From bd73b2845b2e7cadf38c441babeeb9765896b2be Mon Sep 17 00:00:00 2001
From: gingerBill <bill@gingerbill.org>
Date: Wed, 27 Apr 2022 15:03:48 +0100
Subject: [PATCH] Unify default `Sema` and `Atomic_Sema` behaviour

---
 core/sync/primitives_atomic.odin | 65 +++++++++++++++-----------------
 core/sync/sema_internal.odin     | 42 ++-------------------
 2 files changed, 34 insertions(+), 73 deletions(-)

diff --git a/core/sync/primitives_atomic.odin b/core/sync/primitives_atomic.odin
index 11fff4e60..22771443d 100644
--- a/core/sync/primitives_atomic.odin
+++ b/core/sync/primitives_atomic.odin
@@ -400,30 +400,28 @@ atomic_cond_broadcast :: proc(c: ^Atomic_Cond) {
 //
 // An Atomic_Sema must not be copied after first use
 Atomic_Sema :: struct {
-	mutex: Atomic_Mutex,
-	cond:  Atomic_Cond,
-	count: int,
+	count: Futex,
 }
 
 atomic_sema_post :: proc(s: ^Atomic_Sema, count := 1) {
-	atomic_mutex_lock(&s.mutex)
-	defer atomic_mutex_unlock(&s.mutex)
-
-	s.count += count
-	atomic_cond_signal(&s.cond)
+	atomic_add_explicit(&s.count, Futex(count), .Release)
+	if count == 1 {
+		futex_signal(&s.count)
+	} else {
+		futex_broadcast(&s.count)
+	}
 }
 
 atomic_sema_wait :: proc(s: ^Atomic_Sema) {
-	atomic_mutex_lock(&s.mutex)
-	defer atomic_mutex_unlock(&s.mutex)
-
-	for s.count == 0 {
-		atomic_cond_wait(&s.cond, &s.mutex)
-	}
-
-	s.count -= 1
-	if s.count > 0 {
-		atomic_cond_signal(&s.cond)
+	for {
+		original_count := atomic_load_explicit(&s.count, .Relaxed)
+		for original_count == 0 {
+			futex_wait(&s.count, u32(original_count))
+			original_count = s.count
+		}
+		if original_count == atomic_compare_exchange_strong_explicit(&s.count, original_count, original_count-1, .Acquire, .Acquire) {
+			return
+		}
 	}
 }
 
@@ -431,25 +429,22 @@ atomic_sema_wait_with_timeout :: proc(s: ^Atomic_Sema, duration: time.Duration)
 	if duration <= 0 {
 		return false
 	}
-	atomic_mutex_lock(&s.mutex)
-	defer atomic_mutex_unlock(&s.mutex)
-	
-	start := time.tick_now()
+	for {
 
-	for s.count == 0 {
-		remaining := duration - time.tick_since(start)
-		if remaining < 0 {
-			return false
+		original_count := atomic_load_explicit(&s.count, .Relaxed)
+		for start := time.tick_now(); original_count == 0; /**/ {
+			remaining := duration - time.tick_since(start)
+			if remaining < 0 {
+				return false
+			}
+
+			if !futex_wait_with_timeout(&s.count, u32(original_count), remaining) {
+				return false
+			}
+			original_count = s.count
 		}
-		
-		if !atomic_cond_wait_with_timeout(&s.cond, &s.mutex, remaining) {
-			return false
+		if original_count == atomic_compare_exchange_strong_explicit(&s.count, original_count, original_count-1, .Acquire, .Acquire) {
+			return true
 		}
 	}
-
-	s.count -= 1
-	if s.count > 0 {
-		atomic_cond_signal(&s.cond)
-	}
-	return true
 }
diff --git a/core/sync/sema_internal.odin b/core/sync/sema_internal.odin
index e4a3c0bfc..5e2203c34 100644
--- a/core/sync/sema_internal.odin
+++ b/core/sync/sema_internal.odin
@@ -6,53 +6,19 @@ import "core:time"
 
 when #config(ODIN_SYNC_SEMA_USE_FUTEX, true) {
 	_Sema :: struct {
-		count: Futex,
+		atomic: Atomic_Sema,
 	}
 
 	_sema_post :: proc(s: ^Sema, count := 1) {
-		atomic_add_explicit(&s.impl.count, Futex(count), .Release)
-		if count == 1 {
-			futex_signal(&s.impl.count)
-		} else {
-			futex_broadcast(&s.impl.count)
-		}
+		atomic_sema_post(&s.impl.atomic, count)
 	}
 
 	_sema_wait :: proc(s: ^Sema) {
-		for {
-			original_count := atomic_load_explicit(&s.impl.count, .Relaxed)
-			for original_count == 0 {
-				futex_wait(&s.impl.count, u32(original_count))
-				original_count = s.impl.count
-			}
-			if original_count == atomic_compare_exchange_strong_explicit(&s.impl.count, original_count, original_count-1, .Acquire, .Acquire) {
-				return
-			}
-		}
+		atomic_sema_wait(&s.impl.atomic)
 	}
 
 	_sema_wait_with_timeout :: proc(s: ^Sema, duration: time.Duration) -> bool {
-		if duration <= 0 {
-			return false
-		}
-		for {
-		
-			original_count := atomic_load_explicit(&s.impl.count, .Relaxed)
-			for start := time.tick_now(); original_count == 0; /**/ {
-				remaining := duration - time.tick_since(start)
-				if remaining < 0 {
-					return false
-				}
-				
-				if !futex_wait_with_timeout(&s.impl.count, u32(original_count), remaining) {
-					return false
-				}
-				original_count = s.impl.count
-			}
-			if original_count == atomic_compare_exchange_strong_explicit(&s.impl.count, original_count, original_count-1, .Acquire, .Acquire) {
-				return true
-			}
-		}
+		return atomic_sema_wait_with_timeout(&s.impl.atomic, duration)
 	}
 } else {
 	_Sema :: struct {