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The ACT full stack MVC framework
package act.db.util;
/*-
* #%L
* ACT Framework
* %%
* Copyright (C) 2014 - 2017 ActFramework
* %%
* 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.
* #L%
*/
import act.app.DbServiceManager;
import act.conf.AppConfig;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicLong;
/**
* Define the interface that can generate next or retrieve current sequence number
*/
public interface _SequenceNumberGenerator {
/**
* Generate next sequence number
* @param name the name of the sequence
* @return the next sequence number
*/
long next(String name);
/**
* Returns the current sequence number
* @param name the name of the sequence
* @return the current sequence number
*/
long get(String name);
/**
* Configure the sequence generator
*/
void configure(AppConfig config, DbServiceManager dbManager);
class InMemorySequenceNumberGenerator implements _SequenceNumberGenerator {
private ConcurrentMap seqs = new ConcurrentHashMap();
@Override
public long next(String name) {
return getSeq(name).getAndIncrement();
}
@Override
public long get(String name) {
return getSeq(name).get();
}
private AtomicLong getSeq(String name) {
AtomicLong al = seqs.get(name);
if (null == al) {
AtomicLong newAl = new AtomicLong(0);
al = seqs.putIfAbsent(name, newAl);
if (null == al) {
al = newAl;
}
}
return al;
}
@Override
public void configure(AppConfig config, DbServiceManager dbManager) {
// do nothing configuration
}
}
}