locator/abstract_replication_strategy: Add recognized_options() helper

Add a helper function for obtaining a vector of supported replication
strategy options. This is needed for validation.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

locator/abstract_replication_strategy.hh

@@ -74,6 +74,7 @@ public:
     virtual ~abstract_replication_strategy() {}
     static std::unique_ptr<abstract_replication_strategy> create_replication_strategy(const sstring& ks_name, const sstring& strategy_name, token_metadata& token_metadata, const std::map<sstring, sstring>& config_options);
     virtual std::vector<inet_address> get_natural_endpoints(const token& search_token);
+    virtual std::experimental::optional<std::set<sstring>> recognized_options() const = 0;
     virtual size_t get_replication_factor() const = 0;
     uint64_t get_cache_hits_count() const { return _cache_hits_count; }
     replication_strategy_type get_type() const { return _my_type; }

locator/local_strategy.cc

@@ -21,6 +21,11 @@ std::vector<inet_address> local_strategy::calculate_natural_endpoints(const toke
     return std::vector<inet_address>({utils::fb_utilities::get_broadcast_address()});
 }
 
+std::experimental::optional<std::set<sstring>> local_strategy::recognized_options() const {
+    // LocalStrategy doesn't expect any options.
+    return {};
+}
+
 size_t local_strategy::get_replication_factor() const {
     return 1;
 }

locator/local_strategy.hh

@@ -6,6 +6,9 @@
 
 #include "abstract_replication_strategy.hh"
 
+#include <experimental/optional>
+#include <set>
+
 // forward declaration since database.hh includes this file
 class keyspace;
 
@@ -27,6 +30,8 @@ public:
      * LocalStrategy may be used before tokens are set up.
      */
     std::vector<inet_address> get_natural_endpoints(const token& search_token) override;
+
+    virtual std::experimental::optional<std::set<sstring>> recognized_options() const override;
 };
 
 }

locator/network_topology_strategy.cc

@@ -181,6 +181,11 @@ network_topology_strategy::calculate_natural_endpoints(
     return std::move(replicas.get_vector());
 }
 
+std::experimental::optional<std::set<sstring>> network_topology_strategy::recognized_options() const {
+    // We explicitely allow all options
+    return std::experimental::nullopt;
+}
+
 inline bool network_topology_strategy::has_sufficient_replicas(
         const sstring& dc,
         std::unordered_map<sstring,

locator/network_topology_strategy.hh

@@ -24,6 +24,9 @@
 #include "locator/abstract_replication_strategy.hh"
 #include "exceptions/exceptions.hh"
 
+#include <experimental/optional>
+#include <set>
+
 namespace locator {
 class network_topology_strategy : public abstract_replication_strategy {
 public:
@@ -54,6 +57,8 @@ protected:
     virtual std::vector<inet_address> calculate_natural_endpoints(
         const token& search_token) const override;
 
+    virtual std::experimental::optional<std::set<sstring>> recognized_options() const override;
+
 private:
     bool has_sufficient_replicas(
         const sstring& dc,
@@ -80,15 +85,6 @@ private:
         }
     }
 
-    // ????
-    #if 0
-    public Collection<String> recognized_options()
-    {
-        // We explicitely allow all options
-        return null;
-    }
-    #endif
-
 private:
     // map: data centers -> replication factor
     std::unordered_map<sstring, size_t> _dc_rep_factor;

locator/simple_strategy.cc

@@ -52,6 +52,10 @@ size_t simple_strategy::get_replication_factor() const {
     return _replication_factor;
 }
 
+std::experimental::optional<std::set<sstring>>simple_strategy::recognized_options() const {
+    return {{ "replication_factor" }};
+}
+
 using registry = class_registrator<abstract_replication_strategy, simple_strategy, const sstring&, token_metadata&, snitch_ptr&, const std::map<sstring, sstring>&>;
 static registry registrator("org.apache.cassandra.locator.SimpleStrategy");
 static registry registrator_short_name("SimpleStrategy");

locator/simple_strategy.hh

@@ -6,6 +6,9 @@
 
 #include "abstract_replication_strategy.hh"
 
+#include <experimental/optional>
+#include <set>
+
 namespace locator {
 
 class simple_strategy : public abstract_replication_strategy {
@@ -15,7 +18,7 @@ public:
     simple_strategy(const sstring& keyspace_name, token_metadata& token_metadata, snitch_ptr& snitch, const std::map<sstring, sstring>& config_options);
     virtual ~simple_strategy() {};
     virtual size_t get_replication_factor() const override;
-
+    virtual std::experimental::optional<std::set<sstring>> recognized_options() const override;
 private:
     size_t _replication_factor = 1;
 };