/*

 * Copyright (c) 1998, 2013, 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 com.sun.jdi.event;

import com.sun.jdi.*;

/**

 * Manager of incoming debugger events for a target VM.

 * Events are always grouped in {@link EventSet}s.

 * EventSets generated by the debugger back end can be read

 * here. There is one instance of EventQueue assigned to a particular

 * {@link com.sun.jdi.VirtualMachine VirtualMachine}.

 * <P>

 * Some events cause the suspension of the target VM - event requests

 * ({@link com.sun.jdi.request}) with a

 * {@link com.sun.jdi.request.EventRequest#suspendPolicy() suspend policy}

 * of {@link com.sun.jdi.request.EventRequest#SUSPEND_ALL SUSPEND_ALL}

 * or {@link com.sun.jdi.request.EventRequest#SUSPEND_EVENT_THREAD

 * SUSPEND_EVENT_THREAD} and sometimes

 * {@link VMStartEvent}.

 * If these suspensions are not resumed the target VM will hang.

 * Thus, it is always good policy to

 * {@link #remove() remove()} every EventSet from the

 * event queue until an EventSet containing a

 * {@link VMDisconnectEvent} is read.

 * Unless {@link com.sun.jdi.VirtualMachine#resume() resume} is

 * being handled in another way, each EventSet should invoke

 * {@link EventSet#resume()}.

 *

 * @see EventSet

 * @see VirtualMachine

 *

 * @author Robert Field

 * @since  1.3

 */

@jdk.Exported

public interface EventQueue extends Mirror {

    /**

     * Waits forever for the next available event.

     *

     * @return the next {@link EventSet}.

     * @throws InterruptedException if any thread has interrupted

     * this thread.

     * @throws com.sun.jdi.VMDisconnectedException if the connection

     * to the target VM is no longer available.  Note this will always

     * be preceded by a {@link com.sun.jdi.event.VMDisconnectEvent}.

     */

    EventSet remove() throws InterruptedException;

    /**

     * Waits a specified time for the next available event.

     *

     * @param timeout Time in milliseconds to wait for the next event

     * @return the next {@link EventSet}, or null if there is a timeout.

     * @throws InterruptedException if any thread has interrupted

     * this thread.

     * @throws com.sun.jdi.VMDisconnectedException if the connection

     * to the target VM is no longer available.  Note this will always

     * be preceded by a {@link com.sun.jdi.event.VMDisconnectEvent}.

     * @throws IllegalArgumentException if the timeout argument

     * contains an illegal value.

     */

    EventSet remove(long timeout) throws InterruptedException;

}