Class SpinLock

include/sonic/allocator.h:77–103

SpinLock is copied from https://rigtorp.se/spinlock/

// SpinLock is copied from https://rigtorp.se/spinlock/
class SpinLock {
 private:
  std::atomic<bool> lock_ = {false};

 public:
  void lock() {
    for (;;) {
      if (!lock_.exchange(true, std::memory_order_acquire)) {
        break;
      }
      while (lock_.load(std::memory_order_relaxed)) {
        // use pause or yield instruction will slow down lock acquisition
        // on contended locks.
#ifndef SONIC_SPINLOCK_NO_PAUSE

#if defined(__x86_64__) || defined(_M_AMD64)
        __builtin_ia32_pause();
#elif defined(__aarch64__) || defined(_M_ARM64)
        asm volatile("yield");
#endif

#endif
      }
    }
  }
  void unlock() { lock_.store(false, std::memory_order_release); }
};

#ifdef SONIC_LOCKED_ALLOCATOR
#define LOCK_GUARD std::lock_guard<SpinLock> guard(lock_);