Back Midas Rome Roody Rootana
  Midas DAQ System, Page 127 of 146  Not logged in ELOG logo
ID Date Author Topicdown Subject
  2786   04 Jul 2024 Nick HastingsBug ReportFail to build in the examples/experiment
I think this may only be an issue on the development branch.
Can you confirm that that is what you are using?

If so, I suggest you try the most recent stable tag 2022-05-c.

> Dear experts,
> I am a new user of MIDAS. I try to follow the instruction from 
> https://daq00.triumf.ca/MidasWiki/index.php/Quickstart_Linux
> to install MIDAS in Fedora 39.
> 
> When I try to have a try in the section of "Clients run on Localhost only"
> https://daq00.triumf.ca/MidasWiki/index.php/Quickstart_Linux#Clients_run_on_Localhost_only
> 
> I get the error of "undefined reference to" several variables in the mfe.cxx. For example the variable "max_event_size_frag". May I know any idea about this issue? Thank you.
> 
> 
> Best,
> Terry
  2789   05 Jul 2024 Tam Kai ChungBug ReportFail to build in the examples/experiment
Hello Nick,
I am using the most updated tag: midas-2022-05-c-1284-g4a77127b.

Here would be some of the examples of the error listed:
/usr/bin/ld: /packages/midas/lib/mfe.o: in function
/usr/bin/ld: /packages/midas/src/mfe.cxx:2537: undefined reference to `event_buffer_size'
...
Also several undefined reference. Any idea about it? Thank you.

Best,
Terry


> I think this may only be an issue on the development branch.
> Can you confirm that that is what you are using?
> 
> If so, I suggest you try the most recent stable tag 2022-05-c.
> 
> > Dear experts,
> > I am a new user of MIDAS. I try to follow the instruction from 
> > https://daq00.triumf.ca/MidasWiki/index.php/Quickstart_Linux
> > to install MIDAS in Fedora 39.
> > 
> > When I try to have a try in the section of "Clients run on Localhost only"
> > https://daq00.triumf.ca/MidasWiki/index.php/Quickstart_Linux#Clients_run_on_Localhost_only
> > 
> > I get the error of "undefined reference to" several variables in the mfe.cxx. For example the variable "max_event_size_frag". May I know any idea about this issue? Thank you.
> > 
> > 
> > Best,
> > Terry
  2794   31 Jul 2024 Lukas GerritzenBug ReportNew history plots: Zooming in on logarithmic y axis does not work as expected
Using the mouse to click and drag on a logarithmic y axis triggers a zooming behaviour as if the user zoomed in on a linear axis. 

How to reproduce:
Take a plot that ranges from 1e-20 to 100, for example. Click around the middle of the axis and drag the mouse up to about 3/4.

Expected result:
Limit the y axis to the approximate range 1e-10 to 1e-4

Actual result:
The y axis limits are around 50 and 75.


P.S. Is there a way to configure the history plot in a way that values of 0.00 are ignored rather than showing up as 1e-20?
  2795   31 Jul 2024 Stefan RittBug ReportNew history plots: Zooming in on logarithmic y axis does not work as expected
I fixed that and committed the change to megon02, just reload your browser. I also set ymin and ymax of the Vacuum plot to meaningful 
values (not to zero!).

Stefan
  2798   07 Aug 2024 Lukas GerritzenBug ReportFile name bug in csv export
When I export data from a history plot, I get nonsensical filenames. For example, for data from today, I got "Xenon-Vacuum-20247107-152815-20247107-160032.csv".
The month shouldn't be 71 but rather 08. The problem is that in the code it's generated as
("0" + leftDate.getUTCMonth() + 1).slice(-2)
The first '+' is a string concatenation, and so is the second. It should be an addition though. A possible fix is to add parentheses around the addition:
("0" + (leftDate.getUTCMonth() + 1)).slice(-2)
  2799   07 Aug 2024 Stefan RittBug ReportFile name bug in csv export
Thanks. Fixed. Committed. Pulled on megon02.

Stefan
  2800   07 Aug 2024 Lukas GerritzenBug ReportFile name bug in csv export
Thanks. I think, mplot.js:1844 should be changed as well, but I haven't tried it with mplot.
  2801   07 Aug 2024 Stefan RittBug ReportFile name bug in csv export
Fixed as well.
  2815   30 Aug 2024 Zaher SalmanBug ReportParams not initialized when starting sequencer
The issue with the parameters should be fixed now. Please test and let me know if it still happens.


