Changes in libcfa/src/concurrency/select.hfa [e23b3ce:6f774be]

File:

• libcfa/src/concurrency/select.hfa (modified) (2 diffs)

libcfa/src/concurrency/select.hfa

@@ -103 +103 @@
 //=============================================================================================
 
+static inline void __make_select_node_unsat( select_node & this ) with( this ) {
+    __atomic_store_n( clause_status, __SELECT_UNSAT, __ATOMIC_SEQ_CST );
+}
+static inline void __make_select_node_sat( select_node & this ) with( this ) {
+    __atomic_store_n( clause_status, __SELECT_SAT, __ATOMIC_SEQ_CST );
+}
+
 // used for the 2-stage avail needed by the special OR case
 static inline bool __mark_select_node( select_node & this, unsigned long int val ) with( this ) {
@@ -116 +123 @@
 }
 
-static inline void __make_select_node_unsat( select_node & this ) with( this ) {
-    __atomic_store_n( clause_status, __SELECT_UNSAT, __ATOMIC_SEQ_CST );
-}
-static inline void __make_select_node_sat( select_node & this ) with( this ) {
-    __atomic_store_n( clause_status, __SELECT_SAT, __ATOMIC_SEQ_CST );
+// used for the 2-stage avail by the thread who owns a pending node
+static inline bool __pending_set_other( select_node & other, select_node & mine, unsigned long int val ) with( other ) {
+    /* paranoid */ verify( park_counter == 0p );
+    /* paranoid */ verify( clause_status != 0p );
+
+    unsigned long int cmp_status = __SELECT_UNSAT;
+    while( !__atomic_compare_exchange_n( clause_status, &cmp_status, val, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST ) ) {
+        if ( cmp_status != __SELECT_PENDING )
+            return false;
+
+        // toggle current status flag to avoid starvation/deadlock
+        __make_select_node_unsat( mine );
+        cmp_status = __SELECT_UNSAT;
+        if ( !__atomic_compare_exchange_n( mine.clause_status, &cmp_status, __SELECT_PENDING, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST ) )
+            return false;
+        cmp_status = __SELECT_UNSAT;
+    }
+    return true;
 }