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RE: [cdt-dev] CDI - Variables and Expressions views are generatingunnecessary requests
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Hi Laurent,
The variables and expressions are evaluated lazily. At
least that's how it is supposed to work. If you can provide a simple test case
and submit it to bugzilla I can track the problem you are
seeing.
The evaluation of an _expression_ is different than of a
variable for a simple reason: the _expression_ is evaluated for all active
contexts (stack frames), variables only for the context they are created
in.
Regards,
Mikhail
Greetings.
I have a
pointer lcb (large control block) to a large structure, that contains 201
elements. I have a breakpoint on a function that takes lcb as a
parameter.
I have
two concerns (this is with CDI):
a) When I
stop at the breakpoint, even if lcb is collapsed, and (sometimes even if the
Variables view is not active), I see a ptype lcb request being sent on the MI
interface.
[1,239,842,202,394] 2761 ptype
lcb
[1,239,842,202,395] ~"ptype lcb\n"
[1,239,842,202,399] ~"type = struct
largedata_ {\n"
>>> followed by 201
elements.
My
concern is that the response generates a lot of traffic. Which can
introduce a significant delay on a slow interface.
If lcb is
also added to the Expressions view, I see two additional
ptypes
[1,239,852,566,876] 4066-var-create - *
lcb
[1,239,852,566,885]
4066^done,name="var139",numchild="201",type="largedata *"
[1,239,852,566,885]
(gdb)
[1,239,852,566,885] 4067 ptype largedata *
[1,239,852,566,886]
~"ptype largedata *\n"
[1,239,852,566,891] ~"type = struct largedata_
{\n"
skipped lines: 201
[1,239,852,568,439] ~"}
*\n"
[1,239,852,568,442] 4067^done
[1,239,852,568,442]
(gdb)
[1,239,852,568,443] 4068 ptype lcb
[1,239,852,568,444] ~"ptype
lcb\n"
[1,239,852,568,448] ~"type = struct largedata_ {\n"
skipped lines:
201
[1,239,852,570,069] ~"} *\n"
It looks
like a lot of redundant traffic, the more if the pointer variable is collapsed
and I'm only interested in the pointer variable value. It's also
interesting the Variables view and the Expressions view have two different
behaviors.
These 2
ptypes are observed, even if the Expressions view is not active, or at least
sometimes.
b) When
lcb is added to the Expressions view, in addition to the two ptypes, if the view
is active, I will see ptypes for all unique element types in the structure,
even if lcb is collapsed. And for each single step, I see
a
[1,239,852,896,259] 4173-var-list-children
var139
[1,239,852,897,848]
4173^done,numchild="201",children=[child={name="var139.field1",exp="fiel\
skipped
lines: 157
So
my two questions are:
1) is
there a way to have a lazy evaluation, so that expressions or variables are only
evaluated on request. I see that partially, for instance for the Variables
view, I see a ptype, but no var-list-children - while the Expressions view
is more chatty. I'd like to defer all children actions to when the
variable is expanded. Or at a minimum, not to request a
var-list-children when the variable is collapsed.
2) the
observed behavior is not consistent. Sometimes I see requests, even if the
view is not selected, other times I don't see them. So I wonder if this is
an issue that is already reported.
Thank
you
Laurent
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