Defer HostTarget destruction until after the instance has been unregistered

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/ReactInstanceManager.java

@@ -701,7 +701,6 @@ public void onViewDetachedFromWindow(View v) {
   @Deprecated
   public void onHostDestroy() {
     UiThreadUtil.assertOnUiThread();
-    destroyInspectorTarget();
 
     if (mUseDeveloperSupport) {
       mDevSupportManager.setDevSupportEnabled(false);
@@ -752,7 +751,6 @@ public void destroy() {
     }
 
     mHasStartedDestroying = true;
-    destroyInspectorTarget();
 
     if (mUseDeveloperSupport) {
       mDevSupportManager.setDevSupportEnabled(false);
@@ -782,6 +780,12 @@ public void destroy() {
       }
     }
 
+    // If the host is being destroyed, now that the current context/instance
+    // has been destroyed, we can safely destroy the host's inspector target.
+    if (mLifecycleState == LifecycleState.BEFORE_CREATE) {
+      destroyInspectorHostTarget();
+    }
+
     mHasStartedCreatingInitialContext = false;
     if (!mKeepActivity) {
       mCurrentActivity = null;
@@ -835,6 +839,10 @@ private synchronized void moveToBeforeCreateLifecycleState() {
       if (mLifecycleState == LifecycleState.BEFORE_RESUME) {
         currentContext.onHostDestroy(mKeepActivity);
       }
+    } else {
+      // There's no current context that requires the host inspector target to
+      // be kept alive, so we can destroy it immediately.
+      destroyInspectorHostTarget();
     }
     mLifecycleState = LifecycleState.BEFORE_CREATE;
   }
@@ -1542,7 +1550,8 @@ public void onResume() {
     return mInspectorTarget;
   }
 
-  private void destroyInspectorTarget() {
+  @ThreadConfined(UI)
+  private void destroyInspectorHostTarget() {
     if (mInspectorTarget != null) {
       mInspectorTarget.close();
       mInspectorTarget = null;

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridge/CatalystInstanceImpl.java

@@ -7,6 +7,7 @@
 
 package com.facebook.react.bridge;
 
+import static com.facebook.infer.annotation.Assertions.assertCondition;
 import static com.facebook.infer.annotation.ThreadConfined.UI;
 import static com.facebook.systrace.Systrace.TRACE_TAG_REACT_JAVA_BRIDGE;
 
@@ -112,6 +113,8 @@ public String toString() {
 
   public native NativeMethodCallInvokerHolderImpl getNativeMethodCallInvokerHolder();
 
+  private @Nullable ReactInstanceManagerInspectorTarget mInspectorTarget;
+
   private CatalystInstanceImpl(
       final ReactQueueConfigurationSpec reactQueueConfigurationSpec,
       final JavaScriptExecutor jsExecutor,
@@ -134,6 +137,7 @@ private CatalystInstanceImpl(
     mJSExceptionHandler = jSExceptionHandler;
     mNativeModulesQueueThread = mReactQueueConfiguration.getNativeModulesQueueThread();
     mTraceListener = new JSProfilerTraceListener(this);
+    mInspectorTarget = inspectorTarget;
     Systrace.endSection(TRACE_TAG_REACT_JAVA_BRIDGE);
 
     FLog.d(ReactConstants.TAG, "Initializing React Xplat Bridge before initializeBridge");
@@ -146,7 +150,7 @@ private CatalystInstanceImpl(
         mNativeModulesQueueThread,
         mNativeModuleRegistry.getJavaModules(this),
         mNativeModuleRegistry.getCxxModules(),
-        inspectorTarget);
+        mInspectorTarget);
     FLog.d(ReactConstants.TAG, "Initializing React Xplat Bridge after initializeBridge");
     Systrace.endSection(TRACE_TAG_REACT_JAVA_BRIDGE);
 
@@ -346,6 +350,11 @@ public void destroy() {
       return;
     }
 
+    if (mInspectorTarget != null) {
+      assertCondition(
+          mInspectorTarget.isValid(),
+          "ReactInstanceManager inspector target destroyed before instance was unregistered");
+    }
     unregisterFromInspector();
 
