable_forceFrameRate,
+    unstable_startLoggingProfilingEvents: unstable_startLoggingProfilingEvents,
+    unstable_stopLoggingProfilingEvents: unstable_stopLoggingProfilingEvents,
     get unstable_IdlePriority() {
       return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED
         .Scheduler.unstable_IdlePriority;
@@ -138,5 +154,9 @@
       return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED
         .Scheduler.unstable_UserBlockingPriority;
     },
+    get unstable_sharedProfilingBuffer() {
+      return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED
+        .Scheduler.unstable_getFirstCallbackNode;
+    },
   });
 });

packages/scheduler/npm/umd/scheduler.profiling.min.js

@@ -104,6 +104,20 @@
     );
   }
 
+  function unstable_startLoggingProfilingEvents() {
+    return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.Scheduler.unstable_startLoggingProfilingEvents.apply(
+      this,
+      arguments
+    );
+  }
+
+  function unstable_stopLoggingProfilingEvents() {
+    return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.Scheduler.unstable_stopLoggingProfilingEvents.apply(
+      this,
+      arguments
+    );
+  }
+
   return Object.freeze({
     unstable_now: unstable_now,
     unstable_scheduleCallback: unstable_scheduleCallback,
@@ -118,6 +132,8 @@
     unstable_pauseExecution: unstable_pauseExecution,
     unstable_getFirstCallbackNode: unstable_getFirstCallbackNode,
     unstable_forceFrameRate: unstable_forceFrameRate,
+    unstable_startLoggingProfilingEvents: unstable_startLoggingProfilingEvents,
+    unstable_stopLoggingProfilingEvents: unstable_stopLoggingProfilingEvents,
     get unstable_IdlePriority() {
       return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED
         .Scheduler.unstable_IdlePriority;
@@ -138,5 +154,9 @@
       return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED
         .Scheduler.unstable_UserBlockingPriority;
     },
+    get unstable_sharedProfilingBuffer() {
+      return global.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED
+        .Scheduler.unstable_getFirstCallbackNode;
+    },
   });
 });