Implement basic automatic attachment/detachment of c++ threads to JVM. (

#405) * Implement basic automatic attachment/detachment of c++ threads to JVM. No side effects if not enabled Compile with -DEXPERIMENTAL_AUTO_CPP_THREAD_ATTACH to enable Requires a compiler with C++11 support Borrows code/idea from #372 (comment) * Place assignment outside of define.
dropbox · Dec 30, 2018 · 51bf14f · 51bf14f
1 parent 625c78d
commit 51bf14f
Showing 1 changed file with 11 additions and 1 deletion.
diff --git a/support-lib/jni/djinni_support.cpp b/support-lib/jni/djinni_support.cpp
@@ -72,7 +72,17 @@ void jniShutdown() {
 JNIEnv * jniGetThreadEnv() {
     assert(g_cachedJVM);
     JNIEnv * env = nullptr;
-    const jint get_res = g_cachedJVM->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6);
+    jint get_res = g_cachedJVM->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6);
+    #ifdef EXPERIMENTAL_AUTO_CPP_THREAD_ATTACH
+    if (get_res == JNI_EDETACHED) {
+        get_res = g_cachedJVM->AttachCurrentThread(&env, nullptr);
+        thread_local struct DetachOnExit {
+            ~DetachOnExit() {
+                g_cachedJVM->DetachCurrentThread();
+            }
+        } detachOnExit;
+    }
+    #endif
     if (get_res != 0 || !env) {
         // :(
         std::abort();