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/*
* Copyright 2014 Open Networking Laboratory
*
* 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 org.onosproject.core.impl;
import java.util.concurrent.atomic.AtomicBoolean;
import org.onosproject.core.IdBlock;
import org.onosproject.core.IdGenerator;
import org.onosproject.core.UnavailableIdException;
import static com.google.common.base.Preconditions.checkNotNull;
/**
* Base class of {@link IdGenerator} implementations which use {@link IdBlockAllocator} as
* backend.
*/
public class BlockAllocatorBasedIdGenerator implements IdGenerator {
protected final IdBlockAllocator allocator;
protected IdBlock idBlock;
protected AtomicBoolean initialized;
/**
* Constructs an ID generator which use {@link IdBlockAllocator} as backend.
*
* @param allocator the ID block allocator to use
*/
protected BlockAllocatorBasedIdGenerator(IdBlockAllocator allocator) {
this.allocator = checkNotNull(allocator, "allocator cannot be null");
this.initialized = new AtomicBoolean(false);
}
@Override
public long getNewId() {
try {
if (!initialized.get()) {
synchronized (allocator) {
if (!initialized.get()) {
idBlock = allocator.allocateUniqueIdBlock();
initialized.set(true);
}
}
}
return idBlock.getNextId();
} catch (UnavailableIdException e) {
synchronized (allocator) {
idBlock = allocator.allocateUniqueIdBlock();
}
return idBlock.getNextId();
}
}
}
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