19 Feb 2024, Pavel Murat, Forum, number of entries in a given ODB subdirectory ?
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> > Hmm... is there any use case where you want to know the number of directory entries, but you will not iterate
> > over them later?
>
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01 Jan 2009, Konstantin Olchanski, Info, odb "hot link" magic explored
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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
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14 Jan 2009, Stefan Ritt, Info, odb "hot link" magic explored
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[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]
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23 Dec 2010, Konstantin Olchanski, Bug Report, odb corruption, odb race condition?
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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?
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> 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().
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24 Dec 2010, Konstantin Olchanski, Bug Report, odb corruption, odb race condition?
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> > 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.
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08 Aug 2022, Konstantin Olchanski, Info, odb disallow key names that start or end with spaces
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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
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13 Oct 2017, Konstantin Olchanski, Info, odb multithread support repaired
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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
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20 Feb 2019, Konstantin Olchanski, Info, odb needs protection against ctrl-c
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Even with the cm_watchdog signal removed, some trouble from UNIX signals remains.
This time, when one presses Ctrl-C at the wrong time, the Ctrl-C signal handler will run at the wrong time
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20 Feb 2019, Stefan Ritt, Info, odb needs protection against ctrl-c
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Not sure if you realized, but there is a two-stage Ctrl-C handling inside midas. The first time you hit ctrl-c, the handler just sets a flag for the main
event loop, so that the program can gracefully exit without trouble. This is
done inside cm_ctrlc_handler(), which sets _ctrlc_pressed true if called. Then cm_yield() tests this flag and returns RPC_SHUTDOWN if so. I agree not very |
20 Feb 2019, Konstantin Olchanski, Info, odb needs protection against ctrl-c
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Commit f81ff3c protects db_lock/unlock, but not any of the other functions. What if we do ctrl-c in the middle
of some odb write operation in the middle of memory allocation, etc.
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20 Feb 2019, Konstantin Olchanski, Info, odb needs protection against ctrl-c
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> Not sure if you realized, but there is a two-stage Ctrl-C handling inside midas.
Hmm... I am looking at the ctrl-c handler inside odbedit.
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20 Feb 2019, Stefan Ritt, Info, odb needs protection against ctrl-c
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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 |
18 Feb 2009, Konstantin Olchanski, Info, odbc sql history mlogger update
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> mhttpd and mlogger have been updated with potentially troublesome changes.
> These new features are now available:
> - a "feature complete" implementation of "history in an SQL database".
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07 May 2009, Konstantin Olchanski, Bug Report, odbedit bad ctrl-C
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When using "/bin/bash" shell, if I exit odbedit (and other midas programs) using ctrl-C, the terminal
enters a funny state, "echo" is turned off (I cannot see what I type), "delete" key does not work (echoes
^H instead).
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04 Jun 2009, Stefan Ritt, Bug Report, odbedit bad ctrl-C
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> When using "/bin/bash" shell, if I exit odbedit (and other midas programs) using ctrl-C, the terminal
> enters a funny state, "echo" is turned off (I cannot see what I type), "delete" key does not work (echoes
> ^H instead).
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26 Jul 2013, Konstantin Olchanski, Bug Report, odbedit fixed size buffer overrun
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odbedit uses a fixed size buffer for ODB data. If an array in ODB is bugger than this size,
db_get_data() correctly returns DB_TRUNCATED and there is no memory overwrite, but the following
code for printing the data does not know about this truncation and proceeds printing memory
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25 Nov 2009, Konstantin Olchanski, Bug Report, once in 100 years midas shared memory bug
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We were debugging a strange problem in the event builder, where out of 14
fragments, two fragments were always getting serial number mismatches and the
serial numbers were not sequentially increasing (the other 12 fragments were
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15 Apr 2024, Konstantin Olchanski, Bug Report, open MIDAS RPC ports
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we had a bit of trouble with open network ports recently and I now think security of MIDAS RPC
ports needs to be tightened.
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15 Apr 2024, Stefan Ritt, Bug Report, open MIDAS RPC ports
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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
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