QPID-4027 Marked the jclass references as global refs to prevent them

from being cleaned up. The jmethodID's will remain valid until the
corresponding jclass is cleaned up.
Created convinience methods for looking up class defs and methods.

git-svn-id: https://svn.apache.org/repos/asf/qpid/branches/address-refactor2@1347726 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 48 insertions, 29 deletions

diff --git a/qpid/cpp/bindings/swig_java_cpp_helper.i b/qpid/cpp/bindings/swig_java_cpp_helper.i
index 4120124194..98b364d4b5 100644
--- a/qpid/cpp/bindings/swig_java_cpp_helper.i
+++ b/qpid/cpp/bindings/swig_java_cpp_helper.i
@@ -20,6 +20,7 @@
 /*
  * ======================== Contents on this file ===========================
  * 1. Static C++ Helper Methods.
+ * 2. JNICALL JNI_OnLoad method for initializing global variables.
  * 2. Wrappers for C++ Objects (handwritten c++ classes).
  * 3. SWIG Interface definitions for the above classes.
  * ==========================================================================
@@ -29,7 +30,7 @@
 
 
 /*
- * ===================== static C++ Helper Methods ==========================
+ * ===================== Static C++ Helper Methods ==========================
  * Static helper methods in support of typemaps,
  * for converting between C++ and Java.
  * ==========================================================================
@@ -37,10 +38,12 @@
 
 %begin %{
 
-// These are initialized during library loading via JNI_OnLoad.
-// This is done for performance reasons.
-// These variables are marked as global references.
-
+/*
+ * These are initialized during library loading via JNI_OnLoad.
+ * This is done for performance reasons.
+ * Thee jclass variables are marked as global references.
+ * The jmethod variables remain valid until the corresponding jclass ref is valid.
+ */
 static JavaVM* cachedJVM=0;
 
 static jclass JAVA_STRING_CLASS;
@@ -76,6 +79,21 @@ static jmethodID JAVA_DOUBLE_VALUE_METHOD;
 static jclass JAVA_ILLEGAL_ARGUMENT_EXP;
 static jclass JAVA_JNI_LAYER_EXP;
 
+static jobject createGlobalRef(JNIEnv* env,jobject obj)
+{
+    return env->NewGlobalRef(obj);
+}
+
+static jclass findClass(JNIEnv* env,const char* name)
+{
+    return env->FindClass(name);
+}
+
+static jmethodID getMethodID(JNIEnv* env, jclass clazz, const char* name, const char* sig)
+{
+    return env->GetMethodID(clazz,name,sig);
+}
+
 /*
  * ========================= init() for the module ==========================
  *
@@ -98,46 +116,47 @@ JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *jvm, void *reserved)
       std::cout << "JNI env ref is null!, aborting" << std::endl;
       return JNI_ERR;
    }
-   JAVA_STRING_CLASS = env->FindClass("java/lang/String");
+
+   JAVA_STRING_CLASS = (jclass)createGlobalRef(env,findClass(env,"java/lang/String"));
    std::cout << "Loaded java string" << std::endl;
 
-   JAVA_BOOLEAN_CLASS = env->FindClass("java/lang/Boolean");
+   JAVA_BOOLEAN_CLASS = (jclass)createGlobalRef(env,findClass(env,"java/lang/Boolean"));
+   JAVA_BOOLEAN_CTOR = getMethodID(env,JAVA_BOOLEAN_CLASS, "<init>", "(Z)V");
+   JAVA_BOOLEAN_VALUE_METHOD = getMethodID(env,JAVA_BOOLEAN_CLASS,"booleanValue", "()Z");
    std::cout << "Loaded java boolean"<< std::endl;
-   JAVA_BOOLEAN_CTOR = env->GetMethodID(JAVA_BOOLEAN_CLASS, "<init>", "(Z)V");
-   JAVA_BOOLEAN_VALUE_METHOD = env->GetMethodID(JAVA_BOOLEAN_CLASS,"booleanValue", "()Z");
 
-   JAVA_BYTE_CLASS = env->FindClass("java/lang/Byte");
+   JAVA_BYTE_CLASS = (jclass)createGlobalRef(env,findClass(env,"java/lang/Byte"));
+   JAVA_BYTE_CTOR = getMethodID(env,JAVA_BYTE_CLASS, "<init>", "(B)V");
+   JAVA_BYTE_VALUE_METHOD = getMethodID(env,JAVA_BYTE_CLASS,"byteValue", "()B");
    std::cout << "Loaded java byte"<< std::endl;
-   JAVA_BYTE_CTOR = env->GetMethodID(JAVA_BYTE_CLASS, "<init>", "(B)V");
-   JAVA_BYTE_VALUE_METHOD = env->GetMethodID(JAVA_BYTE_CLASS,"byteValue", "()B");
 
