/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.brooklyn.util.core.mutex;
import java.util.List;
import java.util.Set;
import org.apache.brooklyn.api.mgmt.ManagementContext;
import org.apache.brooklyn.api.mgmt.Task;
import org.apache.brooklyn.util.collections.MutableList;
import org.apache.brooklyn.util.collections.MutableSet;
import org.apache.brooklyn.util.core.task.Tasks;
import org.apache.brooklyn.util.time.Time;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
/** A subclass of {@link SemaphoreWithOwners}
* which additionally sets Task blocking information.
* <p>
* TODO As tasks are distributed this should support distribution across the management context. */
public class SemaphoreForTasks extends SemaphoreWithOwners {
private static final long serialVersionUID = 7898283056223005952L;
/** unused at present, but wanted on the API for when this may be federated */
@SuppressWarnings("unused")
private final ManagementContext mgmt;
final private MutableList<Task<?>> owningTasks = new MutableList<Task<?>>();
final private MutableSet<Task<?>> requestingTasks = new MutableSet<Task<?>>();
public SemaphoreForTasks(String name, ManagementContext mgmt) {
super(name);
this.mgmt = Preconditions.checkNotNull(mgmt);
}
public SemaphoreForTasks(String name, int permits, boolean fair, ManagementContext mgmt) {
super(name, permits, fair);
this.mgmt = Preconditions.checkNotNull(mgmt);
}
public synchronized Set<Task<?>> getRequestingTasks() {
return ImmutableSet.copyOf(requestingTasks);
}
public synchronized List<Task<?>> getOwningTasks() {
return ImmutableList.copyOf(owningTasks);
}
@Override
protected synchronized void onRequesting() {
if (!owningTasks.isEmpty() || !requestingTasks.isEmpty()) {
Tasks.setBlockingTask( !requestingTasks.isEmpty() ? Iterables.getLast(requestingTasks) : Iterables.getFirst(owningTasks, null) );
Tasks.setBlockingDetails("Waiting on semaphore "+getName()+" ("+getDescription()+"); "
+ "queued at "+Time.makeDateString()+" when "+getRequestingThreads().size()+" ahead in queue");
}
requestingTasks.addIfNotNull(Tasks.current());
super.onRequesting();
}
@Override
protected synchronized void onRequestFinished() {
super.onRequestFinished();
requestingTasks.removeIfNotNull(Tasks.current());
Tasks.resetBlockingDetails();
Tasks.resetBlockingTask();
}
@Override
protected synchronized void onAcquired(int permits) {
super.onAcquired(permits);
for (int i=0; i<permits; i++)
owningTasks.appendIfNotNull(Tasks.current());
}
@Override
protected synchronized void onReleased(int permits) {
super.onReleased(permits);
for (int i=0; i<permits; i++)
owningTasks.removeIfNotNull(Tasks.current());
}
@Override
public synchronized String toString() {
return super.toString()+"["
+ "owningTasks="+owningTasks
+ "; requestingTasks="+requestingTasks+"]";
}
}