首页 \ 问答 \ 使用Java AtomicStampedReference的算法可以被认为是非阻塞的吗？(Can algorithm using Java AtomicStampedReference can be considered non-blocking?)

使用Java AtomicStampedReference的算法可以被认为是非阻塞的吗？(Can algorithm using Java AtomicStampedReference can be considered non-blocking?)

 我正在尝试使用Java实现此处所述的非阻塞二进制搜索树 。 该算法基于单世界CAS，但是：  
 
  状态和信息字段一起存储在CAS对象中。 因此，内部节点使用四个字的存储器。  
 
 我决定使用AtomicStampedReference来存储这些数据。 问题在于它  
 
  通过创建表示“盒装”[引用，整数]对的内部对象来维护标记引用。  
 
 这种结构的内部实施：  
public boolean compareAndSet(V   expectedReference,
                             V   newReference,
                             int expectedStamp,
                             int newStamp) {
    Pair<V> current = pair;
    return
        expectedReference == current.reference &&
        expectedStamp == current.stamp &&
        ((newReference == current.reference &&
          newStamp == current.stamp) ||
         casPair(current, Pair.of(newReference, newStamp)));
}
 
 对定义为：  
private static class Pair<T> {
    final T reference;
    final int stamp;
    private Pair(T reference, int stamp) {
        this.reference = reference;
        this.stamp = stamp;
    }
    static <T> Pair<T> of(T reference, int stamp) {
        return new Pair<T>(reference, stamp);
    }
}
 
 这种实现是否仍然是非阻塞的？  
 还有一个额外的问题：什么使compareAndSet操作成为原子？ 

I'm trying to implement non-blocking binary search tree as described here using Java. This algorithm is based on single-world CAS but: 
 
 The state and info fields are stored together in a CAS object. Thus, an internal node uses four words of memory. 
 
I decided to use AtomicStampedReference to store this data. The problem is that it 
 
 maintains stamped references by creating internal objects representing "boxed" [reference, integer] pairs. 
 
Internal implementation of this structure: 
public boolean compareAndSet(V   expectedReference,
                             V   newReference,
                             int expectedStamp,
                             int newStamp) {
    Pair<V> current = pair;
    return
        expectedReference == current.reference &&
        expectedStamp == current.stamp &&
        ((newReference == current.reference &&
          newStamp == current.stamp) ||
         casPair(current, Pair.of(newReference, newStamp)));
}
 
Pair defined as: 
private static class Pair<T> {
    final T reference;
    final int stamp;
    private Pair(T reference, int stamp) {
        this.reference = reference;
        this.stamp = stamp;
    }
    static <T> Pair<T> of(T reference, int stamp) {
        return new Pair<T>(reference, stamp);
    }
}
 
Is this implementation still non-blocking?  
And the extra question: what's making this compareAndSet operation atomic ?

原文：https://stackoverflow.com/questions/23529087

更新时间：2024-01-29 11:01

最满意答案

 Firebase有一个AuthError枚举，告诉您FirebaseException中每个ErrorCode的含义，文档位于： https ：//firebase.google.com/docs/reference/unity/namespace/firebase/auth  
 要用西班牙语获取错误消息，我这样做：  
public static string GetErrorMessage(Exception exception)
{
    Debug.Log(exception.ToString());
    Firebase.FirebaseException firebaseEx = exception as Firebase.FirebaseException;
    if (firebaseEx != null)
    {
        var errorCode = (AuthError)firebaseEx.ErrorCode;
        return GetErrorMessage(errorCode);
    }

    return exception.ToString();
}

private static string GetErrorMessage(AuthError errorCode)
{
    var message = "";
    switch (errorCode)
    {
        case AuthError.AccountExistsWithDifferentCredentials:
            message = "Ya existe la cuenta con credenciales diferentes";
            break;
        case AuthError.MissingPassword:
            message = "Hace falta el Password";
            break;
        case AuthError.WeakPassword:
            message = "El password es debil";
            break;
        case AuthError.WrongPassword:
            message = "El password es Incorrecto";
            break;
        case AuthError.EmailAlreadyInUse:
            message = "Ya existe la cuenta con ese correo electrónico";
            break;
        case AuthError.InvalidEmail:
            message = "Correo electronico invalido";
            break;
        case AuthError.MissingEmail:
            message = "Hace falta el correo electrónico";
            break;
        default:
            message = "Ocurrió un error";
            break;
    }
    return message;
}

Firebase has a AuthError enum that tells you the meaning of each ErrorCode in the FirebaseException, the documentation is here: https://firebase.google.com/docs/reference/unity/namespace/firebase/auth 
To get the error message in Spanish I am doing this: 
public static string GetErrorMessage(Exception exception)
{
    Debug.Log(exception.ToString());
    Firebase.FirebaseException firebaseEx = exception as Firebase.FirebaseException;
    if (firebaseEx != null)
    {
        var errorCode = (AuthError)firebaseEx.ErrorCode;
        return GetErrorMessage(errorCode);
    }

    return exception.ToString();
}

private static string GetErrorMessage(AuthError errorCode)
{
    var message = "";
    switch (errorCode)
    {
        case AuthError.AccountExistsWithDifferentCredentials:
            message = "Ya existe la cuenta con credenciales diferentes";
            break;
        case AuthError.MissingPassword:
            message = "Hace falta el Password";
            break;
        case AuthError.WeakPassword:
            message = "El password es debil";
            break;
        case AuthError.WrongPassword:
            message = "El password es Incorrecto";
            break;
        case AuthError.EmailAlreadyInUse:
            message = "Ya existe la cuenta con ese correo electrónico";
            break;
        case AuthError.InvalidEmail:
            message = "Correo electronico invalido";
            break;
        case AuthError.MissingEmail:
            message = "Hace falta el correo electrónico";
            break;
        default:
            message = "Ocurrió un error";
            break;
    }
    return message;
}

使用Java AtomicStampedReference的算法可以被认为是非阻塞的吗？(Can algorithm using Java AtomicStampedReference can be considered non-blocking?)

最满意答案

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