| /* |
| * Copyright (c) 2015, 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 |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| import java.io.IOException; |
| import java.util.LinkedList; |
| import java.util.Objects; |
| import java.util.stream.Stream; |
| |
| // Each stream has one of these for input. Each Http2Connection has one |
| // for output. Can be used blocking or asynchronously. |
| |
| public class Queue<T> implements ExceptionallyCloseable { |
| |
| private final LinkedList<T> q = new LinkedList<>(); |
| private boolean closed = false; |
| private boolean closing = false; |
| private Throwable exception = null; |
| private int waiters; // true if someone waiting |
| private final T closeSentinel; |
| |
| Queue(T closeSentinel) { |
| this.closeSentinel = Objects.requireNonNull(closeSentinel); |
| } |
| |
| public synchronized int size() { |
| return q.size(); |
| } |
| |
| public synchronized boolean isClosed() { |
| return closed; |
| } |
| |
| public synchronized boolean isClosing() { |
| return closing; |
| } |
| |
| public synchronized void put(T obj) throws IOException { |
| Objects.requireNonNull(obj); |
| if (closed || closing) { |
| throw new IOException("stream closed"); |
| } |
| |
| q.add(obj); |
| |
| if (waiters > 0) { |
| notifyAll(); |
| } |
| } |
| |
| // Other close() variants are immediate and abortive |
| // This allows whatever is on Q to be processed first. |
| |
| public synchronized void orderlyClose() { |
| if (closing || closed) |
| return; |
| |
| try { |
| put(closeSentinel); |
| } catch (IOException e) { |
| e.printStackTrace(); |
| } |
| closing = true; |
| } |
| |
| @Override |
| public synchronized void close() { |
| if (closed) |
| return; |
| closed = true; |
| notifyAll(); |
| } |
| |
| @Override |
| public synchronized void closeExceptionally(Throwable t) { |
| if (exception == null) exception = t; |
| else if (t != null && t != exception) { |
| if (!Stream.of(exception.getSuppressed()) |
| .filter(x -> x == t) |
| .findFirst() |
| .isPresent()) |
| { |
| exception.addSuppressed(t); |
| } |
| } |
| close(); |
| } |
| |
| public synchronized T take() throws IOException { |
| if (closed) { |
| throw newIOException("stream closed"); |
| } |
| try { |
| while (q.size() == 0) { |
| waiters++; |
| wait(); |
| if (closed) { |
| throw newIOException("Queue closed"); |
| } |
| waiters--; |
| } |
| T item = q.removeFirst(); |
| if (item.equals(closeSentinel)) { |
| closed = true; |
| assert q.isEmpty(); |
| return null; |
| } |
| return item; |
| } catch (InterruptedException ex) { |
| throw new IOException(ex); |
| } |
| } |
| |
| public synchronized T poll() throws IOException { |
| if (closed) { |
| throw newIOException("stream closed"); |
| } |
| |
| if (q.isEmpty()) { |
| return null; |
| } |
| return take(); |
| } |
| |
| private IOException newIOException(String msg) { |
| if (exception == null) { |
| return new IOException(msg); |
| } else { |
| return new IOException(msg, exception); |
| } |
| } |
| } |