GaudiGSL package

The GslSvc is the service which perform intelligent error handling for GSL (GNU Scientific Library). It provides a choice between different "Error Handling Policies". The current implementation supports the following ones, which are driven by "ErrorPolicy" property of class GslSvc:

• GSL. It is the simplest error policy, which implies no action, the error handling defined in GSL is not redefined
• Off. The GSL empty error handling is used, what means the ignorance of all GSL errors. Program continues after any error, so the return values from any library routines must be checked. This policy is recommended by GSL team for production programs
• Abort. The default GSL error policy, causes abort on error.
• Ignore. The policy which is essentially the same as "Off" but performed with local error handler GslErrorHandlers::ignoreTheError
• Exception. This policy throws the GaudiException with tag *GSL Error" to be thrown at the error. The policy implemented by local error handler GslErrorHandlers::throwException.
• Handle. The policy which uses the call back from local error handle GslErrorHandlers::handleTheError to IGslSvc::handle method.

Current implementation of this method is sequential execution of declared handlers, defined thought the property "Handlers" of class GslSvc in a format:

GslSvc.Handlers = { "H1Type/H1Name" , "H2Type/H2Name" , "H3ype/3Name" };

The "handlers" must implement IGslErrorHandler interface. The three concrete simple handlers are provided in GaudiGSL package:

class GslErorCount, GslErrorPrint and GslErrorException.

Typical job-configurations:

// This configuration perform the "on-flight" printout of all GSL
// errors and the printout of overall statistics of all errors
// at the end of the job

ApplicationMgr.DLLs += { "GaudiGSL" };
ApplicationMgr.ExtSvc += { "GslSvc" };
ApplicationMgr.ErrorPolicy = "Handle" ;
ApplicationMgr.Handlers += { "GslErrorPrint/GslPrint" };
ApplicationMgr.Handlers += { "GslErrorCount/GslCount" };

// This configuration is good for massive production.
// Program continues after any error, so the return values from
// any library routines must be checked. This policy is recommended
// by GSL team for production programs

ApplicationMgr.DLLs += { "GaudiGSL" };
ApplicationMgr.ExtSvc += { "GslSvc" };
ApplicationMgr.ErrorPolicy = "Off" ;

// This configuration corresponds to default GSL behaviour and
// functional it is equivalent to the absence of special error
// handling at all. Program just makes abortion on errors.

ApplicationMgr.DLLs += { "GaudiGSL" };
ApplicationMgr.ExtSvc += { "GslSvc" };
ApplicationMgr.ErrorPolicy = "Abort" ;

// Under this configuration on the error the handler throws
// GaudiException with tag = *GSL Error*

ApplicationMgr.DLLs += { "GaudiGSL" };
ApplicationMgr.ExtSvc += { "GslSvc" };
ApplicationMgr.ErrorPolicy = "Exception" ;

// This configuration is similar to the previous one
// but GaudiException is throwed by specialized handler, and
// thus it could be combined in a sequence with other
// specialized handlers

ApplicationMgr.DLLs += { "GaudiGSL" };
ApplicationMgr.ExtSvc += { "GslSvc" };
ApplicationMgr.ErrorPolicy = "Handle" ;

// "Everything altogether" configuration.
// It prints the error message, accumulate statistics of errors
// and throws the exception

ApplicationMgr.DLLs += { "GaudiGSL" };
ApplicationMgr.ExtSvc += { "GslSvc" };
ApplicationMgr.ErrorPolicy = "Handle" ;
ApplicationMgr.Handlers += { "GslErrorPrint/GslPrint" };
ApplicationMgr.Handlers += { "GslErrorCount/GslCount" };
ApplicationMgr.Handlers += { "GslErrorException/GslException" };

The handling of some error codes could be suppressed explicitly, e.g.:

GslSvc.IgnoreCodes = { 0 , 15 , -1 , 158 } ;

(this option is valid only for "Handle" mode). In addition one could forbid the exception throws for certain error codes:

GslException.IgnoreCodes = { 0 , -1 };