ROOTDeserializer.h

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#ifndef FWCore_SharedMemory_ROOTDeserializer_h
#define FWCore_SharedMemory_ROOTDeserializer_h
// -*- C++ -*-
//
// Package:     FWCore/SharedMemory
// Class  :     ROOTDeserializer
//
//
// Original Author:  Chris Jones
//         Created:  22/01/2020
//

// system include files
#include "TClass.h"
#include "TBufferFile.h"

// user include files

// forward declarations

namespace edm::shared_memory {
  template <typename T, typename READBUFFER>
  class ROOTDeserializer {
  public:
    ROOTDeserializer(READBUFFER& iBuffer)
        : buffer_{iBuffer}, class_{TClass::GetClass(typeid(T))}, bufferFile_(TBuffer::kRead) {}

    ROOTDeserializer(const ROOTDeserializer&) = delete;
    const ROOTDeserializer& operator=(const ROOTDeserializer&) = delete;
    ROOTDeserializer(ROOTDeserializer&&) = delete;
    const ROOTDeserializer& operator=(ROOTDeserializer&&) = delete;

    // ---------- const member functions ---------------------

    // ---------- member functions ---------------------------
    T deserialize() {
      T value;
      if (previousBufferIdentifier_ != buffer_.bufferIdentifier()) {
        auto buff = buffer_.buffer();
        bufferFile_.SetBuffer(buff.first, buff.second, kFALSE);
        previousBufferIdentifier_ = buffer_.bufferIdentifier();
      }

      class_->ReadBuffer(bufferFile_, &value);
      bufferFile_.Reset();
      return value;
    }

  private:
    // ---------- member data --------------------------------
    READBUFFER& buffer_;
    TClass* const class_;
    TBufferFile bufferFile_;
    int previousBufferIdentifier_ = 0;
  };
}  // namespace edm::shared_memory

#endif