[kst] [Bug 399039] New: No live plotting from the file

[b***@kde.org]

https://bugs.kde.org/show_bug.cgi?id=399039

Bug ID: 399039
Summary: No live plotting from the file
Product: kst
Version: 2.0.8
Platform: Ubuntu Packages
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: datasources
Assignee: ***@kde.org
Reporter: ***@gmail.com
Target Milestone: ---

SUMMARY
I have a "live" (100 ms refresh rate) ASCII file with 2 columns of float
numbers. File has always the same size - new point is adding to the end and the
first (oldest) value is removing from the file.
Problem is that Kst does not update plots (no matter 1 or 2 columns are used).
Plots are updating if I manually press Refresh button though. I tried different
settings and don't get the desired behavior.

PLATFORM
Ubuntu 18 default
Qt 5.9.5 from apt
Kst 2.0.8-2 from apt

[b***@kde.org]

https://bugs.kde.org/show_bug.cgi?id=399039

***@astro.utoronto.ca changed:

What |Removed |Added
----------------------------------------------------------------------------
CC| |***@astro.utoronto.
| |ca

--- Comment #1 from ***@astro.utoronto.ca ---
Unfortunately, this is not how kst realtime works - it only works with growing
files. If instead of deleting the oldest line, you just leave it and let the
file grow, it will work fine, at the expense of a small amount of disk usage.

One could, in principle, put in a timer based reload, but without also
implementing some sort of file locking strategy, this would lead to race
conditions or partial reads, so I am hesitant to implement it.

Is there a reason why you can't keep the old data and let the file grow?

[b***@kde.org]

https://bugs.kde.org/show_bug.cgi?id=399039

***@gmail.com changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|REPORTED |RESOLVED
Resolution|--- |NOT A BUG

--- Comment #2 from ***@gmail.com ---
OK, I see it's working now, thank you. The reason I limit the file size is just
thoughts to save a disk space. Also, gnuplot have been able to reread such file
without any issues, but works generally worse, kst is better for this
application.