Changeset b353a49

Timestamp:

Aug 14, 2020, 12:31:56 PM (4 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

4998155

Parents:

fa5e0112

Message:

Added oneshot semaphore type

File:

• libcfa/src/bits/locks.hfa (modified) (1 diff)

libcfa/src/bits/locks.hfa

@@ -219 +219 @@
                 }
         }
+
+        // Semaphore which only supports a single thread and one post
+        // Semaphore which only supports a single thread
+        struct oneshot {
+                struct $thread * volatile ptr;
+        };
+
+        static inline {
+                void  ?{}(oneshot & this) {
+                        this.ptr = 0p;
+                }
+
+                void ^?{}(oneshot & this) {}
+
+                bool wait(oneshot & this) {
+                        for() {
+                                struct $thread * expected = this.ptr;
+                                if(expected == 1p) return false;
+                                /* paranoid */ verify( expected == 0p );
+                                if(__atomic_compare_exchange_n(&this.ptr, &expected, active_thread(), false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
+                                        park( __cfaabi_dbg_ctx );
+                                        /* paranoid */ verify( this.ptr == 1p );
+                                        return true;
+                                }
+                        }
+                }
+
+                bool post(oneshot & this) {
+                        struct $thread * got = __atomic_exchange_n( &this.ptr, 1p, __ATOMIC_SEQ_CST);
+                        if( got == 0p ) return false;
+                        unpark( got __cfaabi_dbg_ctx2 );
+                        return true;
+                }
+        }
 #endif