1 files changed, 38 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/lib/utils/thread_utils/semaphore.cpp b/comm/third_party/botan/src/lib/utils/thread_utils/semaphore.cpp
new file mode 100644
index 0000000000..0858a013f2
--- /dev/null
+++ b/comm/third_party/botan/src/lib/utils/thread_utils/semaphore.cpp
@@ -0,0 +1,38 @@
+/*
+* Semaphore
+* (C) 2013 Joel Low
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/internal/semaphore.h>
+
+// Based on code by Pierre Gaston (http://p9as.blogspot.com/2012/06/c11-semaphores.html)
+
+namespace Botan {
+
+void Semaphore::release(size_t n)
+   {
+   for(size_t i = 0; i != n; ++i)
+      {
+      std::lock_guard<std::mutex> lock(m_mutex);
+
+      if(m_value++ < 0)
+         {
+         ++m_wakeups;
+         m_cond.notify_one();
+         }
+      }
+   }
+
+void Semaphore::acquire()
+   {
+   std::unique_lock<std::mutex> lock(m_mutex);
+   if(m_value-- <= 0)
+       {
+       m_cond.wait(lock, [this] { return m_wakeups > 0; });
+       --m_wakeups;
+       }
+   }
+
+}