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