Thomas Senger wrote:
Hi Zaher,
thanks for your help.
I just tried the bug fix, but it still seems not to work properly.
It seems that if the script is short, it will work, but if many SUBROUTINES are integrated, it does not work and the parameter are initialized empty.
Best regards,
Thomas
  2821   04 Sep 2024 Lukas GerritzenBug ReportMultiple issues with mhist
Hi,

I am having some trouble with mhist. I suppose that the problems are at least partially due to our specific needs which might exceed what has been tested. For context, in MEG II we have some 10^4 history variables in ~30 different events.

1. mhist -l crashes. After displaying around 7000 lines, I get the following error message:
[mhist,ERROR] [midas.cxx:5949:bm_validate_client_index,ERROR] My client index 10 in buffer 'SYSMSG' 
is invalid: client name '', pid 0 should be my pid 3773321
[mhist,ERROR] [midas.cxx:5952:bm_validate_client_index,ERROR] Maybe this client was removed by a 
timeout. See midas.log. Cannot continue, aborting...
Aborted (core dumped)
Timing the execution shows around 33 seconds before the process is aborted.

I'm not sure if this would actually fix the problem, but while trying to circumvent the issue, I tried the
following:
mhist -e "Xenon" -l
This doesn't seem to be implemented. Listing only the variables of a single event would be nice
regardless of our specific issue.

2. mhist and history files.
We have a directory directory with about 2500 history files (mhf_...dat) for the past 1.5 years. Older
history files are archived in other directories with similar numbers of files. When trying to access them, I
encountered two issues:
It seems like it is not possible to pass a "history directory" as an argument. To dump the history for a full
year in the archive directory, I would need to run mhist many times with -f and then combine all the dumps.

If it really does not work, please consider this a feature request.
Also, even using single files does not work at the moment:
$ mhist -e "Xenon" -v "Det XeTmp 0-0" -t 100000 -s 200101 -p 250101 -f 
/data2/history/2022/mhf_1644698398_20220212_xenon.dat
ID 980316009, Aug 13 19:10:56, size 1851749486
This command was supposed to show me the rough time frame covered in this particular history file. I was
informed that the history files are in the new "FILE" format and mhist might not work with them properly.

tl;dr
  • Bug: mhist -l crashes
  • Bug: mhist -f does not work with "FILE" history format
  • Feature request: mhist -e "Name" -l to only show variables of event "Name"
  • Feature request: Set temporary history dir with a flag

Lukas
  2822   04 Sep 2024 Lukas GerritzenBug ReportParams not initialized when starting sequencer
I think I have had similar issues in a custom page, where I wrote values to the ODB and they were not ready when I needed them. If you found a fix to such race conditions, could you maybe share how to properly treat this issue? If the solution reliably works, we could also consider including it in the documentation (midaswiki or example.html).


Zaher Salman wrote:
The issue with the parameters should be fixed now. Please test and let me know if it still happens.
  2823   04 Sep 2024 Zaher SalmanBug ReportParams not initialized when starting sequencer
The problem here was that the JS code did not wait to msequencer to finish preparing the "/Sequencer/Param" in the ODB, so I had to change to code to wait for "/Sequencer/Command/Load new file" to be false before proceeding.

As for your problem I recommend that you handle in the following way:

mjsonrpc_db_paste(paths,values).then(function (rpc) {
if (rpc.result.status.every(status => status === 1) {
// do something
} else {
// failed to set values, do something else
}
}).catch(function (error) {
console.error(error);
});

alternatively (for a single ODB) you can use the checkODBValue() function in sequencer.js. This function monitors a specific ODB path until it reaches a specific value and then calls funcCall with args.

var NcheckValue = 0;
// What for ODB in path to have value
// If value is not reached, give up after 10s
function checkODBValue(path,value,funcCall,args) {
/* Arguments:
path - ODB path to monitor for value
value - the value to be reached and return success
funcCall - function name to call when value is reached
args - argument to pass to funcCall
*/
// Call the mjsonrpc_db_get_values function
mjsonrpc_db_get_values([path]).then(function(rpc) {
if (rpc.result.status[0] === 1 && rpc.result.data[0] !== value) {
console.log("Value not reached yet", NcheckValue);
NcheckValue++;
if (NcheckValue < 100) {
// Wait 0.1 second and then call checkODBValue again
// Time out after 10 s
setTimeout(() => {
checkODBValue(path,value,funcCall,args);
}, 100);
}
} else {
if (funcCall) funcCall(args);
console.log("Value reached, proceeding...");
// reset counter
NcheckValue = 0;
}
}).catch(function(error) {
console.error(error);
});
}



Lukas Gerritzen wrote:
I think I have had similar issues in a custom page, where I wrote values to the ODB and they were not ready when I needed them. If you found a fix to such race conditions, could you maybe share how to properly treat this issue? If the solution reliably works, we could also consider including it in the documentation (midaswiki or example.html).


