| /* |
| * Copyright 2007 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 com.sun.jmx.event; |
| |
| import com.sun.jmx.remote.util.ClassLogger; |
| import java.util.concurrent.Executor; |
| import java.util.concurrent.RejectedExecutionException; |
| |
| /** |
| * <p>A task that is repeatedly run by an Executor. The task will be |
| * repeated as long as the {@link #isSuspended()} method returns true. Once |
| * that method returns false, the task is no longer executed until someone |
| * calls {@link #resume()}.</p> |
| * @author sjiang |
| */ |
| public abstract class RepeatedSingletonJob implements Runnable { |
| public RepeatedSingletonJob(Executor executor) { |
| if (executor == null) { |
| throw new NullPointerException("Null executor!"); |
| } |
| |
| this.executor = executor; |
| } |
| |
| public boolean isWorking() { |
| return working; |
| } |
| |
| public void resume() { |
| |
| synchronized(this) { |
| if (!working) { |
| if (logger.traceOn()) { |
| logger.trace("resume", ""); |
| } |
| working = true; |
| execute(); |
| } |
| } |
| } |
| |
| public abstract void task(); |
| public abstract boolean isSuspended(); |
| |
| public void run() { |
| if (logger.traceOn()) { |
| logger.trace("run", "execute the task"); |
| } |
| try { |
| task(); |
| } catch (Exception e) { |
| // A correct task() implementation should not throw exceptions. |
| // It may cause isSuspended() to start returning true, though. |
| logger.trace("run", "failed to execute the task", e); |
| } |
| |
| synchronized(this) { |
| if (!isSuspended()) { |
| execute(); |
| } else { |
| if (logger.traceOn()) { |
| logger.trace("run", "suspend the task"); |
| } |
| working = false; |
| } |
| } |
| |
| } |
| |
| private void execute() { |
| try { |
| executor.execute(this); |
| } catch (RejectedExecutionException e) { |
| logger.warning( |
| "setEventReceiver", "Executor threw exception", e); |
| throw new RejectedExecutionException( |
| "Executor.execute threw exception -" + |
| "should not be possible", e); |
| // User-supplied Executor should not be configured in a way that |
| // might cause this exception, for example if it is shared between |
| // several client objects and doesn't have capacity for one job |
| // from each one. CR 6732037 will add text to the spec explaining |
| // the problem. The rethrown exception will propagate either out |
| // of resume() to user code, or out of run() to the Executor |
| // (which will probably ignore it). |
| } |
| } |
| |
| private boolean working = false; |
| private final Executor executor; |
| |
| private static final ClassLogger logger = |
| new ClassLogger("javax.management.event", "RepeatedSingletonJob"); |
| } |