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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package com.oracle.svm.core.genscavenge;

import org.graalvm.nativeimage.Platform;
import org.graalvm.nativeimage.Platforms;
import org.graalvm.word.UnsignedWord;

import com.oracle.svm.core.heap.ObjectVisitor;
import com.oracle.svm.core.log.Log;

A Generation is a collection of one or more Spaces. /** A Generation is a collection of one or more Spaces. */
abstract class Generation {
    private final String name;

    @Platforms(Platform.HOSTED_ONLY.class)
    Generation(String name) {
        this.name = name;
    }

    
Walk the Objects in this Space, passing each to a Visitor.
Params:
visitor – An ObjectVisitor.
Returns:
True if all visits returned true, false otherwise./**
     * Walk the Objects in this Space, passing each to a Visitor.
     *
     * @param visitor An ObjectVisitor.
     * @return True if all visits returned true, false otherwise.
     */
    public abstract boolean walkObjects(ObjectVisitor visitor);

    public String getName() {
        return name;
    }

    
Report some statistics about the Generation to a Log. /** Report some statistics about the Generation to a Log. */
    public abstract Log report(Log log, boolean traceHeapChunks);

    
Promote an Object to this Generation, either by HeapChunk motion or copying. If the original
is copied, a forwarding pointer to the new Object is left in place of the original Object.
This turns an Object from white to grey: the object is in this Generation, but has not yet
had its interior pointers visited.
Params:
original – The original Object to be promoted.
header – The header of the object that should be promoted.
Returns:
The promoted Object, either the original if promotion was done by HeapChunk motion,
        or a new Object if promotion was done by copying./**
     * Promote an Object to this Generation, either by HeapChunk motion or copying. If the original
     * is copied, a forwarding pointer to the new Object is left in place of the original Object.
     *
     * This turns an Object from white to grey: the object is in this Generation, but has not yet
     * had its interior pointers visited.
     *
     * @param original The original Object to be promoted.
     * @param header The header of the object that should be promoted.
     * @return The promoted Object, either the original if promotion was done by HeapChunk motion,
     *         or a new Object if promotion was done by copying.
     */
    protected abstract Object promoteObject(Object original, UnsignedWord header);

    protected abstract boolean verify(HeapVerifier.Occasion occasion);
}