Zaher Salman wrote:
The issue with the parameters should be fixed now. Please test and let me know if it still happens.
  2834   11 Sep 2024 Konstantin OlchanskiBug ReportMultiple issues with mhist
I think I can offer some insight into your problems:

1) your mhist crash is due to the ODB timeout, it is probably set to 30 seconds in ODB /programs/mhist. you will 
have to make it biigger.

2) 1.5 years of files. yes. I have 10 years of files for ALPHA at CERN. and the number of files is a problem. 
But it should be better than the old system with 3 files per day (1000 files per year).

One solution you can try is symlinks. Assuming you have 10 years of history files in 10 per-year directory, you 
symlink as many of them as you need into the "current" directory, then remove the symlinks.

Why remove the symlinks? I use "ls" to read the list of history files and Unix/Linux does not have a syscall to 
"give me the 100 files with the newest mtime". I have to read the whole directory and that takes forever (if ZFS 
on HDD), it is quick with ZFS on SSD if ZFS cache is hot (you can have a cron job do "ls" every 5 minutes to 
keep the ZFS cache hot).

Now that I wrote the above, I think I see a way to make it "automatic", let me ponder this. (plus I always 
wanted to implement compressed history files (using "free" lz4)).

K.O.



I am having some trouble with mhist. I suppose that the problems are at least partially due to our specific 
needs which might exceed what has been tested. For context, in MEG II we have some 10^4 history variables in ~30 
different events. 

1. mhist -l crashes. After displaying around 7000 lines, I get the following error message:
[CODE]
[mhist,ERROR] [midas.cxx:5949:bm_validate_client_index,ERROR] My client index 10 in buffer 'SYSMSG' 
is invalid: client name '', pid 0 should be my pid 3773321
[mhist,ERROR] [midas.cxx:5952:bm_validate_client_index,ERROR] Maybe this client was removed by a 
timeout. See midas.log. Cannot continue, aborting...
Aborted (core dumped)
[/CODE]
Timing the execution shows around 33 seconds before the process is aborted.

I'm not sure if this would actually fix the problem, but while trying to circumvent the issue, I tried the 
following: [CODE]mhist -e "Xenon" -l[/CODE] This doesn't seem to be implemented. Listing only the variables of a 
single event would be nice 
regardless of our specific issue.

2. mhist and history files.
We have a directory directory with about 2500 history files (mhf_...dat) for the past 1.5 years. Older 
history files are archived in other directories with similar numbers of files. When trying to access them, I 
encountered two issues:
It seems like it is not possible to pass a "history directory" as an argument. To dump the history for a full 
year in the archive directory, I would need to run mhist many times with -f and then combine all the dumps.

If it really does not work, please consider this a feature request.
Also, even using single files does not work at the moment:
[CODE]
$ mhist -e "Xenon" -v "Det XeTmp 0-0" -t 100000 -s 200101 -p 250101 -f 
/data2/history/2022/mhf_1644698398_20220212_xenon.dat
ID 980316009, Aug 13 19:10:56, size 1851749486
[/CODE]
This command was supposed to show me the rough time frame covered in this particular history file. I was 
informed that the history files are in the new "FILE" format and mhist might not work with them properly.

tl;dr
[LIST]
[*] Bug: mhist -l crashes
[*] Bug: mhist -f does not work with "FILE" history format
[*] Feature request: mhist -e "Name" -l to only show variables of event "Name"
[*] Feature request: Set temporary history dir with a flag
[/LIST]

Lukas[/quote]
  2841   13 Sep 2024 Konstantin OlchanskiBug Reportmfe.cxx with RO_STOPPED and EQ_POLLED
> > I noticed that a check was added to mfe.cxx in 1961af0d6:

This is the reason I recommend against using mfe.c based frontends. There was never any
proper documentation on how they work and what different settings in ODB common
and elsewhere do. My attempts to document it by reverse-engineering were only partially
successful. Since then a number of changes was made that were also hard-to-impossible
to document.

