std::lock_guard<std::mutex> l(hasSebDtored_->l_);

if(this->isSwapping()) {

queued_.push_back(std::move(cb));

return false;

}

return eb_->runInEventBaseThread([eb = eb_, cb_ = std::move(cb)]() mutable {

return cb_(*eb);

});

std::lock_guard<std::mutex> l(hasSebDtored_->l_);

auto const alreadySwapping = this->isSwapping();

nextEb_ = &newEb;

if(alreadySwapping) {

return;

}

eb_->runInEventBaseThread([this, hasSebDtored = hasSebDtored_]() {

std::lock_guard<std::mutex> lInner(hasSebDtored->l_);

if(hasSebDtored->destroyed_) {

// SEB was destroyed, any queued callbacks were appended to the old eb_

return;

}

eb_ = nextEb_;

nextEb_ = nullptr;

// enqueue tasks that were being buffered while this was waiting

// for the previous EB to drain

for(auto& cb : queued_) {

eb_->runInEventBaseThread([cb = std::move(cb), eb = eb_]() mutable {

return cb(*eb);

});

}

queued_.clear();

});