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From: "valera.mironow at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/106772] atomic<T>::wait shouldn't touch waiter pool
 if used platform wait
Date: Tue, 20 Sep 2022 15:45:40 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106772

--- Comment #13 from Mkkt Bkkt <valera.mironow at gmail dot com> ---
example of simple mutex pseudocode that don't need call notify every unlock:
Same possible for other cases, if it doesn't please share example for me

```
int kUnlocked =3D 0;
int kLocked =3D 1;
int kLockedWithWaiters =3D 2;

std::atomic<int> state{0};

lock:
  // some spin
  if (state.cas(kUnlocked, kLocked)) {
    return;
  }
  do {
    if (state =3D=3D kLockedWithWaiters || state.cas(kLocked, kLockedWithWa=
iters))
{
      state.wait(kLockedWithWaiters);
    }
  } while (!state.cas(kUnlocked, kLockedWithWaiters));

unlock:
  if (state.exchange(kUnlocked) =3D=3D kLockedWithWaiters) {
    state.notify_one();
  }
```=