I recommend that all use the new c++ tmfe frontend, which was designed for easy documentation,
and explanation. See tmfe.md for full documentation.

(pending improvements is to integrate TMEvent support, add the data-transmit thread and event fifo).

K.O.
  2845   16 Sep 2024 Marius KöppelBug ReportCrash using ODB watch
Hi all,

last week I was running MIDAS with the commit 3ad98c5. Today I updated MIDAS and now all my watch functions are crashing. Attached I have a minimal example frontend of the problem.

In our software we have two functions one which sets up the ODB values of the frontend and another one which sets up all watch functions. So overall we connect two time to the ODB during fronend_init one time to create the values and one time to create the watch. In the example code a simple version of this setup is shown:

INT frontend_init() {

  cm_msg(MINFO, "frontend_init() setup", "Test FE");

  odb settings = {
    {"Test", 123},
    {"sub", {}}
  };
  settings.connect_and_fix_structure("/Equipment/Test FE/Settings");
  // settings.watch(watch); <-- this works without segmentation fault

  odb new_settings("/Equipment/Test FE/Settings");
  new_settings.watch(watch); // <-- here I am getting a segmentation fault

  return CM_SUCCESS;
}

When I directly set the watch everything runs fine however, when I create a new ODB object and use this one to set a watch I am getting the following segmentation fault:

Process 18474 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x34)
    frame #0: 0x000000010004fa38 test_fe`midas::odb::watch_callback(hDB=<unavailable>, hKey=<unavailable>, index=0, info=0x00006000002001c0) at odbxx.cxx:96:25 [opt]
   93  	      if (po->m_data == nullptr)
   94  	         mthrow("Callback received for a midas::odb object which went out of scope");
   95  	      midas::odb *poh = search_hkey(po, hKey);
-> 96  	      poh->m_last_index = index;
   97  	      po->m_watch_callback(*poh);
   98  	      poh->m_last_index = -1;
   99  	   }

Best,
Marius
Attachment 1: test_fe.cpp
#include <algorithm>
#include <math.h>
#include <random>
#include <array>
#include <string>
#include <stdio.h>
#include <stdlib.h>

#include "midas.h"
#include "msystem.h"
#include "odbxx.h"
#include "mfe.h"

using namespace std;
using midas::odb;


/*-- Globals -------------------------------------------------------*/
/* The frontend name (client name) as seen by other MIDAS clients   */
const char *frontend_name = "Test FE";
/* The frontend file name, don't change it */
const char *frontend_file_name = __FILE__;

/* frontend_loop is called periodically if this variable is TRUE    */
BOOL frontend_call_loop = FALSE;

/* a frontend status page is displayed with this frequency in ms    */
INT display_period = 0;

/* maximum event size produced by this frontend */
INT max_event_size = 32 * (1024 * 1024); // 32MiB

/* maximum event size for fragmented events (EQ_FRAGMENTED) */
INT max_event_size_frag = 5 * 1024 * 1024;

/* buffer size to hold events */
INT event_buffer_size = 4 * max_event_size;

BOOL equipment_common_overwrite = TRUE;//true is overwriting the common odb

/*-- Function declarations -----------------------------------------*/
INT read_odb(char * pevent, INT);
void watch(odb o);
/*-- Equipment list ------------------------------------------------*/

EQUIPMENT equipment[] = {

  {
    "Test FE",      /* equipment name */
    {1, 0,          /* event ID, trigger mask */
    "SYSTEM",      /* event buffer */
    EQ_PERIODIC,   /* equipment type */
    0,             /* event source */
    "MIDAS",       /* format */
    TRUE,          /* enabled */
    RO_ALWAYS | RO_ODB,  /* read always and update ODB */
    1000,          /* read every 1 sec */
    0,             /* stop run after this event limit */
    0,             /* number of sub events */
    0,             /* log history every event */
    "", "", ""},
    read_odb,       /* readout routine */
  },

  {""}};

/*-- Dummy routines ------------------------------------------------*/

INT poll_event(INT, INT count, BOOL test)  {
    return 0;
}

INT interrupt_configure(INT, INT, POINTER_T) {
    return 1;
}
/*-- Frontend Init -------------------------------------------------*/

