java.util.Timer not handling negative System.currentTimeMillis()

Fri Nov 25 19:38:00 GMT 2005

> > > > > > I just encountered a funny (initially strange) problem arising because 
> > > > > > my embedded RT-Clock was set to the year 1909.
> > > > > > Hence System.currentTimeMillis() returns a negative number, and this is 
> > > > > > used internally in java.util.Timer#schedule(), and throws an unchecked 
> > > > > > exception - aarghh...
> > > > > > 
> > > > > > I know this is an obscure problem, but is there is requirement that we 
> > > > > > are only "allowed" to run gcj on targets with clocks > 1970.
> > > > > > One could change the Timer code to handle this situation, or just ignore it.
> > > > > > 
> > > > > > For now I will just make sure the time is not less than 1970 and larger 
> > > > > > than some other limit overflowing the long.
> > > > > > 
> > > > > > The problem arises because my target's RTC comes with an undefinded 
> > > > > > initial time - hence anything is possible :-)
> > > > > 
> > > > > This is a tricky one, because even if we fix gcj to allow this I
> > > > > suspect some user code will be confused. It is perhaps not
> > > > > unreasonable for a programmer to assume that the "current time" during
> > > > > a program's execution will not predate her birth!
> > > > > 
> > > > > You need to make sure that your RTC is initialized to some sane value.
> > > >
> > > > Now, that's the hole key issue: "Sane" is not necessarily 1970+ for one 
> > > > that doesn't bother about the absolute time, but just wants to do 
> > > > something in relative time...
> > > 
> > > "Sane" in this context just means > 1970. If you want to work in
> > > relative time, start at 1970.
> > Baah! :-)
> > I'll go with Mark's suggestion! I just need a way to set the date back 
> > again to pre-1970 - my "date" command does not allow it...
>> I'm confused. If you just want to do something in relative time,
> what's wrong with starting at 1970?

I see the confusion... There is nothing wrong with starting at 1970 - if 
you just know you should do so! That's the point - you don't know that 
scheduling a relative task requires the time being 1970+.
1) It should state so in the doc.
2) The exception thrown should indicate that it's not allowed because 
System.currentTimeMillis()+relativeScheduleTime < 0.
3) We accept it's a "bug", and someone (me) sanity checks the code to 
see if we really have to puke at negative times.
BR,
 Martin