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 * Copyright (c) 2020, 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.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import jdk.jfr.Configuration;
import jdk.jfr.EventType;

Event that contains information about event types and configurations.
Since:
16/**
 * Event that contains information about event types and configurations.
 *
 * @since 16
 */
public final class MetadataEvent {
    private final List<EventType> current;
    private final List<EventType> previous;
    private final List<Configuration> configurations;
    private List<EventType> added;
    private List<EventType> removed;

    /* package private */
    MetadataEvent(List<EventType> previous, List<EventType> current, List<Configuration> configs) {
        this.previous = previous;
        this.current = current;
        this.configurations = configs;
    }

    
Returns a list of the current event types being used.
Returns:
an immutable list of event types, not null/**
     * Returns a list of the current event types being used.
     *
     * @return an immutable list of event types, not {@code null}
     */
    public final List<EventType> getEventTypes() {
        return Collections.unmodifiableList(current);
    }

    
Returns a list of added event types since the last metadata event.

The delta will be from the last metadata event. If no metadata event has been
emitted earlier, all known event types will be in the list.
Returns:
an immutable list of added event types, not null/**
     * Returns a list of added event types since the last metadata event.
     * <p>
     * The delta will be from the last metadata event. If no metadata event has been
     * emitted earlier, all known event types will be in the list.
     *
     * @return an immutable list of added event types, not {@code null}
     */
    public final List<EventType> getAddedEventTypes() {
        if (added == null) {
            calculateDelta();
        }
        return added;
    }

    
Returns a list of removed event types since the last metadata event.

The delta will be from the last metadata event. If no metadata event has been
emitted earlier, the list will be empty.
Returns:
an immutable list of added event types, not null/**
     * Returns a list of removed event types since the last metadata event.
     * <p>
     * The delta will be from the last metadata event. If no metadata event has been
     * emitted earlier, the list will be empty.
     *
     * @return an immutable list of added event types, not {@code null}
     */
    public final List<EventType> getRemovedEventTypes() {
        if (removed == null) {
            calculateDelta();
        }
        return removed;
    }

    
Returns a list of configurations.
Returns:
an immutable list of configurations, not null/**
     * Returns a list of configurations.
     *
     * @return an immutable list of configurations, not {@code null}
     */
    public List<Configuration> getConfigurations() {
        return configurations;
    }

    private void calculateDelta() {
        List<EventType> added = new ArrayList<>();
        Map<Long, EventType> previousSet = new HashMap<>(previous.size());
        for (EventType eventType : previous) {
            previousSet.put(eventType.getId(), eventType);
        }
        for (EventType eventType : current) {
            EventType t = previousSet.remove(eventType.getId());
            if (t == null) {
                added.add(eventType);
            }
        }
        this.removed = Collections.unmodifiableList(new ArrayList<>(previousSet.values()));
        this.added = Collections.unmodifiableList(added);
    }
}