InteractionManager: DEV warning for possibly unclosed handles

Libraries/Interaction/InteractionManager.js

@@ -19,6 +19,13 @@ var invariant = require('invariant');
 var keyMirror = require('keyMirror');
 var setImmediate = require('setImmediate');
 
+type Handle = number;
+
+/**
+ * Maximum time a handle can be open before warning in DEV.
+ */
+var DEV_TIMEOUT = 2000;
+
 var _emitter = new EventEmitter();
 var _interactionSet = new Set();
 var _addInteractionSet = new Set();
@@ -83,17 +90,25 @@ var InteractionManager = {
   /**
    * Notify manager that an interaction has started.
    */
-  createInteractionHandle(): number {
+  createInteractionHandle(): Handle {
     scheduleUpdate();
     var handle = ++_inc;
     _addInteractionSet.add(handle);
+    if (__DEV__) {
+      // Capture the stack trace of what created the handle.
+      var error = new Error(
+        'InteractionManager: interaction handle not cleared within ' +
+        DEV_TIMEOUT + ' ms.'
+      );
+      setDevTimeoutHandle(handle, error, DEV_TIMEOUT);
+    }
     return handle;
   },
 
   /**
    * Notify manager that an interaction has completed.
    */
-  clearInteractionHandle(handle: number) {
+  clearInteractionHandle(handle: Handle) {
     invariant(
       !!handle,
       'Must provide a handle to clear.'
@@ -151,4 +166,19 @@ function processUpdate() {
   _deleteInteractionSet.clear();
 }
 
+/**
+ * Wait until `timeout` has passed and warn if the handle has not been cleared.
+ */
+function setDevTimeoutHandle(
+  handle: Handle,
+  error: Error,
+  timeout: number
+): void {
+  setTimeout(() => {
+    if (_interactionSet.has(handle)) {
+      console.warn(error.message + '\n' + error.stack);
+    }
+  }, timeout);
+}
+
 module.exports = InteractionManager;