From 92a75cfa80767257b2fd1a0ab4820aeb2d6da00f Mon Sep 17 00:00:00 2001
From: Nekotekina <nekotekina@gmail.com>
Date: Mon, 9 Sep 2019 04:41:47 +0300
Subject: [PATCH] Remove `unique_cond`

Not very useful.
---
 Utilities/cond.cpp | 48 ----------------------------------------------
 Utilities/cond.h   | 47 ---------------------------------------------
 2 files changed, 95 deletions(-)

diff --git a/Utilities/cond.cpp b/Utilities/cond.cpp
index 8c70be1b3f..64c0515323 100644
--- a/Utilities/cond.cpp
+++ b/Utilities/cond.cpp
@@ -54,54 +54,6 @@ void cond_variable::imp_wake(u32 _count) noexcept
 	}));
 }
 
-bool unique_cond::imp_wait(u64 _timeout) noexcept
-{
-	// State transition: c_sig -> c_lock \ c_lock -> c_wait
-	const u32 _old = m_value.fetch_sub(1);
-	if (LIKELY(_old == c_sig))
-		return true;
-
-	return balanced_wait_until(m_value, _timeout, [&](u32& value, auto... ret) -> int
-	{
-		if (value == c_sig)
-		{
-			value = c_lock;
-			return +1;
-		}
-
-		if constexpr (sizeof...(ret))
-		{
-			value = c_lock;
-			return -1;
-		}
-
-		return 0;
-	});
-}
-
-void unique_cond::imp_notify() noexcept
-{
-	auto [old, ok] = m_value.fetch_op([](u32& v)
-	{
-		if (UNLIKELY(v > 0 && v < c_sig))
-		{
-			v = c_sig;
-			return true;
-		}
-
-		return false;
-	});
-
-	verify(HERE), old <= c_sig;
-
-	if (LIKELY(!ok || old == c_lock))
-	{
-		return;
-	}
-
-	balanced_awaken(m_value, 1);
-}
-
 bool shared_cond::imp_wait(u32 slot, u64 _timeout) noexcept
 {
 	if (slot >= 32)
diff --git a/Utilities/cond.h b/Utilities/cond.h
index 02c9143e14..01a23d83eb 100644
--- a/Utilities/cond.h
+++ b/Utilities/cond.h
@@ -62,53 +62,6 @@ public:
 	static constexpr u64 max_timeout = u64{UINT32_MAX} / 1000 * 1000000;
 };
 
-// Condition variable fused with a pseudo-mutex which is never supposed to be locked concurrently.
-class unique_cond
-{
-	enum : u32
-	{
-		c_wait = 1,
-		c_lock = 2,
-		c_sig  = 3,
-	};
-
-	atomic_t<u32> m_value{0};
-
-	bool imp_wait(u64 _timeout) noexcept;
-	void imp_notify() noexcept;
-
-public:
-	constexpr unique_cond() = default;
-
-	void lock() noexcept
-	{
-		// Shouldn't be locked by more than one thread concurrently
-		while (UNLIKELY(!m_value.compare_and_swap_test(0, c_lock)))
-			;
-	}
-
-	void unlock() noexcept
-	{
-		m_value = 0;
-	}
-
-	bool wait(std::unique_lock<unique_cond>& lock, u64 usec_timeout = -1) noexcept
-	{
-		AUDIT(lock.owns_lock());
-		AUDIT(lock.mutex() == this);
-		return imp_wait(usec_timeout);
-	}
-
-	void notify() noexcept
-	{
-		// Early exit if notification is not required
-		if (LIKELY(!m_value))
-			return;
-
-		imp_notify();
-	}
-};
-
 // Condition variable fused with a pseudo-mutex supporting only reader locks (up to 32 readers).
 class shared_cond
 {