Extract state queue into own class. Use in device, plugins

fairmq/StateQueue.h

@@ -0,0 +1,94 @@
+/********************************************************************************
+ *    Copyright (C) 2019 GSI Helmholtzzentrum fuer Schwerionenforschung GmbH    *
+ *                                                                              *
+ *              This software is distributed under the terms of the             *
+ *              GNU Lesser General Public Licence (LGPL) version 3,             *
+ *                  copied verbatim in the file "LICENSE"                       *
+ ********************************************************************************/
+
+#ifndef FAIRMQSTATEQUEUE_H_
+#define FAIRMQSTATEQUEUE_H_
+
+#include <fairmq/States.h>
+
+#include <queue>
+#include <mutex>
+#include <chrono>
+#include <utility> // pair
+#include <condition_variable>
+
+namespace fair
+{
+namespace mq
+{
+
+class StateQueue
+{
+  public:
+    StateQueue() {}
+    ~StateQueue() {}
+
+    fair::mq::State WaitForNext()
+    {
+        std::unique_lock<std::mutex> lock(fMtx);
+        while (fStates.empty()) {
+            fCV.wait_for(lock, std::chrono::milliseconds(50));
+        }
+
+        fair::mq::State state = fStates.front();
+
+        if (state == fair::mq::State::Error) {
+            throw DeviceErrorState("Controlled device transitioned to error state.");
+        }
+
+        fStates.pop();
+        return state;
+    }
+
+    template<typename Rep, typename Period>
+    std::pair<bool, fair::mq::State> WaitForNext(std::chrono::duration<Rep, Period> const& duration)
+    {
+        std::unique_lock<std::mutex> lock(fMtx);
+        fCV.wait_for(lock, duration);
+
+        if (fStates.empty()) {
+            return { false, fair::mq::State::Ok };
+        }
+
+        fair::mq::State state = fStates.front();
+
+        if (state == fair::mq::State::Error) {
+            throw DeviceErrorState("Controlled device transitioned to error state.");
+        }
+
+        fStates.pop();
+        return { true, state };
+    }
+
+    void WaitForState(fair::mq::State state) { while (WaitForNext() != state) {} }
+
+    void Push(fair::mq::State state)
+    {
+        {
+            std::lock_guard<std::mutex> lock(fMtx);
+            fStates.push(state);
+        }
+        fCV.notify_all();
+    }
+
+    void Clear()
+    {
+        std::lock_guard<std::mutex> lock(fMtx);
+        fStates = std::queue<fair::mq::State>();
+    }
+
+  private:
+    std::queue<fair::mq::State> fStates;
+    std::mutex fMtx;
+    std::condition_variable fCV;
+};
+
+} // namespace mq
+} // namespace fair
+
+#endif /* FAIRMQSTATEQUEUE_H_ */