| /* |
| * Copyright 2008-2009 Sun Microsystems, Inc. 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. Sun designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| * CA 95054 USA or visit www.sun.com if you need additional information or |
| * have any questions. |
| */ |
| |
| package sun.nio.fs; |
| |
| import java.nio.file.*; |
| import java.util.*; |
| |
| /** |
| * Base implementation class for watch keys. |
| */ |
| |
| abstract class AbstractWatchKey extends WatchKey { |
| |
| /** |
| * Maximum size of event list (in the future this may be tunable) |
| */ |
| static final int MAX_EVENT_LIST_SIZE = 512; |
| |
| /** |
| * Special event to signal overflow |
| */ |
| static final Event<Void> OVERFLOW_EVENT = |
| new Event<Void>(StandardWatchEventKind.OVERFLOW, null); |
| |
| /** |
| * Possible key states |
| */ |
| private static enum State { READY, SIGNALLED }; |
| |
| // reference to watcher |
| private final AbstractWatchService watcher; |
| |
| // key state |
| private State state; |
| |
| // pending events |
| private List<WatchEvent<?>> events; |
| |
| protected AbstractWatchKey(AbstractWatchService watcher) { |
| this.watcher = watcher; |
| this.state = State.READY; |
| this.events = new ArrayList<WatchEvent<?>>(); |
| } |
| |
| final AbstractWatchService watcher() { |
| return watcher; |
| } |
| |
| /** |
| * Enqueues this key to the watch service |
| */ |
| final void signal() { |
| synchronized (this) { |
| if (state == State.READY) { |
| state = State.SIGNALLED; |
| watcher.enqueueKey(this); |
| } |
| } |
| } |
| |
| /** |
| * Adds the event to this key and signals it. |
| */ |
| @SuppressWarnings("unchecked") |
| final void signalEvent(WatchEvent.Kind<?> kind, Object context) { |
| synchronized (this) { |
| int size = events.size(); |
| if (size > 1) { |
| // don't let list get too big |
| if (size >= MAX_EVENT_LIST_SIZE) { |
| kind = StandardWatchEventKind.OVERFLOW; |
| context = null; |
| } |
| |
| // repeated event |
| WatchEvent<?> prev = events.get(size-1); |
| if (kind == prev.kind()) { |
| boolean isRepeat; |
| if (context == null) { |
| isRepeat = (prev.context() == null); |
| } else { |
| isRepeat = context.equals(prev.context()); |
| } |
| if (isRepeat) { |
| ((Event<?>)prev).increment(); |
| return; |
| } |
| } |
| } |
| |
| // non-repeated event |
| events.add(new Event<Object>((WatchEvent.Kind<Object>)kind, context)); |
| signal(); |
| } |
| } |
| |
| @Override |
| public final List<WatchEvent<?>> pollEvents() { |
| synchronized (this) { |
| List<WatchEvent<?>> result = events; |
| events = new ArrayList<WatchEvent<?>>(); |
| return result; |
| } |
| } |
| |
| @Override |
| public final boolean reset() { |
| synchronized (this) { |
| if (state == State.SIGNALLED && isValid()) { |
| if (events.isEmpty()) { |
| state = State.READY; |
| } else { |
| // pending events so re-queue key |
| watcher.enqueueKey(this); |
| } |
| } |
| return isValid(); |
| } |
| } |
| |
| /** |
| * WatchEvent implementation |
| */ |
| private static class Event<T> extends WatchEvent<T> { |
| private final WatchEvent.Kind<T> kind; |
| private final T context; |
| |
| // synchronize on watch key to access/increment count |
| private int count; |
| |
| Event(WatchEvent.Kind<T> type, T context) { |
| this.kind = type; |
| this.context = context; |
| this.count = 1; |
| } |
| |
| @Override |
| public WatchEvent.Kind<T> kind() { |
| return kind; |
| } |
| |
| @Override |
| public T context() { |
| return context; |
| } |
| |
| @Override |
| public int count() { |
| return count; |
| } |
| |
| // for repeated events |
| void increment() { |
| count++; |
| } |
| } |
| } |