better sema

Author: dileping

ExecutionContext/Semaphore.swift

@@ -51,7 +51,6 @@ public class Semaphore {
     public func wait(until:NSDate? = nil) -> Bool {
         underlyingSemaphore.lock()
         defer {
-            value -= 1
             underlyingSemaphore.unlock()
         }
 
@@ -63,6 +62,10 @@ public class Semaphore {
             }
         }
 
+        if signaled {
+            value -= 1
+        }
+        
         return signaled
     }