> > Dear all,
> > 
> > we are experiencing a connection problem to the MySQL server that we use to log informations. Is there an 
> > option to retry multiple times the I/O on the MySQL?
> > 
> > The error we are experiencing is the following (hiding the IP address):
> > 
> > [Logger,ERROR] [mlogger.cxx:2455:write_runlog_sql,ERROR] Failed to connect to database: Error: Can't 
> > connect to MySQL server on 'xxx.xxx.xxx.xxx:6033' (110)
> > 
> > Then the logger stops, and must be restarted. This eventually happens only during the BOR or the EOR.
> 
> What would you propose? If the connection does not work, most likely the server is down or busy. If we retry, 
> the connection still might not work. If we retry many times, people will complain that the run start or stop 
> takes very long. If we then just continue (without stopping the logger), the MySQL database will miss important 
> information and the runs probably cannot be analyzed later. So I believe it's better to really stop the logger 
> so that people get aware that there is a problem and fix the source, rather than curing the symptoms.
> 
> In the MEG experiment at PSI we run the logger with a MySQL database and we never see any connection issue, 
> except when the MySQL server gets in maintenance (once a year), but usually we don't take data then. Since we 
> use the same logger code, it cannot be a problem there. So I would try to fix the problem on the MySQL side.
> 
> Best,
> Stefan


Dear Stefan,

a possible solution could be to define the number of times to retry as a parameter that is 0 by default, as well as a wait time between two subsequent tries. This 
would leave the decision on how to handle a possible failed connection to the user. In our case, for example, we would prefer to not stop the acquisition in case 
of a failed connection to the external SQL. In addition, we have other software that, with a retry procedure, doesn’t fail: with 1 re-try and a sleep time of 0.5 s 
we already recover 100% of the faults.

Anyway, we implemented a local database, which is a mirror of the external one, and the problems disappeared.

Thanks,
Stefano.

Hi Konstantin,
thanks for this update |

My main interest for PostgreSQL is usage of TimescaleDB
(https://github.com/timescale/timescaledb) a PostgreSQL extension that
makes possible usage of downsampling functions on time-series...

here at INFN-Napoli we have a large history dataset that we manage
with MIDAS history and MySQL tables. We have a lot of issues 
(wait time, browser hangs, crashes) when we use MIDAS history plot 
pages on large time period because the Javascript web page try to 
download million of records in order to display them on a plot of 
(max) 2000 pixel width...

with native downsampling we can reduce a large dataset keeping the
"shape" of the curve using only the points needed by the plot area;

in TimescaleDB there is "lttb" ( Largest Triangle Three Bucket) a very 
nice and impressive downsampling function that preserve very well the
shape of the series.

If you are interested to see a lttb at work on some data you can open this page:
   https://www.base.is/flot

In next days I will work to add TimescaleDB backend to MIDAS history (it will be
similar to PostgreSQL backend) and we can discuss on how to add these 
downsampling features to history plot web pages, I already developed some
solutions and I will be happy to share them with MIDAS community;

Cheers,
Gennaro

> > some minutes ago I published a PR for PostgreSQL support I developed
> > at INFN-Napoli for Darkside experiment...
> > 
> > I don't know if you receive a notification about this PR and in doubt
> > I wrote this message...
> 
> Hi, Gennaro, thank you for the very useful contribution. I saw the previous version 
> of your pull request and everything looked quite good. But that pull request was 
> for an older version of midas and it would not have applied cleanly to the current 
> version. I will take a look at your updated pull request. In theory it should only 
> add the Postgres class and modify a few other places in history_schema.cxx and have 
> no changes to anything else. (if you need those changes, it should be a separate 
> pull request).
> 
> Also I am curious what benefits and drawbacks of Postgres vs mysql/mariadb you have 
> observed for storing and using midas history data.
> 
> K.O.

Hi 


> > some minutes ago I published a PR for PostgreSQL support I developed
> > at INFN-Napoli for Darkside experiment...
> > 
> > I don't know if you receive a notification about this PR and in doubt
> > I wrote this message...
> 
> Hi, Gennaro, thank you for the very useful contribution. I saw the previous version 
> of your pull request and everything looked quite good. But that pull request was 
> for an older version of midas and it would not have applied cleanly to the current 
> version. I will take a look at your updated pull request. In theory it should only 
> add the Postgres class and modify a few other places in history_schema.cxx and have 
> no changes to anything else. (if you need those changes, it should be a separate 
> pull request).
> 
> Also I am curious what benefits and drawbacks of Postgres vs mysql/mariadb you have 
> observed for storing and using midas history data.
> 
> K.O.

> some minutes ago I published a PR for PostgreSQL support I developed
> at INFN-Napoli for Darkside experiment...
> 
> I don't know if you receive a notification about this PR and in doubt
> I wrote this message...

