Merge pull request #646 from Thrameos/weak_proxy

Weak proxy
jpype-project · Mar 31, 2020 · 715ad94 · 715ad94
2 parents 86faece + 38c3862
commit 715ad94
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Showing 6 changed files with 65 additions and 9 deletions.
diff --git a/doc/CHANGELOG.rst b/doc/CHANGELOG.rst
@@ -132,7 +132,12 @@ This changelog *only* contains changes from the *first* pypi release (0.5.4.3) o
     for complience when accessing ``java.util.List`` elements.
 
   - java.lang.NullPointerException can be caught with ValueError
-    for consistency with Python exception usage..
+    for consistency with Python exception usage.
+
+  - JProxy only creates one copy of the invocation handler per
+    garbage collection rather than once per use.  Thus proxy objects
+    placed in memory containers will have the same object id so long
+    as Java holds on to it.
 
 - **0.7.1 - 12-16-2019**
 

diff --git a/native/common/include/jp_javaframe.h b/native/common/include/jp_javaframe.h
@@ -123,6 +123,9 @@ class JPJavaFrame
 	 */
 	void DeleteLocalRef(jobject obj);
 
+	jweak NewWeakGlobalRef(jobject obj);
+	void DeleteWeakGlobalRef(jweak obj);
+
 	JNIEnv* getEnv() const
 	{
 		return m_Env;

diff --git a/native/common/include/jp_proxy.h b/native/common/include/jp_proxy.h
@@ -58,6 +58,7 @@ class JPProxy
 	PyObject*     m_Instance; // This is a PyJPProxy
 	JPObjectRef   m_Proxy;
 	JPClassList   m_InterfaceClasses;
+	jweak         m_Ref;
 } ;
 
 /** Special wrapper for round trip returns

diff --git a/native/common/jp_javaframe.cpp b/native/common/jp_javaframe.cpp
@@ -1,5 +1,5 @@
 /*****************************************************************************
-   Copyright 2004-2008 Steve MÃ©nard
+   Copyright 2004-2008 Steve MÃƒÂ©nard
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
@@ -116,12 +116,22 @@ JPJavaFrame::~JPJavaFrame()
 
 void JPJavaFrame::DeleteLocalRef(jobject obj)
 {
-	m_Env->functions->DeleteLocalRef(m_Env, obj);
+	m_Env->DeleteLocalRef(obj);
 }
 
 void JPJavaFrame::DeleteGlobalRef(jobject obj)
 {
-	m_Env->functions->DeleteGlobalRef(m_Env, obj);
+	m_Env->DeleteGlobalRef(obj);
+}
+
+jweak JPJavaFrame::NewWeakGlobalRef(jobject obj)
+{
+	return m_Env->NewWeakGlobalRef(obj);
+}
+
+void JPJavaFrame::DeleteWeakGlobalRef(jweak obj)
+{
+	return m_Env->DeleteWeakGlobalRef(obj);
 }
 
 jobject JPJavaFrame::NewLocalRef(jobject a0)

diff --git a/native/common/jp_proxy.cpp b/native/common/jp_proxy.cpp
@@ -216,11 +216,23 @@ JPProxy::JPProxy(JPProxyFactory* factory, PyObject* inst, JPClassList& intf)
 	jobject proxy = frame.CallStaticObjectMethodA(m_Factory->m_ProxyClass.get(),
 			m_Factory->m_NewProxyID, v);
 	m_Proxy = JPObjectRef(m_Factory->m_Context, proxy);
+	m_Ref = NULL;
 	JP_TRACE_OUT;
 }
 
 JPProxy::~JPProxy()
 {
+	try
+	{
+		JPContext *context = getContext();
+		if (m_Ref != NULL && context->isRunning())
+		{
+			context->getEnv()->DeleteWeakGlobalRef(m_Ref);
+		}
+	} catch (JPypeException &ex)
+	{
+		// Cannot throw
+	}
 }
 
 jvalue JPProxy::getProxy()
@@ -229,12 +241,21 @@ jvalue JPProxy::getProxy()
 	JPContext* context = getContext();
 	JPJavaFrame frame(context);
 
-	// Use the proxy to make an instance
-	JP_TRACE("Create handler");
-	Py_INCREF(m_Instance);
-	jobject instance = frame.CallObjectMethodA(m_Proxy.get(),
-			m_Factory->m_NewInstanceID, 0);
+	jobject instance = NULL;
+	if (m_Ref != NULL)
+	{
+		instance = frame.NewLocalRef(m_Ref);
+	}
 
+	if (instance == NULL)
+	{
+		// Use the proxy to make an instance
+		JP_TRACE("Create handler");
+		Py_INCREF(m_Instance);
+		instance = frame.CallObjectMethodA(m_Proxy.get(),
+				m_Factory->m_NewInstanceID, 0);
+		m_Ref = frame.NewWeakGlobalRef(instance);
+	}
 	jvalue out;
 	out.l = frame.keep(instance);
 	return out;

diff --git a/test/jpypetest/test_proxy.py b/test/jpypetest/test_proxy.py
@@ -443,3 +443,19 @@ class R(object):
         self.assertIsInstance(s.getClass(), java.lang.Class)
         self.assertIsInstance(s.toString(), java.lang.String)
         self.assertIsInstance(s.hashCode(), int)
+
+    def testWeak(self):
+        hc = java.lang.System.identityHashCode
+        @JImplements("java.io.Serializable")
+        class MyObj(object):
+            pass
+        def f():
+            obj = MyObj()
+            jobj = JObject(obj)
+            i = hc(obj)
+            return i, obj
+        i0, obj = f()
+        i1 = hc(obj)
+        # These should be the same if unless the reference was broken
+        self.assertEqual(i0, i1)
+