validation: add is_cql_key_invalid()

validation.cc

@@ -49,24 +49,32 @@ namespace validation {
 /**
  * Based on org.apache.cassandra.thrift.ThriftValidation#validate_key()
  */
-void
-validate_cql_key(const schema& schema, partition_key_view key) {
+std::optional<sstring> is_cql_key_invalid(const schema& schema, partition_key_view key) {
     // C* validates here that the thrift key is not empty.
     // It can only be empty if it is not composite and its only component in CQL form is empty.
     if (schema.partition_key_size() == 1 && key.begin(schema)->empty()) {
-        throw exceptions::invalid_request_exception("Key may not be empty");
+        return sstring("Key may not be empty");
     }
 
     // check that key can be handled by FBUtilities.writeShortByteArray
     auto b = key.representation();
     if (b.size() > max_key_size) {
-        throw exceptions::invalid_request_exception(format("Key length of {:d} is longer than maximum of {:d}", b.size(), max_key_size));
+        return format("Key length of {:d} is longer than maximum of {:d}", b.size(), max_key_size);
     }
 
     try {
         key.validate(schema);
     } catch (const marshal_exception& e) {
-        throw exceptions::invalid_request_exception(e.what());
+        return sstring(e.what());
+    }
+
+    return std::nullopt;
+}
+
+void
+validate_cql_key(const schema& schema, partition_key_view key) {
+    if (const auto err = is_cql_key_invalid(schema, key); err) {
+        throw exceptions::invalid_request_exception(std::move(*err));
     }
 }
 

validation.hh

@@ -51,6 +51,8 @@ namespace validation {
 
 constexpr size_t max_key_size = std::numeric_limits<uint16_t>::max();
 
+// Returns an error string if key is invalid, a disengaged optional otherwise.
+std::optional<sstring> is_cql_key_invalid(const schema& schema, partition_key_view key);
 void validate_cql_key(const schema& schema, partition_key_view key);
 schema_ptr validate_column_family(database& db, const sstring& keyspace_name, const sstring& cf_name);
 schema_ptr validate_column_family(const sstring& keyspace_name, const sstring& cf_name);