Remove federated type registry (ExpediaGroup#861)

* Remove FederatedTypeRegistry

* Fix test file

* Update docs on type registry

Co-authored-by: Shane Myrick <accounts@shanemyrick.com>

docs/federated/federated-schemas.md

@@ -1,17 +1,17 @@
 ---
-id: federated-schemas 
+id: federated-schemas
 title: Federated Schemas
 ---
 
-`graphql-kotlin-federation` library extends the functionality of the `graphql-kotlin-schema-generator` and allows you to 
-easily generate federated GraphQL schemas directly from the code. Federated schema is generated by calling 
-`toFederatedSchema` function that accepts federated configuration as well as a list of regular queries, mutations and 
+`graphql-kotlin-federation` library extends the functionality of the `graphql-kotlin-schema-generator` and allows you to
+easily generate federated GraphQL schemas directly from the code. Federated schema is generated by calling
+`toFederatedSchema` function that accepts federated configuration as well as a list of regular queries, mutations and
 subscriptions exposed by the schema.
 
-All [federated directives](federated-directives) are provided as annotations that are used to decorate your classes, 
-properties and functions. Since federated types might not be accessible through the regular query execution path, they 
+All [federated directives](federated-directives) are provided as annotations that are used to decorate your classes,
+properties and functions. Since federated types might not be accessible through the regular query execution path, they
 are explicitly picked up by the schema generator based on their directives. Due to the above, we also need to provide
-a way to instantiate the underlying federated objects by implementing corresponding `FederatedTypeResolvers`. See 
+a way to instantiate the underlying federated objects by implementing corresponding `FederatedTypeResolvers`. See
 [type resolution wiki](type-resolution) for more details on how federated types are resolved. Final federated schema
 is then generated by invoking the `toFederatedSchema` function
 ([link](https://github.com/ExpediaGroup/graphql-kotlin/blob/master/graphql-kotlin-federation/src/main/kotlin/com/expediagroup/graphql/federation/toFederatedSchema.kt#L34)).
@@ -26,7 +26,7 @@ it**. Federated Gateway (e.g. Apollo) will then combine the individual graphs to
 
 Base schema defines GraphQL types that will be extended by schemas exposed by other GraphQL services. In the example
 below, we define base `Product` type with `id` and `description` fields. `id` is the primary key that uniquely
-identifies the `Product` type object and is specified in `@key` directive. Since it is a base schema that doesn't expose 
+identifies the `Product` type object and is specified in `@key` directive. Since it is a base schema that doesn't expose
 any extended functionality our FederatedTypeRegistry does not include any federated resolvers.
 
 ```kotlin
@@ -40,8 +40,8 @@ class ProductQuery {
 }
 
 // Generate the schema
-val federatedTypeRegistry = FederatedTypeRegistry(emptyMap())
-val config = FederatedSchemaGeneratorConfig(supportedPackages = listOf("org.example"), hooks = FederatedSchemaGeneratorHooks(federatedTypeRegistry))
+val hooks = FederatedSchemaGeneratorHooks(emptyList())
+val config = FederatedSchemaGeneratorConfig(supportedPackages = listOf("org.example"), hooks = hooks)
 val queries = listOf(TopLevelObject(ProductQuery()))
 
 toFederatedSchema(config, queries)
@@ -78,32 +78,33 @@ Extended federated GraphQL schemas provide additional functionality to the types
 services. In the example below, `Product` type is extended to add new `reviews` field to it. Primary key needed to
 instantiate the `Product` type (i.e. `id`) has to match the `@key` definition on the base type. Since primary keys are
 defined on the base type and are only referenced from the extended type, all of the fields that are part of the field
-set specified in `@key` directive have to be marked as `@external`. Finally, we also need to specify an "entry point" 
-for the federated type - we need to create a FederatedTypeResolver that will be used to instantiate the federated 
+set specified in `@key` directive have to be marked as `@external`. Finally, we also need to specify an "entry point"
+for the federated type - we need to create a FederatedTypeResolver that will be used to instantiate the federated
 `Product` type when processing federated queries.
 
