From: Jean Privat <jean@pryen.org>
Date: Mon, 9 Nov 2015 15:39:14 +0000 (-0500)
Subject: Merge: Java FFI: add GC pinning support
X-Git-Tag: v0.8~100
X-Git-Url: http://nitlanguage.org?hp=883a6deafab95f0c7cc675094e66add5a4e45779

Merge: Java FFI: add GC pinning support

Adds a missing features to the Java FFI: pinning references to Nit objects from Java. Both services, `..._incr_ref` and `..._decr_ref`, are "simple" redirections from Java to the nitni service in C through the JNI.

Pull-Request: #1820
Reviewed-by: Jean Privat <jean@pryen.org>
---

diff --git a/src/ffi/java.nit b/src/ffi/java.nit
index eca32ac..1adb9c9 100644
--- a/src/ffi/java.nit
+++ b/src/ffi/java.nit
@@ -220,6 +220,9 @@ redef class MModule
 		for cb in callbacks do
 			jni_methods.add_all(cb.jni_methods_declaration(self))
 		end
+		for cb in callbacks_used_from_java.types do
+			jni_methods.add_all(cb.jni_methods_declaration(self))
+		end
 
 		var cf = new CFunction("void nit_ffi_with_java_register_natives(JNIEnv* env, jclass jclazz)")
 		cf.exprs.add """
@@ -470,6 +473,38 @@ redef class MType
 	# Used by `JavaLanguage::compile_extern_method` when calling JNI's `CallStatic*Method`.
 	# This strategy is used by JNI to type the return of callbacks to Java.
 	private fun jni_signature_alt: String do return "Int"
+
+	redef fun compile_callback_to_java(mmodule, mainmodule, ccu)
+	do
+		var java_file = mmodule.java_file
+		if java_file == null then return
+
+		for variation in ["incr", "decr"] do
+			var friendly_name = "{mangled_cname}_{variation}_ref"
+
+			# C
+			var csignature = "void {mmodule.impl_java_class_name}_{friendly_name}(JNIEnv *env, jclass clazz, jint object)"
+			var cf = new CFunction("JNIEXPORT {csignature}")
+			cf.exprs.add "\tnitni_global_ref_{variation}((void*)(long)object);"
+			ccu.add_non_static_local_function cf
+
+			# Java
+			java_file.class_content.add "private native static void {friendly_name}(int object);\n"
+		end
+	end
+
+	redef fun jni_methods_declaration(from_mmodule)
+	do
+		var arr = new Array[String]
+		for variation in ["incr", "decr"] do
+			var friendly_name = "{mangled_cname}_{variation}_ref"
+			var jni_format = "(I)V"
+			var cname = "{from_mmodule.impl_java_class_name}_{friendly_name}"
+			arr.add """{"{{{friendly_name}}}", "{{{jni_format}}}", {{{cname}}}}"""
+		end
+
+		return arr
+	end
 end
 
 redef class MClassType
diff --git a/tests/sav/test_ffi_java_refs.res b/tests/sav/test_ffi_java_refs.res
new file mode 100644
index 0000000..422c2b7
--- /dev/null
+++ b/tests/sav/test_ffi_java_refs.res
@@ -0,0 +1,2 @@
+a
+b
diff --git a/tests/test_ffi_java_refs.nit b/tests/test_ffi_java_refs.nit
new file mode 100644
index 0000000..efab321
--- /dev/null
+++ b/tests/test_ffi_java_refs.nit
@@ -0,0 +1,27 @@
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import java
+
+class A
+	fun foo in "Java" `{
+		A_incr_ref(self);
+		System.out.println("a");
+		A_decr_ref(self);
+		System.out.println("b");
+	`}
+end
+
+var a = new A
+a.foo