JSONSink.cpp

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/***********************************************************************************\
* (c) Copyright 2022 CERN for the benefit of the LHCb and ATLAS collaborations      *
*                                                                                   *
* This software is distributed under the terms of the Apache version 2 licence,     *
* copied verbatim in the file "LICENSE".                                            *
*                                                                                   *
* In applying this licence, CERN does not waive the privileges and immunities       *
* granted to it by virtue of its status as an Intergovernmental Organization        *
* or submit itself to any jurisdiction.                                             *
\***********************************************************************************/
 
#include <Gaudi/BaseSink.h>
#include <Gaudi/MonitoringHub.h>
 
#include <fstream>
 
#include <string>
 
namespace Gaudi::Monitoring {
 
  class JSONSink : public BaseSink {
 
  public:
    using BaseSink::BaseSink;
 
    StatusCode stop() override {
      return BaseSink::stop().andThen( [&] {
        if ( m_fileName.empty() ) { return StatusCode::SUCCESS; }
        nlohmann::json output;
        applytoAllEntities( [&output]( auto& ent ) {
          output.emplace_back( nlohmann::json{
              { "name", ent.name },
              { "component", ent.component },
              { "entity", ent.toJSON() },
          } );
        } );
        info() << "Writing JSON file " << m_fileName.value() << endmsg;
        std::ofstream os( m_fileName, std::ios::out );
        os << output.dump( 4 );
        os.close();
        return StatusCode::SUCCESS;
      } );
    }
 
  private:
    Gaudi::Property<std::string> m_fileName{ this, "FileName", "json_output.json",
                                             "Name of output json file. Empty fileName means no output" };
  };
 
  DECLARE_COMPONENT( JSONSink )
 
} // namespace Gaudi::Monitoring