From 800772642df81934a6d061e4ac5ed1097002b367 Mon Sep 17 00:00:00 2001
From: Emeric Chevalier <emericchevalier.pro@gmail.com>
Date: Mon, 12 Jan 2015 23:06:55 +0100
Subject: [PATCH] Add posix like get_val for semaphore

---
 src/libstd/sync/semaphore.rs | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/src/libstd/sync/semaphore.rs b/src/libstd/sync/semaphore.rs
index 8d44084671aad..37b446c04982e 100644
--- a/src/libstd/sync/semaphore.rs
+++ b/src/libstd/sync/semaphore.rs
@@ -96,6 +96,20 @@ impl Semaphore {
         self.acquire();
         SemaphoreGuard { sem: self }
     }
+
+    /// Get the current value of the semaphore.
+    ///
+    /// This method could be used to unlock a semaphore in an unknown state.
+    /// ```
+    /// for i in range(sem.get_value(),1) {
+    ///    sem.release();
+    /// }
+    /// Or simply to monitor a semaphore state.
+    /// ```
+    pub fn get_value(&self) -> int {
+        *self.lock.lock().unwrap()
+    }
+
 }
 
 #[unsafe_destructor]
@@ -198,4 +212,21 @@ mod tests {
         }
         rx.recv().unwrap(); // wait for child to be done
     }
+
+    #[test]
+    fn test_sem_get_val() {
+        let s = Arc::new(Semaphore::new(-5));
+        let s2 = s.clone();
+        let (tx, rx) = channel();
+        let _t = Thread::spawn(move|| {
+            let _ = rx.recv();
+            for _ in range(s2.get_value(),1){
+                s2.release();
+            }
+        });
+        tx.send(()).unwrap();
+        s.acquire();
+    }
+
+
 }