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Java example source code file (StackFrameStream.java)

This example Java source code file (StackFrameStream.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

frame, registermap, stackframestream

The StackFrameStream.java Java example source code

/*
 * Copyright (c) 2000, 2004, 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.
 *
 */

package sun.jvm.hotspot.runtime;

import sun.jvm.hotspot.utilities.*;

/** <P> StackFrameStream iterates through the frames of a thread
    starting from top most frame. It automatically takes care of
    updating the location of all (callee-saved) registers. Notice: If
    a thread is stopped at a safepoint, all registers are saved, not
    only the callee-saved ones. </P>

    <P> Use: 

<PRE> for(StackFrameStream fst = new StackFrameStream(thread); !fst.isDone(); fst.next()) { ... } </PRE> */ public class StackFrameStream { private Frame fr; private RegisterMap regMap; private boolean isDone; /** Equivalent to StackFrameStream(thread, true) */ public StackFrameStream(JavaThread thread) { this(thread, true); } public StackFrameStream(JavaThread thread, boolean update) { if (!VM.getVM().isDebugging()) { if (Assert.ASSERTS_ENABLED) { Assert.that(thread.hasLastJavaFrame(), "sanity check"); } fr = thread.getLastFrame(); regMap = thread.newRegisterMap(update); isDone = false; } else { // Special case code to find the topmost Java frame // FIXME: should check to see whether we're at safepoint, and if // so, skip the "current frame guess" call and unnecessary // stackwalking work fr = thread.getCurrentFrameGuess(); regMap = thread.newRegisterMap(update); while ((fr != null) && (!fr.isJavaFrame())) { if (fr.isFirstFrame()) { fr = null; } else { fr = fr.sender(regMap); } } if (fr == null) { isDone = true; } } } /** Iteration */ public boolean isDone() { if (isDone) { return true; } else { if (fr == null) { isDone = true; return true; } isDone = fr.isFirstFrame(); return false; } } public void next() { if (!isDone) { fr = fr.sender(regMap); } } /** Query */ public Frame getCurrent() { return fr; } public RegisterMap getRegisterMap() { return regMap; } }

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