Introducting `UIManager.setLocalData()`, the way to provide environmental data to ShadowNode

Summary:
In some cases we need a way to provide some peice of data to shadow node
to improve layout (or do something similar), `setLocalData` allows to do this.

Reviewed By: AaaChiuuu

Differential Revision: D5828368

fbshipit-source-id: bf6a04f460dc7695a16269426d365b78909bc8eb

ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactShadowNode.java

@@ -181,6 +181,18 @@ public interface ReactShadowNode<T extends ReactShadowNode> {
 
   boolean isDescendantOf(T ancestorNode);
 
+  /*
+   * In some cases we need a way to specify some environmental data to shadow node
+   * to improve layout (or do something similar), so {@code localData} serves these needs.
+   * For example, any stateful embedded native views may benefit from this.
+   * Have in mind that this data is not supposed to interfere with the state of
+   * the shadow node.
+   * Please respect one-directional data flow of React.
+   * Use  {@link UIManagerModule#setViewLocalData} to set this property
+   * (to provide local/environmental data for a shadow node) from the main thread.
+   */
+  public void setLocalData(Object data);
+
   /**
    * Returns the offset within the native children owned by all layout-only nodes in the subtree
    * rooted at this node for the given child. Put another way, this returns the number of native

ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactShadowNodeImpl.java

@@ -518,6 +518,18 @@ public class ReactShadowNodeImpl implements ReactShadowNode<ReactShadowNodeImpl>
     return isDescendant;
   }
 
+  /*
+   * In some cases we need a way to specify some environmental data to shadow node
+   * to improve layout (or do something similar), so {@code localData} serves these needs.
+   * For example, any stateful embedded native views may benefit from this.
+   * Have in mind that this data is not supposed to interfere with the state of
+   * the shadow node.
+   * Please respect one-directional data flow of React.
+   * Use  {@link ReactUIManagerModule#setViewLocalData} to set this property
+   * (to provide local/environmental data for a shadow node) from the main thread.
+   */
+  public void setLocalData(Object data) {}
+
   /**
    * Returns the offset within the native children owned by all layout-only nodes in the subtree
    * rooted at this node for the given child. Put another way, this returns the number of native

ReactAndroid/src/main/java/com/facebook/react/uimanager/UIImplementation.java

@@ -236,12 +236,20 @@ public class UIImplementation {
     cssNode.setStyleWidth(newWidth);
     cssNode.setStyleHeight(newHeight);
 
-    // If we're in the middle of a batch, the change will automatically be dispatched at the end of
-    // the batch. As all batches are executed as a single runnable on the event queue this should
-    // always be empty, but that calling architecture is an implementation detail.
-    if (mOperationsQueue.isEmpty()) {
-      dispatchViewUpdates(-1); // -1 = no associated batch id
+    dispatchViewUpdatesIfNeeded();
+  }
+
+  public void setViewLocalData(int tag, Object data) {
+    ReactShadowNode shadowNode = mShadowNodeRegistry.getNode(tag);
+
+    if (shadowNode == null) {
+      throw new IllegalViewOperationException(
+          "Trying to set local data for view with unknown tag: " + tag);
     }
+
+    shadowNode.setLocalData(data);
+
+    dispatchViewUpdatesIfNeeded();
   }
 
   public void profileNextBatch() {
@@ -641,6 +649,17 @@ public class UIImplementation {
     }
   }
 
+  private void dispatchViewUpdatesIfNeeded() {
+    // If we are in the middle of a batch update, any additional changes
+    // will automatically be dispatched at the end of the batch.
+    // If we are not, we have to initiate new batch update.
+    // As all batches are executed as a single runnable on the event queue
+    // this should always be empty, but that calling architecture is an implementation detail.
+    if (mOperationsQueue.isEmpty()) {
+      dispatchViewUpdates(-1); // "-1" means "no associated batch id"
+    }
+  }
+
   protected void updateViewHierarchy() {
     Systrace.beginSection(
       Systrace.TRACE_TAG_REACT_JAVA_BRIDGE,

ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerModule.java

@@ -324,6 +324,29 @@ public class UIManagerModule extends ReactContextBaseJavaModule implements
     mUIImplementation.updateNodeSize(nodeViewTag, newWidth, newHeight);
   }
 
+  /**
+   * Sets local data for a shadow node corresponded with given tag.
+   * In some cases we need a way to specify some environmental data to shadow node
+   * to improve layout (or do something similar), so {@code localData} serves these needs.
+   * For example, any stateful embedded native views may benefit from this.
+   * Have in mind that this data is not supposed to interfere with the state of
+   * the shadow view.
+   * Please respect one-directional data flow of React.
+   */
+  public void setViewLocalData(final int tag, final Object data) {
+    final ReactApplicationContext reactApplicationContext = getReactApplicationContext();
+
+    reactApplicationContext.assertOnUiQueueThread();
+
+    reactApplicationContext.runUIBackgroundRunnable(
+        new GuardedRunnable(reactApplicationContext) {
+          @Override
+          public void runGuarded() {
+            mUIImplementation.setViewLocalData(tag, data);
+          }
+        });
+  }
+
   @ReactMethod
   public void createView(int tag, String className, int rootViewTag, ReadableMap props) {
     if (DEBUG) {