[lwip-users] Re: [lwip] sys_timeout()

[Adam Dunkels]

Hi Peter!

On Wednesday 17 October 2001 16:36, you wrote:
> Am I right with the following assumptions?
>
> 1. The call to sys_timeout() shall not block the calling thread.

Correct. The call will only schedule a time-out to happen some time in the 
future.

> 2. Even if the time is over, the system must not call the timeout handler
> unless the thread which called corresponding sys_timeout() blocks.

Correct again.

> 3. After finishing the timeout handler, execution continues with the thread
> that has been running before the timeout handler was invoked by the system.

There are no reqiurements of this kind - this is up to the underlying process 
scheduler in the kernel. The time-out scheduling should not be confused with 
thread scheduling, which is handled by the kernel on which lwIP is run. 

Time-outs can be implemented without thread support from any underlying 
kernel - take a look at the sys_arch code for the C64 port of lwIP in 
src/arch/6502/sys_c64.c. Here, time-outs are processed by a single function, 
sys_main(), that sits in a while(1) loop waiting for time-outs to occur.

/adam
-- 
Adam Dunkels <address@hidden>
http://www.sics.se/~adam
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