Re: Threading synchronization: does a primitive exists?
Re: Threading synchronization: does a primitive exists?
- Subject: Re: Threading synchronization: does a primitive exists?
- From: eveningnick eveningnick <email@hidden>
- Date: Thu, 05 May 2011 22:08:13 +0300
Ken,
Thanks for a detailed response
Still not sure how would it be possible to do using NSConditionLock,
but i managed to do it using NSCondition :)
2011/5/5 Ken Thomases <email@hidden>:
> On May 5, 2011, at 8:51 AM, eveningnick eveningnick wrote:
>
>> 2011/5/5 Heath Borders <email@hidden>:
>>> Try NSConditionLock. Its documentation should be pretty self-explanatory.
>>>
>>
>> Health,
>> thanks for the response.
>> However, i can't see how can i use NSConditionLock in my situation.
>> For every lock (or mutex/semaphore - which essentially is the same) i
>> need to acquire it 1 time at least to stop the the thread when a
>> second attempt to acquire it from a different thread is made.
>> What i need - is to stop the thread A immediately after the thread B
>> has been spawned by a thread A. I am afraid if i acquire the lock from
>> A, and then acquire it as soon as B starts (in B routine), the thread
>> A may even finish before the thread B _actually_ starts (or rather B's
>> threadfunction starts executing).
>> Am i wrong somewhere here?
>
> NSConditionLock allows one to lock waiting for specific conditions. The lock can be created in an initial condition, say THREAD_B_NOT_RUNNING. Then, Thread A can spawn B and lock waiting for condition THREAD_B_RUNNING. Thread B can take the lock unconditionally and, when it's ready, unlock it with condition THREAD_B_RUNNING. Or whatever.
>
> Other possible techniques include using a pipe to send a signal byte from one thread to the other. So, thread A would do a blocking read from the pipe. Thread B would write a single byte to the pipe to signal whatever condition.
>
> There are all sorts of other approaches.
>
> Regards,
> Ken
>
>
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