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/*
* Copyright (c) 2005, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
#include <jni.h>
#include <stdio.h>
extern "C" {
/* A C function that takes a reference to java Object(a circular Linked list)
and utilizes this reference to do a java method callback to determine the
number of elements in the linked list */
JNIEXPORT jint JNICALL
Java_gc_gctests_nativeGC02_nativeGC02_nativeMethod02
(JNIEnv *env, jobject obj, jobject linked_list) {
jclass cls, clss;
jmethodID mid, mid2;
jfieldID fid;
jobject llist;
int elementCount;
/* Store a reference to the linked list in the C stack */
clss = env->GetObjectClass(obj);
fid = env->GetFieldID(clss, "cl", "Lnsk/share/gc/CircularLinkedList;");
if (fid == nullptr) {
printf("could not locate field - cl\n");
return -1;
}
llist = env->GetObjectField(obj, fid);
/* force a GC by invoking a callback where System.gc() is called
*/
cls = env->GetObjectClass(obj);
mid = env->GetMethodID(cls, "callbackGC", "()V");
if (mid == nullptr) {
printf("couldnt locate method callbackGC()\n");
return -1;
}
env->CallVoidMethod(obj,mid);
/* Now that a GC has been done, invoke the callback
that counts the number of elements in the
circular linked list
*/
clss = env->GetObjectClass(linked_list);
mid2 = env->GetMethodID(clss, "getLength", "(Lnsk/share/gc/CircularLinkedList;)I");
if (mid2 == nullptr) {
printf("couldnt locate method getLength(CircularLinkedList)\n");
return -1;
}
elementCount = env->CallIntMethod(linked_list, mid2, llist);
return elementCount;
}
}
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