Hi, Gennaro, thank you for the very useful contribution. I saw the previous version 
of your pull request and everything looked quite good. But that pull request was 
for an older version of midas and it would not have applied cleanly to the current 
version. I will take a look at your updated pull request. In theory it should only 
add the Postgres class and modify a few other places in history_schema.cxx and have 
no changes to anything else. (if you need those changes, it should be a separate 
pull request).

Also I am curious what benefits and drawbacks of Postgres vs mysql/mariadb you have 
observed for storing and using midas history data.

K.O.

Hi,

some minutes ago I published a PR for PostgreSQL support I developed
at INFN-Napoli for Darkside experiment...

I don't know if you receive a notification about this PR and in doubt
I wrote this message...

Thanks in advance,
Gennaro

> Dear all,
> 
> we are experiencing a connection problem to the MySQL server that we use to log informations. Is there an 
> option to retry multiple times the I/O on the MySQL?
> 
> The error we are experiencing is the following (hiding the IP address):
> 
> [Logger,ERROR] [mlogger.cxx:2455:write_runlog_sql,ERROR] Failed to connect to database: Error: Can't 
> connect to MySQL server on 'xxx.xxx.xxx.xxx:6033' (110)
> 
> Then the logger stops, and must be restarted. This eventually happens only during the BOR or the EOR.

What would you propose? If the connection does not work, most likely the server is down or busy. If we retry, 
the connection still might not work. If we retry many times, people will complain that the run start or stop 
takes very long. If we then just continue (without stopping the logger), the MySQL database will miss important 
information and the runs probably cannot be analyzed later. So I believe it's better to really stop the logger 
so that people get aware that there is a problem and fix the source, rather than curing the symptoms.

In the MEG experiment at PSI we run the logger with a MySQL database and we never see any connection issue, 
except when the MySQL server gets in maintenance (once a year), but usually we don't take data then. Since we 
use the same logger code, it cannot be a problem there. So I would try to fix the problem on the MySQL side.

Best,
Stefan

Dear all,

we are experiencing a connection problem to the MySQL server that we use to log informations. Is there an 
option to retry multiple times the I/O on the MySQL?

The error we are experiencing is the following (hiding the IP address):

[Logger,ERROR] [mlogger.cxx:2455:write_runlog_sql,ERROR] Failed to connect to database: Error: Can't 
connect to MySQL server on 'xxx.xxx.xxx.xxx:6033' (110)

Then the logger stops, and must be restarted. This eventually happens only during the BOR or the EOR.

Best,
Stefano.

> I agree with you, option 2 is better and works well. 
> The only problem is that if you are showing multiple histograms in the same window the keyDown even will affect all of the histories in the window. 
> This may be the intended behaviour, but I think that if we can find a way to have the event affecting only the intended history (focused element for example) it would be better.

The history panels are simple pictures from the perspective of the browser and have no concept of a focus. This would have to be tweaked somehow. If you want to reset a single history, 
just click on its reset button (circle arrow at the right top).

Stefan

I agree with you, option 2 is better and works well. 
The only problem is that if you are showing multiple histograms in the same window the keyDown even will affect all of the histories in the window. 
This may be the intended behaviour, but I think that if we can find a way to have the event affecting only the intended history (focused element for example) it would be better.

Zaher 

> > The histories capture key events from 'r' 'u' 'y' and 'Escape' for various functions like rescaling etc. However, this also means that if we include an editable modbvalue and a history in the same custom page then changing the modbvalue to something that includes 'ruy' is not possible.
> > 
> > In mhistory.js we have
> > 
> > // Keyboard event handler (has to be on the window!)
> > window.addEventListener("keydown", this.keyDown.bind(this));
> > 
> > I am not sure why it "has to be on the window". For now, I am bypassing this issue by changing the event listener to "keyup" but maybe there is a more elegant solution for this. Adding the event listener to the div element that includes the history does not seem to work.
> 
> I could reproduce the problem. I see two options there:
> 
> 1) We replace 'r' with 'Ctrl-r' etc. 
> 
> 2) We change the history JS code not to process keyboard inputs if we are currently editing a value.
> 
> I added 2) to give it a try. It works fine for me. The additional code is
> 
> MhistoryGraph.prototype.keyDown = function (e) {
>    // don't consume events if we are editing a value
>    if (e.target.tagName === "INPUT")
>       return;
>    ...
> }
> 
> 
> Feedback is welcome.
> 
> Stefan

> The histories capture key events from 'r' 'u' 'y' and 'Escape' for various functions like rescaling etc. However, this also means that if we include an editable modbvalue and a history in the same custom page then changing the modbvalue to something that includes 'ruy' is not possible.
> 
> In mhistory.js we have
> 
> // Keyboard event handler (has to be on the window!)
> window.addEventListener("keydown", this.keyDown.bind(this));
> 
> I am not sure why it "has to be on the window". For now, I am bypassing this issue by changing the event listener to "keyup" but maybe there is a more elegant solution for this. Adding the event listener to the div element that includes the history does not seem to work.

