| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 2293.1 | Using ASTs? | HELENA::ORGOVAN | Vince Orgovan | Fri Feb 16 1990 17:16 | 2 |
| I think it's possible to get that error if you accidently call
into Dwtlib at user AST level. Any chance that's the problem?
|
| 2293.2 | See 2224.1 | LEOVAX::TREGGIARI | | Sat Feb 17 1990 07:58 | 3 |
| Also see 2224.1.
Leo
|
| 2293.3 | AST's were the problem ,but now....
| SHARIF::BULLARD | Charlie's retiired 9-NOV-1989 !! | Thu Mar 01 1990 10:35 | 47 |
| Thanks for the replies the customer was using the routine from an AST
which explains the problem.As I understand it it is only possible
to use XLib at the AST level.So I set about modifying the routine
to only use XLib.
void wndw_flush (display_id,widget_id)
Display *display_id;
Widget widget_id;
{
char event_not_wip_expose;
Window *wipwindow;
XEvent event;
XFlush (display_id);
wipwindow = XtWindow (widget_id);
event_not_wip_expose = XPeekEvent (display_id,&event);
while (event_not_wip_expose) {
XNextEvent (display_id,&event) ;
XSendEvent (display_id,wipwindow,FALSE,FALSE,&event);
if (event.xexpose.type == Expose &&
event.xexpose.window == wipwindow &&
event.xexpose.count == 0) {
event_not_wip_expose = FALSE ;
} else {
event_not_wip_expose = XPeekEvent (display_id,&event);
}
} XFlush (display_id);
}
This use of XSendEvent has been documented before which is where I got
the information from.However now the expose event to put text into
my Work In Progress Box does not appear until I return to XtMainLoop,
despite several XFlushes .
Any ideas
regards Mark
|
| 2293.4 | This may just be plain impossible | FEGPX::SWEENEY | Patrick Sweeney in Hong Kong | Tue Mar 06 1990 06:06 | 34 |
| "As I understand it it is only possible to use XLib at the AST level."
One possible parse of this sentence is "one can use Xlib at ONLY the AST
level (and not at non-AST level)" Clearly, this is incorrect.
Another one is "one can use ONLY Xlib (and not the toolkit) at AST
level". Well, I for one don't think Xlib works reliably from the AST
level either.
Many notes have been written on this topic. Unfortunately, the
conference doesn't have a keyword "AST".
Calling Xlib from AST level is not supported in the SPD for DECwindows.
Which is really the only description for the level of support that you
should rely on for you customer.
The claim that the current VMS/DECwindows version of Xlib is AST-reentrant
has been qualified or completely refuted depending on whom you ask.
Pragmatically, you may be able to work around the immediate problem of
why Xlib doesn't flush when so told, but long-term prospects for
support and maintenance of such a program frighten me.
It's my guess (and I don't have access to sources) that Xlib sets a
flag early with the semantics of "Xlib has been called already", and
when a request arrives that flag is checked and the request is queued
without any processing. That flag is cleared after the user AST routine
returns and the non-AST thread of execution continues inside Xlib until
Xlib returns to the user. In a toolkit based application, that would
be observed as XtMainLoop.
Were it true, allowing Xlib to be reentered seems to me quite a feat of
installing interlocks on lots of data structures.
to be quite
|
| 2293.5 | | DECWIN::JMSYNGE | James M Synge, VMS Development | Tue Mar 06 1990 11:50 | 18 |
| Re: .3
I'm not sure I understand the intent of your wndw_flush routine. Can
you please explain your (customer's) goal more clearly.
>This use of XSendEvent has been documented before which is where I got
>the information from.
Can you point me to where this is documented?
>However now the expose event to put text into
>my Work In Progress Box does not appear until I return to XtMainLoop,
>despite several XFlushes .
You don't need to do several XFlushes. One will be enough. They
really do cause a flush to occur.
James
|
| 2293.6 | | PSW::WINALSKI | Careful with that VAX, Eugene | Wed Mar 07 1990 16:17 | 6 |
| RE: .4
Last time I looked, Xlib was *intended* to be AST-reentrant, but was not, due
to a bug or two.
--PSW
|
| 2293.7 | | STAR::KLEINSORGE | Fred Kleinsorge, VMS Development | Tue Mar 13 1990 13:42 | 14 |
|
Having written a lot of code (for UISX) that depends on Xlib to be
AST-reentrant, I can tell you that it "mostly" works. It has varied
up and down from release to release, but looks reasonably good in
V5.3-1 and V5.4. There are some problems that may be impossible to
get around in V1 servers, and even in the V5.3 server (i.e. late
event AST's after a connection closure). The UISX product had to
drop it's intention of supporting V5.1 and later because of some of
these problems and support only V5.3 and later.
I know it was meant to be AST reeentrant (I think a very important
customer kind-of required it).
_Fred
|