Model-based testing of simulated full cluster (#584)

This PR adds support for generating randomized workloads that will be executed
against a simulated cluster, as well as against a correctness model. Initially
this just generates ScanAll and CreateVertex requests, and anything that it
creates, it also inserts into a `std::set`, and when we do a ScanAll, it asserts
that we get the same number of requests back. This will become much more
sophisticated over time, but it's already hitting pay-dirt.

src/io/address.hpp

@@ -15,6 +15,7 @@
 
 #include <fmt/format.h>
 #include <boost/asio/ip/tcp.hpp>
+#include <boost/functional/hash.hpp>
 #include <boost/uuid/uuid.hpp>
 #include <boost/uuid/uuid_generators.hpp>
 #include <boost/uuid/uuid_io.hpp>
@@ -78,6 +79,13 @@ struct Address {
     };
   }
 
+  PartialAddress ToPartialAddress() const {
+    return PartialAddress{
+        .ip = last_known_ip,
+        .port = last_known_port,
+    };
+  }
+
   friend bool operator==(const Address &lhs, const Address &rhs) = default;
 
   /// unique_id is most dominant for ordering, then last_known_ip, then last_known_port
@@ -103,4 +111,30 @@ struct Address {
     return in;
   }
 };
+
 };  // namespace memgraph::io
+
+namespace std {
+template <>
+struct hash<memgraph::io::PartialAddress> {
+  size_t operator()(const memgraph::io::PartialAddress &pa) const {
+    using boost::hash_combine;
+    using boost::hash_value;
+
+    // Start with a hash value of 0    .
+    std::size_t seed = 0;
+
+    if (pa.ip.is_v4()) {
+      auto h = std::hash<boost::asio::ip::address_v4>()(pa.ip.to_v4());
+      hash_combine(seed, h);
+    } else {
+      auto h = std::hash<boost::asio::ip::address_v6>()(pa.ip.to_v6());
+      hash_combine(seed, h);
+    }
+    hash_combine(seed, hash_value(pa.port));
+
+    // Return the result.
+    return seed;
+  }
+};
+}  // namespace std