INT frontend_init() {

  cm_msg(MINFO, "frontend_init() setup", "Test FE");

  odb settings = {
    {"Test", 123},
    {"sub", {}}
  };
  settings.connect_and_fix_structure("/Equipment/Test FE/Settings");
  // settings.watch(watch); <-- this works without segmentation fault

  odb new_settings("/Equipment/Test FE/Settings");
  new_settings.watch(watch); // <-- here I am getting a segmentation fault

  return CM_SUCCESS;
}

void watch(odb o) {
    std::string name = o.get_name();

    if (name == "Test") {
      printf("I am a watch on Test\n");
    }
}

/*-- Frontend Exit -------------------------------------------------*/

INT frontend_exit() {
  return CM_SUCCESS;
}

/*-- Frontend Loop -------------------------------------------------*/

INT frontend_loop() {
  return CM_SUCCESS;
}

/*-- Begin of Run --------------------------------------------------*/

INT begin_of_run(INT run_number, char *error) {
  return CM_SUCCESS;
}

/*-- End of Run ----------------------------------------------------*/

INT end_of_run(INT run_number, char *error) {
  return CM_SUCCESS;
}

/*-- Pause Run -----------------------------------------------------*/

INT pause_run(INT run_number, char *error) {
  return CM_SUCCESS;
}

/*-- Resume Run ----------------------------------------------------*/

INT resume_run(INT run_number, char *error) {
  return CM_SUCCESS;
}

/* -- Readout --*/
INT read_odb(char *pevent, INT){

    return 0;

}
  2846   16 Sep 2024 Stefan RittBug ReportCrash using ODB watch
The answer is in the error message: „Object went out of scope“. When your frontent_init() exits, the odb objects are destroyed. When you get a callback, it‘s linked to the
destroyed object. This is like if you have a local string and pass a reference to that string in the return of the function.

Use a global object (bad) or use „new“ (potential memory leak). I would use a global structure which holds all odb objects.

Stefan
 
> 
> last week I was running MIDAS with the commit 3ad98c5. Today I updated MIDAS and now all my watch functions are crashing. Attached I have a minimal example frontend of the problem.
> 
> In our software we have two functions one which sets up the ODB values of the frontend and another one which sets up all watch functions. So overall we connect two time to the ODB during fronend_init one time to create the values and one time to create the watch. In the example code a simple version of this setup is shown:
> 
> INT frontend_init() {
> 
>   cm_msg(MINFO, "frontend_init() setup", "Test FE");
> 
>   odb settings = {
>     {"Test", 123},
>     {"sub", {}}
>   };
>   settings.connect_and_fix_structure("/Equipment/Test FE/Settings");
>   // settings.watch(watch); <-- this works without segmentation fault
> 
>   odb new_settings("/Equipment/Test FE/Settings");
>   new_settings.watch(watch); // <-- here I am getting a segmentation fault
> 
>   return CM_SUCCESS;
> }
> 
> When I directly set the watch everything runs fine however, when I create a new ODB object and use this one to set a watch I am getting the following segmentation fault:
> 
> Process 18474 stopped
> * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x34)
>     frame #0: 0x000000010004fa38 test_fe`midas::odb::watch_callback(hDB=<unavailable>, hKey=<unavailable>, index=0, info=0x00006000002001c0) at odbxx.cxx:96:25 [opt]
>    93  	      if (po->m_data == nullptr)
>    94  	         mthrow("Callback received for a midas::odb object which went out of scope");
>    95  	      midas::odb *poh = search_hkey(po, hKey);
> -> 96  	      poh->m_last_index = index;
>    97  	      po->m_watch_callback(*poh);
>    98  	      poh->m_last_index = -1;
>    99  	   }
> 
> Best,
> Marius
  2847   16 Sep 2024 Marius KoeppelBug ReportCrash using ODB watch
This is not the case here. Note that the error message: "Callback received for a midas::odb object which went out of scope" is not called! The segmentation fault happens later line 96.

