Procedure as a Thread

BackupUser · Post by **BackupUser** » Wed Jan 29, 2003 4:51 pm

Restored from previous forum. Originally posted by TerryHough.

I have a Procedure that is working perfectly. It is called with four
parameters.

I need to make that to operate as a Thread.

But, when I try that it immediately GPFs. I cannot find the cause.

I have read most of the topics here about threads and still haven't
a clue. I suspect it has something to do with the four string
fields that are used by the Procedure as parameters. I thought
that they would be Global to the Thread. Maybe I am wrong.

Sorry, I can't post the code...

Any suggestions on how to make this work?

Thanks
Terry

BackupUser · Post by **BackupUser** » Wed Jan 29, 2003 5:03 pm

Restored from previous forum. Originally posted by PB.

> Any suggestions on how to make this work?

Not without any code!

Here's a simple example showing how to create a looping thread, which
may (or may not) help you out. It'll help newbies, anyway. If you
can post some code, it would definitely help...

Code: Select all

Procedure TimedProcedure()
  Repeat
    Delay(1000) ; Wait 1 second.
    MessageBeep_(#MB_ICONASTERISK)
  ForEver
EndProcedure
;
CreateThread(@TimedProcedure(),0)
;
OpenWindow(0,200,200,200,150,#PB_Window_SystemMenu,"Chime every second...")
CreateGadgetList(WindowID()) : ButtonGadget(0,20,20,60,20,"Click me")
Repeat
  ev=WaitWindowEvent()
  If ev=#PB_Event_Gadget
    MessageRequester("Wow","Thread is running in the background!",0)
  EndIf
Until ev=#PB_Event_CloseWindow

BackupUser · Post by **BackupUser** » Wed Jan 29, 2003 6:02 pm

Restored from previous forum. Originally posted by Pupil.

Can you atleast show how you have declared the procedure you want run as a thread, and show the CreateThread line in your code.

BackupUser · Post by **BackupUser** » Wed Jan 29, 2003 6:43 pm

Restored from previous forum. Originally posted by TerryHough.

Hmmm... I got past the GPF it appears.

The problem is that variables in the main program needed by the
Thread aren't getting there.

This is my first effort with threads, so I am probably overlooking
the obvious. Silly me, I thought that I should be able to change
a working Procedure into a Thread with minimal effort.

Thanks for the example PB. Got one that shares a variable between
the thread and the main code?

Terry

BackupUser · Post by **BackupUser** » Wed Jan 29, 2003 7:20 pm

Restored from previous forum. Originally posted by TerryHough.

Originally posted by Pupil

Can you atleast show how you have declared the procedure you want run as a thread, and show the CreateThread line in your code.

Code: Select all

Procedure GetFileFTP()
        If FtpGetFile_(hInternetConnect, FileName$,FTPDnloadDir+"\"+FileName$, 0, 
.
.snip.
.
.
        EndIf
EndProcedure

.
.snip.
.
CreateThread(@GetFileFTP(),1)
.
.

Unfortunately, the variables never get to the thread.

BackupUser · Post by **BackupUser** » Wed Jan 29, 2003 7:42 pm

Restored from previous forum. Originally posted by Rings.

i guess that it has something to do with the stringhandling from Pure.Try to use 'Normal' Memory or avoid working with strings in the thread.just a hint.

Its a long way to the top if you wanna .....CodeGuru

BackupUser · Post by **BackupUser** » Wed Jan 29, 2003 7:49 pm

Restored from previous forum. Originally posted by Danilo.

Every Thread-procedure MUST have 1 parameter,
see help for CreateThread().
Always ONE param, if you use it or not.

Code: Select all

Procedure myThread(value)  Repeat
   Beep_(800,20):Delay(80)
  ForEver
EndProcedure

CreateThread(@myThread(),0)
MessageRequester("Info","Thread running",0)

For giving more than 1 parameter, you can use structures.

Code: Select all

Procedure MyThread(*p.MyStructure)
EndProcedure

CreateThread(@MyThread(),a.MyStructure)

And Rings is right, if you use strings at the same
time in your program (in the thread and in the main loop,
or in 2 threads at the same time), the program will
all go crazy...

cya,
...Danilo
(registered PureBasic user)

BackupUser · Post by **BackupUser** » Wed Jan 29, 2003 10:03 pm

Restored from previous forum. Originally posted by TerryHough.

