libcruft-util/test/thread/flag.cpp

74 lines
1.8 KiB
C++

#include "thread/flag.hpp"
#include "tap.hpp"
#include <thread>
int
main ()
{
util::TAP::logger tap;
util::thread::flag f;
std::atomic<int> value = 0;
std::thread t1 ([&] () {
f.wait ();
value = 1;
});
std::this_thread::sleep_for (std::chrono::milliseconds (100));
tap.expect_eq (value, 0, "value hasn't been set during wait");
tap.expect_eq (f.notify (), 1, "notify reports one thread woke");
t1.join ();
tap.expect_eq (value, 1, "value has been changed after wait");
std::thread t2 ([&] () {
f.wait ();
value = 2;
});
std::this_thread::sleep_for (std::chrono::milliseconds (100));
tap.expect_eq (value, 2, "second wait didn't appear to block");
t2.join ();
{
// perform a stress test to (hopefully) discover deadlocks
//
// * create a large matrix of flag variables
// * create a bank of threads which:
// * wait on each flag of each row, or
// * notify if the flag index matches the thread index
constexpr int iterations = 1024;
constexpr int parallelism = 16;
std::vector<
std::array<util::thread::flag,parallelism>
> flags (iterations);
const auto func = [&flags] (const int idx) {
for (auto &row: flags) {
for (int i = 0; i < parallelism; ++i) {
if (i == idx)
row[i].notify ();
else
row[i].wait ();
}
}
};
std::vector<std::thread> workers;
for (int i = 0; i < parallelism; ++i)
workers.emplace_back (func, i);
for (auto &t: workers)
t.join ();
tap.expect (true, "flag sequence did not block");
}
return tap.status ();
}