I could reproduce the problem. I see two options there:

1) We replace 'r' with 'Ctrl-r' etc. 

2) We change the history JS code not to process keyboard inputs if we are currently editing a value.

I added 2) to give it a try. It works fine for me. The additional code is

MhistoryGraph.prototype.keyDown = function (e) {
   // don't consume events if we are editing a value
   if (e.target.tagName === "INPUT")
      return;
   ...
}


Feedback is welcome.

Stefan

> Is it possible to impose requirements on certain output variables in an interlock-like fashion? For example: "As long as the temperature exceeds a certain threshold, a light switched by a relay cannot be turned on."
> 
> A workaround would be to set an alarm on that variable and call a script which turns the light back off, but that might not be ideal in certain scenarios. For safety-critical situations, a PLC would be preferred, but I am missing an option between those two.

No, interlocks of that kind are not implemented in midas. And that is for a good reason. Interlocks are critical, so one must be sure 100% that they are working. This cannot be done with complex software such as midas. You have to use dedicated hardware for that. 
Most people use a PLC controller which is made for that. Midas is then only used to read and display the status of the interlock controller.

Stefan

Is it possible to impose requirements on certain output variables in an interlock-like fashion? For example: "As long as the temperature exceeds a certain threshold, a light switched by a relay cannot be turned on."

A workaround would be to set an alarm on that variable and call a script which turns the light back off, but that might not be ideal in certain scenarios. For safety-critical situations, a PLC would be preferred, but I am missing an option between those two.

These debug statements were added by K.O. on June 24, 2021. He should remove it.

https://bitbucket.org/tmidas/midas/commits/21f7ba89a745cfb0b9d38c66b4297e1aa843cffd

Best,
Stefan

Hi everyone,

It has been a long time since my last message. While porting Midas front-end 
programs developed for the T2K experiment in 2008 to a modern version of Midas, 
I noticed that some debug printf remain in mhttpd.cxx.

A number of debug messages are printed on stdout each time a graph is displayed 
in the OldHistory window (which is the style of history plots that will continue 
to be used in the upgraded T2K experiment for some technical reasons).

Here is an example of such debug messages:
Load from ODB History/Display/HA_EP_0/V33: hist plot: 8 variables
timescale: 1h, minimum: 0.000000, maximum: 0.000000, zero_ylow: 0, log_axis: 0, 
show_run_markers: 1, show_values: 1, show_fill: 0, show_factor 0, enable_factor: 
1
var[0] event [HA_TPC_SC][E0M00FEM_V33] formula [], colour [#00AAFF] label 
[Mod_0] show_raw_value 0 factor 1.000000 offset 0.000000 voffset 0.000000 order 
10
var[1] event [HA_TPC_SC][E0M01FEM_V33] formula [], colour [#FF9000] label 
[Mod_1] show_raw_value 0 factor 1.000000 offset 0.000000 voffset 0.000000 order 
20
var[2] event [HA_TPC_SC][E0M02FEM_V33] formula [], colour [#FF00A0] label 
[Mod_2] show_raw_value 0 factor 1.000000 offset 0.000000 voffset 0.000000 order 
30
var[3] event [HA_TPC_SC][E0M03FEM_V33] formula [], colour [#00C030] label 
[Mod_3] show_raw_value 0 factor 1.000000 offset 0.000000 voffset 0.000000 order 
40
var[4] event [HA_TPC_SC][E0M04FEM_V33] formula [], colour [#A0C0D0] label 
[Mod_4] show_raw_value 0 factor 1.000000 offset 0.000000 voffset 0.000000 order 
50
var[5] event [HA_TPC_SC][E0M05FEM_V33] formula [], colour [#D0A060] label 
[Mod_5] show_raw_value 0 factor 1.000000 offset 0.000000 voffset 0.000000 order 
60
var[6] event [HA_TPC_SC][E0M06FEM_V33] formula [], colour [#C04010] label 
[Mod_6] show_raw_value 0 factor 1.000000 offset 0.000000 voffset 0.000000 order 
70
var[7] event [HA_TPC_SC][E0M07FEM_V33] formula [], colour [#807060] label 
[Mod_7] show_raw_value 0 factor 1.000000 offset 0.000000 voffset 0.000000 order 
80
read_history: nvars 10, hs_read() status 1
read_history: 0: event [HA_TPC_SC], var [E0M00FEM_V33], index 0, odb index 0, 
status 1, num_entries 475
read_history: 1: event [HA_TPC_SC], var [E0M01FEM_V33], index 0, odb index 1, 
status 1, num_entries 475
read_history: 2: event [HA_TPC_SC], var [E0M02FEM_V33], index 0, odb index 2, 
status 1, num_entries 475
read_history: 3: event [HA_TPC_SC], var [E0M03FEM_V33], index 0, odb index 3, 
status 1, num_entries 475
read_history: 4: event [HA_TPC_SC], var [E0M04FEM_V33], index 0, odb index 4, 
status 1, num_entries 475
read_history: 5: event [HA_TPC_SC], var [E0M05FEM_V33], index 0, odb index 5, 
status 1, num_entries 475
read_history: 6: event [HA_TPC_SC], var [E0M06FEM_V33], index 0, odb index 6, 
status 1, num_entries 475
read_history: 7: event [HA_TPC_SC], var [E0M07FEM_V33], index 0, odb index 7, 
status 1, num_entries 475
read_history: 8: event [Run transitions], var [State], index 0, odb index -1, 
status 1, num_entries 0
read_history: 9: event [Run transitions], var [Run number], index 0, odb index 
-2, status 1, num_entries 0


