mcs-lock: fixup Relacy code

Also, switch out 'compare_exchange_strong()' for 'compare_exchange()',
since we don't support the _strong syntax right now.

diff --git a/mcs-lock/mcs-lock.h b/mcs-lock/mcs-lock.h
index df64d8b999c050688f08cea52c7a8a1dd540406b..47c2f8f00536e06ace6da9cc668898d836fea29b 100644 (file)
--- 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 );
        }
 };