Hi folks,

Is there a GetAndSet function (corresponding to cas (compare and set) function) in D?

Thanks.

On 12/25/2011 09:25 AM, Adrian Mercieca wrote:
> Hi folks,
>
> Is there a GetAndSet function (corresponding to cas (compare and set)
> function) in D?
>
> Thanks.

core.atomic.cas

http://dlang.org/phobos/core_atomic.html#cas

-- 
Mike Wey

On Sun, 25 Dec 2011 13:37:32 +0100, Mike Wey wrote:

> On 12/25/2011 09:25 AM, Adrian Mercieca wrote:
>> Hi folks,
>>
>> Is there a GetAndSet function (corresponding to cas (compare and set)
>> function) in D?
>>
>> Thanks.
> 
> core.atomic.cas
> 
> http://dlang.org/phobos/core_atomic.html#cas

I know of the cas function in D.

I was asking if there was a getAndSet function.

Tks.

Hi folks,

Would anyone answer me on this please?

To clarify, in Java there is are getAndSet methods on Atomic type objects (along with compareAndSet).

I know that in D there is the cas function (equivalent to Java's compareAndSet); is there an equivalent D function for Java's getAndSet please?


Thanks.

On Mon, Dec 26, 2011 at 2:34 PM, Adrian Mercieca <amercieca@gmail.com> wrote:
> Hi folks,
>
> Would anyone answer me on this please?
>
> To clarify, in Java there is are getAndSet methods on Atomic type objects
> (along with compareAndSet).
>
> I know that in D there is the cas function (equivalent to Java's compareAndSet); is there an equivalent D function for Java's getAndSet please?
>
>
> Thanks.

>From Java:
---
    public final boolean getAndSet(boolean newValue) {
        for (;;) {
            boolean current = get();
            if (compareAndSet(current, newValue))
                return current;
        }
    }
---

getAndSet is just a wrapped version of compareAndSet.

On Monday, December 26, 2011 20:34:39 Adrian Mercieca wrote:
> Hi folks,
> 
> Would anyone answer me on this please?
> 
> To clarify, in Java there is are getAndSet methods on Atomic type objects
> (along with compareAndSet).
> 
> I know that in D there is the cas function (equivalent to Java's compareAndSet); is there an equivalent D function for Java's getAndSet please?

If it's not in core.atomic, then probably not. It has atomicLoad and atomicStore, but I don't see anything that tries to combine the two, assuming that that's what you want be getAndSet.

- Jonathan M Davis

On Mon, Dec 26, 2011 at 4:05 PM, Jonathan M Davis <jmdavisProg@gmx.com> wrote:
> On Monday, December 26, 2011 20:34:39 Adrian Mercieca wrote:
>> Hi folks,
>>
>> Would anyone answer me on this please?
>>
>> To clarify, in Java there is are getAndSet methods on Atomic type objects
>> (along with compareAndSet).
>>
>> I know that in D there is the cas function (equivalent to Java's compareAndSet); is there an equivalent D function for Java's getAndSet please?
>
> If it's not in core.atomic, then probably not. It has atomicLoad and atomicStore, but I don't see anything that tries to combine the two, assuming that that's what you want be getAndSet.

getAndSet can easily be implemented as a utility method using cas and atomicLoad. It's not a primitive atomic operation, it's just a convenience function.

T getAndSet(T)(shared(T)* location, T newValue) {
    while(1) {
        auto current = atomicLoad(*location);
        if(cas(location, current, newValue))
            return current;
    }
}

Someone who knows more about the options to atomicLoad could probably make this faster, but because we're using cas, it's guaranteed to be correct.

On Mon, 26 Dec 2011 15:06:57 -0600, Andrew Wiley wrote:

> On Mon, Dec 26, 2011 at 2:34 PM, Adrian Mercieca <amercieca@gmail.com> wrote:
>> Hi folks,
>>
>> Would anyone answer me on this please?
>>
>> To clarify, in Java there is are getAndSet methods on Atomic type
>> objects (along with compareAndSet).
>>
>> I know that in D there is the cas function (equivalent to Java's compareAndSet); is there an equivalent D function for Java's getAndSet please?
>>
>>
>> Thanks.
> 
>>From Java:
> ---
>     public final boolean getAndSet(boolean newValue) {
>         for (;;) {
>             boolean current = get();
>             if (compareAndSet(current, newValue))
>                 return current;
>         }
>     }
> ---
> 
> getAndSet is just a wrapped version of compareAndSet.


Hi Andrew,

It is indeed; should have thought of that.

Anyway, thanks for pointing it out.

Regards.

Hi Andrew,

Actually, what would be the equivalent of the 'get' function in D?

Thanks.