TParallelMergingFile.cxx

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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.             *
 *************************************************************************/
 
//////////////////////////////////////////////////////////////////////////
//                                                                      //
// 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 "TParallelMergingFile.h"
#include "TSocket.h"
#include "TArrayC.h"
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor.
/// We do no yet open any connection to the server.  This will be done at the
/// time the first upload will be requested.
 
TParallelMergingFile::TParallelMergingFile(const char *filename, Option_t *option /* = "" */,
                                           const char *ftitle /* = "" */, Int_t compress /* = 1 */) :
   TMemFile(filename,option,ftitle,compress)
{
   TString serverurl = strstr(fUrl.GetOptions(),"pmerge=");
   if (serverurl.Length()) {
      serverurl.ReplaceAll("pmerge=","pmerge://");
      fServerLocation = TUrl(serverurl);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor.
 
TParallelMergingFile::~TParallelMergingFile()
{
   // We need to call Close, right here so that it is executed _before_
   // the data member of TParallelMergingFile are destructed.
   Close();
}
 
////////////////////////////////////////////////////////////////////////////////
 
void TParallelMergingFile::Close(Option_t *option)
{
   TMemFile::Close(option);
   if (fSocket) {
      if (0==fSocket->Send("Finished")) {          // tell server we are finished
         Warning("Close","Failed to send the finishing message to the server %s:%d",fServerLocation.GetHost(),fServerLocation.GetPort());
      }
      fSocket->Close();
      fSocket.reset();
   }
}
 
/// Attempts to connect to the server. Has no effect if the file is already connected.
/// Returns true if the file is connected after calling this function (including if it was connected already).
/// Note: normally it's not necessary to explicitly call this as it will be called automatically by Write().
Bool_t TParallelMergingFile::OpenConnection()
{
   if (fSocket)
      return kTRUE;
 
   const char *path = fServerLocation.GetFile();
   if (path && strlen(path) > 0 && path[0] == '/') {
      // UNIX domain socket
      fSocket.reset(new TSocket(path));
      if (!fSocket->IsValid()) {
         Error("UploadAndReset", "Could not contact the server %s\n", path);
         fSocket.reset();
         return kFALSE;
      }
   } else {
      // TCP socket
      const char *host = fServerLocation.GetHost();
      Int_t port = fServerLocation.GetPort();
      if (host == 0 || host[0] == '\0') {
         host = "localhost";
      }
      if (port <= 0) {
         port = 1095;
      }
      fSocket.reset(new TSocket(host, port));
      if (!fSocket->IsValid()) {
         Error("UploadAndReset", "Could not contact the server %s:%d\n", host, port);
         fSocket.reset();
         return kFALSE;
      }
   }
   // Wait till we get the start message
   // server tells us who we are
   Int_t kind;
   Int_t n = fSocket->Recv(fServerIdx, kind);
 
   if (n < 0 && kind != 0 /* kStartConnection */)
   {
      Error("UploadAndReset","Unexpected server message: kind=%d idx=%d\n",kind,fServerIdx);
      fSocket.reset();
      return kTRUE;
   }
   n = fSocket->Recv(fServerVersion, kind);
   if (n < 0 && kind != 1 /* kProtocol */)
   {
      Fatal("UploadAndReset","Unexpected server message: kind=%d status=%d\n",kind,fServerVersion);
   } else {
      Info("UploadAndReset","Connected to fastMergeServer version %d with index %d\n",fServerVersion,fServerIdx);
   }
   TMessage::EnableSchemaEvolutionForAll(kTRUE);
 
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Upload the current file data to the merging server.
/// Reset the file and return true in case of success.
 
Bool_t TParallelMergingFile::UploadAndReset()
{
   OpenConnection();
 
   fMessage.Reset(kMESS_ANY); // re-use TMessage object
   fMessage.WriteInt(fServerIdx);
   fMessage.WriteTString(GetName());
   fMessage.WriteLong64(GetEND());
   CopyTo(fMessage);
 
   if (int error = fSocket->Send(fMessage); error <= 0) {
      Error("UploadAndReset","Upload to the merging server failed with %d\n",error);
      fSocket.reset();
      return kFALSE;
   }
 
   // Record the StreamerInfo we sent over.
   Int_t isize = fClassIndex->GetSize();
   if (!fClassSent) {
      fClassSent.reset(new TArrayC(isize));
   } else {
      if (isize > fClassSent->GetSize()) {
         fClassSent->Set(isize);
      }
   }
   for(Int_t c = 0; c < isize; ++c) {
      if (fClassIndex->fArray[c]) {
         fClassSent->fArray[c] = 1;
      }
   }
   ResetAfterMerge(0);
 
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Write memory objects to this file and upload them to the parallel merge server.
/// Then reset all the resetable object (those with a ResetAfterMerge routine,
/// like TTree).
///
/// Loop on all objects in memory (including subdirectories).
/// A new key is created in the KEYS linked list for each object.
/// The list of keys is then saved on the file (via WriteKeys)
/// as a single data record.
/// For values of opt see TObject::Write().
/// The directory header info is rewritten on the directory header record.
/// The linked list of FREE segments is written.
/// The file header is written (bytes 1->fBEGIN).
 
Int_t TParallelMergingFile::Write(const char *, Int_t opt, Int_t bufsize)
{
   std::size_t prevSize = GetBytesWritten();
   auto nbytes = TMemFile::Write(0,opt,bufsize);
   std::size_t newSize = GetBytesWritten();
   // NOTE: we don't rely on nbytes > 0 to do UploadAndReset() because nbytes may be 0 if the file
   // only contains non-TObject objects (as they are not written by TMemFile::Write).
   if (newSize > prevSize) {
      UploadAndReset();
   }
   return nbytes;
}
 
////////////////////////////////////////////////////////////////////////////////
/// One can not save a const TDirectory object.
 
Int_t TParallelMergingFile::Write(const char *n, Int_t opt, Int_t bufsize) const
{
   Error("Write const","A const TFile object should not be saved. We try to proceed anyway.");
   return const_cast<TParallelMergingFile*>(this)->Write(n, opt, bufsize);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Write the list of TStreamerInfo as a single object in this file
/// The class Streamer description for all classes written to this file
/// is saved. See class TStreamerInfo.
 
void TParallelMergingFile::WriteStreamerInfo()
{
   if (!fWritable) return;
   if (!fClassIndex) return;
   //no need to update the index if no new classes added to the file
   if (fClassIndex->fArray[0] == 0) return;
 
   // clear fClassIndex for anything we already sent.
   if (fClassSent) {
      Int_t isize = fClassIndex->GetSize();
      Int_t ssize = fClassSent->GetSize();
      for(Int_t c = 0; c < isize && c < ssize; ++c) {
         if (fClassSent->fArray[c]) {
            fClassIndex->fArray[c] = 0;
         }
      }
   }
 
   TMemFile::WriteStreamerInfo();
}