Feature: Add data loader reload API for development environments

graphql-dgs-spring-graphql/src/main/java/com/netflix/graphql/dgs/springgraphql/conditions/ConditionalOnDgsReload.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2025 Netflix, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.netflix.graphql.dgs.springgraphql.conditions;
+
+import org.springframework.context.annotation.Conditional;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+
+/**
+ * Conditional that matches when it is established that the DGS Framework should consider reloading components at runtime.
+ * Consider that reloading components should only be enabled in <i>local</i> and/or <i>development</i> since
+ * call latencies will increase significantly while _reloading_ of the components is happening.
+ */
+
+@Target({ ElementType.TYPE, ElementType.METHOD })
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Conditional(OnDgsReloadCondition.class)
+public @interface ConditionalOnDgsReload {
+}

graphql-dgs-spring-graphql/src/main/java/module-info.java

@@ -9,6 +9,7 @@
     requires static spring.webflux;
     requires kotlin.stdlib;
     requires org.slf4j;
+    requires spring.core;
 
 
     exports com.netflix.graphql.dgs.autoconfig to kotlin.reflect, spring.beans, spring.core;

graphql-dgs-spring-graphql/src/main/kotlin/com/netflix/graphql/dgs/springgraphql/autoconfig/DgsSpringGraphQLAutoConfiguration.kt

@@ -21,6 +21,7 @@ import com.netflix.graphql.dgs.DgsComponent
 import com.netflix.graphql.dgs.DgsDataLoaderCustomizer
 import com.netflix.graphql.dgs.DgsDataLoaderInstrumentation
 import com.netflix.graphql.dgs.DgsDataLoaderOptionsProvider
+import com.netflix.graphql.dgs.DgsDataLoaderReloadController
 import com.netflix.graphql.dgs.DgsDefaultPreparsedDocumentProvider
 import com.netflix.graphql.dgs.DgsExecutionResult
 import com.netflix.graphql.dgs.DgsFederationResolver
@@ -38,6 +39,8 @@ import com.netflix.graphql.dgs.context.GraphQLContextContributorInstrumentation
 import com.netflix.graphql.dgs.exceptions.DefaultDataFetcherExceptionHandler
 import com.netflix.graphql.dgs.internal.DataFetcherResultProcessor
 import com.netflix.graphql.dgs.internal.DefaultDataLoaderOptionsProvider
+import com.netflix.graphql.dgs.internal.DefaultDgsDataLoaderProvider
+import com.netflix.graphql.dgs.internal.DefaultDgsDataLoaderReloadController
 import com.netflix.graphql.dgs.internal.DefaultDgsGraphQLContextBuilder
 import com.netflix.graphql.dgs.internal.DgsDataLoaderInstrumentationDataLoaderCustomizer
 import com.netflix.graphql.dgs.internal.DgsDataLoaderProvider
@@ -50,6 +53,7 @@ import com.netflix.graphql.dgs.internal.FluxDataFetcherResultProcessor
 import com.netflix.graphql.dgs.internal.GraphQLJavaErrorInstrumentation
 import com.netflix.graphql.dgs.internal.MonoDataFetcherResultProcessor
 import com.netflix.graphql.dgs.internal.QueryValueCustomizer
+import com.netflix.graphql.dgs.internal.ReloadableDgsDataLoaderProvider
 import com.netflix.graphql.dgs.internal.method.ArgumentResolver
 import com.netflix.graphql.dgs.internal.method.MethodDataFetcherFactory
 import com.netflix.graphql.dgs.mvc.internal.method.HandlerMethodArgumentResolverAdapter
@@ -61,6 +65,8 @@ import com.netflix.graphql.dgs.springgraphql.DgsGraphQLSourceBuilder
 import com.netflix.graphql.dgs.springgraphql.ReloadableGraphQLSource
 import com.netflix.graphql.dgs.springgraphql.SpringGraphQLDgsQueryExecutor
 import com.netflix.graphql.dgs.springgraphql.SpringGraphQLDgsReactiveQueryExecutor
+import com.netflix.graphql.dgs.springgraphql.conditions.ConditionalOnDgsReload
+import com.netflix.graphql.dgs.springgraphql.conditions.OnDgsReloadCondition
 import com.netflix.graphql.dgs.springgraphql.webflux.DgsWebFluxGraphQLInterceptor
 import com.netflix.graphql.dgs.springgraphql.webmvc.DgsWebMvcGraphQLInterceptor
 import graphql.GraphQLError
@@ -100,6 +106,7 @@ import org.springframework.boot.system.JavaVersion
 import org.springframework.context.ApplicationContext
 import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.Configuration
+import org.springframework.context.annotation.Primary
 import org.springframework.core.DefaultParameterNameDiscoverer
 import org.springframework.core.Ordered
 import org.springframework.core.PriorityOrdered
@@ -144,7 +151,7 @@ import java.util.function.Consumer
 import java.util.stream.Collectors
 
