src/jdk.jfr/share/classes/jdk/jfr/consumer/LongMap.java

/*
 * Copyright (c) 2016, 2018, 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
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package jdk.jfr.consumer;

import java.util.HashMap;
import java.util.Iterator;

/**
 * Commonly used data structure for looking up objects given an id (long value)
 *
 * TODO: Implement without using Map and Long objects, to minimize allocation
 *
 * @param <T>
 */
final class LongMap<T> implements Iterable<T> {
    private final HashMap<Long, T> map;

    LongMap() {
        map = new HashMap<>(101);
    }

    void put(long id, T object) {
        map.put(id, object);
    }

    T get(long id) {
        return map.get(id);
    }

    @Override
    public Iterator<T> iterator() {
        return map.values().iterator();
    }

    Iterator<Long> keys() {
        return map.keySet().iterator();
    }
}