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#include "thread-pool.hh"
namespace nix {
ThreadPool::ThreadPool(size_t _nrThreads)
: nrThreads(_nrThreads)
{
if (!nrThreads) {
nrThreads = std::thread::hardware_concurrency();
if (!nrThreads) nrThreads = 1;
}
}
void ThreadPool::enqueue(const work_t & t)
{
auto state_(state.lock());
state_->left.push(t);
wakeup.notify_one();
}
void ThreadPool::process()
{
printMsg(lvlDebug, format("starting pool of %d threads") % nrThreads);
std::vector<std::thread> workers;
for (size_t n = 0; n < nrThreads; n++)
workers.push_back(std::thread([&]() {
bool first = true;
while (true) {
work_t work;
{
auto state_(state.lock());
if (state_->exception) return;
if (!first) {
assert(state_->pending);
state_->pending--;
}
first = false;
while (state_->left.empty()) {
if (!state_->pending) {
wakeup.notify_all();
return;
}
if (state_->exception) return;
state_.wait(wakeup);
}
work = state_->left.front();
state_->left.pop();
state_->pending++;
}
try {
work();
} catch (std::exception & e) {
auto state_(state.lock());
if (state_->exception) {
if (!dynamic_cast<Interrupted*>(&e))
printMsg(lvlError, format("error: %s") % e.what());
} else {
state_->exception = std::current_exception();
wakeup.notify_all();
}
}
}
}));
for (auto & thr : workers)
thr.join();
{
auto state_(state.lock());
if (state_->exception)
std::rethrow_exception(state_->exception);
}
}
}
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