> The answer is in the error message: „Object went out of scope“. When your frontent_init() exits, the odb objects are destroyed. When you get a callback, it‘s linked to the
> destroyed object. This is like if you have a local string and pass a reference to that string in the return of the function.
> 
> Use a global object (bad) or use „new“ (potential memory leak). I would use a global structure which holds all odb objects.
> 
> Stefan
>  
> > 
> > last week I was running MIDAS with the commit 3ad98c5. Today I updated MIDAS and now all my watch functions are crashing. Attached I have a minimal example frontend of the problem.
> > 
> > In our software we have two functions one which sets up the ODB values of the frontend and another one which sets up all watch functions. So overall we connect two time to the ODB during fronend_init one time to create the values and one time to create the watch. In the example code a simple version of this setup is shown:
> > 
> > INT frontend_init() {
> > 
> >   cm_msg(MINFO, "frontend_init() setup", "Test FE");
> > 
> >   odb settings = {
> >     {"Test", 123},
> >     {"sub", {}}
> >   };
> >   settings.connect_and_fix_structure("/Equipment/Test FE/Settings");
> >   // settings.watch(watch); <-- this works without segmentation fault
> > 
> >   odb new_settings("/Equipment/Test FE/Settings");
> >   new_settings.watch(watch); // <-- here I am getting a segmentation fault
> > 
> >   return CM_SUCCESS;
> > }
> > 
> > When I directly set the watch everything runs fine however, when I create a new ODB object and use this one to set a watch I am getting the following segmentation fault:
> > 
> > Process 18474 stopped
> > * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x34)
> >     frame #0: 0x000000010004fa38 test_fe`midas::odb::watch_callback(hDB=<unavailable>, hKey=<unavailable>, index=0, info=0x00006000002001c0) at odbxx.cxx:96:25 [opt]
> >    93  	      if (po->m_data == nullptr)
> >    94  	         mthrow("Callback received for a midas::odb object which went out of scope");
> >    95  	      midas::odb *poh = search_hkey(po, hKey);
> > -> 96  	      poh->m_last_index = index;
> >    97  	      po->m_watch_callback(*poh);
> >    98  	      poh->m_last_index = -1;
> >    99  	   }
> > 
> > Best,
> > Marius
  2848   16 Sep 2024 Stefan RittBug ReportCrash using ODB watch
Well, the object *went* out of scope. For my code it‘s hard to realize this, so the error reporting is poor. Also the first object should have the same
problem. Just by accident that it does not crash.

Stefan 

> This is not the case here. Note that the error message: "Callback received for a midas::odb object which went out of scope" is not called! The segmentation fault happens later line 96.
> 
> > The answer is in the error message: „Object went out of scope“. When your frontent_init() exits, the odb objects are destroyed. When you get a callback, it‘s linked to the
> > destroyed object. This is like if you have a local string and pass a reference to that string in the return of the function.
> > 
> > Use a global object (bad) or use „new“ (potential memory leak). I would use a global structure which holds all odb objects.
> > 
> > Stefan
> >  
> > > 
> > > last week I was running MIDAS with the commit 3ad98c5. Today I updated MIDAS and now all my watch functions are crashing. Attached I have a minimal example frontend of the problem.
> > > 
> > > In our software we have two functions one which sets up the ODB values of the frontend and another one which sets up all watch functions. So overall we connect two time to the ODB during fronend_init one time to create the values and one time to create the watch. In the example code a simple version of this setup is shown:
> > > 
> > > INT frontend_init() {
> > > 
> > >   cm_msg(MINFO, "frontend_init() setup", "Test FE");
> > > 
> > >   odb settings = {
> > >     {"Test", 123},
> > >     {"sub", {}}
> > >   };
> > >   settings.connect_and_fix_structure("/Equipment/Test FE/Settings");
> > >   // settings.watch(watch); <-- this works without segmentation fault
> > > 
> > >   odb new_settings("/Equipment/Test FE/Settings");
> > >   new_settings.watch(watch); // <-- here I am getting a segmentation fault
> > > 
> > >   return CM_SUCCESS;
> > > }
> > > 
> > > When I directly set the watch everything runs fine however, when I create a new ODB object and use this one to set a watch I am getting the following segmentation fault:
> > > 
> > > Process 18474 stopped
> > > * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x34)
> > >     frame #0: 0x000000010004fa38 test_fe`midas::odb::watch_callback(hDB=<unavailable>, hKey=<unavailable>, index=0, info=0x00006000002001c0) at odbxx.cxx:96:25 [opt]
> > >    93  	      if (po->m_data == nullptr)
> > >    94  	         mthrow("Callback received for a midas::odb object which went out of scope");
> > >    95  	      midas::odb *poh = search_hkey(po, hKey);
> > > -> 96  	      poh->m_last_index = index;
> > >    97  	      po->m_watch_callback(*poh);
> > >    98  	      poh->m_last_index = -1;
> > >    99  	   }
> > > 
> > > Best,
> > > Marius
  2849   16 Sep 2024 Marius KoeppelBug ReportCrash using ODB watch
Okay, but this is then a big issue IMO. For Mu3e we do this in every frontend and I also checked again all of these watches are broken at the moment (with commit 3ad98c5 they worked).
 
