| /* |
| * 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(); |
| } |
| } |
| } |