Subject:
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Re: signals / legOS internals
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Wed, 23 Jun 1999 19:31:31 GMT
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Viewed:
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1021 times
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On Wed, 23 Jun 1999, Ola Liljedahl wrote:
> Why signals?!?
>
> Unix-style asynchronous signals is the last feature I would
> ever want to implement or use. Brain-dead and very dangerous
> "feature". As you write; "The problem is that a signal can
> happen at any time". You shouldn't pass this problem on to the
> application writer, it should be handled in the kernel and
> reliable (synchronous) mechanisms (for instance semaphores,
> message queues or OSE style message passing) should be presented
> to the application.
An asynchronous signal models a hardware interrupt. There are times when
that is the appropriate interface. There are times when other interfaces
are less error prone and are easier to write correctly. Frequently using
only synchronous communication involves creating additional buffer threads.
The additional overhead for such an approach is not always justified.
John A. Tamplin Traveller Information Services
jat@LiveOnTheNet.COM 2104 West Ferry Way
256/705-7007 - FAX 256/705-7100 Huntsville, AL 35801
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Message has 1 Reply:
 | | Re: signals / legOS internals
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| (...) But hardware interrupts schedule a different context (the interrupt process or ISR) from the one already executing. A Unix-style signal asynchronously signal interrupts the executing process and jumps to a different location in the code that (...) (25 years ago, 23-Jun-99, to lugnet.robotics.rcx.legos)
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Message is in Reply To:
| | Re: signals / legOS internals
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| (...) Why signals?!? Unix-style asynchronous signals is the last feature I would ever want to implement or use. Brain-dead and very dangerous "feature". As you write; "The problem is that a signal can happen at any time". You shouldn't pass this (...) (25 years ago, 23-Jun-99, to lugnet.robotics.rcx.legos)
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