 ```kotlin
 @KeyDirective(fields = FieldSet("id"))
 @ExtendsDirective
 data class Product(@ExternalDirective val id: Int) {
-
-    fun reviews(): List<Review> {
-        // returns list of product reviews
-    }
+    // Add the "reviews" field to the type
+    suspend fun reviews(): List<Review> = getReviewByProductId(id)
 }
 
 data class Review(val reviewId: String, val text: String)
 
-// Generate the schema
-val productResolver = object: FederatedTypeResolver<Product> {
-    override suspend fun resolve(representations: List<Map<String, Any>>): List<Product?> = representations.map { keys ->
-        keys["id"]?.toString()?.toIntOrNull()?.let { id ->
-            Product(id)
-	}
+// Resolve a "Product" type from the _entities query
+class ProductResolver : FederatedTypeResolver<Product> {
+    override val typeName = "Product"
+
+    override suspend fun resolve(environment: DataFetchingEnvironment, representations: List<Map<String, Any>>): List<Product?> = representations.map { keys ->
+        keys["id"]?.toString()?.toIntOrNull()?.let { id -> Product(id) }
     }
 }
-val federatedTypeRegistry = FederatedTypeRegistry(mapOf("Product" to productResolver))
-val config = FederatedSchemaGeneratorConfig(supportedPackages = listOf("org.example"), hooks = FederatedSchemaGeneratorHooks(federatedTypeRegistry))
+
+// Generate the schema
+val resolvers = listOf(ProductResolver())
+val hooks = FederatedSchemaGeneratorHooks(resolvers)
+val config = FederatedSchemaGeneratorConfig(supportedPackages = listOf("org.example"), hooks = hooks)
 
 toFederatedSchema(config)
 ```
@@ -139,7 +140,7 @@ type _Service {
 
 #### Federated GraphQL schema
 
-Once we have both base and extended GraphQL services up and running, we will also need to configure Federated Gateway 
+Once we have both base and extended GraphQL services up and running, we will also need to configure Federated Gateway
 to combine them into a single schema. Using the examples above, our final federated schema will be generated as:
 
 ```graphql

docs/federated/type-resolution.md

@@ -33,9 +33,7 @@ query ($_representations: [_Any!]!) {
 ### Federated Type Resolver
 
 In order to simplify the integrations, `graphql-kotlin-federation` provides a default `_entities` query resolver that
-relies on
-[FederatedTypeRegistry](https://github.com/ExpediaGroup/graphql-kotlin/blob/master/graphql-kotlin-federation/src/main/kotlin/com/expediagroup/graphql/federation/execution/FederatedTypeRegistry.kt)
-to retrieve the
+retrieves the
 [FederatedTypeResolver](https://github.com/ExpediaGroup/graphql-kotlin/blob/master/graphql-kotlin-federation/src/main/kotlin/com/expediagroup/graphql/federation/execution/FederatedTypeResolver.kt)
 that is used to resolve the specified `__typename`.
 
@@ -69,9 +67,10 @@ class ProductResolver : FederatedTypeResolver<Product> {
     }
 }
 
