Initial check-in of shard map ideas

src/CMakeLists.txt

@@ -18,6 +18,7 @@ add_subdirectory(query/v2)
 add_subdirectory(slk)
 add_subdirectory(rpc)
 add_subdirectory(auth)
+add_subdirectory(coordinator)
 
 if (MG_ENTERPRISE)
   add_subdirectory(audit)

src/coordinator/shard_map.hpp

@@ -0,0 +1,55 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <map>
+#include <vector>
+
+#include "io/address.hpp"
+
+namespace memgraph::coordinator {
+
+enum class Status : uint8_t {
+  CONSENSUS_PARTICIPANT,
+  INITIALIZING,
+  // TODO(tyler) this will possibly have more states,
+  // depending on the reconfiguration protocol that we
+  // implement.
+};
+
+struct AddressAndStatus {
+  memgraph::io::Address address;
+  Status status;
+};
+
+using CompoundKey = std::vector<memgraph::storage::PropertyValue>;
+using Shard = std::vector<AddressAndStatus>;
+using Shards = std::map<CompoundKey, Shard>;
+
+// TODO(tyler) ask Bendzo or Jure what this type should actually be
+using Label = std::string;
+
+class ShardMap {
+  uint64_t shard_map_version_;
+  std::map<Label, Shards> shards_;
+
+ public:
+  Shards GetShardsForRange(Label label, CompoundKey start, CompoundKey end);
+
+  // TODO(tyler) ask Kostas if this would ever actually be useful
+  Shard GetShardForKey(Label label, CompoundKey key);
+
+  /// This splits the previous shard
+  bool SplitShard(uint64_t previous_shard_map_version, Label label, CompoundKey split_key);
+};
+
+}  // namespace memgraph::coordinator