1 files changed, 109 insertions, 0 deletions
diff --git a/ml/dlib/dlib/threads/rmutex_extension.h b/ml/dlib/dlib/threads/rmutex_extension.h
new file mode 100644
index 000000000..b7bf998be
--- /dev/null
+++ b/ml/dlib/dlib/threads/rmutex_extension.h
@@ -0,0 +1,109 @@
+// Copyright (C) 2005  Davis E. King (davis@dlib.net)
+// License: Boost Software License   See LICENSE.txt for the full license.
+#ifndef DLIB_RMUTEX_EXTENSIOn_
+#define DLIB_RMUTEX_EXTENSIOn_
+
+#include "threads_kernel.h"
+#include "rmutex_extension_abstract.h"
+
+namespace dlib
+{
+
+// ----------------------------------------------------------------------------------------
+
+    class rmutex
+    {
+        /*!
+            INITIAL VALUE
+                count == 0
+                thread_id == 0
+
+            CONVENTION
+                - count == lock_count()
+
+                - if (no thread currently has a lock on this mutex) then
+                    - count == 0
+                - else
+                    - count == the number of times the thread that owns this mutex has
+                      called lock()
+                    - thread_id == the id of this thread.
+        !*/
+    public:
+
+        rmutex (
+        ) : s(m),
+            thread_id(0),
+            count(0)
+        {}
+
+        ~rmutex (
+        )
+        {}
+
+        unsigned long lock_count (
+        ) const
+        {
+            return count;
+        }
+
+        void lock (
+            unsigned long times = 1
+        ) const
+        {
+            const thread_id_type current_thread_id = get_thread_id();
+            m.lock();
+            if (thread_id == current_thread_id)
+            {
+                // we already own this mutex in this case
+                count += times;                
+            }
+            else
+            {
+                // wait for our turn to claim this rmutex
+                while (count != 0)
+                    s.wait();
+
+                count = times;
+                thread_id = current_thread_id;
+            }
+            m.unlock();
+        }
+
+        void unlock (
+            unsigned long times = 1
+        ) const
+        {
+            const thread_id_type current_thread_id = get_thread_id();
+            m.lock();
+            if (thread_id == current_thread_id)
+            {
+                if (count <= times)
+                {
+                    count = 0;
+                    s.signal();
+                }
+                else
+                {
+                    count -= times;
+                }
+            }
+            m.unlock();
+        }
+
+    private:
+        mutex m;
+        signaler s;
+        mutable thread_id_type thread_id;
+        mutable unsigned long count;
+
+        // restricted functions
+        rmutex(rmutex&);        // copy constructor
+        rmutex& operator=(rmutex&);    // assignment operator
+    };
+
+// ----------------------------------------------------------------------------------------
+
+}
+
+#endif // DLIB_RMUTEX_EXTENSIOn_
+