| using J2N.Threading.Atomic; |
| using System; |
| using System.Runtime.CompilerServices; |
| |
| namespace Lucene.Net.Util |
| { |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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. |
| */ |
| |
| /// <summary> |
| /// Manages reference counting for a given object. Extensions can override |
| /// <see cref="Release()"/> to do custom logic when reference counting hits 0. |
| /// </summary> |
| public class RefCount<T> |
| { |
| private readonly AtomicInt32 refCount = new AtomicInt32(1); |
| |
| protected internal readonly T m_object; |
| |
| public RefCount(T @object) |
| { |
| this.m_object = @object; |
| } |
| |
| /// <summary> |
| /// Called when reference counting hits 0. By default this method does nothing, |
| /// but extensions can override to e.g. release resources attached to object |
| /// that is managed by this class. |
| /// </summary> |
| protected virtual void Release() |
| { |
| } |
| |
| /// <summary> |
| /// Decrements the reference counting of this object. When reference counting |
| /// hits 0, calls <see cref="Release()"/>. |
| /// </summary> |
| public void DecRef() |
| { |
| int rc = refCount.DecrementAndGet(); |
| if (rc == 0) |
| { |
| bool success = false; |
| try |
| { |
| Release(); |
| success = true; |
| } |
| finally |
| { |
| if (!success) |
| { |
| // Put reference back on failure |
| refCount.IncrementAndGet(); |
| } |
| } |
| } |
| else if (rc < 0) |
| { |
| throw new InvalidOperationException("too many DecRef() calls: refCount is " + rc + " after decrement"); |
| } |
| } |
| |
| [MethodImpl(MethodImplOptions.AggressiveInlining)] |
| public T Get() |
| { |
| return m_object; |
| } |
| |
| /// <summary> |
| /// Returns the current reference count. </summary> |
| [MethodImpl(MethodImplOptions.AggressiveInlining)] |
| public int GetRefCount() // LUCENENET NOTE: although this would be a good candidate for a property, doing so would cause a naming conflict |
| { |
| return refCount; |
| } |
| |
| /// <summary> |
| /// Increments the reference count. Calls to this method must be matched with |
| /// calls to <see cref="DecRef()"/>. |
| /// </summary> |
| [MethodImpl(MethodImplOptions.AggressiveInlining)] |
| public void IncRef() |
| { |
| refCount.IncrementAndGet(); |
| } |
| } |
| } |