 /**
- * Framework auto configuration based on open source Spring only, without Netflix integrations.
+ * Framework autoconfiguration based on open source Spring only, without Netflix integrations.
  * This does NOT have logging, tracing, metrics and security integration.
  */
 @Suppress("SpringJavaInjectionPointsAutowiringInspection")
@@ -221,16 +228,82 @@ open class DgsSpringGraphQLAutoConfiguration(
         extensionProviders: List<DataLoaderInstrumentationExtensionProvider>,
         customizers: List<DgsDataLoaderCustomizer>,
     ): DgsDataLoaderProvider =
-        DgsDataLoaderProvider(
+        DefaultDgsDataLoaderProvider(
             applicationContext = applicationContext,
             extensionProviders = extensionProviders,
+            customizers = customizers,
             dataLoaderOptionsProvider = dataloaderOptionProvider,
             scheduledExecutorService = dgsScheduledExecutorService,
             scheduleDuration = dataloaderConfigProps.scheduleDuration,
             enableTickerMode = dataloaderConfigProps.tickerModeEnabled,
-            customizers = customizers,
         )
 
+    /**
+     * Autoconfiguration for DGS Data Loader reloading.
+     *
+     * This configuration is only activated when the 'dgs.reload' property is set to `true`.
+     * It provides the necessary beans for data loader reloading, including:
+     * - [ReloadableDgsDataLoaderProvider] that wraps the default provider implementation, the [DefaultDgsDataLoaderProvider].
+     * - An implementation of a [DgsDataLoaderReloadController] that can be used ot force reloading of _Data Loaders_.
+     *
+     * **The reloading functionality is designed to be used primarily in development**,
+     * it is discouraged to be used in production.
+     */
+    @AutoConfiguration
+    @ConditionalOnDgsReload
+    open class DgsDataLoaderReloadAutoConfiguration(
+        private val dataloaderConfigProps: DgsDataloaderConfigurationProperties,
+    ) {
+        /**
+         * Creates a [ReloadableDgsDataLoaderProvider] that wraps the standard [DgsDataLoaderProvider].
+         *
+         * This provider supports dynamic reloading of data loaders based on the [DgsReloadDataLoadersIndicator].
+         * It maintains the same interface as the standard provider but adds reload capabilities.
+         *
+         * The `@Primary` annotation ensures this bean takes precedence over the standard `DgsDataLoaderProvider`
+         * when reload functionality is enabled.
+         *
+         */
+        @Bean
+        @Primary
+        open fun reloadableDgsDataLoaderProvider(
+            applicationContext: ApplicationContext,
+            dataLoaderOptionProvider: DgsDataLoaderOptionsProvider,
+            @Qualifier("dgsScheduledExecutorService") dgsScheduledExecutorService: ScheduledExecutorService,
+            extensionProviders: List<DataLoaderInstrumentationExtensionProvider>,
+            customizers: List<DgsDataLoaderCustomizer>,
+        ): DgsDataLoaderProvider {
+            LOG.info("Creating reloadable data loader provider with reload support enabled")
+            return ReloadableDgsDataLoaderProvider(
+                applicationContext = applicationContext,
+                extensionProviders = extensionProviders,
+                customizers = customizers,
+                dataLoaderOptionsProvider = dataLoaderOptionProvider,
+                scheduledExecutorService = dgsScheduledExecutorService,
+                scheduleDuration = dataloaderConfigProps.scheduleDuration,
+                enableTickerMode = dataloaderConfigProps.tickerModeEnabled,
+            )
+        }
+
+        /**
+         * Creates the default data loader reload controller.
+         *
+         * This controller provides a programmatic API for triggering data loader reloads
+         * and accessing reload statistics. It's only available when reload functionality is enabled.
+         *
+         * @return DgsDataLoaderReloadController instance
+         */
+        @Bean
+        @ConditionalOnMissingBean
+        open fun dgsDataLoaderReloadController(
+            reloadableDgsDataLoaderProvider: ReloadableDgsDataLoaderProvider,
+        ): DgsDataLoaderReloadController {
+            LOG.info("Creating data loader reload controller")
+            // Get the actual ReloadableDgsDataLoaderProvider instance from the context
+            return DefaultDgsDataLoaderReloadController(reloadableDgsDataLoaderProvider)
+        }
+    }
+
     @Bean
     open fun entityFetcherRegistry(): EntityFetcherRegistry = EntityFetcherRegistry()
 
