I would like to document a few problems I ran into while setting up a new
experiment (two USB interfaces to Alice TPC electronics, plus maybe a USB
interface to CAMAC). I am using a midas cvs checkout from last October, so I am
not sure if these problems exist in the very latest code. I have fixes for all
of them and I will commit them after some more testing and after I figure out
how to commit into this new svn thingy.
- mxml: writing xml into an in-memory buffer probably produces invalid xml
because one of the mxml functions always writes "/>" into writer->fh, which is 0
for in-memory writers, so the "/>" tag goes to the console instead of the xml
- hs_write_event() closes fd 0 (standard input), which confuses ss_getch(),
which makes mlogger not work (at least on my machine). I traced this down to the
history file file descriptors being initialized to zero and hs_write_event()
closing files without checking that it ever opened them.
- mevb: event builder did not work with a single frontend (a two-liner fix, once
Pierre showed me where to look. Why? My second TPC-USB interface did not yet
arrive and I wanted to test my frontend code. Yes, it had enough bugs to prevent
the event builder from working).
- mevb: consumes 100% CPU. Fix: add a delay in the main busy-loop.
- mlogger ROOT tree output does not work for data banks coming through the event
builder: mlogger looks for the bank definition under the event_id of mevb, in
/equipment/evb/variables, which is empty, as the data banks are under
/equipment/frontendNN/variables. This may be hard to fix: bank "TPCA" may be
under "fe01", "TPCB" under "fe02" and mlogger knows nothing about any of this.
Fix: go back to .mid files.