Originally posted by Danilo
For giving more than 1 parameter, you can use structures.

And Rings is right, if you use strings at the same
time in your program (in the thread and in the main loop,
or in 2 threads at the same time), the program will
all go crazy...

Thanks for the tip on structures Danilo. Sounds like that is
what I need. So, now I have to go learn about structures in PB.

EDITED LATER: Danilo, I haven't been able to get a structure
passed to the thread. I am a newbie to structures, so if possible
could you show the Structure definition also so I can see how it relates to this Thread call? Thanks.

I understand about simultaneous use of the strings. Sure is likely
to mess up things.

Terry

BackupUser · Post by **BackupUser** » Thu Jan 30, 2003 7:30 am

Restored from previous forum. Originally posted by Danilo.

Structure Example for Threads:

Code: Select all

Structure MyStructure  delay.l
  freq.l
  duration.l
  times.l
EndStructure

Procedure myThread(*p.MyStructure)
  For a = 0 To *p\times
   Beep_(*p\freq,*p\duration):Delay(*p\delay)
  Next a
EndProcedure

my.MyStructure
my\freq     = 800
my\duration = 100
my\times    = 10
my\delay    = 100

CreateThread(@myThread(),@my)
MessageRequester("Info","Thread running",0)

Another example with strings:

Code: Select all

Structure MyStructure
   caption.s
   message.s
EndStructure

Procedure myThread(*p.MyStructure)
   MessageRequester(*p\caption,*p\message,0)
EndProcedure

my.MyStructure
my\caption = "Information"
my\message = "Inside Thread"
Thread1 = CreateThread(@myThread(),my)

WaitThread(Thread1)

MessageRequester("Info","Thread ended",0)

cya,
...Danilo
(registered PureBasic user)

BackupUser · Post by **BackupUser** » Thu Jan 30, 2003 7:16 pm

Restored from previous forum. Originally posted by TerryHough.

Originally posted by Danilo
Structure Example for Threads:

Thanks Danilo!

That got tme started. Sometimes an example is all you really need.

The way that PB handles describing structures and pointers is very
much different than the language (largely unheard of) that I have
been using for 18 years. Trying to forget enough of that to learn
PB usage is difficult.

You example shows the WaitThread and your example works. At the
moment, my program including the thread does nothing once the Waitthread is executed. Gotta figure out why...

You must have read my mind, because I really need to have the main
program kind of idle while the thread is running until it completes.
I know, it sounds strange, but is necessary to accomplish a few
things I need to do.

Thanks again for your help.

Terry

BackupUser · Post by **BackupUser** » Fri Jan 31, 2003 10:25 pm

Restored from previous forum. Originally posted by TerryHough.

Danilo,

I want to thank you again for the example thread code using strings.
And, for your continuing imput and help on this forum.

I now have my program operating correctly, and just need a bit more
polish before releasing it to my clients general use.

I could not have done it without your input and assistance.

Terry

BackupUser · Post by **BackupUser** » Sat Feb 01, 2003 7:40 am

Restored from previous forum. Originally posted by Danilo.

You'r welcome

cya,
...Danilo
(registered PureBasic user)

Michael Vogel · Post by **Michael Vogel** » Mon Mar 20, 2006 12:59 pm

Every Thread-procedure MUST have 1 parameter,<br />see help for CreateThread().<br />Always ONE param, if you use it or not.
[...]

Silly question, is the parameter a long type variable?
What happens, if I do something like this...

Code: Select all

Procedure xxx(x.w)
...
EndProcedure

Handle=CreateThread(@xxx(),1)

;...or...

x.w=1
Handle=CreateThread(@xxx(),x)

Post by **Fred** » Mon Mar 20, 2006 1:37 pm

You are lucky in this case, as it will work. But the best is to set it as a long. Always.

Nik · Post by **Nik** » Mon Mar 20, 2006 4:27 pm

You should also be able to pass pointers since on 32 bit windows they are longs. In fact the API CreateThread uses a void* and since this is a command Fred can only wrap it should apply here too.