First of all it's important to understand that the slow control system has nothing to do
with events. So if you look at event statistics, these are the events with the slow control
data sent to the midas data file, not the history database. So the logging period (the one you 
decreased from 60s to 10s to 6s) only affect the generation of events. 

What is important in your case is the number of events sent to the ODB. You see these in the
screen output of the slow control frontend (see attachment). This number show increase every
second.

I tried your modification (change nulldev with a sine function), and left the sc_fe.cxx
otherwise untouched. I then started with a fresh ODB ("rm /"). Started logger, mhttpd, sc_fe
and started a run. In the attachments is what I see. So I don't understand what your problem
is.

> > 3) Make /Sequencer/State/Path relative to <exp>/userfiles. Like if /Sequencer/State/Path=test would then result to a final directory <exp>/userfiles/sequencer/test
> > 
> > I'm kind of tempted to go with 3), since this allows the experiment to define different subdirectories under <exp>/userfiles/sequencer/... depending on the situation of the experiment.
> > 
> > Best,
> > Stefan
> 
> For me the option 3) seems the most coherent one.
> Andreas

Ok, I implemented option 3) above. This means everybody using the midas sequencer has to change /Sequencer/State/Path to an empty string and move the 
sequencer files under <exp>/userfiles/sequencer as a starting point. I tested most thing, including the INCLUDE statements, but there could still be
a bug here or there, so please give it a try and report any issue to me.

Best,
Stefan

> Also, I think that having a sine wave displayed by midas/examples/slowcont/scfe.cxx 
> would make this example even more helpful.

Indeed. I reworked the example to have a out-of-the-box sine wave plotter, including the
automatic creation of a history panel. Thanks for the hint.

Best,
Stefan

Custom plots including scatter, histogram and color map plots have been 
implemented. This lets you plot graphs of X/Y data or histogram data stored in the 
ODB on a custom page. For some examples and documentation please go to

https://daq00.triumf.ca/MidasWiki/index.php/Custom_plots_with_mplot

Enjoy!
Stefan

> the DNS alias for midas.triumf.ca moved from old ladd00.triumf.ca to new 
> daq00.triumf.ca. same as before it redirects to the MidasWiki and to the midas 
> forum (elog) that moved from ladd00 to daq00 quite some time ago. if you see any 
> anomalies in accessing them (broken links, bad https certificates), please report 
> them to this forum or to me directly at olchansk@triumf.ca. K.O.

I found the first issue: The link to

https://midas.triumf.ca/MidasWiki/index.php/Custom_plots_with_mplot

does not work any more. The link

https://daq00.triumf.ca/MidasWiki/index.php/Custom_plots_with_mplot

however does work. Same with

https://midas.triumf.ca/MidasWiki/index.php/Sequencer

and

https://daq00.triumf.ca/MidasWiki/index.php/Sequencer

I have a few cases in mhttpd where I link directly to our documentation. I prefer
to have those link with "midas.triumf.ca" instead of "daq00.triumf.ca" in case you
change the machine again in the future.

Best,
Stefan

> > git pull
> > git submodule update
> 
> confirmed. just run into this myself. I think "make" should warn about out of 
> date git modules. Also check that the build git version is tagged with "-dirty".
> 
> K.O.

The submodule business becomes kind of annoying. I updated the documentation at

https://daq00.triumf.ca/MidasWiki/index.php/Quickstart_Linux#MIDAS_Package_Installatio
n

to tell people to use 

1) "git clone ... --recurse-submodules" during the first clone
2) "git submodule update --init --recursive" in case they forgot 1)
3) "git pull --recurse-submodules" for each update or to use
4) "git config submodule.recurse true" to make the --recurse-submodules the default

I use 4) since a while and it works nicely, so one does not have to remember to pull 
recursively each time.

Stefan

Put a 

  ss_sleep(10);

into your frontend_loop(), then you should be fine.

The event loop runs as fast as possible in order not to miss any (triggered) event, so no seep in the 
event loop, because this would limit the (triggered) event rate to 100 Hz (minimum sleep is 10 ms). 
Therefore, you have to slow down the event loop manually with the method described above.

Best,
Stefan

> Hi Stefan, thanks a lot !
> 
> I just thought that for the EQ_SLOW type equipment calls to sleep() could be hidden in mfe.cxx 
> and handled based on the requested frequency of the history updates.

Most people combine EQ_SLOW with EQ_POLLED, so they want to read out as quickly as possible. Since 
the framework cannot "guess" what the users want there, I removed all sleep() in the framework.



> Doing the same in the user side is straighforward - the important part is to know where the 
> responsibility line goes (: smile :) 


Pushing this to the user gives you more freedom. Like you can add sleep() for some frontends, but not 
for others, only when the run is stopped and more.

Stefan

Have you updated to the current midas version? This issue has been fixed a while ago. Below 
you see a screenshot of a long list scrolled all the way to the bottom.

Revision: Thu Dec 7 14:26:37 2023 +0100 - midas-2022-05-c-762-g1eb9f627-dirty on branch 
develop

Chrome on MacOSX 14.2.1

The fix is actually in "controls.js", so make sure your browser does not cache an old 
version of that file. I usually have to clear my browser history to get the new file from 
mhttpd.

