The FEE Server Control Engine of the ALICE-TRD - Westfälische ...

5 The FEEServer Control Engine
a test, string triggerTransition (char * ) calls the function ROCControl::parseCompleteHeader
(cfdat_header * header) first. This function configures the complete control engine. It extracts
the offsets to three of the four sections in the configuration and calls the functions
which process the information in these sections:
• The cfdat_error_header is passed to patch_maker. Based on these data the patchmaker
creates the necessary SCSN commands which cause the MCMs to deactivate
their damaged parts. Furthermore it creates a list of damaged MCMs which the
class SCSNBus uses to bridge the linkpairs if necessary.
• The rocinfo_header is passed to class ROCInfo. ROCInfo stores the general chamber
informations and provides get-functions to access this information. For example the
function ROCInfo::getRocType() returns the roc type or ROCInfo::getNLinks() returns
the number of linkpairs.
• The cfdat_temp_calib is passed to class TempControl. Since no calibration values are
available yet cfdat_temp_calib is set to zero and the data are not processed further.
In case of any valid transition string CEStateMachine::triggerTransition(char * ) calls void
ROCControl::execCommands(cfdat_header * header). The function checks if the version of
the configuration is compatible with the version of the control engine, writes the name
of the configuration to the logging system and extracts the list of SCSN commands. The
list of commands is passed to void ROCExecutor::execute(cfdat_command * cmds, unsigned
int n_cmd).
The class ROCExecutor handles the execution of all SCSN commands. It is derived from
class SCSNBus. The function void ROCControl::execute(cfdat_command * cmds, unsigned int
n_cmd) loops over the list of SCSN commands. Blocks of normal SCSN commands 3 are
passed to the inherited function void execute(cfdat_command * cmds, unsigned int n_cmd)
of class SCSNBus. Extended SCSN commands are handled by private functions of
ROCExecutor. Table B.1 in the appendix gives an overview over all defined extended
SCSN commands. After the list of SCSN commands is processed successfully the control
flow returns to function string CEStateMachine::triggerTransition(char * ). The function updates
the FSM state and unlocks the mutex. Afterwards the system is ready to process
the next transition request.
In case of an extended SCSN command, like the command to run tests, it is possible
that the function called to handle this command creates a list of SCSN commands which
need to be executed. Usually one would create just a new instance of class ROCExecutor
and use this new instance to execute the commands. But in case of the control engine this
class and some other classes store configuration values and cannot be re-created when an
instance of these classes is needed. Furthermore, classes developed for the libTRD use
the class SCSNBus from libTRD to access the SCSN Bus but in the control engine the SCSN
Bus access is provided by ROCExecutor. All classes from libTRD should automatically use
ROCExecutor when running in the control engine.
To meet all these requirements a pair of classes was developed by Thomas Dietel:
trd_factory for the libTRD and TRDCEFactory for the libce. Both classes are designed as
singleton classes 4 [GHJV94].
3 Commands with a number less then 16, see table B.1.
4 A singleton class has some properties of a global variable. During runtime only one instance of the class
can exist and this instance is accessible from every part of the program.
57