-// The FederatedTypeRegistry provides mapping between the "__typename" and the corresponding type resolver
-// If you are using "graphql-kotlin-spring-server" this is created for you if your FederatedTypeResolvers are marked as Spring beans
-val federatedTypeRegistry = FederatedTypeRegistry(listOf(productResolver))
-val config = FederatedSchemaGeneratorConfig(supportedPackages = listOf("org.example"), hooks = FederatedSchemaGeneratorHooks(federatedTypeRegistry))
+// If you are using "graphql-kotlin-spring-server", your FederatedTypeResolvers can be marked as Spring beans
+// and will automatically be added to the hooks
+val resolvers = listOf(productResolver)
+val hooks = FederatedSchemaGeneratorHooks(resolvers)
+val config = FederatedSchemaGeneratorConfig(supportedPackages = listOf("org.example"), hooks = hooks)
 val schema = toFederatedSchema(config)
 ```

docs/spring-server/spring-beans.md

@@ -17,20 +17,25 @@ can be customized by providing custom beans in your application context. See sec
 
 
 ## Non-Federated Schema
+_Created only if federation is disabled_
+
 | Bean                             | Description |
 |:---------------------------------|:------------|
 | SchemaGeneratorConfig          | Schema generator configuration information, see [Schema Generator Configuration](../schema-generator/customizing-schemas/generator-config.md) for details. Can be customized by providing `TopLevelNames`, [SchemaGeneratorHooks](../schema-generator/customizing-schemas/generator-config.md) and `KotlinDataFetcherFactoryProvider` beans. |
 | GraphQLSchema                  | GraphQL schema generated based on the schema generator configuration and  `Query`, `Mutation` and `Subscription` objects available in the application context. |
 
 
 ## Federated Schema
+_Created only if federation is enabled_
+
 | Bean                             | Description |
 |:---------------------------------|:------------|
-| FederatedTypeRegistry          | Default type registry that adds any resolvers also marked as Spring beans. See [Federated Type Resolution](../federated/type-resolution.md) for more details.<br><br>_Created only if federation is enabled. You should register your custom type registry bean whenever implementing federated GraphQL schema with extended types_. |
-| FederatedSchemaGeneratorHooks  | Schema generator hooks used to build federated schema.<br><br>_Created only if federation is enabled_. |
-| FederatedSchemaGeneratorConfig | Federated schema generator configuration information. You can customize the configuration by providing `TopLevelNames`, `FederatedSchemaGeneratorHooks` and `KotlinDataFetcherFactoryProvider` beans.<br><br>_Created instead of default `SchemaGeneratorConfig` if federation is enabled_. |
+| FederatedTypeResolvers         | List of `FederatedTypeResolvers` marked as beans that should be added to hooks. See [Federated Type Resolution](../federated/type-resolution.md) for more details |
+| FederatedSchemaGeneratorHooks  | Schema generator hooks used to build federated schema |
+| FederatedSchemaGeneratorConfig | Federated schema generator configuration information. You can customize the configuration by providing `TopLevelNames`, `FederatedSchemaGeneratorHooks` and `KotlinDataFetcherFactoryProvider` beans |
 | GraphQLSchema                  | GraphQL schema generated based on the federated schema generator configuration and  `Query`, `Mutation` and `Subscription` objects available in the application context. |
 
+
 ## GraphQL Configuration
 | Bean                             | Description |
 |:---------------------------------|:------------|
@@ -39,6 +44,8 @@ can be customized by providing custom beans in your application context. See sec
 
 
 ## Subscriptions
+_Created only if the `Subscription` marker interface is used _
+
 | Bean                             | Description |
 |:---------------------------------|:------------|
