fix(android): fix deadlock in component registry

Adds to:
33cd751

Author: hannojg

packages/react-native/ReactCommon/react/renderer/componentregistry/ComponentDescriptorRegistry.cpp

@@ -48,8 +48,6 @@ void ComponentDescriptorRegistry::addMultipleAsync(
       facebook::jni::Environment::ensureCurrentThreadIsAttached();
     #endif
 
-    std::unique_lock lock(self->mutex_);
-
     for (const auto& provider : providers) {
       auto componentDescriptor = provider.constructor(
           {parametersCopy.eventDispatcher,
@@ -62,6 +60,9 @@ void ComponentDescriptorRegistry::addMultipleAsync(
       auto sharedComponentDescriptor =
           std::shared_ptr<const ComponentDescriptor>(std::move(componentDescriptor));
 
+      // Only lock when inserting into the maps
+      // The componentDescriptor constructor might calls into this ComponentDescriptorRegistry::at(), so we want to avoid deadlocks
+      std::unique_lock lock(self->mutex_);
       self->_registryByHandle[provider.handle] = sharedComponentDescriptor;
       self->_registryByName[provider.name] = sharedComponentDescriptor;
     }
@@ -92,8 +93,6 @@ void ComponentDescriptorRegistry::add(
 
 void ComponentDescriptorRegistry::registerComponentDescriptor(
     const SharedComponentDescriptor& componentDescriptor) const {
-  std::unique_lock lock(mutex_);
-
   ComponentHandle componentHandle = componentDescriptor->getComponentHandle();
   _registryByHandle[componentHandle] = componentDescriptor;
 
@@ -126,9 +125,12 @@ const ComponentDescriptor& ComponentDescriptorRegistry::at(
   }
 
   if (it == _registryByName.end()) {
+    lock.unlock();
     auto componentDescriptor = std::make_shared<
         const UnstableLegacyViewManagerAutomaticComponentDescriptor>(
         parameters_, unifiedComponentName);
+
+    std::unique_lock writeLock(mutex_);
     registerComponentDescriptor(componentDescriptor);
     return *_registryByName.find(unifiedComponentName)->second;
   }
@@ -166,6 +168,7 @@ bool ComponentDescriptorRegistry::hasComponentDescriptorAt(
 
 void ComponentDescriptorRegistry::setFallbackComponentDescriptor(
     const SharedComponentDescriptor& descriptor) {
+  std::unique_lock lock(mutex_);
   _fallbackComponentDescriptor = descriptor;
   registerComponentDescriptor(descriptor);
 }