From 8d847d6f1c423eef63b818563ee02050b688f15a Mon Sep 17 00:00:00 2001
From: Nekotekina <nekotekina@gmail.com>
Date: Tue, 3 Mar 2020 17:53:27 +0300
Subject: [PATCH] Thread: internal cleanup

Use different, simpler algorithm in wait_for.
Although the very idea of such notifications was rotten.
---
 Utilities/Thread.cpp | 52 +++++++-------------------------------------
 Utilities/Thread.h   |  8 +------
 2 files changed, 9 insertions(+), 51 deletions(-)

diff --git a/Utilities/Thread.cpp b/Utilities/Thread.cpp
index b4da25526c..e240be18c5 100644
--- a/Utilities/Thread.cpp
+++ b/Utilities/Thread.cpp
@@ -1921,48 +1921,12 @@ void thread_ctrl::_wait_for(u64 usec, bool alert /* true */)
 	}
 #endif
 
-	std::unique_lock lock(_this->m_mutex, std::defer_lock);
-
-	while (true)
+	if (_this->m_signal && _this->m_signal.exchange(0))
 	{
-		// Mutex is unlocked at the start and after the waiting
-		if (u32 sig = _this->m_signal.load())
-		{
-			if (sig & 1)
-			{
-				_this->m_signal &= ~1;
-				return;
-			}
-		}
-
-		if (usec == 0)
-		{
-			// No timeout: return immediately
-			return;
-		}
-
-		if (!lock)
-		{
-			lock.lock();
-		}
-
-		// Double-check the value
-		if (u32 sig = _this->m_signal.load())
-		{
-			if (sig & 1)
-			{
-				_this->m_signal &= ~1;
-				return;
-			}
-		}
-
-		_this->m_cond.wait_unlock(usec, lock);
-
-		if (usec < cond_variable::max_timeout)
-		{
-			usec = 0;
-		}
+		return;
 	}
+
+	_this->m_signal.wait(0, atomic_wait_timeout{usec <= 0xffff'ffff'ffff'ffff / 1000 ? usec * 1000 : 0xffff'ffff'ffff'ffff});
 }
 
 std::string thread_ctrl::get_name_cached()
@@ -2012,11 +1976,11 @@ void thread_base::join() const
 
 void thread_base::notify()
 {
-	if (!(m_signal & 1))
+	// Increment with saturation
+	if (m_signal.try_inc())
 	{
-		m_signal |= 1;
-		m_mutex.lock_unlock();
-		m_cond.notify_one();
+		// Considered impossible to have a situation when not notified
+		m_signal.notify_all();
 	}
 }
 
diff --git a/Utilities/Thread.h b/Utilities/Thread.h
index c4bc06700e..4fa11af2d3 100644
--- a/Utilities/Thread.h
+++ b/Utilities/Thread.h
@@ -100,13 +100,7 @@ class thread_base
 	// Thread handle (platform-specific)
 	atomic_t<std::uintptr_t> m_thread{0};
 
-	// Thread mutex
-	mutable shared_mutex m_mutex;
-
-	// Thread condition variable
-	cond_variable m_cond;
-
-	// Thread flags
+	// Thread playtoy, that shouldn't be used
 	atomic_t<u32> m_signal{0};
 
 	// Thread state