MDEV-24142 rw_lock_t has unnecessarily complex wait logicbb-10.5-MDEV-24142

Let us use a single rw_lock_t::wait_mutex and two condition
variables wait_cond, wait_cond_ex instead of two os_event_t
(which wrap a mutex and condition variable and some other data)

sync_array_wait_event(): Implement new waiting rules for rw_lock_t.
FIXME: Sometimes, rw_lock_x_lock_wait_func() hangs here, with
lock->lock_word == -X_LOCK_HALF_DECR.
Perhaps we should treat not only the values 0 and -X_LOCK_HALF_DECR
but also X_LOCK_HALF_DECR specially?

rw_lock_x_unlock_func(): Clean up.

1 files changed, 3 insertions, 1 deletions

diff --git a/include/my_atomic_wrapper.h b/include/my_atomic_wrapper.h
index c0e18ea7c91..b256ba1069a 100644
--- a/include/my_atomic_wrapper.h
+++ b/include/my_atomic_wrapper.h
@@ -41,7 +41,9 @@ public:
   Atomic_relaxed(Type val) : m(val) {}
   Atomic_relaxed() {}
 
-  operator Type() const { return m.load(std::memory_order_relaxed); }
+  Type load(std::memory_order o= std::memory_order_relaxed) const
+  { return m.load(o); }
+  operator Type() const { return load(); }
   Type operator=(const Type val)
   { m.store(val, std::memory_order_relaxed); return val; }
   Type operator=(const Atomic_relaxed<Type> &rhs) { return *this= Type{rhs}; }