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Subject: Re: [Boost-users] boost::mutex synchronization problem
From: Anthony Williams (anthony.ajw_at_[hidden])
Date: 2009-05-05 16:32:14

Ovanes Markarian <om_boost_at_[hidden]> writes:

>> On Tue, May 5, 2009 at 12:42 PM, Anthony Williams <anthony.ajw_at_[hidden]>
>> wrote:
>> Zachary Turner <divisortheory_at_[hidden]> writes:
>> > I've been trying to figure out if there's a simple way using condition
>> > variables and mutexes to design a function with the following properties
>> > (cliffs notes first, and then longer version in case it's not enough
>> info):
>> >
>> > 1) there is a section of code in the function such that two threads
>> cannot
>> > enter that section at the same time.
>> > 2) after leaving the section of code, the thread should wait for
>> something to
>> > happen (signalled by another thread)
>> > 3) the waits in step 2 should be awoken in the order they occured.
>> There's nothing in boost to do this. I remember a thread on
>> comp.programming.threads about a FIFO mutex (which is what you seem to
>> want). Someone provided an implementation (which may well do what you
>> want), but the consensus seemed to be "don't do that". If your program
>> behaviour depends on threads being woken in a specific order then it may
>> be better to rewrite the code so it doesn't.

> Is not barrier suitable for that?

No. Barrier forces N threads to wait until all N have reached the
barrier, then releases them all.


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