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/*
 * Copyright 2015, Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *    * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *    * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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package org.glowroot.agent.shaded.grpc.internal;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * Base implementation for all reference counted objects.
 */
public abstract class AbstractReferenceCounted implements ReferenceCounted {
  private final AtomicInteger refCount = new AtomicInteger(1);

  @Override
  public final int referenceCount() {
    return refCount.get();
  }

  @Override
  public final ReferenceCounted retain() {
    int newCount = refCount.incrementAndGet();
    if (newCount <= 1) {
      throw illegalReferenceCount(newCount);
    }
    return this;
  }

  @Override
  public final ReferenceCounted release() {
    int newCount = refCount.decrementAndGet();
    if (newCount < 0) {
      throw illegalReferenceCount(newCount);
    }
    if (newCount == 0) {
      deallocate();
    }
    return this;
  }

  /**
   * Called once {@link #referenceCount()} is equals 0.
   */
  protected abstract void deallocate();

  private IllegalStateException illegalReferenceCount(int count) {
    throw new IllegalStateException(String.format("Illegal reference count for class %s: %d",
            getClass().getName(),
            count));
  }
}