added benchmark test suite

test/utils/RecordingObserver.cpp

@@ -0,0 +1,28 @@
+#include "RecordingObserver.hpp"
+
+namespace matador::test {
+RecordingObserver::RecordingObserver(utils::message_bus& bus) {
+  subscriptions.push_back(bus.subscribe<sql::statement_accessed_event>([this](const sql::statement_accessed_event &ev) {
+    std::lock_guard lock(mutex);
+    events.push(utils::message::from_ref(ev));
+  }));
+  subscriptions.push_back(bus.subscribe<sql::statement_added_event>([this](const sql::statement_added_event &ev) {
+    std::lock_guard lock(mutex);
+    events.push(utils::message::from_ref(ev));
+  }));
+  subscriptions.push_back(bus.subscribe<sql::statement_evicted_event>([this](const sql::statement_evicted_event &ev) {
+    std::lock_guard lock(mutex);
+    events.push(utils::message::from_ref(ev));
+  }));
+}
+
+std::optional<utils::message> RecordingObserver::poll() {
+  std::lock_guard lock(mutex);
+  if (events.empty()) {
+    return std::nullopt;
+  }
+  auto evt = events.front();
+  events.pop();
+  return evt;
+}
+}