From: Tomas Pospisek's Mailing Lists <tpo2@...>
Date: 2007-03-02T07:48:16+09:00
Subject: Re: replacing the use of gettimeofday in the scheduler

On Fri, 2 Mar 2007, Eric Hodel wrote:

> On Mar 1, 2007, at 13:30, Tomas Pospisek's Mailing Lists wrote:
>> On Fri, 2 Mar 2007, Eric Hodel wrote:
>>> The Ruby thread scheduler uses setitimer(2) and select(2).  It depends on 
>>> the wall-clock for implementing features defined in terms of the 
>>> wall-clock (Kernel#sleep and Thread#join).
>> 
>> You need to add Timeout#timeout to this.
>
> Nope.  Timeout calls Kernel#sleep in a thread.

Um. When I do a "timeout(5) { do_something };" and set the system clock 
back by a minute, then the timeout will not *ever* time out.

>> But:
>> 
>> $ ri Kernel#sleep
>>
>>     Suspends the current thread for _duration_ seconds (which may be
>>     any number, including a +Float+ with fractional seconds). Returns
>>     the actual number of seconds slept (rounded), which may be less
>>     than that asked for if another thread calls +Thread#run+. Zero
>>     arguments causes +sleep+ to sleep forever.
>> 
>> No reference to wall-clock in there. What do you mean by "defined in terms 
>> of the wall-clock"?
>
> When I write "sleep 5" I expect at least five seconds on the clock on my wall 
> to go by before the next statement is executed.

That's right, However this will not happen, when you change the system 
time while the 5 seconds have not gone by.
*t

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   Tomas Pospisek
   http://sourcepole.com -  Linux & Open Source Solutions
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