Concurrency/test/test_threadSafeOutputFileStream.cpp

0001 #include "FWCore/Concurrency/interface/ThreadSafeOutputFileStream.h"
0002
0003 #include <atomic>
0004 #include <sstream>
0005 #include <thread>
0006 #include <vector>
0007
0008 namespace {
0009
0010   std::atomic<int> nWaitingForThreads{};
0011
0012   void logToFile(unsigned const thread_index, edm::ThreadSafeOutputFileStream& f) {
0013     --nWaitingForThreads;
0014     while (nWaitingForThreads != 0)
0015       ;  // Spin until all threads have been launched.
0016
0017     std::ostringstream oss;
0018     oss << "Thread index: " << thread_index << " Entry: ";
0019     auto const& prefix = oss.str();
0020     for (int i{}; i < 4; ++i) {
0021       f.write(prefix + std::to_string(i) + "\n");
0022     }
0023   }
0024 }  // namespace
0025
0026 int main() {
0027   edm::ThreadSafeOutputFileStream f{"thread_safe_ofstream_test.txt"};
0028   std::vector<std::thread> threads;
0029   unsigned const nThreads{3};
0030   nWaitingForThreads = nThreads;
0031   for (unsigned i{}; i < nThreads; ++i) {
0032     threads.emplace_back(logToFile, i, std::ref(f));
0033   }
0034
0035   for (auto& thread : threads)
0036     thread.join();
0037 }