Add notify

src/snmalloc/ds/combininglock.h

@@ -6,6 +6,8 @@
 #include <atomic>
 #include <functional>
 
+#define SNMALLOC_USE_NOTIFY
+
 namespace snmalloc
 {
   class CombineLockNode;
@@ -52,6 +54,15 @@ namespace snmalloc
     // Stores the C++ lambda associated with this node in the queue.
     void (*f_raw)(CombineLockNode*);
 
+    void set_status(LockStatus s)
+    {
+      status.store(s, std::memory_order_release);
+#ifdef SNMALLOC_USE_NOTIFY
+      status.notify_one();
+#endif
+    }
+
+
   public:
     constexpr CombineLockNode(void (*f)(CombineLockNode*)) : f_raw(f) {}
 
@@ -66,9 +77,12 @@ namespace snmalloc
         prev->next = this;
 
         // Wait to for predecessor to complete
+#ifdef SNMALLOC_USE_NOTIFY
+        status.wait(LockStatus::WAITING);
+#else
         while (status.load() == LockStatus::WAITING)
           Aal::pause();
-
+#endif
         // Determine if another thread completed our work.
         if (status.load() == LockStatus::DONE)
           return;
@@ -92,7 +106,7 @@ namespace snmalloc
         {
           // Signal this work was completed and move on to
           // next item.
-          curr->status = LockStatus::DONE;
+          curr->set_status(LockStatus::DONE);
           curr = n;
           continue;
         }
@@ -104,7 +118,7 @@ namespace snmalloc
         {
           // Queue was successfully closed.
           // Notify last element the work was completed.
-          curr->status = LockStatus::DONE;
+          curr->set_status(LockStatus::DONE);
           return;
         }
 
@@ -115,12 +129,12 @@ namespace snmalloc
 
         // As we had to wait, give the job to the next thread
         // to carry on performing the work.
-        curr->next.load()->status = LockStatus::READY;
+        curr->next.load()->set_status(LockStatus::READY);
 
         // Notify the thread that we completed its work.
         // Note that this needs to be done last, as we can't read
         // curr->next after setting curr->status
-        curr->status = LockStatus::DONE;
+        curr->set_status(LockStatus::DONE);
         return;
       }
     }