Add replica state to SHOW REPLICAS (#379)

src/query/frontend/ast/ast.lcp

@@ -2391,6 +2391,9 @@ cpp<#
     (lcp:define-enum sync-mode
         (sync async)
       (:serialize))
+    (lcp:define-enum replica-state
+        (ready replicating recovery invalid)
+      (:serialize))
     #>cpp
     ReplicationQuery() = default;
 

src/query/interpreter.cpp

@@ -231,7 +231,20 @@ class ReplQueryHandler final : public query::ReplicationQueryHandler {
       if (repl_info.timeout) {
         replica.timeout = *repl_info.timeout;
       }
-
+      switch (repl_info.state) {
+        case storage::replication::ReplicaState::READY:
+          replica.state = ReplicationQuery::ReplicaState::READY;
+          break;
+        case storage::replication::ReplicaState::REPLICATING:
+          replica.state = ReplicationQuery::ReplicaState::REPLICATING;
+          break;
+        case storage::replication::ReplicaState::RECOVERY:
+          replica.state = ReplicationQuery::ReplicaState::RECOVERY;
+          break;
+        case storage::replication::ReplicaState::INVALID:
+          replica.state = ReplicationQuery::ReplicaState::INVALID;
+          break;
+      }
       return replica;
     };
 
@@ -486,6 +499,7 @@ Callback HandleReplicationQuery(ReplicationQuery *repl_query, const Parameters &
                                   fmt::format("Replica {} is registered.", repl_query->replica_name_));
       return callback;
     }
+
     case ReplicationQuery::Action::DROP_REPLICA: {
       const auto &name = repl_query->replica_name_;
       callback.fn = [handler = ReplQueryHandler{interpreter_context->db}, name]() mutable {
@@ -496,8 +510,9 @@ Callback HandleReplicationQuery(ReplicationQuery *repl_query, const Parameters &
                                   fmt::format("Replica {} is dropped.", repl_query->replica_name_));
       return callback;
     }
+
     case ReplicationQuery::Action::SHOW_REPLICAS: {
-      callback.header = {"name", "socket_address", "sync_mode", "timeout"};
+      callback.header = {"name", "socket_address", "sync_mode", "timeout", "state"};
       callback.fn = [handler = ReplQueryHandler{interpreter_context->db}, replica_nfields = callback.header.size()] {
         const auto &replicas = handler.ShowReplicas();
         auto typed_replicas = std::vector<std::vector<TypedValue>>{};
@@ -508,6 +523,7 @@ Callback HandleReplicationQuery(ReplicationQuery *repl_query, const Parameters &
 
           typed_replica.emplace_back(TypedValue(replica.name));
           typed_replica.emplace_back(TypedValue(replica.socket_address));
+
           switch (replica.sync_mode) {
             case ReplicationQuery::SyncMode::SYNC:
               typed_replica.emplace_back(TypedValue("sync"));
@@ -516,12 +532,28 @@ Callback HandleReplicationQuery(ReplicationQuery *repl_query, const Parameters &
               typed_replica.emplace_back(TypedValue("async"));
               break;
           }
+
           if (replica.timeout) {
             typed_replica.emplace_back(TypedValue(*replica.timeout));
           } else {
             typed_replica.emplace_back(TypedValue());
           }
 
+          switch (replica.state) {
+            case ReplicationQuery::ReplicaState::READY:
+              typed_replica.emplace_back(TypedValue("ready"));
+              break;
+            case ReplicationQuery::ReplicaState::REPLICATING:
+              typed_replica.emplace_back(TypedValue("replicating"));
+              break;
+            case ReplicationQuery::ReplicaState::RECOVERY:
+              typed_replica.emplace_back(TypedValue("recovery"));
+              break;
+            case ReplicationQuery::ReplicaState::INVALID:
+              typed_replica.emplace_back(TypedValue("invalid"));
+              break;
+          }
+
           typed_replicas.emplace_back(std::move(typed_replica));
         }
         return typed_replicas;

src/query/interpreter.hpp

@@ -127,6 +127,7 @@ class ReplicationQueryHandler {
     std::string socket_address;
     ReplicationQuery::SyncMode sync_mode;
     std::optional<double> timeout;
+    ReplicationQuery::ReplicaState state;
   };
 
   /// @throw QueryRuntimeException if an error ocurred.

src/storage/v2/storage.cpp

@@ -306,6 +306,13 @@ Storage::Storage(Config config)
       uuid_(utils::GenerateUUID()),
       epoch_id_(utils::GenerateUUID()),
       global_locker_(file_retainer_.AddLocker()) {
+  if (config_.durability.snapshot_wal_mode == Config::Durability::SnapshotWalMode::DISABLED &&
+      replication_role_ == ReplicationRole::MAIN) {
+    spdlog::warn(
+        "The instance has the MAIN replication role, but durability logs and snapshots are disabled. Please consider "
+        "enabling durability by using --storage-snapshot-interval-sec and --storage-wal-enabled flags because "
+        "without write-ahead logs this instance is not replicating any data.");
+  }
   if (config_.durability.snapshot_wal_mode != Config::Durability::SnapshotWalMode::DISABLED ||
       config_.durability.snapshot_on_exit || config_.durability.recover_on_startup) {
     // Create the directory initially to crash the database in case of