feat(java): SCAPIX_JAVA_AUTO_ATTACH_THREAD option

With SCAPIX_JAVA_AUTO_ATTACH_THREAD option, Scapix automatically calls AttachCurrentThread() if current thread is not attached to JNI Env.
scapix-com · May 15, 2022 · 0256e3f · 0256e3f
1 parent 0120e5a
commit 0256e3f
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Showing 8 changed files with 90 additions and 170 deletions.
diff --git a/source/scapix/link/java/detail/api/ref.h b/source/scapix/link/java/detail/api/ref.h
@@ -7,7 +7,7 @@
 #ifndef SCAPIX_LINK_JAVA_DETAIL_API_REF_H
 #define SCAPIX_LINK_JAVA_DETAIL_API_REF_H
 
-#include <scapix/link/java/detail/config.h>
+#include <scapix/link/java/env.h>
 
 namespace scapix::link::java::detail::api {
 

diff --git a/source/scapix/link/java/detail/config.h b/source/scapix/link/java/detail/config.h
diff --git a/source/scapix/link/java/env.h b/source/scapix/link/java/env.h
@@ -7,15 +7,92 @@
 #ifndef SCAPIX_LINK_JAVA_ENV_H
 #define SCAPIX_LINK_JAVA_ENV_H
 
-#include <scapix/link/java/detail/config.h>
+#include <jni.h>
+#include <boost/config.hpp>
+#include <scapix/core/function_traits.h>
 
 namespace scapix::link::java {
+namespace detail {
+
+/*
+
+jni.h (JDK) uses void** type:
+
+	jint JNI_CreateJavaVM(JavaVM**, void**, void*);
+	jint AttachCurrentThread(JavaVM*, void**, void*);
+	jint AttachCurrentThreadAsDaemon(JavaVM*, void**, void*);
+
+jni.h (Android NDK) uses JNIEnv** type:
+
+	jint JNI_CreateJavaVM(JavaVM**, JNIEnv**, void*);
+	jint AttachCurrentThread(JavaVM*, JNIEnv**, void*);
+	jint AttachCurrentThreadAsDaemon(JavaVM*, JNIEnv**, void*);
+
+*/
+
+using jnienv_type = function_traits<std::remove_pointer_t<decltype(&JNI_CreateJavaVM)>>::argument_type<1>;
+
+inline JavaVM* jvm_ptr;
+
+inline JavaVM* jvm() noexcept
+{
+	return jvm_ptr;
+}
+
+struct thread_env
+{
+	~thread_env()
+	{
+		if (ptr)
+			jvm()->DetachCurrentThread();
+	}
+
+	jnienv_type addr() { return reinterpret_cast<jnienv_type>(&ptr); }
+	void** addr_void() { return reinterpret_cast<void**>(&ptr); }
+
+	JNIEnv* ptr = nullptr;
+};
+
+inline thread_local thread_env env_;
+
+} // namespace detail
 
 inline jint get_env(jint version = JNI_VERSION_1_6) noexcept
 {
-	return detail::jvm()->GetEnv((void**)&detail::env(), version);
+	return detail::jvm()->GetEnv(detail::env_.addr_void(), version);
+}
+
+inline jint attach_current_thread(void *args = nullptr) noexcept
+{
+	return detail::jvm()->AttachCurrentThread(detail::env_.addr(), args);
+}
+
+inline jint attach_current_thread_as_daemon(void *args = nullptr) noexcept
+{
+	return detail::jvm()->AttachCurrentThreadAsDaemon(detail::env_.addr(), args);
+}
+
+inline jint detach_current_thread() noexcept
+{
+	detail::env_.ptr = nullptr;
+	return detail::jvm()->DetachCurrentThread();
+}
+
+namespace detail {
+
+inline JNIEnv* env() noexcept
+{
+#ifdef SCAPIX_JAVA_AUTO_ATTACH_THREAD
+
+	if (BOOST_UNLIKELY(!env_.ptr))
+		attach_current_thread();
+
+#endif
+
+	return env_.ptr;
 }
 
+} // namespace detail
 } // namespace scapix::link::java
 
 #endif // SCAPIX_LINK_JAVA_ENV_H
diff --git a/source/scapix/link/java/init.h b/source/scapix/link/java/init.h
@@ -49,7 +49,7 @@ class class_loader
 
 inline jint on_load(JavaVM *vm, void *reserved) noexcept
 {
-	detail::jvm() = vm;
+	detail::jvm_ptr = vm;
 	get_env();
 
 #ifdef SCAPIX_CACHE_CLASS_LOADER
@@ -61,7 +61,7 @@ inline jint on_load(JavaVM *vm, void *reserved) noexcept
 
 inline void on_unload(JavaVM *vm, void *reserved) noexcept
 {
-	detail::jvm() = nullptr;
+	detail::jvm_ptr = nullptr;
 }
 
 } // namespace scapix::link::java

diff --git a/source/scapix/link/java/native_method.h b/source/scapix/link/java/native_method.h
@@ -122,7 +122,7 @@ class native_method
 	{
 		static param_type<JniR> func(JNIEnv* env, jobject thiz, param_type<JniArgs>... args)
 		{
-			detail::env() = env;
+			detail::env_.ptr = env;
 
 			try
 			{
@@ -156,7 +156,7 @@ class native_method
 	{
 		static param_type<JniR> func(JNIEnv* env, jclass clazz, param_type<JniArgs>... args)
 		{
-			detail::env() = env;
+			detail::env_.ptr = env;
 
 			try
 			{

diff --git a/source/scapix/link/java/thread.h b/source/scapix/link/java/thread.h
diff --git a/source/scapix/link/java/type_traits.h b/source/scapix/link/java/type_traits.h
@@ -9,7 +9,7 @@
 
 #include <type_traits>
 #include <scapix/meta/string.h>
-#include <scapix/link/java/detail/config.h>
+#include <scapix/link/java/env.h>
 
 namespace scapix::link::java {
 

diff --git a/source/scapix/link/java/vm.h b/source/scapix/link/java/vm.h
@@ -7,32 +7,32 @@
 #ifndef SCAPIX_LINK_JAVA_VM_H
 #define SCAPIX_LINK_JAVA_VM_H
 
-#include <scapix/link/java/detail/config.h>
+#include <scapix/link/java/env.h>
 
 namespace scapix::link::java {
 
 inline bool init_created_vm() noexcept
 {
 	jint count;
-	JNI_GetCreatedJavaVMs(&detail::jvm(), 1, &count);
+	JNI_GetCreatedJavaVMs(&detail::jvm_ptr, 1, &count);
 	return count != 0;
 }
 
 inline void deinit_created_vm() noexcept
 {
-	detail::jvm() = nullptr;
+	detail::jvm_ptr = nullptr;
 }
 
 inline jint create_vm(void* args) noexcept
 {
-	return JNI_CreateJavaVM(&detail::jvm(), reinterpret_cast<detail::jnienv_type>(&detail::env()), args);
+	return JNI_CreateJavaVM(&detail::jvm_ptr, detail::env_.addr(), args);
 }
 
 inline jint destroy_vm() noexcept
 {
 	auto r = detail::jvm()->DestroyJavaVM();
 	if (r == JNI_OK)
-		detail::jvm() = nullptr;
+		detail::jvm_ptr = nullptr;
 	return r;
 }