 | SubscriptionHandler              | Web socket handler for executing GraphQL subscriptions, defaults to [SimpleSubscriptionHandler](https://github.com/ExpediaGroup/graphql-kotlin/blob/master/graphql-kotlin-spring-server/src/main/kotlin/com/expediagroup/graphql/spring/execution/SubscriptionHandler.kt#L49).<br><br>_Created only if `Subscription` bean is available in the context._ |

examples/federation/base-app/src/main/kotlin/com/expediagroup/graphql/examples/Application.kt

@@ -17,16 +17,15 @@
 package com.expediagroup.graphql.examples
 
 import com.expediagroup.graphql.examples.hooks.CustomFederationSchemaGeneratorHooks
-import com.expediagroup.graphql.federation.execution.FederatedTypeRegistry
 import org.springframework.boot.autoconfigure.SpringBootApplication
 import org.springframework.boot.runApplication
 import org.springframework.context.annotation.Bean
 
 @SpringBootApplication
 class Application {
+
     @Bean
-    fun hooks(federatedTypeRegistry: FederatedTypeRegistry) =
-        CustomFederationSchemaGeneratorHooks(federatedTypeRegistry)
+    fun hooks() = CustomFederationSchemaGeneratorHooks(emptyList())
 }
 
 @Suppress("SpreadOperator")

examples/federation/base-app/src/main/kotlin/com/expediagroup/graphql/examples/hooks/CustomFederationSchemaGeneratorHooks.kt

@@ -17,7 +17,7 @@
 package com.expediagroup.graphql.examples.hooks
 
 import com.expediagroup.graphql.federation.FederatedSchemaGeneratorHooks
-import com.expediagroup.graphql.federation.execution.FederatedTypeRegistry
+import com.expediagroup.graphql.federation.execution.FederatedTypeResolver
 import graphql.language.StringValue
 import graphql.schema.Coercing
 import graphql.schema.GraphQLScalarType
@@ -28,7 +28,7 @@ import kotlin.reflect.KType
 /**
  * Schema generator hook that adds additional scalar types.
  */
-class CustomFederationSchemaGeneratorHooks(federatedTypeRegistry: FederatedTypeRegistry) : FederatedSchemaGeneratorHooks(federatedTypeRegistry) {
+class CustomFederationSchemaGeneratorHooks(resolvers: List<FederatedTypeResolver<*>>) : FederatedSchemaGeneratorHooks(resolvers) {
 
     /**
      * Register additional GraphQL scalar types.

graphql-kotlin-federation/src/main/kotlin/com/expediagroup/graphql/federation/FederatedSchemaGeneratorHooks.kt

@@ -27,7 +27,7 @@ import com.expediagroup.graphql.federation.directives.KEY_DIRECTIVE_TYPE
 import com.expediagroup.graphql.federation.directives.PROVIDES_DIRECTIVE_TYPE
 import com.expediagroup.graphql.federation.directives.REQUIRES_DIRECTIVE_TYPE
 import com.expediagroup.graphql.federation.execution.EntityResolver
-import com.expediagroup.graphql.federation.execution.FederatedTypeRegistry
+import com.expediagroup.graphql.federation.execution.FederatedTypeResolver
 import com.expediagroup.graphql.federation.extensions.addDirectivesIfNotPresent
 import com.expediagroup.graphql.federation.types.ANY_SCALAR_TYPE
 import com.expediagroup.graphql.federation.types.FIELD_SET_SCALAR_TYPE
@@ -51,7 +51,7 @@ import kotlin.reflect.full.findAnnotation
 /**
  * Hooks for generating federated GraphQL schema.
  */
-open class FederatedSchemaGeneratorHooks(private val federatedTypeRegistry: FederatedTypeRegistry) : SchemaGeneratorHooks {
+open class FederatedSchemaGeneratorHooks(private val resolvers: List<FederatedTypeResolver<*>>) : SchemaGeneratorHooks {
     private val scalarDefinitionRegex = "(^\".+\"$[\\r\\n])?^scalar (_FieldSet|_Any)$[\\r\\n]*".toRegex(setOf(RegexOption.MULTILINE, RegexOption.IGNORE_CASE))
     private val emptyQueryRegex = "^type Query(?!\\s*\\{)\\s+".toRegex(setOf(RegexOption.MULTILINE, RegexOption.IGNORE_CASE))
     private val validator = FederatedSchemaValidator()
@@ -114,7 +114,7 @@ open class FederatedSchemaGeneratorHooks(private val federatedTypeRegistry: Fede
             val entityField = generateEntityFieldDefinition(entityTypeNames)
             federatedQuery.field(entityField)
 
-            federatedCodeRegistry.dataFetcher(FieldCoordinates.coordinates(originalQuery.name, entityField.name), EntityResolver(federatedTypeRegistry))
+            federatedCodeRegistry.dataFetcher(FieldCoordinates.coordinates(originalQuery.name, entityField.name), EntityResolver(resolvers))
