Implement event-specific pooling for SyntheticEvent (#10237)

* Remove PooledClass from FallbackCompositionState

The only module that uses FallbackCompositonState is BeforeInputEventPlugin. The way its structured means there can only be a single instance of FallbackCompositionState at any given time (stored in a local variable at the top-level) so we don't really need pooling here at all. Instead, a single object is now stored in FallbackCompositionState, and access (initializing, reseting, getting data) is gaurded by the exported helper object.

* Use new FallbackCompositionState API in BeforeInputEventPlugin

* Implement event-specific pooling in SyntheticEvent

* Remove PooledClass from TopLevelCallbackBookKeeping

* Update results.json

* Add pooled event test fixtures (#1)

* Fix fixture lint

fixtures/dom/src/components/Header.js

@@ -61,6 +61,7 @@ class Header extends React.Component {
                 <option value="/buttons">Buttons</option>
                 <option value="/date-inputs">Date Inputs</option>
                 <option value="/error-handling">Error Handling</option>
+                <option value="/event-pooling">Event Pooling</option>
               </select>
             </label>
             <label htmlFor="react_version">

fixtures/dom/src/components/fixtures/event-pooling/hit-box.js

@@ -0,0 +1,38 @@
+const React = window.React;
+
+class HitBox extends React.Component {
+  state = {
+    x: 0,
+    y: 0,
+  };
+
+  static defaultProps = {
+    onMouseMove: n => n,
+  };
+
+  onMove = event => {
+    this.setState({x: event.clientX, y: event.clientY});
+    this.props.onMouseMove(event);
+  };
+
+  render() {
+    const {x, y} = this.state;
+
+    const boxStyle = {
+      padding: '10px 20px',
+      border: '1px solid #d9d9d9',
+      margin: '10px 0 20px',
+    };
+
+    return (
+      <div onMouseMove={this.onMove} style={boxStyle}>
+        <p>Trace your mouse over this box.</p>
+        <p>
+          Last movement: {x},{y}
+        </p>
+      </div>
+    );
+  }
+}
+
+export default HitBox;

fixtures/dom/src/components/fixtures/event-pooling/index.js

@@ -0,0 +1,18 @@
+import FixtureSet from '../../FixtureSet';
+import MouseMove from './mouse-move';
+import Persistence from './persistence';
+
+const React = window.React;
+
+class EventPooling extends React.Component {
+  render() {
+    return (
+      <FixtureSet title="Event Pooling" description="">
+        <MouseMove />
+        <Persistence />
+      </FixtureSet>
+    );
+  }
+}
+
+export default EventPooling;

fixtures/dom/src/components/fixtures/event-pooling/mouse-move.js

@@ -0,0 +1,51 @@
+import TestCase from '../../TestCase';
+import HitBox from './hit-box';
+
+const React = window.React;
+
+class MouseMove extends React.Component {
+  state = {
+    events: [],
+  };
+
+  checkEvent = event => {
+    let {events} = this.state;
+
+    if (event.type === 'mousemove' && events.indexOf(event) === -1) {
+      this.setState({events: events.concat(event)});
+    }
+  };
+
+  render() {
+    const {events} = this.state;
+
+    return (
+      <TestCase title="Mouse Move" description="">
+        <TestCase.Steps>
+          <li>Mouse over the box below</li>
+        </TestCase.Steps>
+
+        <TestCase.ExpectedResult>
+          Mousemove should share the same instance of the event between
+          dispatches.
+        </TestCase.ExpectedResult>
+
+        <HitBox onMouseMove={this.checkEvent} />
+
+        <p>
+          Was the event pooled?{' '}
+          <b>
+            {events.length ? events.length <= 1 ? 'Yes' : 'No' : 'Unsure'}
+            {' '}
+            (
+            {events.length}
+            {' '}
+            events)
+          </b>
+        </p>
+      </TestCase>
+    );
+  }
+}
+
+export default MouseMove;

fixtures/dom/src/components/fixtures/event-pooling/persistence.js

@@ -0,0 +1,65 @@
+import TestCase from '../../TestCase';
+import HitBox from './hit-box';
+
+const React = window.React;
+
+class Persistence extends React.Component {
+  state = {
+    persisted: 0,
+    pooled: [],
+  };
+
+  addPersisted = event => {
+    let {persisted, pooled} = this.state;
+
+    event.persist();
+
+    if (event.type === 'mousemove') {
+      this.setState({
+        persisted: persisted + 1,
+        pooled: pooled.filter(e => e !== event),
+      });
+    }
+  };
+
+  addPooled = event => {
+    let {pooled} = this.state;
+
+    if (event.type === 'mousemove' && pooled.indexOf(event) === -1) {
+      this.setState({pooled: pooled.concat(event)});
+    }
+  };
+
+  render() {
+    const {pooled, persisted} = this.state;
+
+    return (
+      <TestCase title="Persistence" description="">
+        <TestCase.Steps>
+          <li>Mouse over the pooled event box</li>
+          <li>Mouse over the persisted event box</li>
+        </TestCase.Steps>
+
+        <TestCase.ExpectedResult>
+          The pool size should not increase above 1, but reduce to 0 when hovering over the persisted region.
+        </TestCase.ExpectedResult>
+
+        <h2>Add Pooled Event:</h2>
+        <HitBox onMouseMove={this.addPooled} />
+
+        <h2>Add Persisted Event:</h2>
+        <HitBox onMouseMove={this.addPersisted} />
+
+        <p>
+          Pool size: {pooled.length}
+        </p>
+
+        <p>
+          Persisted size: {persisted}
+        </p>
+      </TestCase>
+    );
+  }
+}
+
+export default Persistence;

fixtures/dom/src/components/fixtures/index.js

@@ -8,6 +8,7 @@ import PasswordInputFixtures from './password-inputs';
 import ButtonFixtures from './buttons';
 import DateInputFixtures from './date-inputs';
 import ErrorHandling from './error-handling';
+import EventPooling from './event-pooling';
 
 const React = window.React;
 
@@ -37,6 +38,8 @@ function FixturesPage() {
       return <DateInputFixtures />;
     case '/error-handling':
       return <ErrorHandling />;
+    case '/event-pooling':
+      return <EventPooling />;
     default:
       return <p>Please select a test fixture.</p>;
   }