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Re: WaitForMultipleObjects() analog? [message #16135 is a reply to message #16106]

Wed, 28 May 2008 22:19

Mindtraveller
Messages: 917
Registered: August 2007
Location: Russia, Moscow rgn.

Experienced Contributor

hojtsy wrote on Wed, 28 May 2008 12:16

Mindtraveller,

What are you trying to achieve with multiple Semaphores? I would expect that an alternative implementation could use Monitors. These are fancy mutexes which also have Wait and Pulse methods.
I am working on a U++ example code which uses Monitors to implement a Producer-Consumer queue.

See the concept explained in http://www.albahari.com/threading/part4.html

Hojtsy

I just didn`t fully understand about Monitors usage as we don`t have ones in U++ for now.
Then about waiting a number of Semaphores. Let`s imagine the real world application. Your program must heavily work with a number of devices attached to serial port (or ethernet or something else). Of course it is solved by adding a class which creates new thread and have cycle which is sleeping most of time. But there is a number of awake signal types. And these signals could be activated from within: this thread, OS and main thread. These signals are:

application close event. sleeping i/o thread should do finalization and close.
OS i/o event. sleeping thread should handle the fact of newly sent or received data.
queue event. sleeping thread just got a new task to do. this task was added by another thread.
timer event (timeout). happens when system i/o functions didn`t respond in time or final value of some deferred OS call didn`t arive in time.

These events are dramatically different from each other and when my thread is awakened I should know the type of this event to handle it. So I use one synchronization object (let`s say Semaphore for simplicity) for each event type. Doing this with one Semaphore would be a nightmare, wouldn`t it?

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[Message index]

		WaitForMultipleObjects() analog? By: Mindtraveller on Thu, 20 March 2008 00:53
		Re: WaitForMultipleObjects() analog? By: mirek on Sun, 23 March 2008 08:36
		Re: WaitForMultipleObjects() analog? By: Mindtraveller on Fri, 25 April 2008 03:35
		Re: WaitForMultipleObjects() analog? By: hojtsy on Wed, 28 May 2008 10:16
		Re: WaitForMultipleObjects() analog? By: Mindtraveller on Wed, 28 May 2008 22:19
		Re: WaitForMultipleObjects() analog? By: hojtsy on Thu, 29 May 2008 15:12
		Re: WaitForMultipleObjects() analog? By: Mindtraveller on Thu, 29 May 2008 20:32

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