1 /* 2 * Copyright 2018 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 package org.webrtc; 12 13 import androidx.annotation.Nullable; 14 import java.util.concurrent.atomic.AtomicInteger; 15 16 /** 17 * Implementation of RefCounted that executes a Runnable once the ref count reaches zero. 18 */ 19 class RefCountDelegate implements RefCounted { 20 private final AtomicInteger refCount = new AtomicInteger(1); 21 private final @Nullable Runnable releaseCallback; 22 23 /** 24 * @param releaseCallback Callback that will be executed once the ref count reaches zero. 25 */ RefCountDelegate(@ullable Runnable releaseCallback)26 public RefCountDelegate(@Nullable Runnable releaseCallback) { 27 this.releaseCallback = releaseCallback; 28 } 29 30 @Override retain()31 public void retain() { 32 int updated_count = refCount.incrementAndGet(); 33 if (updated_count < 2) { 34 throw new IllegalStateException("retain() called on an object with refcount < 1"); 35 } 36 } 37 38 @Override release()39 public void release() { 40 int updated_count = refCount.decrementAndGet(); 41 if (updated_count < 0) { 42 throw new IllegalStateException("release() called on an object with refcount < 1"); 43 } 44 if (updated_count == 0 && releaseCallback != null) { 45 releaseCallback.run(); 46 } 47 } 48 49 /** 50 * Tries to retain the object. Can be used in scenarios where it is unknown if the object has 51 * already been released. Returns true if successful or false if the object was already released. 52 */ safeRetain()53 boolean safeRetain() { 54 int currentRefCount = refCount.get(); 55 while (currentRefCount != 0) { 56 if (refCount.weakCompareAndSet(currentRefCount, currentRefCount + 1)) { 57 return true; 58 } 59 currentRefCount = refCount.get(); 60 } 61 return false; 62 } 63 } 64