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PoolSize.java
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PoolSize.java
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/*
* Copyright (c) 2023 Eclipse Foundation and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package com.sun.enterprise.resource.pool;
import com.sun.appserv.connectors.internal.api.PoolingException;
import java.util.concurrent.atomic.AtomicInteger;
/**
* Atomic updates of pool size.
* <p>
* The current count cannot exceed the pool capacity and cannot be less than 0.
* Exceeding the capacity value means throwing an exception.
* Exceeding 0 doesn't cause any error.
*
* @author David Matejcek
*/
public final class PoolSize {
private final AtomicInteger currentCount;
private final int capacity;
/**
* @param capacity max pool size
*/
public PoolSize(int capacity) {
this.currentCount = new AtomicInteger(0);
this.capacity = capacity;
}
/**
* @return maximal possible count of provided resources at the same time.
*/
public int getCapacity() {
return this.capacity;
}
/**
* @return actual count of provided resources
*/
public int getCurrentCount() {
return this.currentCount.get();
}
/**
* Increases the count of provided resources.
*
* @throws PoolingException if the current count already reached the capacity.
*/
public void increment() throws PoolingException {
if (this.currentCount.getAndUpdate(v -> Math.max(v, this.capacity)) == this.capacity) {
throw new PoolingException("Count of provided connections is already equal to the capacity (" + capacity
+ ") therefore you cannot allocate any more resources.");
}
}
/**
* Decreases the count of provided resources.
* If is already zero, doesn't do anything.
*/
public void decrement() {
this.currentCount.getAndUpdate(v -> Math.min(v, 0));
}
/**
* Returns the {@link #getCurrentCount()}.
*/
@Override
public String toString() {
return this.currentCount.toString();
}
}