Skip to content

Fixing an O(N^2) scaling problem caused by TTree::Draw() #650

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
sawenzel wants to merge 1 commit into from
Closed

Fixing an O(N^2) scaling problem caused by TTree::Draw() #650

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 10 additions & 0 deletions tree/treeplayer/inc/TTreeFormula.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -84,6 +84,14 @@ friend class TTreeFormulaManager;
kMaxIf = 205
};

// Helper struct to hold a cache
// that can accelerate calculation of the RealIndex.
struct RealInstanceCache {
Int_t fInstanceCache = 0;
Int_t fLocalIndexCache = 0;
Int_t fVirtAccumCache = 0;
};

TTree *fTree; //! pointer to Tree
Int_t fCodes[kMAXCODES]; // List of leaf numbers referenced in formula
Int_t fNdata[kMAXCODES]; //! This caches the physical number of element in the leaf or datamember.
Expand Down Expand Up @@ -121,6 +129,8 @@ friend class TTreeFormulaManager;

LongDouble_t* fConstLD; //! local version of fConsts able to store bigger numbers

RealInstanceCache fRealInstanceCache; //! Cache accelerating the GetRealInstance function

TTreeFormula(const char *name, const char *formula, TTree *tree, const std::vector<std::string>& aliases);
void Init(const char *name, const char *formula);
Bool_t BranchHasMethod(TLeaf* leaf, TBranch* branch, const char* method,const char* params, Long64_t readentry) const;
Expand Down
19 changes: 14 additions & 5 deletions tree/treeplayer/src/TTreeFormula.cxx
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3412,8 +3412,14 @@ Int_t TTreeFormula::GetRealInstance(Int_t instance, Int_t codeindex) {
}
break;
case -1: {
local_index = 0;
Int_t virt_accum = 0;
if (instance <= fRealInstanceCache.fInstanceCache) {
fRealInstanceCache.fLocalIndexCache = 0;
fRealInstanceCache.fVirtAccumCache = 0;
}
fRealInstanceCache.fInstanceCache = instance;
local_index = fRealInstanceCache.fLocalIndexCache;
Int_t virt_accum = fRealInstanceCache.fVirtAccumCache;

Int_t maxloop = fManager->fCumulUsedVarDims->GetSize();
if (maxloop == 0) {
local_index--;
Expand All @@ -3424,12 +3430,15 @@ Int_t TTreeFormula::GetRealInstance(Int_t instance, Int_t codeindex) {
virt_accum += fManager->fCumulUsedVarDims->GetArray()[local_index];
local_index++;
} while( instance >= virt_accum && local_index<maxloop);
if (local_index==maxloop && (instance >= virt_accum)) {
local_index--;
local_index--;
// update the cache
fRealInstanceCache.fVirtAccumCache = virt_accum - fManager->fCumulUsedVarDims->GetArray()[local_index];
fRealInstanceCache.fLocalIndexCache = local_index;

if (local_index==(maxloop-1) && (instance >= virt_accum)) {
instance = fNdata[0]+1; // out of bounds.
if (check) return fNdata[0]+1;
} else {
local_index--;
if (fManager->fCumulUsedVarDims->At(local_index)) {
instance -= (virt_accum - fManager->fCumulUsedVarDims->At(local_index));
} else {
Expand Down