1 files changed, 60 insertions, 0 deletions
diff --git a/fnet/src/vespa/fnet/transport_debugger.h b/fnet/src/vespa/fnet/transport_debugger.h
new file mode 100644
index 00000000000..ed3738bb9fe
--- /dev/null
+++ b/fnet/src/vespa/fnet/transport_debugger.h
@@ -0,0 +1,60 @@
+// Copyright Verizon Media. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#pragma once
+
+#include "transport.h"
+#include <vespa/vespalib/util/rendezvous.h>
+#include <vespa/vespalib/util/time.h>
+#include <memory>
+
+namespace fnet {
+
+/**
+ * This class is used to control transport threads during unit
+ * testing.
+ * 
+ * The TimeTools created by this class should be used when setting up
+ * all transports used in the test. The supplied TimeTools will make
+ * sure no thread ever blocks waiting for io-events and also make sure
+ * all threads observe the same externally controlled current
+ * time. After the transport layers are started, the attach function
+ * is used to start controlling event loop execution. While attached,
+ * calling the step function will run each transport thread event loop
+ * exactly once (in parallel), wait for pending dns resolving, wait
+ * for pending tls handshake work and advance the current time with
+ * 5ms (making sure 'time passes' and 'stuff happens' at a reasonable
+ * relative rate). It is important to call detach to release the
+ * transports before trying to shut them down.
+ * 
+ * Note that both server and client should be controlled by the same
+ * debugger when testing rpc. Using external services will result in
+ * (synthetic) time passing too fast compared to stuff actually
+ * happening, since you do not control the other end-point in the same
+ * way.
+ *
+ * Take a look at the unit test for this class for an example of how
+ * to use it.
+ **/
+class TransportDebugger
+{
+private:
+    struct Meet : vespalib::Rendezvous<bool,bool> {
+        Meet(size_t N) : vespalib::Rendezvous<bool,bool>(N) {}
+        void mingle() override;
+    };
+    vespalib::steady_time _time;
+    std::shared_ptr<Meet> _meet;
+
+public:
+    TransportDebugger();
+    ~TransportDebugger();
+    vespalib::steady_time time() const { return _time; }
+    TimeTools::SP time_tools() {
+        return TimeTools::make_debug(vespalib::duration::zero(), [this]() noexcept { return time(); });
+    }
+    void attach(std::initializer_list<std::reference_wrapper<FNET_Transport> > list);
+    void step();
+    void detach();
+};
+
+}