/**
* Copyright 2011-2014 Asakusa Framework Team.
*
* Licensed 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 com.asakusafw.yaess.jobqueue;
import java.util.Arrays;
import java.util.Collection;
import com.asakusafw.yaess.jobqueue.client.JobClient;
/**
* Provides a {@link JobClient}.
* @since 0.2.6
*/
public class JobClientProvider {
private final JobClient[] clients;
private final boolean[] blackList;
private int location;
/**
* Creates a new instance.
* @param clients the components
* @throws IllegalArgumentException if {@code clients} was null or empty
*/
public JobClientProvider(Collection<? extends JobClient> clients) {
if (clients == null) {
throw new IllegalArgumentException("clients must not be null"); //$NON-NLS-1$
}
if (clients.isEmpty()) {
throw new IllegalArgumentException("clients must not be empty"); //$NON-NLS-1$
}
this.clients = clients.toArray(new JobClient[clients.size()]);
this.blackList = new boolean[clients.size()];
this.location = 0;
}
/**
* Returns the number of available clients.
* @return the number of available clients
*/
public int count() {
return clients.length;
}
/**
* Returns a client.
* @return a client.
*/
public JobClient get() {
JobClient[] cs = clients;
boolean[] bs = blackList;
assert cs.length >= 1;
while (true) {
synchronized (cs) {
for (int i = 0; i < cs.length; i++) {
JobClient client = cs[location];
boolean enabled = blackList[location] == false;
location = (location + 1) % cs.length;
if (enabled) {
return client;
}
}
}
// clear black list
synchronized (cs) {
Arrays.fill(bs, false);
}
}
}
/**
* Tells the error occurred while using the client.
* @param client the client which was failed
* @throws IllegalArgumentException if some parameters were {@code null}
*/
public void setError(JobClient client) {
if (client == null) {
throw new IllegalArgumentException("client must not be null"); //$NON-NLS-1$
}
int index = -1;
JobClient[] cs = clients;
for (int i = 0; i < cs.length; i++) {
if (cs[i] == client) {
index = i;
break;
}
}
if (index >= 0) {
boolean[] bs = blackList;
synchronized (cs) {
bs[index] = true;
}
}
}
}