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[tree] avoid resetting index in entry list copy constructor #19039

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[tree] avoid resetting index in entry list copy constructor #19039

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68a20d8
[tree] avoid resetting index in entry list copy constructor
ferdymercury Jun 13, 2025
ba079f5
[test] add entry list copy test
ferdymercury Jun 13, 2025
dce7cc6
[nfc] clangformat
ferdymercury Jun 13, 2025
1e29698
[test] missing header
ferdymercury Jun 13, 2025
6ad61f8
[test] fix typo
ferdymercury Jun 16, 2025
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4 changes: 2 additions & 2 deletions tree/tree/src/TEntryList.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -287,8 +287,8 @@ TEntryList::TEntryList(const TEntryList &elist) : TNamed(elist)
fFileName = elist.fFileName;
fStringHash = elist.fStringHash;
fTreeNumber = elist.fTreeNumber;
fLastIndexQueried = -1;
fLastIndexReturned = 0;
fLastIndexQueried = elist.fLastIndexQueried;
fLastIndexReturned = elist.fLastIndexReturned;
Comment on lines +290 to +291
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It is a bit surprising changing for the usual starting point to the previously visited entry fixes the problem. Those 2 data members are meant to be accelerator and so the default value should have been fine. ... What is the mechanism leading to the failure?

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I guess it was an empirical fix. Without this, the returned value is PreviousVisitedEntry + 1, so 16 even if Index is -1
It seems as if the variable index is -1 but the entry pointer is still at 15.

fN = elist.fN;
fShift = elist.fShift;
fLists = nullptr;
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59 changes: 59 additions & 0 deletions tree/tree/test/entrylist_addsublist.cxx
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Expand Up @@ -4,6 +4,7 @@
#include "TFile.h"
#include "TSystem.h"
#include "TTree.h"
#include "TChain.h"

#include "gtest/gtest.h"

Expand Down Expand Up @@ -66,3 +67,61 @@ TEST(TEntryList, addSubList) {
gSystem->Unlink(filename1);
gSystem->Unlink(filename2);
}

TEST(TEntryList, copySubList)
{
auto filename1{"entrylist_copysublist_tree1.root"};
auto filename2{"entrylist_copysublist_tree2.root"};
auto treename{"t"};
int x = 0;
for (auto filename : {filename1, filename2}) {
TFile f(filename, "RECREATE");
TTree t(treename, treename);
t.Branch("x", &x);
t.Fill();
++x;
t.Fill();
++x;
f.Write();
f.Close();
}
{
TEntryList l1("l1", "l1", treename, filename1);
l1.Enter(0);
l1.Enter(1);
TEntryList l2("l2", "l2", treename, filename2);
l2.Enter(1);
TEntryList l;
l.Add(&l1);
l.Add(&l2);
TChain c(treename);
for (auto filename : {filename1, filename2})
c.Add(filename);
c.SetEntryList(&l);

int treenum;
auto value = l.GetEntryAndTree(0, treenum);
EXPECT_EQ(value, 0);
EXPECT_EQ(treenum, 0);
value = l.GetEntryAndTree(1, treenum);
EXPECT_EQ(value, 1);
EXPECT_EQ(treenum, 0);
value = l.GetEntryAndTree(2, treenum);
EXPECT_EQ(value, 1);
EXPECT_EQ(treenum, 1);

TEntryList lcopy(l);
value = lcopy.GetEntryAndTree(0, treenum);
EXPECT_EQ(value, 0);
EXPECT_EQ(treenum, 0);
value = lcopy.GetEntryAndTree(1, treenum);
EXPECT_EQ(value, 1);
EXPECT_EQ(treenum, 0);
value = lcopy.GetEntryAndTree(2, treenum);
EXPECT_EQ(value, 1);
EXPECT_EQ(treenum, 1);
}

for (auto filename : {filename1, filename2})
gSystem->Unlink(filename);
}
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