Changeset 454f478 for libcfa/src/concurrency/locks.cfa

Timestamp:

Jan 20, 2021, 5:35:39 PM (3 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

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

Children:

9db2c92

Parents:

dafbde8

Message:

Re-arranged and commented low-level headers.
Main goal was for better support of weakso locks that are comming.

File:

• libcfa/src/concurrency/locks.cfa (modified) (1 diff)

libcfa/src/concurrency/locks.cfa

@@ -356 +356 @@
         bool wait( condition_variable(L) & this, L & l, uintptr_t info, Time time         ) with(this) { WAIT_TIME( info, &l , time ) }
 }
+
+//-----------------------------------------------------------------------------
+// Semaphore
+void  ?{}( semaphore & this, int count = 1 ) {
+        (this.lock){};
+        this.count = count;
+        (this.waiting){};
+}
+void ^?{}(semaphore & this) {}
+
+bool P(semaphore & this) with( this ){
+        lock( lock __cfaabi_dbg_ctx2 );
+        count -= 1;
+        if ( count < 0 ) {
+                // queue current task
+                append( waiting, active_thread() );
+
+                // atomically release spin lock and block
+                unlock( lock );
+                park();
+                return true;
+        }
+        else {
+            unlock( lock );
+            return false;
+        }
+}
+
+bool V(semaphore & this) with( this ) {
+        $thread * thrd = 0p;
+        lock( lock __cfaabi_dbg_ctx2 );
+        count += 1;
+        if ( count <= 0 ) {
+                // remove task at head of waiting list
+                thrd = pop_head( waiting );
+        }
+
+        unlock( lock );
+
+        // make new owner
+        unpark( thrd );
+
+        return thrd != 0p;
+}
+
+bool V(semaphore & this, unsigned diff) with( this ) {
+        $thread * thrd = 0p;
+        lock( lock __cfaabi_dbg_ctx2 );
+        int release = max(-count, (int)diff);
+        count += diff;
+        for(release) {
+                unpark( pop_head( waiting ) );
+        }
+
+        unlock( lock );
+
+        return thrd != 0p;
+}