Function DEFINE_FLAG

extern/re2/re2/testing/dfa_test.cc:24–365

DEFINE_FLAG(int, size, 8, "log2(number of DFA nodes)");
DEFINE_FLAG(int, repeat, 2, "Repetition count.");
DEFINE_FLAG(int, threads, 4, "number of threads");

namespace re2 {

static int state_cache_resets = 0;
static int search_failures = 0;

struct SetHooks {
  SetHooks() {
    hooks::SetDFAStateCacheResetHook([](const hooks::DFAStateCacheReset&) {
      ++state_cache_resets;
    });
    hooks::SetDFASearchFailureHook([](const hooks::DFASearchFailure&) {
      ++search_failures;
    });
  }
} set_hooks;

// Check that multithreaded access to DFA class works.

// Helper function: builds entire DFA for prog.
static void DoBuild(Prog* prog) {
  ASSERT_TRUE(prog->BuildEntireDFA(Prog::kFirstMatch, nullptr));
}

TEST(Multithreaded, BuildEntireDFA) {
  // Create regexp with 2^FLAGS_size states in DFA.
  std::string s = "a";
  for (int i = 0; i < GetFlag(FLAGS_size); i++)
    s += "[ab]";
  s += "b";
  Regexp* re = Regexp::Parse(s, Regexp::LikePerl, NULL);
  ASSERT_TRUE(re != NULL);

  // Check that single-threaded code works.
  {
    Prog* prog = re->CompileToProg(0);
    ASSERT_TRUE(prog != NULL);

    std::thread t(DoBuild, prog);
    t.join();

    delete prog;
  }

  // Build the DFA simultaneously in a bunch of threads.
  for (int i = 0; i < GetFlag(FLAGS_repeat); i++) {
    Prog* prog = re->CompileToProg(0);
    ASSERT_TRUE(prog != NULL);

    std::vector<std::thread> threads;
    for (int j = 0; j < GetFlag(FLAGS_threads); j++)
      threads.emplace_back(DoBuild, prog);
    for (int j = 0; j < GetFlag(FLAGS_threads); j++)
      threads[j].join();

    // One more compile, to make sure everything is okay.