Looking at the source code of mhttpd, these messages originate from:

[mhttpd.cxx line 10279] printf("Load from ODB %s: ", path.c_str());
[mhttpd.cxx line 10280] PrintHistPlot(*hp);
...
[mhttpd.cxx line  8336] int read_history(...
...
[mhttpd.cxx line  8343] int debug = 1;
...

Although seeing many debug messages in the mhttpd does not hurt, these can hide 
important error messages. I would rather suggest to turn off these debug 
messages by commenting out the relevant lines of code and setting the debug 
variable to 0 in read_history().

That is a minor detail and it is always a pleasure to use Midas.

Best regards,
Denis.
 

> > serious (but rare) bug was fixed in the history reader.
> previous fix was incomplete. please update to git commit
> https://bitbucket.org/tmidas/midas/commits/b343c3c98e4e6fd00a00cf686c74c7ccc6da0c63

a race condition between reading history file in mhttpd and writing history file in 
mlogger was accidentally introduced. mhttpd would file spurious errors about "timestamp 
is after last timestamp".

fixed, please update to git commit
https://bitbucket.org/tmidas/midas/commits/7a9f6e0c58ffddcacb9ee19934ce3e2033a805ef

fix race condition in history file reader - a race condition was added accidentally - 
first the reader remembers the history file size and the time of the last entry, then it 
goes to read the file and bombs if at the same time mlogger added more entries - their 
time is after the remembered time of last entry and error "timestamp is after last 
timestamp" is triggered.

K.O.

> > midas currently does not compile on linux
> > fix is to give open in midas/examples/lowlevel/split.cxx a default mode, e.g. 006600

I got more warnings from split.cxx, looked at the code and see so many problems that it is easier
to delete it than it is to fix it.

Check for end of file is done incorrectly (check for read() return 0, -1 or short read),
memory overrun if given file name is longer than 80 bytes, no check for valid event length
read from the file, and so on and so on.

A better example for reading and writing midas files is in midasio/test_midasio.cxx. Proper c++ coding, and can read compressed files.

K.O.

> midas currently does not compile on linux
> 
> /usr/include/x86_64-linux-gnu/bits/fcntl2.h:50:24: error: call to ‘__open_missing_mode’ declared with attribute error: open with O_CREAT or O_TMPFILE in second argument needs 3 arguments
>    50 |    __open_missing_mode ();
> 
> giving the mode is mandatory: https://man7.org/linux/man-pages/man2/open.2.html
> 
> fix is to give open in midas/examples/lowlevel/split.cxx a default mode, e.g. 006600

Thanks. Fixed.

Stefan

midas currently does not compile on linux

/usr/include/x86_64-linux-gnu/bits/fcntl2.h:50:24: error: call to ‘__open_missing_mode’ declared with attribute error: open with O_CREAT or O_TMPFILE in second argument needs 3 arguments
   50 |    __open_missing_mode ();

giving the mode is mandatory: https://man7.org/linux/man-pages/man2/open.2.html

fix is to give open in midas/examples/lowlevel/split.cxx a default mode, e.g. 006600

The histories capture key events from 'r' 'u' 'y' and 'Escape' for various functions like rescaling etc. However, this also means that if we include an editable modbvalue and a history in the same custom page then changing the modbvalue to something that includes 'ruy' is not possible.

In mhistory.js we have

// Keyboard event handler (has to be on the window!)
window.addEventListener("keydown", this.keyDown.bind(this));

I am not sure why it "has to be on the window". For now, I am bypassing this issue by changing the event listener to "keyup" but maybe there is a more elegant solution for this. Adding the event listener to the div element that includes the history does not seem to work.

Ok, I implemented and committed that. Just call

o.set_write_protect(true)

on a key you don't want to modify. If you do so, an exception gets thrown.

Best,
Stefan