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/* * Copyright (c) 1997, 2008, 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.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * 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. */  /* * The Original Code is HAT. The Initial Developer of the * Original Code is Bill Foote, with contributions from others * at JavaSoft/Sun. */ package com.sun.tools.hat.internal.model; import java.util.Enumeration;import java.util.HashMap;import java.util.Map;import com.sun.tools.hat.internal.util.Misc;  /** * * @author      Bill Foote */ /** * Represents an object that's allocated out of the Java heap.  It occupies * memory in the VM, and is the sort of thing that in a JDK 1.1 VM had * a handle.  It can be a * JavaClass, a JavaObjectArray, a JavaValueArray or a JavaObject. */ public abstract class JavaHeapObject extends JavaThing {     //    // Who we refer to.  This is heavily optimized for space, because it's    // well worth trading a bit of speed for less swapping.    // referers and referersLen go through two phases:  Building and    // resolved.  When building, referers might have duplicates, but can    // be appended to.  When resolved, referers has no duplicates or    // empty slots.    //    private JavaThing[] referers = null;    private int referersLen = 0;        // -1 when resolved     public abstract JavaClass getClazz();    public abstract int getSize();    public abstract long getId();     /**     * Do any initialization this thing needs after its data is read in.     * Subclasses that override this should call super.resolve().     */    public void resolve(Snapshot snapshot) {        StackTrace trace = snapshot.getSiteTrace(this);        if (trace != null) {            trace.resolve(snapshot);        }    }     //    //  Eliminate duplicates from referers, and size the array exactly.    // This sets us up to answer queries.  See the comments around the    // referers data member for details.    //    void setupReferers() {        if (referersLen > 1) {            // Copy referers to map, screening out duplicates            Map<JavaThing, JavaThing> map = new HashMap<JavaThing, JavaThing>();            for (int i = 0; i < referersLen; i++) {                if (map.get(referers[i]) == null) {                    map.put(referers[i], referers[i]);                }            }             // Now copy into the array            referers = new JavaThing[map.size()];            map.keySet().toArray(referers);        }        referersLen = -1;    }      /**     * @return the id of this thing as hex string     */    public String getIdString() {        return Misc.toHex(getId());    }     public String toString() {        return getClazz().getName() + "@" + getIdString();    }     /**     * @return the StackTrace of the point of allocation of this object,     *          or null if unknown     */    public StackTrace getAllocatedFrom() {        return getClazz().getSiteTrace(this);    }     public boolean isNew() {        return getClazz().isNew(this);    }     void setNew(boolean flag) {        getClazz().setNew(this, flag);    }     /**     * Tell the visitor about all of the objects we refer to     */    public void visitReferencedObjects(JavaHeapObjectVisitor v) {        v.visit(getClazz());    }     void addReferenceFrom(JavaHeapObject other) {        if (referersLen == 0) {            referers = new JavaThing[1];        // It was null        } else if (referersLen == referers.length) {            JavaThing[] copy = new JavaThing[(3 * (referersLen + 1)) / 2];            System.arraycopy(referers, 0, copy, 0, referersLen);            referers = copy;        }        referers[referersLen++] = other;        // We just append to referers here.  Measurements have shown that        // around 10% to 30% are duplicates, so it's better to just append        // blindly and screen out all the duplicates at once.    }     void addReferenceFromRoot(Root r) {        getClazz().addReferenceFromRoot(r, this);    }     /**     * If the rootset includes this object, return a Root describing one     * of the reasons why.     */    public Root getRoot() {        return getClazz().getRoot(this);    }     /**     * Tell who refers to us.     *     * @return an Enumeration of JavaHeapObject instances     */    public Enumeration getReferers() {        if (referersLen != -1) {            throw new RuntimeException("not resolved: " + getIdString());        }        return new Enumeration() {             private int num = 0;             public boolean hasMoreElements() {                return referers != null && num < referers.length;            }             public Object nextElement() {                return referers[num++];            }        };    }     /**     * Given other, which the caller promises is in referers, determines if     * the reference is only a weak reference.     */    public boolean refersOnlyWeaklyTo(Snapshot ss, JavaThing other) {        return false;    }     /**     * Describe the reference that this thing has to target.  This will only     * be called if target is in the array returned by getChildrenForRootset.     */    public String describeReferenceTo(JavaThing target, Snapshot ss) {        return "??";    }     public boolean isHeapAllocated() {        return true;    } }