JavaGlobalObj::dtor: Hold JNIGlobalRef lock while fetching jobject and call into java mNotifyDeleted

2 files changed, 9 insertions, 5 deletions

diff --git a/include/jau/jni/jni_mem.hpp b/include/jau/jni/jni_mem.hpp
index ba5a282..b99f68a 100644
--- a/include/jau/jni/jni_mem.hpp
+++ b/include/jau/jni/jni_mem.hpp
@@ -80,6 +80,7 @@ extern thread_local JNIEnvContainer jni_env;
  */
 class JNIGlobalRef {
 private:
+    friend class JavaGlobalObj;
     mutable std::mutex mtx;
     jobject object;
 
diff --git a/java_jni/jni/helper_jni.cxx b/java_jni/jni/helper_jni.cxx
index 51f84cc..bd8a91b 100644
--- a/java_jni/jni/helper_jni.cxx
+++ b/java_jni/jni/helper_jni.cxx
@@ -341,12 +341,15 @@ jobject jau::get_new_arraylist(JNIEnv *env, jsize size, jmethodID *add)
 //
 
 JavaGlobalObj::~JavaGlobalObj() noexcept {
-    jobject obj = javaObjectRef.getObject();
-    if( nullptr == obj || nullptr == mNotifyDeleted ) {
-        return;
-    }
     JNIEnv *env = *jni_env;
-    env->CallVoidMethod(obj, mNotifyDeleted);
+    {
+        std::unique_lock<std::mutex> lock(javaObjectRef.mtx);
+        jobject obj = javaObjectRef.object;
+        if( nullptr == obj || nullptr == mNotifyDeleted ) {
+            return;
+        }
+        env->CallVoidMethod(obj, mNotifyDeleted);
+    }
     java_exception_check_and_throw(env, E_FILE_LINE); // would abort() if thrown
 }