From 9094154d460d8f01fe3a3748d1cd366ce893e63b Mon Sep 17 00:00:00 2001
From: heck <heck@pep.foundation>
Date: Mon, 28 Feb 2022 23:29:32 +0100
Subject: [PATCH] Import: module 'Semaphore' from libpEpAdapter

---
 src/Semaphore.hh | 51 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 src/Semaphore.hh

diff --git a/src/Semaphore.hh b/src/Semaphore.hh
new file mode 100644
index 0000000..c026185
--- /dev/null
+++ b/src/Semaphore.hh
@@ -0,0 +1,51 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
+#ifndef LIBPEPADAPTER_SEMAPHORE_HH
+#define LIBPEPADAPTER_SEMAPHORE_HH
+
+#include <mutex>
+#include <condition_variable>
+#include <atomic>
+
+namespace pEp {
+    class Semaphore {
+        std::mutex mtx;
+        std::condition_variable cv;
+        // Atomic types are types that encapsulate a value whose access is guaranteed
+        // to not cause data races and can be used to synchronize memory accesses among
+        // different threads.
+        // To synchronize threads, ALWAYS use <atomic> types
+        std::atomic_bool _stop;
+
+    public:
+        Semaphore() : _stop(false) {}
+
+        void stop()
+        {
+            std::unique_lock<std::mutex> lock(mtx);
+            _stop.store(true);
+        }
+
+        void try_wait()
+        {
+            std::unique_lock<std::mutex> lock(mtx);
+            if (!_stop.load()) {
+                return;
+            }
+
+            while (_stop.load()) {
+                cv.wait(lock);
+            }
+        }
+
+        void go()
+        {
+            std::unique_lock<std::mutex> lock(mtx);
+            _stop.store(false);
+            cv.notify_all();
+        }
+    };
+} // namespace pEp
+
+#endif // LIBPEPADAPTER_SEMAPHORE_HH