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#include "FWCore/Concurrency/interface/WaitingThreadPool.h"
#include <cassert>
#include <string_view>
#include <pthread.h>
namespace edm::impl {
WaitingThread::WaitingThread() {
thread_ = std::thread(&WaitingThread::threadLoop, this);
static constexpr auto poolName = "edm async pool";
// pthread_setname_np() string length is limited to 16 characters,
// including the null termination
static_assert(std::string_view(poolName).size() < 16);
int err = pthread_setname_np(thread_.native_handle(), poolName);
// According to the glibc documentation, the only error
// pthread_setname_np() can return is about the argument C-string
// being too long. We already check above the C-string is shorter
// than the limit was at the time of writing. In order to capture
// if the limit shortens, or other error conditions get added,
// let's assert() anyway (exception feels overkill)
assert(err == 0);
}
WaitingThread::~WaitingThread() noexcept {
// When we are shutting down, we don't care about any possible
// system errors anymore
CMS_SA_ALLOW try {
stopThread();
thread_.join();
} catch (...) {
}
}
void WaitingThread::threadLoop() noexcept {
std::unique_lock lk(mutex_);
while (true) {
cond_.wait(lk, [this]() { return static_cast<bool>(func_) or stopThread_; });
if (stopThread_) {
// There should be no way to stop the thread when it as the
// func_ assigned, but let's make sure
assert(not thisPtr_);
break;
}
func_();
// Must return this WaitingThread to the ReusableObjectHolder in
// the WaitingThreadPool before resettting func_ (that holds the
// WaitingTaskWithArenaHolder, that enables the progress in the
// TBB thread pool) in order to meet the requirement of
// ReusableObjectHolder destructor that there are no outstanding
// objects.
thisPtr_.reset();
decltype(func_)().swap(func_);
}
}
} // namespace edm::impl
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