     // TODO: tell all APIs to shut down

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridge/ReactInstanceManagerInspectorTarget.java

@@ -7,12 +7,14 @@
 
 package com.facebook.react.bridge;
 
+import com.facebook.infer.annotation.Nullsafe;
 import com.facebook.jni.HybridData;
 import com.facebook.proguard.annotations.DoNotStripAny;
 import java.util.concurrent.Executor;
 import javax.annotation.Nullable;
 
 @DoNotStripAny
+@Nullsafe(Nullsafe.Mode.LOCAL)
 public class ReactInstanceManagerInspectorTarget implements AutoCloseable {
   public interface TargetDelegate {
     public void onReload();
@@ -46,6 +48,10 @@ public void close() {
     mHybridData.resetNative();
   }
 
+  /*internal*/ boolean isValid() {
+    return mHybridData.isValid();
+  }
+
   static {
     ReactBridge.staticInit();
   }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/ReactHostImpl.java

@@ -892,7 +892,11 @@ private Task<Void> getOrCreateStartTask() {
   @ThreadConfined(UI)
   private void moveToHostDestroy(@Nullable ReactContext currentContext) {
     mReactLifecycleStateManager.moveToOnHostDestroy(currentContext);
-    destroyReactHostInspectorTarget();
+    if (currentContext == null) {
+      // There's no current context/instance that requires the host inspector
+      // target to be kept alive, so we can destroy it immediately.
+      destroyInspectorHostTarget();
+    }
     setCurrentActivity(null);
   }
 
@@ -1333,9 +1337,7 @@ private Task<ReactInstance> getOrCreateReloadTask(String reason) {
                     final ReactInstance reactInstance =
                         reactInstanceTaskUnwrapper.unwrap(task, "1: Starting reload");
 
-                    if (reactInstance != null) {
-                      reactInstance.unregisterFromInspector();
-                    }
+                    unregisterInstanceFromInspector(reactInstance);
 
                     final ReactContext reactContext = mBridgelessReactContextRef.getNullable();
                     if (reactContext == null) {
@@ -1512,9 +1514,7 @@ private Task<Void> getOrCreateDestroyTask(final String reason, @Nullable Excepti
                     final ReactInstance reactInstance =
                         reactInstanceTaskUnwrapper.unwrap(task, "1: Starting destroy");
 
-                    if (reactInstance != null) {
-                      reactInstance.unregisterFromInspector();
-                    }
+                    unregisterInstanceFromInspector(reactInstance);
 
                     // Step 1: Destroy DevSupportManager
                     if (mUseDevSupport) {
@@ -1672,10 +1672,29 @@ public void setJsEngineResolutionAlgorithm(
     return mReactHostInspectorTarget;
   }
 
-  private void destroyReactHostInspectorTarget() {
+  @ThreadConfined(UI)
+  private void destroyInspectorHostTarget() {
     if (mReactHostInspectorTarget != null) {
       mReactHostInspectorTarget.close();
       mReactHostInspectorTarget = null;
     }
   }
+
+  @ThreadConfined(UI)
+  private void unregisterInstanceFromInspector(final @Nullable ReactInstance reactInstance) {
+    if (reactInstance != null) {
+      if (InspectorFlags.getFuseboxEnabled()) {
+        Assertions.assertCondition(
+            mReactHostInspectorTarget != null && mReactHostInspectorTarget.isValid(),
+            "Host inspector target destroyed before instance was unregistered");
+      }
+      reactInstance.unregisterFromInspector();
+    }
+    if (mReactLifecycleStateManager.getLifecycleState() == LifecycleState.BEFORE_CREATE) {
+      // If the host is being destroyed, now that the current context/instance
+      // has been unregistered, we can safely destroy the host's inspector
+      // target.
+      destroyInspectorHostTarget();
+    }
+  }
 }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/ReactHostInspectorTarget.kt

@@ -30,6 +30,10 @@ internal class ReactHostInspectorTarget(private val reactHostImpl: ReactHostImpl
     mHybridData.resetNative()
   }
 
+  fun isValid(): Boolean {
+    return mHybridData.isValid()
+  }
+
   private companion object {
     init {
       SoLoader.loadLibrary("rninstance")