[OMON-406] Add example for Pull Client (#311)

Author: awegrzyn

CMakeLists.txt

@@ -237,6 +237,7 @@ set(EXAMPLES
 
 if(RdKafka_FOUND)
   list(APPEND EXAMPLES "examples/11-KafkaToWebsocket.cxx")
+  list(APPEND EXAMPLES "examples/13-PullClient.cxx")
 endif()
 
 foreach (example ${EXAMPLES})

examples/13-PullClient.cxx

@@ -0,0 +1,27 @@
+///
+/// \file 13-PullClient.cxx
+/// \author Adam Wegrzynek <[email protected]>
+///
+
+#include "Monitoring/MonitoringFactory.h"
+
+using namespace o2::monitoring;
+
+int main()
+{
+  /// List of topics to subscribe
+  std::vector<std::string> topics = {"cru.link_status"};
+  /// Connect to server
+  auto client = MonitoringFactory::GetPullClient("adam-kafka:9092", topics);
+  for (;;) {
+    auto metrics = client->pull();
+    if (!metrics.empty()) {
+      for (auto& metric : metrics) {
+        /// metric.first => topic name; metric.second => metric itself as string
+        /// metric sample: link,serialId=983,endpoint=1,CRU=1,id=11,type=CRU pciAddress="b0:00.0",status=1i 1673940809860009855
+        std::cout << metric.second << std::endl;
+      }
+    }
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  }
+}