dht: add formatter for paritition_range_view and i_partition

before this change, we rely on the default-generated fmt::formatter
created from operator<<, but fmt v10 dropped the default-generated
formatter.

in this change, we define formatters for
`partition_range_view` and `i_partition`, and drop their operator<<:s.

Refs #13245

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#17331

dht/i_partitioner.cc

@@ -10,6 +10,7 @@
 #include "sharder.hh"
 #include <seastar/core/seastar.hh>
 #include <seastar/coroutine/maybe_yield.hh>
+#include "dht/ring_position.hh"
 #include "dht/token-sharding.hh"
 #include "utils/class_registrator.hh"
 #include <boost/range/adaptor/map.hpp>
@@ -58,26 +59,6 @@ std::ostream& operator<<(std::ostream& out, const decorated_key& dk) {
     return out;
 }
 
-std::ostream& operator<<(std::ostream& out, partition_ranges_view v) {
-    out << "{";
-
-    if (v.empty()) {
-        out << " }";
-        return out;
-    }
-
-    auto it = v.begin();
-    out << *it;
-    ++it;
-
-    for (;it != v.end(); ++it) {
-        out << ", " << *it;
-    }
-
-    out << "}";
-    return out;
-}
-
 std::unique_ptr<dht::i_partitioner> make_partitioner(sstring partitioner_name) {
     try {
         return create_object<i_partitioner>(partitioner_name);
@@ -149,11 +130,6 @@ decorated_key::less_comparator::operator()(const decorated_key& lhs, const ring_
     return lhs.tri_compare(*s, rhs) < 0;
 }
 
-std::ostream& operator<<(std::ostream& out, const i_partitioner& p) {
-    out << "{partitioner name = " << p.name();
-    return out << "}";
-}
-
 unsigned static_shard_of(const schema& s, const token& t) {
     return s.get_sharder().shard_of(t);
 }
@@ -518,3 +494,12 @@ auto fmt::formatter<dht::ring_position>::format(const dht::ring_position& pos, f
     }
     return fmt::format_to(out, "}}");
 }
+
+auto fmt::formatter<dht::partition_ranges_view>::format(const dht::partition_ranges_view& v, fmt::format_context& ctx) const
+    -> decltype(ctx.out()) {
+    auto out = fmt::format_to(ctx.out(), "{{");
+    for (auto& range : v) {
+        out = fmt::format_to(out, "{}", range);
+    }
+    return fmt::format_to(out, "}}");
+}

dht/i_partitioner.hh

@@ -73,8 +73,6 @@ public:
     }
 };
 
-std::ostream& operator<<(std::ostream& out, const i_partitioner& p);
-
 // Returns the owning shard number for vnode-based replication strategies.
 // Use table::shard_of() for the general case.
 unsigned static_shard_of(const schema&, const token&);
@@ -120,3 +118,10 @@ dht::token first_token(const dht::partition_range&);
 std::optional<shard_id> is_single_shard(const dht::sharder&, const schema&, const dht::partition_range&);
 
 } // dht
+
+template <> struct fmt::formatter<dht::i_partitioner> : fmt::formatter<std::string_view> {
+    template <typename FormatContext>
+    auto format(const dht::i_partitioner& p, FormatContext& ctx) const {
+        return fmt::format_to(ctx.out(), "{{partitioner name = {}}}", p.name());
+    }
+};

dht/ring_position.hh

@@ -486,8 +486,6 @@ public:
     const dht::partition_range* end() const { return _data + _size; }
 };
 
-std::ostream& operator<<(std::ostream& out, partition_ranges_view v);
-
 } // namespace dht
 
 template<>
@@ -509,3 +507,8 @@ struct fmt::formatter<dht::ring_position> {
     constexpr auto parse(format_parse_context& ctx) { return ctx.begin(); }
     auto format(const dht::ring_position& pos, fmt::format_context& ctx) const -> decltype(ctx.out());
 };
+
+template <> struct fmt::formatter<dht::partition_ranges_view> : fmt::formatter<std::string_view> {
+    auto format(const dht::partition_ranges_view&, fmt::format_context& ctx) const
+      -> decltype(ctx.out());
+};