locator: resolve the dependency of token_metadata.hh on token_range_splitter.hh

define token_metadata_ptr in token_metadata_fwd.hh
So that the declaration of `make_splitter` can be moved
to token_range_splitter.hh, where it belongs,
and so token_metadata.hh won't have to include it.

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>

locator/token_metadata.hh

@@ -15,7 +15,6 @@
 #include <unordered_map>
 #include "gms/inet_address.hh"
 #include "dht/i_partitioner.hh"
-#include "locator/token_range_splitter.hh"
 #include "inet_address_vectors.hh"
 #include <optional>
 #include <memory>
@@ -31,6 +30,7 @@
 
 #include "locator/types.hh"
 #include "locator/topology.hh"
+#include "locator/token_metadata_fwd.hh"
 
 // forward declaration since replica/database.hh includes this file
 namespace replica {
@@ -304,8 +304,6 @@ struct topology_change_info {
     future<> clear_gently();
 };
 
-using token_metadata_ptr = lw_shared_ptr<const token_metadata>;
-using mutable_token_metadata_ptr = lw_shared_ptr<token_metadata>;
 using token_metadata_lock = semaphore_units<>;
 using token_metadata_lock_func = noncopyable_function<future<token_metadata_lock>() noexcept>;
 
@@ -395,6 +393,4 @@ public:
     static future<> mutate_on_all_shards(sharded<shared_token_metadata>& stm, seastar::noncopyable_function<future<> (token_metadata&)> func);
 };
 
-std::unique_ptr<locator::token_range_splitter> make_splitter(token_metadata_ptr);
-
 }

locator/token_metadata_fwd.hh

@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2023-present ScyllaDB
+ */
+
+/*
+ * SPDX-License-Identifier: (AGPL-3.0-or-later and Apache-2.0)
+ */
+
+#include <seastar/core/shared_ptr.hh>
+#include "seastarx.hh"
+
+namespace locator {
+
+class token_metadata;
+
+using token_metadata_ptr = lw_shared_ptr<const token_metadata>;
+using mutable_token_metadata_ptr = lw_shared_ptr<token_metadata>;
+
+} // namespace locator

locator/token_range_splitter.hh

@@ -10,6 +10,7 @@
 
 #include "dht/i_partitioner.hh"
 #include "dht/token.hh"
+#include "locator/token_metadata_fwd.hh"
 
 #include <optional>
 
@@ -39,4 +40,6 @@ public:
     virtual std::optional<dht::token> next_token() = 0;
 };
 
+std::unique_ptr<locator::token_range_splitter> make_splitter(token_metadata_ptr);
+
 }