From 18869c55f75a2801099ef5db7b8e2b95dd2e3e7f Mon Sep 17 00:00:00 2001
From: Brian Norris <banorris@uci.edu>
Date: Tue, 9 Oct 2012 18:08:12 -0700
Subject: [PATCH] mcs-lock: fixup Relacy code

Also, switch out 'compare_exchange_strong()' for 'compare_exchange()',
since we don't support the _strong syntax right now.
---
 mcs-lock/mcs-lock.h | 33 ++++++++++++++++++---------------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/mcs-lock/mcs-lock.h b/mcs-lock/mcs-lock.h
index df64d8b..47c2f8f 100644
--- a/mcs-lock/mcs-lock.h
+++ b/mcs-lock/mcs-lock.h
@@ -1,12 +1,15 @@
 // mcs on stack
 
+#include <stdatomic.h>
+#include <unrelacy.h>
+
 struct mcs_node {
 	std::atomic<mcs_node *> next;
 	std::atomic<int> gate;
 
 	mcs_node() {
-		next($).store(0);
-		gate($).store(0);
+		next.store(0);
+		gate.store(0);
 	}
 };
 
@@ -16,10 +19,10 @@ public:
 	std::atomic<mcs_node *> m_tail;
 
 	mcs_mutex() {
-		m_tail($).store( NULL );
+		m_tail.store( NULL );
 	}
 	~mcs_mutex() {
-		ASSERT( m_tail($).load() == NULL );
+		ASSERT( m_tail.load() == NULL );
 	}
 
 	class guard {
@@ -36,25 +39,25 @@ public:
 
 		// set up my node :
 		// not published yet so relaxed :
-		me->next($).store(NULL, std::mo_relaxed );
-		me->gate($).store(1, std::mo_relaxed );
+		me->next.store(NULL, std::mo_relaxed );
+		me->gate.store(1, std::mo_relaxed );
 
 		// publish my node as the new tail :
-		mcs_node * pred = m_tail($).exchange(me, std::mo_acq_rel);
+		mcs_node * pred = m_tail.exchange(me, std::mo_acq_rel);
 		if ( pred != NULL ) {
 			// (*1) race here
 			// unlock of pred can see me in the tail before I fill next
 
 			// publish me to previous lock-holder :
-			pred->next($).store(me, std::mo_release );
+			pred->next.store(me, std::mo_release );
 
 			// (*2) pred not touched any more       
 
 			// now this is the spin -
 			// wait on predecessor setting my flag -
 			rl::linear_backoff bo;
-			while ( me->gate($).load(std::mo_acquire) ) {
-				bo.yield($);
+			while ( me->gate.load(std::mo_acquire) ) {
+				bo.yield();
 			}
 		}
 	}
@@ -62,11 +65,11 @@ public:
 	void unlock(guard * I) {
 		mcs_node * me = &(I->m_node);
 
-		mcs_node * next = me->next($).load(std::mo_acquire);
+		mcs_node * next = me->next.load(std::mo_acquire);
 		if ( next == NULL )
 		{
 			mcs_node * tail_was_me = me;
-			if ( m_tail($).compare_exchange_strong( tail_was_me,NULL,std::mo_acq_rel) ) {
+			if ( m_tail.compare_exchange( tail_was_me,NULL,std::mo_acq_rel) ) {
 				// got null in tail, mutex is unlocked
 				return;
 			}
@@ -74,10 +77,10 @@ public:
 			// (*1) catch the race :
 			rl::linear_backoff bo;
 			for(;;) {
-				next = me->next($).load(std::mo_acquire);
+				next = me->next.load(std::mo_acquire);
 				if ( next != NULL )
 					break;
-				bo.yield($);
+				bo.yield();
 			}
 		}
 
@@ -85,6 +88,6 @@ public:
 		//  so no locker can be viewing my node any more        
 
 		// let next guy in :
-		next->gate($).store( 0, std::mo_release );
+		next->gate.store( 0, std::mo_release );
 	}
 };
-- 
2.34.1