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#include "TFile.h"
#include "TTree.h"
#include "TBranch.h"
#include "TClass.h"
#include "TThread.h"
#include "TVirtualStreamerInfo.h"
#include "TList.h"
#include "TMap.h"
#include "TObjString.h"
#include "TH1F.h"
#include "FWCore/FWLite/interface/FWLiteEnabler.h"
#include <memory>
#include <cassert>
#include <iostream>
#include <thread>
#include <atomic>
std::atomic<bool> waitToStart{true};
void printHelp(const char* iName, int iDefaultNThreads) {
std::cout << iName << " [number of threads] [filename] [gDebug value]\n\n"
<< "[number of threads] number of threads to use in test\n"
<< "[filename] name of CMSSW file to read\n"
<< "[gDebug value] value of gDebug to pass to ROOT (gDebug=1 is useful)\n"
<< "If no arguments are given " << iDefaultNThreads
<< " threads will be used and a dummy file will be created." << std::endl;
}
const std::string kDefaultFileName("read_test_dummy.root");
std::tuple<int, std::string, int> parseOptions(int argc, char** argv) {
constexpr int kDefaultNThreads = 4;
int kDefaultgDebug = gDebug;
int nThreads = kDefaultNThreads;
int newGDebug = kDefaultgDebug;
std::string fileName(kDefaultFileName);
if (argc >= 2) {
if (strcmp("-h", argv[1]) == 0) {
printHelp(argv[0], kDefaultNThreads);
exit(0);
}
nThreads = atoi(argv[1]);
}
if (argc >= 3) {
fileName = argv[2];
}
if (argc == 4) {
newGDebug = atoi(argv[3]);
}
if (argc > 4) {
printHelp(argv[0], kDefaultNThreads);
exit(1);
}
return std::make_tuple(nThreads, fileName, newGDebug);
}
void createDummyFile() {
auto theList = new TList();
for (unsigned int i = 0; i < 10; ++i) {
theList->Add(new TList());
theList->Add(new TMap());
theList->Add(new TObjString());
theList->Add(new TH1F());
theList->Add(new TH1D());
}
TFile f(kDefaultFileName.c_str(), "RECREATE", "test");
auto listTree = new TTree("Events", "TheList");
listTree->Branch("theList", "TList", &theList);
for (unsigned int i = 0; i < 100; ++i) {
listTree->Fill();
}
f.Write();
f.Close();
}
int main(int argc, char** argv) {
auto options = parseOptions(argc, argv);
const int kNThreads = std::get<0>(options);
auto const kFileName = std::get<1>(options);
gDebug = std::get<2>(options);
FWLiteEnabler::enable();
//Tell Root we want to be multi-threaded
TThread::Initialize();
//When threading, also have to keep ROOT from logging all TObjects into a list
TObject::SetObjectStat(false);
//Have to avoid having Streamers modify themselves after they have been used
TVirtualStreamerInfo::Optimize(false);
if (kFileName == kDefaultFileName) {
createDummyFile();
}
std::vector<std::shared_ptr<std::thread>> threads;
threads.reserve(kNThreads);
for (int i = 0; i < kNThreads; ++i) {
threads.push_back(std::make_shared<std::thread>(std::thread([&kFileName]() {
static thread_local TThread s_thread_guard;
while (waitToStart)
;
std::unique_ptr<TFile> f{TFile::Open(kFileName.c_str())};
assert(f.get());
TTree* eventTree = dynamic_cast<TTree*>(f.get()->Get("Events"));
assert(eventTree);
for (Long64_t i = 0, iEnd = eventTree->GetEntries(); i != iEnd; ++i) {
eventTree->GetEntry(i, 1);
}
f.get()->Close();
})));
}
waitToStart = false;
for (auto& t : threads) {
t->join();
}
return 0;
}
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