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Subject: Re: [boost] [next gen future-promise] What to call themonadicreturntype?
From: Gottlob Frege (gottlobfrege_at_[hidden])
Date: 2015-05-27 12:21:52

On Tue, May 26, 2015 at 5:29 AM, Niall Douglas
<s_sourceforge_at_[hidden]> wrote:
> On 26 May 2015 at 3:50, Gottlob Frege wrote:
>> Alternatively, with a lock in each and pointers pointing to each other, you
>> avoid deadlock by first setting (via CAS) your own state to be "I'm moving"
>> then (if successful) setting your partner's flag to "see ya later", then
>> (if successful) moving.
>> No one moves without telling the other first. You can get a live lock, but
>> not a dead lock. The live Lock can be dealt with (particularly easily since
>> the relationship (promise vs future) is asymmetrical - just say future
>> always goes first, for example).
> I found via empirical testing that the number of occasions when two
> threads both access promise and future concurrently is extremely
> rare. The stupidly simple method of locking both for every access I
> didn't find was a problem. And it's easy to test, and verify with the
> thread sanitiser.

Same algorithm though, right?

Lock yourself, then try to lock your partner, unlock yourself if you
can't lock your partner, repeat?

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