 20 Feb 2019, Stefan Ritt, Info, odb needs protection against ctrl-c
|
Have you read what I wrote? The current ctrl-c handler just sets the _ctrlc_pressed flag. It might be that some programs do not correctly interprete the
return of cm_yield(), certainly the frontend does it correctly. On the SECOND ctrl-c, the program gets
(internally) hard aborted, equivalent to calling abort(). Not sure if the code works everywhere, I see now that cm_yield(() should maybe return SS_ABORT |
 13 Oct 2017, Konstantin Olchanski, Info, odb multithread support repaired
|
multithreaded access to odb was implemented back in 2013-2014. but recently a bug surfaced -
there was a race condition in the odb locking code against cm_watchdog(). Somehow this only
affected the mserver for the DRAGON experiment at TRIUMF. This is now fixed on the branch
|
|
08 Aug 2022, Konstantin Olchanski, Info, odb disallow key names that start or end with spaces
|
while testing the new odb editor, we ran into a number of problems with key names
that start or end with spaces. we cannot think of any valid use case for such key
names (subdirectories and variables) and we think they could only have been
|
|
23 Dec 2010, Konstantin Olchanski, Bug Report, odb corruption, odb race condition?
|
The following script makes midas very unhappy and eventually causes odb corruption. I suspect the reason is some kind of race condition collision between
client
creation and destruction code and the watchdog activity (each client periodically runs cm_watchdog() to check if other clients are still alive, O(NxN) |
|
24 Dec 2010, Konstantin Olchanski, Bug Report, odb corruption, odb race condition?
|
> Thu Dec 23 12:10:30 2010 [ODBEdit9,ERROR] [odb.c:3247:db_get_value,ERROR] "Name" is of type NULL, not STRING
This is caused by a race condition between client removal in cm_delete_client_info() and cm_exist().
|
|
24 Dec 2010, Konstantin Olchanski, Bug Report, odb corruption, odb race condition?
|
> > Thu Dec 23 12:10:30 2010 [ODBEdit9,ERROR] [odb.c:3247:db_get_value,ERROR] "Name" is of type NULL, not STRING
> This is caused by a race condition between client removal in cm_delete_client_info() and cm_exist().
> ... this race condition seems to be benign.
|
|
01 Jan 2009, Konstantin Olchanski, Info, odb "hot link" magic explored
|
Here are my notes on the MIDAS ODB "hot link" function. Perhaps others can find them useful.
Using db_open_record(key,function), the user can tell MIDAS to call the specified user function when
|
|
14 Jan 2009, Stefan Ritt, Info, odb "hot link" magic explored
|
[quote="KO"]note 1: I do not completely understand the ss_suspend_xxx() stuff. The best I can tell is it creates a number of udp sockets bound to the local
host and at least one udp rpc receive socket ultimately connected to the cm_dispatch_rpc() function.[/quote]
|
|
28 Jan 2024, Pavel Murat, Forum, number of entries in a given ODB subdirectory ?
|
Dear MIDAS experts,
- I have a detector configuration with a variable number of hardware components - FPGA's receiving data
|
|
28 Jan 2024, Konstantin Olchanski, Forum, number of entries in a given ODB subdirectory ?
|
Very good question. It exposes a very nasty problem, the race condition between "ls" and "rm". While you are
looping over directory entries, somebody else is completely permitted to remove one of the files (or add more
files), making the output of "ls" incorrect (contains non-existant/removed files, does not contain newly added
|
28 Jan 2024, Stefan Ritt, Forum, number of entries in a given ODB subdirectory ? 
|
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).
|
|
29 Jan 2024, Pavel Murat, Forum, number of entries in a given ODB subdirectory ?
|
Hi Stefan, Konstantin,
thanks a lot for your responses - they are very teaching and it is good to have them archived in the forum.
|
|
29 Jan 2024, Konstantin Olchanski, Forum, number of entries in a given ODB subdirectory ?
|
> 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
|
|
03 Feb 2024, Pavel Murat, Forum, number of entries in a given ODB subdirectory ?
|
Konstantin is right: KEY.num_values is not the same as the number of subkeys (should it be ?)
For those looking for an example in the future, I attach a working piece of code converted
from the ChatGPT example, together with its printout.
|
|
08 Feb 2024, Stefan Ritt, Forum, number of entries in a given ODB subdirectory ?
|
> 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
|
|
11 Feb 2024, Pavel Murat, Forum, number of entries in a given ODB subdirectory ?
|
> 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
|
|
13 Feb 2024, Stefan Ritt, Forum, number of entries in a given ODB subdirectory ?
|
> > 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
|
|
15 Feb 2024, Konstantin Olchanski, Forum, number of entries in a given ODB subdirectory ?
|
> > > 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
|
|
15 Feb 2024, Konstantin Olchanski, Forum, number of entries in a given ODB subdirectory ?
|
> > 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.
|
|
15 Feb 2024, Stefan Ritt, Forum, number of entries in a given ODB subdirectory ?
|
> Hmm... is there any use case where you want to know the number of directory entries, but you will not iterate
> over them later?
|