Best regards,
Stefan

> 1) In the attached snapshot you see that the values shown from our vacuum Pirani and Penning cells are all zero, which of course is not true.
> It would be nice to have under the equipment settings some formatting options, like the possibility to add units.

You have a 

  /Equipment/LEMVAC/Settings/Format Input

array where you can specify the format for every value. Default is "%f2" for two digits after the period. For vacuum levels you might want to 
consider "%e3" which give you exponential format with three significant digits. The "format" setting is described at

  https://daq00.triumf.ca/MidasWiki/index.php//Equipment_ODB_tree#Format_%3Cvariable%3E

and the details are at

  https://daq00.triumf.ca/MidasWiki/index.php/Custom_Page#Formatting

The was a bug with the format handling, so please pull the current develop branch.


> 2) If one of the number evaluates to Infinity, the table is not shown properly anymore.

I fixed that as well in the current version.

Best,
Stefan

This part of the system has been designed by KO, so he should reply here.

Stefan

I fixed both in the current version, so please give it a try.

Stefan

> What's the best way to make these messages go away? 
> - Change the logic in db_validate_and_repair_key_wlocked() to not worry if keys are 10+ years old? 
> - Write a script to "touch" all the old keys so they've been modified recently?
> - Something else?

The function db_validate_and_repair_key_wlocked() has been written by KO so he should reply here.

In my opinion, I would go with the first one. Changing the function is easier than to write a script
and teach everybody how to use it. This would be one more thing not to forget.

Now changing the function is not so obvious. We could extend the check to let's say 20 years, but
then we meet here again in ten years. Maybe the best choice would be to just check that the time
is not in the future.

Anyhow, most people don't realize, but we all will have fun on Jan 19, 2038, when the Unix time
overflows in 32-bit signed integers. I don't know if midas will be around by then (I will be 74 years),
but before that date one has to worry about many places in midas where we use Unix time. At that time
your date stamps from 2013 would be 25 years old, so we either remove the date check (just keep
the check of not being in the future), or extend it to 26 years.

Stefan

I guess you won't change your FPGA configuration just when you start a run, so I don't consider the race
condition very crucial (although KO is correct, it it there).

I guess rather than any pseudo code you want to see real working code (db_get_num_entries() does not exist!), right?

The easiest these day is to ask ChatGPT. MIDAS has been open source since a long time, so it has been used
to train modern Large Language Models. Attached is the result. Here is the direct link from where you can
copy the code:

https://chat.openai.com/share/d927c78d-9914-4413-ab5e-3b0e5d173132

Please note that you never can be 100% sure that the code from a LLM is correct, so always compile and debug it.
But nevertheless, it's always easier to start from some existing code, even if there is a danger that it's not perfect.

Best,
Stefan

> Please run "git blame" to find out who added that check.

OK ok, was me. But actually 2003. I hope that this being more than 20y ago excuses me not remembering it ;-)

> I think this age check should be removed, but there must be *some* check for invalid/bogus timestamps. Or 
> not, we should check if MIDAS cares about timestamps at all, if ODB functions never use/look at timestamp, 
> maybe we are okey with bogus timestamps. They may look funny in the odb editor, but that's it.

I changed the code to only check for timestamps more than 1h in the future and then complain. This should
avoid glitches when switching daylight savings time.

Stefan

> Konstantin is right: KEY.num_values is not the same as the number of subkeys (should it be ?)

For ODB keys of type TID_KEY, the value num_values IS the number of subkeys. The only issue here is 
what KO mentioned already. If you obtain num_values, start iterating, then someone else might 
change the number of subkeys, then your (old) num_values is off. Therefore it's always good to 
check the return status of all subkey accesses. To do a truely atomic access to a subtree, you need 
db_copy(), but then you have to parse the JSON yourself, and again you have no guarantee that the 
ODB hasn't changed in meantime.

Stefan

> > For ODB keys of type TID_KEY, the value num_values IS the number of subkeys. 
> 
> this logic makes sense, however it doesn't seem to be consistent with the printout of the test example
> at the end of https://daq00.triumf.ca/elog-midas/Midas/240203_095803/a.cc . The printout reports 
> 
> key.num_values = 1, but the actual number of subkeys = 6, and all subkeys being of TID_KEY type
> 
> I'm certain that the ODB subtree in question was not accessed concurrently during the test.

You are right, num_values is always 1 for TID_KEYS. The number of subkeys is stored in 

  ((KEYLIST *) ((char *)pheader + pkey->data))->num_keys

Maybe we should add a function to return this. But so far db_enum_key() was enough.

Stefan

> Hmm... is there any use case where you want to know the number of directory entries, but you will not iterate 
> over them later?

I agree. 

One more way to iterate over subkeys by name is by using the new odbxx API:


   midas::odb tree("/Test/Settings");
   for (midas::odb& key : tree)
      std::cout << key.get_name() << std::endl;


Stefan

Thanks for reporting that bug. I fixed it and committed the change to the develop branch.

Stefan

One thing coming to my mind is the interface binding. If you have a midas host with two networks 
("global" and "local"=192.168.x.x), you can tell to which interface a socket should bind. 
By default it binds both interfaces, but we could restrict the socket only to bind to the local 
interface 192.168.x.x. This way the open port would be invisible from the outside, but from 
your local network everybody can connect easily without the need of a white list.

Stefan