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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;
	}

	}

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