// @(#)root/base:$Name: $:$Id: TFree.cxx,v 1.5 2003/12/30 13:16:50 brun Exp $ // Author: Rene Brun 28/12/94 /************************************************************************* * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers. * * All rights reserved. * * * * For the licensing terms see $ROOTSYS/LICENSE. * * For the list of contributors see $ROOTSYS/README/CREDITS. * *************************************************************************/ #include "TFree.h" #include "TList.h" #include "TFile.h" #include "Bytes.h" ClassImp(TFree) //______________________________________________________________________________ // // Service class for TFile. // Each file has a linked list of free segments. Each free segment // is described by its firts and last address. // When an object is written to a file via TObject::Write, a new Key (see TKey) // is created. The first free segment big enough to accomodate the object // is used. // If the object size has a length corresponding to the size of the free segment, // the free segment is deleted from the list of free segments. // When an object is deleted from a file, a new TFree object is generated. // If the deleted object is contiguous to an already deleted object, the free // segments are merged in one single segment. // //______________________________________________________________________________ TFree::TFree() { //*-*-*-*-*-*-*-*-*-*-*TFree default constructor*-*-*-*-*-*-*-*-*-*-*-*-* //*-* ========================= } //______________________________________________________________________________ TFree::TFree(TList *lfree, Long64_t first, Long64_t last) { //*-*-*-*-*-*-*-*-*-*-*Constructor for a FREE segment*-*-*-*-*-*-*-*-*-*-*-*-* //*-* ============================== fFirst = first; fLast = last; lfree->Add(this); } //______________________________________________________________________________ TFree *TFree::AddFree(TList *lfree, Long64_t first, Long64_t last) { //*-*-*-*-*-*-*-*-*-*Add a new free segment to the list of free segments*-*-* //*-* =================================================== // If last just preceedes an existing free segment, then first becomes // the new starting location of the free segment. // if first just follows an existing free segment, then last becomes // the new ending location of the free segment. // if first just follows an existing free segment AND last just preceedes // an existing free segment, these two segments are merged into // one single segment. // TFree *idcur = this; while (idcur) { Long64_t curfirst = idcur->GetFirst(); Long64_t curlast = idcur->GetLast(); if (curlast == first-1) { idcur->SetLast(last); TFree *idnext = (TFree*)lfree->After(idcur); if (idnext == 0) return idcur; if (idnext->GetFirst() > last+1) return idcur; idcur->SetLast( idnext->GetLast() ); lfree->Remove(idnext); return idcur; } if (curfirst == last+1) { idcur->SetFirst(first); return idcur; } if (first < curfirst) { TFree * newfree = new TFree(); newfree->SetFirst(first); newfree->SetLast(last); lfree->AddBefore(idcur, newfree); return newfree; } idcur = (TFree*)lfree->After(idcur); } return 0; } //______________________________________________________________________________ TFree::~TFree() { //*-*-*-*-*-*-*-*-*-*-*-*TFree Destructor*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* //*-* ================ } //______________________________________________________________________________ void TFree::FillBuffer(char *&buffer) { //*-*-*-*-*-*-*-*-*-*-*Encode FREE structure into output buffer*-*-*-*-*-*-* //*-* ======================================== Version_t version = TFree::Class_Version(); if (fLast > TFile::kStartBigFile) version += 1000; tobuf(buffer, version); //printf("TFree::fillBuffer, fFirst=%lld, fLast=%lld, version=%d\n",fFirst,fLast,version); if (version > 1000) { tobuf(buffer, fFirst); tobuf(buffer, fLast); } else { tobuf(buffer, (Int_t)fFirst); tobuf(buffer, (Int_t)fLast); } } //______________________________________________________________________________ TFree *TFree::GetBestFree(TList *lfree, Int_t nbytes) { //*-*-*-*-*-*-*-*-*-*Return the best free segment where to store nbytes*-*-*-* //*-* ================================================== TFree *idcur = this; if (idcur == 0) return 0; TFree *idcur1 = 0; do { Long64_t nleft = Long64_t(idcur->fLast - idcur->fFirst +1); if (nleft == nbytes) return idcur; //*-* found an exact match if(nleft > (Long64_t)(nbytes+3)) if (idcur1 == 0) idcur1=idcur; idcur = (TFree*)lfree->After(idcur); } while (idcur !=0); if (idcur1) return idcur1; //*-* return first segment >nbytes //try big file idcur = (TFree*)lfree->Last(); Long64_t last = idcur->fLast+1000000000; idcur->SetLast(last); return idcur; } //______________________________________________________________________________ void TFree::ReadBuffer(char *&buffer) { //*-*-*-*-*-*-*-*-*-*-*-*Decode one FREE structure from input buffer*-*-*-*-* //*-* =========================================== Version_t version; frombuf(buffer, &version); if (version > 1000) { frombuf(buffer, &fFirst); frombuf(buffer, &fLast); } else { Int_t first,last; frombuf(buffer, &first); fFirst = (Long64_t)first; frombuf(buffer, &last); fLast = (Long64_t)last; } } //______________________________________________________________________________ Int_t TFree::Sizeof() const { // return number of bytes occupied by this TFree on permanent storage if (fLast > TFile::kStartBigFile) return 18; else return 10; }