'C# and thread-safety of a bool

I am very confused about this subject - whether reading/toggling a bool value is thread-safe.

    // case one, nothing
    private bool v1;
    public bool V1 { get { return v1; } set { v1 = value; } }

    // case two, with Interlocked on set
    private int v2;
    public int V2 { get { return v2; } set { Interlocked.Exchange(ref v2, value); } }

    // case three, with lock on set
    private object fieldLock = new object();
    private bool v3;
    public bool V3 { get { return v3; } set { lock (fieldLock) v3 = value; } }

Are all of them thread-safe?

EDIT

From what I have read (click) atomicity of bool does not guarantee it will be thread safe. Will then volatile type help?

c++sharpmultithreadingthread-safety


Solution 1:[1]

A little bit late but should be useful to the others.

You can implement your own thread safe boolean in the following way:

// default is false, set 1 for true.
private int _threadSafeBoolBackValue = 0;

public bool ThreadSafeBool
{
    get { return (Interlocked.CompareExchange(ref _threadSafeBoolBackValue, 1, 1) == 1); }
    set
    {
        if (value) Interlocked.CompareExchange(ref _threadSafeBoolBackValue, 1, 0);
        else Interlocked.CompareExchange(ref _threadSafeBoolBackValue, 0, 1);
    }
}

Be sure to use Property everywhere, never access int variable directly.

Solution 2:[2]

Nope, it isn't. But the solution is quite easy. To make a bool (or anything, actually) thread safe, it's easy to use lock statement like this:

object locker = new object();
protected bool _somebool;
public bool Somebool
{
    get
    {
        lock (locker)
            return _somebool;
    }
    set
    {
        lock (locker)
            _somebool = value;
    }
}

Now you may enjoy your thread safe of <T>.

Sources

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Source: Stack Overflow

Solution Source
Solution 1 lilo0
Solution 2 Theodor Zoulias

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