Thread lib: #44 Missing binary semaphore in the common library

Semaphore implemented and simple cleanup is made

lib/thread/common/export/ecl/thread/common/mutex.hpp

@@ -10,7 +10,7 @@ namespace common
 class mutex
 {
 public:
-    constexpr mutex();
+    constexpr mutex() { }
 
     void lock();
     void unlock();

lib/thread/common/export/ecl/thread/common/semaphore.hpp

@@ -29,6 +29,26 @@ class semaphore
     std::atomic_int m_counter;
 };
 
+// Empty binary semaphore, acting like spinlock of some kind that can have
+// only two values - 0 or 1
+class binary_semaphore
+{
+public:
+    constexpr binary_semaphore()
+        :m_flag{0} { }
+
+    void signal();
+    void wait();
+    ecl::err try_wait();
+
+    binary_semaphore(const binary_semaphore&)             = delete;
+    binary_semaphore& operator=(const binary_semaphore&)  = delete;
+
+private:
+    std::atomic_bool m_flag;
+};
+
+
 }
 
 }

lib/thread/common/mutex.cpp

@@ -1,9 +1,5 @@
 #include <ecl/thread/common/mutex.hpp>
 
-constexpr ecl::common::mutex::mutex()
-{
-}
-
 void ecl::common::mutex::lock()
 {
 }

lib/thread/common/semaphore.cpp

@@ -27,3 +27,24 @@ ecl::err ecl::common::semaphore::try_wait()
 
     return rc;
 }
+
+//------------------------------------------------------------------------------
+
+void ecl::common::binary_semaphore::signal()
+{
+    m_flag = true;
+}
+
+void ecl::common::binary_semaphore::wait()
+{
+    while (!m_flag) { }
+}
+
+ecl::err ecl::common::binary_semaphore::try_wait()
+{
+    if (m_flag.exchange(false)) {
+        return err::ok;
+    }
+
+    return err::again;
+}

lib/thread/default/export/ecl/thread/semaphore.hpp

@@ -6,6 +6,7 @@
 namespace ecl
 {
     using semaphore = common::semaphore;
+    using binary_semaphore = common::binary_semaphore;
 }
 
 #endif //LIB_THREAD_DEFAULT_SEMAPHORE_