1 files changed, 42 insertions, 0 deletions
diff --git a/src/mongo/util/concurrency/simplerwlock.h b/src/mongo/util/concurrency/simplerwlock.h
new file mode 100644
index 00000000000..7a9b7d91c64
--- /dev/null
+++ b/src/mongo/util/concurrency/simplerwlock.h
@@ -0,0 +1,42 @@
+#pragma once
+
+#include "mongo/bson/util/atomic_int.h"
+
+namespace mongo {
+
+    /** separated out as later the implementation of this may be different than RWLock, 
+        depending on OS, as there is no upgrade etc. facility herein.
+    */
+    class SimpleRWLock : boost::noncopyable { 
+#if defined(_WIN32) && defined(MONGO_USE_SRW_ON_WINDOWS)
+        SRWLOCK _lock;
+#else
+        RWLockBase m;
+#endif
+#if defined(_WIN32) && defined(_DEBUG)
+        AtomicUInt shares;
+        ThreadLocalValue<int> s;
+        unsigned tid;
+#endif
+    public:
+        const string name;
+        SimpleRWLock(const char *name = 0);
+        void lock();
+        void unlock();
+        void lock_shared();
+        void unlock_shared();
+        class Shared : boost::noncopyable {
+            SimpleRWLock& _r;
+        public:
+            Shared(SimpleRWLock& rwlock) : _r(rwlock) {_r.lock_shared(); }
+            ~Shared() { _r.unlock_shared(); }
+        };
+        class Exclusive : boost::noncopyable {
+            SimpleRWLock& _r;
+        public:
+            Exclusive(SimpleRWLock& rwlock) : _r(rwlock) {_r.lock(); }
+            ~Exclusive() { _r.unlock(); }
+        };
+    };
+
+}