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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;
import com.google.common.base.MoreObjects;
import java.util.concurrent.atomic.AtomicLong;
import static com.google.common.base.Preconditions.checkArgument;
/**
* A class representing an ID space.
*/
public final class IdBlock {
private final long start;
private final long size;
private final AtomicLong currentId;
/**
* Constructs a new ID block with the specified size and initial value.
*
* @param start initial value of the block
* @param size size of the block
* @throws IllegalArgumentException if the size is less than or equal to 0
*/
public IdBlock(long start, long size) {
checkArgument(size > 0, "size should be more than 0, but %s", size);
this.start = start;
this.size = size;
this.currentId = new AtomicLong(start);
}
/**
* Returns the initial value.
*
* @return initial value
*/
private long getStart() {
return start;
}
/**
* Returns the last value.
*
* @return last value
*/
private long getEnd() {
return start + size - 1;
}
/**
* Returns the block size.
*
* @return block size
*/
public long getSize() {
return size;
}
/**
* Returns the next ID in the block.
*
* @return next ID
* @throws UnavailableIdException if there is no available ID in the block.
*/
public long getNextId() {
final long id = currentId.getAndIncrement();
if (id > getEnd()) {
throw new UnavailableIdException(String.format(
"used all IDs in allocated space (size: %d, end: %d, current: %d)",
size, getEnd(), id
));
}
return id;
}
@Override
public String toString() {
return MoreObjects.toStringHelper(getClass())
.add("start", start)
.add("size", size)
.add("currentId", currentId)
.toString();
}
}
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