1/* 2 * Copyright (c) 2000, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25package sun.jvm.hotspot.utilities; 26 27/** <p> A two-way unbounded-length message queue useful for 28 communication between threads. Messages written on one side become 29 readable on the other in first-in, first-out order. This is an 30 interface to one of two "sides" of an underlying backend, for 31 example, the MessageQueueBackend. </p> */ 32 33public interface MessageQueue { 34 /** This blocks until a message is available. Even if the thread is 35 interrupted while it is waiting, this will not return until a 36 message is written by the entity on the other side of the 37 queue. */ 38 public Object readMessage(); 39 40 /** This blocks for up to <code>millis</code> milliseconds until a 41 message is available. If no message becomes available within 42 this time period, or the thread is interrupted during the wait, 43 returns null. (This implies that passing the value null back and 44 forth is not distinguishable with this method.) Passing a value 45 of 0 for the <code>millis</code> argument causes this method to 46 return without blocking. The millis argument must be greater 47 than or equal to zero. */ 48 public Object readMessageWithTimeout(long millis); 49 50 /** Write a message to the queue */ 51 public void writeMessage(Object obj); 52} 53