feat!: RedisDataSource::Create should return unique_ptr instead of shared_ptr (#344)

Previously, `RedisDataSource::Create` returned an
`expected<shared_ptr<RedisDataSource>, error>`.


We don't need to force the user into shared ownership in the factory
function - instead, return a `unique_ptr` and let them make the
transformation.

Author: cwaldren-ld

libs/server-sdk-redis-source/include/launchdarkly/server_side/integrations/redis/redis_source.hpp

@@ -16,7 +16,6 @@ class Redis;
 }
 
 namespace launchdarkly::server_side::integrations {
-
 /**
  * @brief RedisDataSource represents a data source for the Server-Side SDK
  * backed by Redis. It is meant to be used in place of the standard
@@ -47,7 +46,7 @@ class RedisDataSource final : public ISerializedDataReader {
      *
      * @return A RedisDataSource, or an error if construction failed.
      */
-    static tl::expected<std::shared_ptr<RedisDataSource>, std::string> Create(
+    static tl::expected<std::unique_ptr<RedisDataSource>, std::string> Create(
         std::string uri,
         std::string prefix);
 
@@ -57,8 +56,6 @@ class RedisDataSource final : public ISerializedDataReader {
     [[nodiscard]] std::string const& Identity() const override;
     [[nodiscard]] bool Initialized() const override;
 
-    ~RedisDataSource();
-
    private:
     RedisDataSource(std::unique_ptr<sw::redis::Redis> redis,
                     std::string prefix);
@@ -70,5 +67,4 @@ class RedisDataSource final : public ISerializedDataReader {
     std::string const inited_key_;
     std::unique_ptr<sw::redis::Redis> redis_;
 };
-
 }  // namespace launchdarkly::server_side::integrations

libs/server-sdk-redis-source/src/redis_source.cpp

@@ -3,11 +3,10 @@
 #include <redis++.h>
 
 namespace launchdarkly::server_side::integrations {
-
-tl::expected<std::shared_ptr<RedisDataSource>, std::string>
+tl::expected<std::unique_ptr<RedisDataSource>, std::string>
 RedisDataSource::Create(std::string uri, std::string prefix) {
     try {
-        return std::shared_ptr<RedisDataSource>(new RedisDataSource(
+        return std::unique_ptr<RedisDataSource>(new RedisDataSource(
             std::make_unique<sw::redis::Redis>(std::move(uri)),
             std::move(prefix)));
     } catch (sw::redis::Error const& e) {
@@ -26,8 +25,6 @@ RedisDataSource::RedisDataSource(std::unique_ptr<sw::redis::Redis> redis,
       inited_key_(prefix_ + ":$inited"),
       redis_(std::move(redis)) {}
 
-RedisDataSource::~RedisDataSource() = default;
-
 ISerializedDataReader::GetResult RedisDataSource::Get(
     ISerializedItemKind const& kind,
     std::string const& itemKey) const {
@@ -54,7 +51,6 @@ ISerializedDataReader::AllResult RedisDataSource::All(
             items.emplace(key, SerializedItemDescriptor::Present(0, val));
         }
         return items;
-
     } catch (sw::redis::Error const& e) {
         return tl::make_unexpected(Error{e.what()});
     }
@@ -72,5 +68,4 @@ bool RedisDataSource::Initialized() const {
         return false;
     }
 }
-
 }  // namespace launchdarkly::server_side::integrations

libs/server-sdk-redis-source/tests/redis_source_test.cpp

@@ -405,6 +405,13 @@ TEST_F(RedisTests, FlagAndSegmentCanCoexistWithSameKey) {
               serialize(boost::json::value_from(segment_in)));
 }
 
+TEST_F(RedisTests, CanConvertRedisDataSourceToDataReader) {
+    auto maybe_source = RedisDataSource::Create("tcp://foobar:1000", "prefix");
+    ASSERT_TRUE(maybe_source);
+
+    std::shared_ptr<ISerializedDataReader> reader = std::move(*maybe_source);
+}
+
 TEST(RedisErrorTests, InvalidURIs) {
     std::vector<std::string> const uris = {"nope, not a redis URI",
                                            "http://foo",
@@ -433,11 +440,11 @@ TEST(RedisErrorTests, ValidURIs) {
 }
 
 TEST(RedisErrorTests, GetReturnsErrorAndNoExceptionThrown) {
-    auto const maybe_source = RedisDataSource::Create(
+    auto maybe_source = RedisDataSource::Create(
         "tcp://foobar:1000" /* no redis service here */, "prefix");
     ASSERT_TRUE(maybe_source);
 
-    auto const source = *maybe_source;
+    auto const source = std::move(*maybe_source);
 
     auto const get_initialized = source->Initialized();
     ASSERT_FALSE(get_initialized);