In the old style we did for example (see https://bitbucket.org/tmidas/midas/src/develop/examples/crfe/crfe.cxx):

INT frontend_init()
{
   HNDLE hKey;

   // create Settings structure in ODB
   db_create_record(hDB, 0, "Equipment/Clock Reset/Settings", strcomb1(cr_settings_str).c_str());
   db_find_key(hDB, 0, "/Equipment/Clock Reset", &hKey);
   assert(hKey);

   db_watch(hDB, hKey, cr_settings_changed, NULL);

   /*
    * Set our transition sequence. The default is 500. Setting it
    * to 600 means we are called AFTER most other clients.
    */
   cm_set_transition_sequence(TR_START, 600);

   return CM_SUCCESS;
}

I thought this will be the same (under the hood) in the current odbxx way via:

odb settings("Equipment/Clock Reset/Settings");
settings.watch(cr_settings_changed);

Best,
Marius


> Well, the object *went* out of scope. For my code it‘s hard to realize this, so the error reporting is poor. Also the first object should have the same
> problem. Just by accident that it does not crash.
> 
> Stefan 
> 
> > This is not the case here. Note that the error message: "Callback received for a midas::odb object which went out of scope" is not called! The segmentation fault happens later line 96.
> > 
> > > The answer is in the error message: „Object went out of scope“. When your frontent_init() exits, the odb objects are destroyed. When you get a callback, it‘s linked to the
> > > destroyed object. This is like if you have a local string and pass a reference to that string in the return of the function.
> > > 
> > > Use a global object (bad) or use „new“ (potential memory leak). I would use a global structure which holds all odb objects.
> > > 
> > > Stefan
> > >  
> > > > 
> > > > last week I was running MIDAS with the commit 3ad98c5. Today I updated MIDAS and now all my watch functions are crashing. Attached I have a minimal example frontend of the problem.
> > > > 
> > > > In our software we have two functions one which sets up the ODB values of the frontend and another one which sets up all watch functions. So overall we connect two time to the ODB during fronend_init one time to create the values and one time to create the watch. In the example code a simple version of this setup is shown:
> > > > 
> > > > INT frontend_init() {
> > > > 
> > > >   cm_msg(MINFO, "frontend_init() setup", "Test FE");
> > > > 
> > > >   odb settings = {
> > > >     {"Test", 123},
> > > >     {"sub", {}}
> > > >   };
> > > >   settings.connect_and_fix_structure("/Equipment/Test FE/Settings");
> > > >   // settings.watch(watch); <-- this works without segmentation fault
> > > > 
> > > >   odb new_settings("/Equipment/Test FE/Settings");
> > > >   new_settings.watch(watch); // <-- here I am getting a segmentation fault
> > > > 
> > > >   return CM_SUCCESS;
> > > > }
> > > > 
> > > > When I directly set the watch everything runs fine however, when I create a new ODB object and use this one to set a watch I am getting the following segmentation fault:
> > > > 
> > > > Process 18474 stopped
> > > > * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x34)
> > > >     frame #0: 0x000000010004fa38 test_fe`midas::odb::watch_callback(hDB=<unavailable>, hKey=<unavailable>, index=0, info=0x00006000002001c0) at odbxx.cxx:96:25 [opt]
> > > >    93  	      if (po->m_data == nullptr)
> > > >    94  	         mthrow("Callback received for a midas::odb object which went out of scope");
> > > >    95  	      midas::odb *poh = search_hkey(po, hKey);
> > > > -> 96  	      poh->m_last_index = index;
> > > >    97  	      po->m_watch_callback(*poh);
> > > >    98  	      poh->m_last_index = -1;
> > > >    99  	   }
> > > > 
> > > > Best,
> > > > Marius
  2850   16 Sep 2024 Mark GrimesBug ReportCrash using ODB watch
Hi,
Maybe I've misunderstood the code, but odb::watch() creates a deep copy of itself to set the watch to.  The comment where this happens specifies that this is in case the current one goes out of scope.  See https://bitbucket.org/tmidas/midas/src/2878647fb73648474b35223ce53a125180f751b3/src/odbxx.cxx#lines-1393:1395
So as far as I can tell allowing the current odb instance to go out of scope is supported.