-   JAVA_SHORT_CLASS = env->FindClass("java/lang/Short");
-   JAVA_SHORT_CTOR = env->GetMethodID(JAVA_SHORT_CLASS, "<init>", "(S)V");
-   JAVA_SHORT_VALUE_METHOD = env->GetMethodID(JAVA_SHORT_CLASS,"shortValue", "()S");
+   JAVA_SHORT_CLASS = (jclass)createGlobalRef(env,findClass(env,"java/lang/Short"));
+   JAVA_SHORT_CTOR = getMethodID(env,JAVA_SHORT_CLASS, "<init>", "(S)V");
+   JAVA_SHORT_VALUE_METHOD = getMethodID(env,JAVA_SHORT_CLASS,"shortValue", "()S");
    std::cout << "Loaded java short"<< std::endl;
 
-   JAVA_INT_CLASS = env->FindClass("java/lang/Integer");
-   JAVA_INT_CTOR = env->GetMethodID(JAVA_INT_CLASS, "<init>", "(I)V");
-   JAVA_INT_VALUE_METHOD = env->GetMethodID(JAVA_INT_CLASS,"intValue", "()I");
+   JAVA_INT_CLASS = (jclass)createGlobalRef(env,findClass(env,"java/lang/Integer"));
+   JAVA_INT_CTOR = getMethodID(env,JAVA_INT_CLASS, "<init>", "(I)V");
+   JAVA_INT_VALUE_METHOD = getMethodID(env,JAVA_INT_CLASS,"intValue", "()I");
    std::cout << "Loaded java int"<< std::endl;
 
-   JAVA_LONG_CLASS = env->FindClass("java/lang/Long");
-   JAVA_LONG_CTOR = env->GetMethodID(JAVA_LONG_CLASS, "<init>", "(J)V");
-   JAVA_LONG_VALUE_METHOD = env->GetMethodID(JAVA_LONG_CLASS,"longValue", "()J");
+   JAVA_LONG_CLASS = (jclass)createGlobalRef(env,findClass(env,"java/lang/Long"));
+   JAVA_LONG_CTOR = getMethodID(env,JAVA_LONG_CLASS, "<init>", "(J)V");
+   JAVA_LONG_VALUE_METHOD = getMethodID(env,JAVA_LONG_CLASS,"longValue", "()J");
    std::cout << "Loaded java long"<< std::endl;
 
-   JAVA_DOUBLE_CLASS = env->FindClass("java/lang/Double");
-   JAVA_DOUBLE_CTOR = env->GetMethodID(JAVA_DOUBLE_CLASS, "<init>", "(D)V");
-   JAVA_DOUBLE_VALUE_METHOD = env->GetMethodID(JAVA_DOUBLE_CLASS,"doubleValue", "()D");
+   JAVA_DOUBLE_CLASS = (jclass)createGlobalRef(env,findClass(env,"java/lang/Double"));
+   JAVA_DOUBLE_CTOR = getMethodID(env,JAVA_DOUBLE_CLASS, "<init>", "(D)V");
+   JAVA_DOUBLE_VALUE_METHOD = getMethodID(env,JAVA_DOUBLE_CLASS,"doubleValue", "()D");
    std::cout << "Loaded java double"<< std::endl;
 
-   JAVA_FLOAT_CLASS = env->FindClass("java/lang/Float");
-   JAVA_FLOAT_CTOR = env->GetMethodID(JAVA_FLOAT_CLASS, "<init>", "(F)V");
-   JAVA_FLOAT_VALUE_METHOD = env->GetMethodID(JAVA_FLOAT_CLASS,"floatValue", "()F");
+   JAVA_FLOAT_CLASS = (jclass)createGlobalRef(env,findClass(env,"java/lang/Float"));
+   JAVA_FLOAT_CTOR = getMethodID(env,JAVA_FLOAT_CLASS, "<init>", "(F)V");
+   JAVA_FLOAT_VALUE_METHOD = getMethodID(env,JAVA_FLOAT_CLASS,"floatValue", "()F");
    std::cout << "Loaded java float"<< std::endl;
 
-   JAVA_ILLEGAL_ARGUMENT_EXP = env->FindClass("java/lang/IllegalArgumentException");
-   JAVA_JNI_LAYER_EXP = env->FindClass("org/apache/qpid/messaging/cpp/JNILayerException");
+   JAVA_ILLEGAL_ARGUMENT_EXP = (jclass)createGlobalRef(env,findClass(env,"java/lang/IllegalArgumentException"));
+   JAVA_JNI_LAYER_EXP = (jclass)createGlobalRef(env,findClass(env,"org/apache/qpid/messaging/cpp/JNILayerException"));
    std::cout << "Loaded java exceptions"<< std::endl;
    return JNI_VERSION_1_4;
 }