             federatedCodeRegistry.typeResolver("_Entity") { env: TypeResolutionEnvironment -> env.schema.getObjectType(env.getObjectName()) }
             federatedSchemaBuilder.additionalType(ANY_SCALAR_TYPE)
         }

graphql-kotlin-federation/src/main/kotlin/com/expediagroup/graphql/federation/execution/EntityResolver.kt

@@ -26,10 +26,18 @@ import kotlinx.coroutines.awaitAll
 import kotlinx.coroutines.future.future
 import java.util.concurrent.CompletableFuture
 
+private const val TYPENAME_FIELD = "__typename"
+private const val REPRESENTATIONS = "representations"
+
 /**
  * Federated _entities query resolver.
  */
-open class EntityResolver(private val federatedTypeRegistry: FederatedTypeRegistry) : DataFetcher<CompletableFuture<DataFetcherResult<List<Any?>>>> {
+open class EntityResolver(resolvers: List<FederatedTypeResolver<*>>) : DataFetcher<CompletableFuture<DataFetcherResult<List<Any?>>>> {
+
+    /**
+     * Pre-compute the resolves by typename so we don't have to search on every request
+     */
+    private val resolverMap: Map<String, FederatedTypeResolver<*>> = resolvers.associateBy { it.typeName }
 
     /**
      * Resolves entities based on the passed in representations argument. Entities are resolved in the same order
@@ -42,15 +50,15 @@ open class EntityResolver(private val federatedTypeRegistry: FederatedTypeRegist
      * @return list of resolved nullable entities
      */
     override fun get(env: DataFetchingEnvironment): CompletableFuture<DataFetcherResult<List<Any?>>> {
-        val representations: List<Map<String, Any>> = env.getArgument("representations")
+        val representations: List<Map<String, Any>> = env.getArgument(REPRESENTATIONS)
 
-        val indexedBatchRequestsByType = representations.withIndex().groupBy { it.value["__typename"].toString() }
+        val indexedBatchRequestsByType = representations.withIndex().groupBy { it.value[TYPENAME_FIELD].toString() }
         return GlobalScope.future {
             val data = mutableListOf<Any?>()
             val errors = mutableListOf<GraphQLError>()
             indexedBatchRequestsByType.map { (typeName, indexedRequests) ->
                 async {
-                    resolveType(env, typeName, indexedRequests, federatedTypeRegistry)
+                    resolveType(env, typeName, indexedRequests, resolverMap)
                 }
             }.awaitAll()
                 .flatten()

graphql-kotlin-federation/src/main/kotlin/com/expediagroup/graphql/federation/execution/resolvers.kt

@@ -24,11 +24,11 @@ internal suspend fun resolveType(
     environment: DataFetchingEnvironment,
     typeName: String,
     indexedRequests: List<IndexedValue<Map<String, Any>>>,
-    federatedTypeRegistry: FederatedTypeRegistry
+    resolverMap: Map<String, FederatedTypeResolver<*>>
 ): List<Pair<Int, Any?>> {
     val indices = indexedRequests.map { it.index }
     val batch = indexedRequests.map { it.value }
-    val results = resolveBatch(environment, typeName, batch, federatedTypeRegistry)
+    val results = resolveBatch(environment, typeName, batch, resolverMap)
     return if (results.size != indices.size) {
         indices.map {
             it to FederatedRequestFailure("Federation batch request for $typeName generated different number of results than requested, representations=${indices.size}, results=${results.size}")
@@ -39,8 +39,13 @@ internal suspend fun resolveType(
 }
 
 @Suppress("TooGenericExceptionCaught")
-private suspend fun resolveBatch(environment: DataFetchingEnvironment, typeName: String, batch: List<Map<String, Any>>, federatedTypeRegistry: FederatedTypeRegistry): List<Any?> {
-    val resolver = federatedTypeRegistry.getFederatedResolver(typeName)
+private suspend fun resolveBatch(
+    environment: DataFetchingEnvironment,
+    typeName: String,
+    batch: List<Map<String, Any>>,
+    resolverMap: Map<String, FederatedTypeResolver<*>>
+): List<Any?> {
+    val resolver = resolverMap[typeName]
     return if (resolver != null) {
         try {
             resolver.resolve(environment, batch)