Thanks,

Mark.


> Okay, but this is then a big issue IMO. For Mu3e we do this in every frontend and I also checked again all of these watches are broken at the moment (with commit 3ad98c5 they worked).
>  
> In the old style we did for example (see https://bitbucket.org/tmidas/midas/src/develop/examples/crfe/crfe.cxx):
> 
> INT frontend_init()
> {
>    HNDLE hKey;
> 
>    // create Settings structure in ODB
>    db_create_record(hDB, 0, "Equipment/Clock Reset/Settings", strcomb1(cr_settings_str).c_str());
>    db_find_key(hDB, 0, "/Equipment/Clock Reset", &hKey);
>    assert(hKey);
> 
>    db_watch(hDB, hKey, cr_settings_changed, NULL);
> 
>    /*
>     * Set our transition sequence. The default is 500. Setting it
>     * to 600 means we are called AFTER most other clients.
>     */
>    cm_set_transition_sequence(TR_START, 600);
> 
>    return CM_SUCCESS;
> }
> 
> I thought this will be the same (under the hood) in the current odbxx way via:
> 
> odb settings("Equipment/Clock Reset/Settings");
> settings.watch(cr_settings_changed);
> 
> Best,
> Marius
> 
> 
> > Well, the object *went* out of scope. For my code it‘s hard to realize this, so the error reporting is poor. Also the first object should have the same
> > problem. Just by accident that it does not crash.
> > 
> > Stefan 
> > 
> > > This is not the case here. Note that the error message: "Callback received for a midas::odb object which went out of scope" is not called! The segmentation fault happens later line 96.
> > > 
> > > > The answer is in the error message: „Object went out of scope“. When your frontent_init() exits, the odb objects are destroyed. When you get a callback, it‘s linked to the
> > > > destroyed object. This is like if you have a local string and pass a reference to that string in the return of the function.
> > > > 
> > > > Use a global object (bad) or use „new“ (potential memory leak). I would use a global structure which holds all odb objects.
> > > > 
> > > > Stefan
> > > >  
> > > > > 
> > > > > last week I was running MIDAS with the commit 3ad98c5. Today I updated MIDAS and now all my watch functions are crashing. Attached I have a minimal example frontend of the problem.
> > > > > 
> > > > > In our software we have two functions one which sets up the ODB values of the frontend and another one which sets up all watch functions. So overall we connect two time to the ODB during fronend_init one time to create the values and one time to create the watch. In the example code a simple version of this setup is shown:
> > > > > 
> > > > > INT frontend_init() {
> > > > > 
> > > > >   cm_msg(MINFO, "frontend_init() setup", "Test FE");
> > > > > 
> > > > >   odb settings = {
> > > > >     {"Test", 123},
> > > > >     {"sub", {}}
> > > > >   };
> > > > >   settings.connect_and_fix_structure("/Equipment/Test FE/Settings");
> > > > >   // settings.watch(watch); <-- this works without segmentation fault
> > > > > 
> > > > >   odb new_settings("/Equipment/Test FE/Settings");
> > > > >   new_settings.watch(watch); // <-- here I am getting a segmentation fault
> > > > > 
> > > > >   return CM_SUCCESS;
> > > > > }
> > > > > 
> > > > > When I directly set the watch everything runs fine however, when I create a new ODB object and use this one to set a watch I am getting the following segmentation fault:
> > > > > 
> > > > > Process 18474 stopped
> > > > > * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x34)
> > > > >     frame #0: 0x000000010004fa38 test_fe`midas::odb::watch_callback(hDB=<unavailable>, hKey=<unavailable>, index=0, info=0x00006000002001c0) at odbxx.cxx:96:25 [opt]
> > > > >    93  	      if (po->m_data == nullptr)
> > > > >    94  	         mthrow("Callback received for a midas::odb object which went out of scope");
> > > > >    95  	      midas::odb *poh = search_hkey(po, hKey);
> > > > > -> 96  	      poh->m_last_index = index;
> > > > >    97  	      po->m_watch_callback(*poh);
> > > > >    98  	      poh->m_last_index = -1;
> > > > >    99  	   }
> > > > > 
> > > > > Best,
> > > > > Marius
ELOG V3.1.4-2e1708b5