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#include "bt2_locks.h"
void mcs_lock::lock(mcs_node &node) {
node.next = nullptr;
mcs_node *pred = q.exchange(&node, std::memory_order_acq_rel);
if (pred) {
node.unlocked = false;
pred->next.store(&node, std::memory_order_release);
spin_while_eq(node.unlocked, false);
}
node.unlocked.load(std::memory_order_acquire);
}
void mcs_lock::unlock(mcs_node &node) {
if (!node.next.load(std::memory_order_acquire)) {
mcs_node *node_ptr = &node;
if (q.compare_exchange_strong(node_ptr,
(mcs_node *)nullptr,
std::memory_order_release))
return;
spin_while_eq(node.next, (mcs_node *)nullptr);
}
node.next.load(std::memory_order_acquire)->unlocked.store(true, std::memory_order_release);
}
void spin_lock::lock() {
cpu_backoff backoff;
while (flag.test_and_set(std::memory_order_acquire))
backoff.pause();
}
void spin_lock::unlock() {
flag.clear(std::memory_order_release);
}
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