TParallelMergingFile.h

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// @(#)root/net:$Id$
// Author: Philippe Canal October 2011.
 
/*************************************************************************
 * Copyright (C) 1995-2011, Rene Brun, Fons Rademakers and al.           *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
#ifndef ROOT_TParallelMergingFile
#define ROOT_TParallelMergingFile
 
 
//////////////////////////////////////////////////////////////////////////
//                                                                      //
// TParallelMergingFile                                                 //
//                                                                      //
// Specialization of TMemFile to connect to a parallel file merger.     //
// Upon a call to UploadAndReset, the content already written to the    //
// file is upload to the server and the object implementing the function//
// ResetAfterMerge (like TTree) are reset.                              //
// The parallel file merger will then collate the information coming    //
// from this client and any other client in to the file described by    //
// the filename of this object.                                         //
//                                                                      //
//////////////////////////////////////////////////////////////////////////
 
#include "TMemFile.h"
#include "TMessage.h"
#include "TUrl.h"
#include <memory>
 
 
class TSocket;
class TArrayC;
 
class TParallelMergingFile : public TMemFile
{
private:
   std::unique_ptr<TSocket> fSocket;    // Socket to the parallel file merger server.
   TUrl     fServerLocation;            // Url of the server.
   Int_t    fServerIdx = -1;            // Index of this socket/file on the server.
   Int_t    fServerVersion = 0;         // Protocol version used by the server.
   std::unique_ptr<TArrayC> fClassSent; // Record which StreamerInfo we already sent.
   TMessage fMessage {kMESS_OBJECT};
 
public:
   TParallelMergingFile(const char *filename, Option_t *option = "", const char *ftitle = "", Int_t compress = ROOT::RCompressionSetting::EDefaults::kUseCompiledDefault);
   ~TParallelMergingFile();
 
   void   Close(Option_t *option="") override;
   Bool_t OpenConnection();
   Bool_t UploadAndReset();
   Int_t  Write(const char *name=nullptr, Int_t opt=0, Int_t bufsize=0) override;
   Int_t  Write(const char *name=nullptr, Int_t opt=0, Int_t bufsize=0) const override;
   void   WriteStreamerInfo() override;
 
   Int_t GetServerIdx() const { return fServerIdx; }
 
   ClassDefOverride(TParallelMergingFile, 0);  // TFile specialization that will semi-automatically upload its content to a merging server.
};
 
#endif // ROOT_TParallelMergingFile