[DUG]Timers

[John Bird]

What everyone is saying is as I hoped, that if I prefer the simple dumb and
safe default situation of one timer needs to finish operation before any
other fires then I don't need to take special precautions.

On the other hand if I put an Application.processmessages in the timer loop,
then it may well fire the other one in the middle, and I should be careful
about the timers interacting.

John



-----Original Message-----
From: delphi-bounces at ns3.123.co.nz [mailto:delphi-bounces at ns3.123.co.nz] On
Behalf Of Leigh Wanstead
Sent: Tuesday, 7 March 2006 10:40 a.m.
To: NZ Borland Developers Group - Delphi List
Subject: RE: [DUG]Timers


Hi Matt and Stefan,

Both of you are right. I just make a project to test that. Just rename the
attachment to timer.zip and unzip to a folder. It is a Delphi 7 project.

Now I realized that the importance of processmessages. ;-)

Regards
Leigh

-----Original Message-----
From: delphi-bounces at ns3.123.co.nz [mailto:delphi-bounces at ns3.123.co.nz]On
Behalf Of Matthew Comb
Sent: Tuesday, 7 March 2006 10:20 a.m.
To: leighw at softtech.co.nz; NZ Borland Developers Group - Delphi List
Cc: NZ Borland Developers Group - Delphi List; Delphi at ns3.123.co.nz
Subject: RE: [DUG]Timers


Delphi Timers are not threaded.

if you have two timers and put a sleep of 30 seconds in one, the time event
for the other will not fire until the first is completed. They are run in
the main application thread and are sequential.

One way you can counter this is if you have a loop in the first timer event,
you can call application.processmessages which would allow the message to
get through to the second timer.

Threaded timers are a completely different story.

Matt.




> Hi John,
>
> It won't hold up others.
>
> You must be very careful  of in modifying variables shared between the 
> two timers. You can use some sorts of locking code to do that.
>
> Regards
> Leigh
> New Zealand's largest stabilizer manufacturer for camera 
> http://www.SmoothArm.com
>
> -----Original Message-----
> From: delphi-bounces at ns3.123.co.nz 
> [mailto:delphi-bounces at ns3.123.co.nz]On Behalf Of John Bird
> Sent: Tuesday, 7 March 2006 9:59 a.m.
> To: 'NZ Borland Developers Group - Delphi List'
> Subject: [DUG]Timers
>
>
> If I have two timers active in a program, and occasionally one of them 
> takes a while to execute its code, does it hold up the other timer 
> from firing until it is done?
>
> Or phrased another way can I think of two timers as if running in 
> separate threads, or in the same thread, so that one finishes before 
> the other can get a chance to run.
>
> The reason I am wondering is if there are any issues to be careful of 
> in modifying variables shared between the two timers.
>
> John
>
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