pipeline support

testApp/remote/pipelineServiceExample.cpp

@@ -0,0 +1,81 @@
+/**
+ * Copyright - See the COPYRIGHT that is included with this distribution.
+ * pvAccessCPP is distributed subject to a Software License Agreement found
+ * in file LICENSE that is included with this distribution.
+ */
+
+#include <pv/pvData.h>
+#include <pv/pipelineServer.h>
+
+using namespace epics::pvData;
+using namespace epics::pvAccess;
+
+static Structure::const_shared_pointer dataStructure =
+        getFieldCreate()->createFieldBuilder()->
+               add("count", pvInt)->
+               createStructure();
+
+class PipelineSessionImpl :
+        public PipelineSession
+{
+public:
+
+    PipelineSessionImpl(
+            epics::pvData::PVStructure::shared_pointer const & /*pvRequest*/
+            ) :
+        m_counter(0)
+    {
+    }
+
+    size_t getMinQueueSize() const {
+        return 16; //1024;
+    }
+
+    Structure::const_shared_pointer getStructure() const {
+        return dataStructure;
+    }
+
+    virtual void request(PipelineControl::shared_pointer const & control, size_t elementCount) {
+        // blocking in this call is not a good thing
+        // but generating a simple counter data is fast
+        // we will generate as much elements as we can
+        size_t count = control->getFreeElementCount();
+        for (size_t i = 0; i < count; i++) {
+            MonitorElement::shared_pointer element = control->getFreeElement();
+            element->pvStructurePtr->getSubField<PVInt>(1 /*"count"*/)->put(m_counter++);
+            control->putElement(element);
+        }
+    }
+
+    virtual void cancel() {
+        // noop, no need to clean any data-source resources
+    }
+
+private:
+    // NOTE: all the request calls will be made from the same thread, so we do not need sync m_counter
+    int32 m_counter;
+};
+
+class PipelineServiceImpl :
+        public PipelineService
+{
+    PipelineSession::shared_pointer createPipeline(
+            epics::pvData::PVStructure::shared_pointer const & pvRequest
+            )
+    {
+        return PipelineSession::shared_pointer(new PipelineSessionImpl(pvRequest));
+    }
+};
+
+int main()
+{
+    PipelineServer server;
+
+    server.registerService("counterPipe", PipelineService::shared_pointer(new PipelineServiceImpl()));
+    // you can register as many services as you want here ...
+
+    server.printInfo();
+    server.run();
+
+    return 0;
+}