Records event data verbatim from ring buffers to disk files. The program monitors the source ring buffer for a begin run item. At that point it opens an event file for that run and begins to record data from the ring.
Runs are recorded in files in the target directory. Event files are named run-runnumber-segment.evt where runnumber is the run number of the run taken from the begin run item, segment is a file segment numbered from zero.
Runs are segmented in file that are no larger than a segment size. This is done to avoid creating files that are too large for a file system to handle or too large for NFS to accurately serve.
An option allows the program to be started by a controlling program for a single run (e.g. by the readout GUI).
Options have sensible defaults. See OPTIONS below.
--checksumIf present, an SHA512 checksum is computed over the data in each run and output to a file named run-nnnn.sha512 in the same directory as the event file. The checksum should match the value that would be produced by the command: sha512sum run-nnnn*.evt
--number-of-sources=nIndicates to the logger the number of end of run items it should expect to see prior to closing the run. Once the first end of run is seen, if there is ever a long time without getting any data from the ring source, the logger will complain about a timeout and close the run anyway.
Once n end of run items are seen in a
single run, the run file is closed. As you might expect,
n must be an integer with a value
that is greater than zero.
--source=ringuriDefines the event source as a Ring buffer Uniform Resource Identifier (URI). The URI can be for a local or a remote ring buffer. By default the ring: tcp://localhost/username where username is the username of the account running the program.
--path=dirProvides the path to the directory in which the program will write its event files. By default, this is current working directory at the time eventlog is started.
eventlog ensures that the path is a directory and is writable.
--segmentsize=size-spec
Specifies the size of the files segments created.
size-spec can be any of an integer number
of bytes or an integer followed by one of the suffixes:
g, m, k
that multiply the integer by a gigabyte, a megabyte and a kilobyte
repsectively.
The default value is a 1900m, which should be suitable for most operating environments.
--oneshotWhen present, the program only records a single run, then exits. The program will also create the .started file in the target directory when it's ready to record data, and the .exited file when it's about to exit.
--run number
When present, the number unconditionally sets
the run number for the run. This requires the --oneshot
switch to be present and eventlog will exit with an error if that is not
the case. This switch is intended to be used with a set of event sources
that either don't have the concept of a run number or, alternatively,
cannot synchronize their run numbers. The NSCLDAQ-11 readoutGui will
use this switch to force the run number of event files created to match the
run number in the ReadoutGUI run number entry.
--combine-runs
When present, the normal checks in --one-shot mode
that would make the event logger exit if run numbers are observed to change
or if there are too many begin runs, are not made.