@@ -272,9 +345,7 @@ open class DgsSpringGraphQLAutoConfiguration(
     @Bean
     @ConditionalOnMissingBean
     open fun defaultReloadSchemaIndicator(environment: Environment): ReloadSchemaIndicator {
-        val isLaptopProfile = environment.activeProfiles.contains("laptop")
-        val hotReloadSetting = environment.getProperty("dgs.reload", Boolean::class.java, isLaptopProfile)
-
+        val hotReloadSetting = OnDgsReloadCondition.evaluate(environment)
         return ReloadSchemaIndicator {
             hotReloadSetting
         }

graphql-dgs-spring-graphql/src/main/kotlin/com/netflix/graphql/dgs/springgraphql/conditions/OnDgsReloadCondition.kt

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2025 Netflix, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.netflix.graphql.dgs.springgraphql.conditions
+
+import org.springframework.boot.autoconfigure.condition.ConditionOutcome
+import org.springframework.boot.autoconfigure.condition.SpringBootCondition
+import org.springframework.context.annotation.ConditionContext
+import org.springframework.core.env.Environment
+import org.springframework.core.type.AnnotatedTypeMetadata
+import kotlin.collections.contains
+
+class OnDgsReloadCondition : SpringBootCondition() {
+    companion object {
+        /**
+         * `true`, if the _DGS Reload flag_ is enabled.
+         */
+        fun evaluate(environment: Environment): Boolean {
+            val isLaptopProfile = environment.activeProfiles.contains("laptop")
+            val reloadEnabled = environment.getProperty("dgs.reload", Boolean::class.java, isLaptopProfile)
+            return reloadEnabled
+        }
+    }
+
+    override fun getMatchOutcome(
+        context: ConditionContext?,
+        metadata: AnnotatedTypeMetadata?,
+    ): ConditionOutcome? {
+        val environment = context!!.environment
+        val reloadEnabled = evaluate(environment)
+        return if (reloadEnabled) {
+            ConditionOutcome.match("DgsReload enabled.")
+        } else {
+            ConditionOutcome.noMatch("DgsReload disabled")
+        }
+    }
+}

graphql-dgs-spring-graphql/src/test/kotlin/com/netflix/graphql/dgs/springgraphql/DefaultDgsDataLoaderReloadControllerTest.kt

@@ -0,0 +1,135 @@
+/*
+ * Copyright 2025 Netflix, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.netflix.graphql.dgs.springgraphql
+
+import com.netflix.graphql.dgs.internal.DefaultDgsDataLoaderReloadController
+import com.netflix.graphql.dgs.internal.ReloadableDgsDataLoaderProvider
+import io.mockk.every
+import io.mockk.mockk
+import io.mockk.verify
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertNotNull
+import org.junit.jupiter.api.assertNull
+
+class DefaultDgsDataLoaderReloadControllerTest {
+    @Test
+    fun `should successfully reload data loaders`() {
+        val mockProvider = mockk<ReloadableDgsDataLoaderProvider>()
+        every { mockProvider.forceReload() } returns true
+
+        val controller = DefaultDgsDataLoaderReloadController(mockProvider)
+
+        val result = controller.reloadDataLoaders()
+
+        assertTrue(result)
+        assertNotNull(controller.getLastReloadTime())
+        verify(exactly = 1) { mockProvider.forceReload() }
+    }
+
+    @Test
+    fun `should handle reload failures gracefully`() {
+        val mockProvider = mockk<ReloadableDgsDataLoaderProvider>()
+        every { mockProvider.forceReload() } returns false
+
+        val controller = DefaultDgsDataLoaderReloadController(mockProvider)
+
+        val result = controller.reloadDataLoaders()
+
+        assertFalse(result)
+        // Last reload time should not be set on failure
+        assertNull(controller.getLastReloadTime())
+        verify(exactly = 1) { mockProvider.forceReload() }
+    }
+
+    @Test
+    fun `should handle provider exceptions`() {
+        val mockProvider = mockk<ReloadableDgsDataLoaderProvider>()
+        every { mockProvider.forceReload() } throws RuntimeException("Test exception")
+
+        val controller = DefaultDgsDataLoaderReloadController(mockProvider)
+
+        val result = controller.reloadDataLoaders()
+
+        assertFalse(result)
+        assertNull(controller.getLastReloadTime())
+        verify(exactly = 1) { mockProvider.forceReload() }
+    }
+
+    @Test
+    fun `should always report reload as enabled`() {
+        val mockProvider = mockk<ReloadableDgsDataLoaderProvider>()
+        val controller = DefaultDgsDataLoaderReloadController(mockProvider)
+
+        assertTrue(controller.isReloadEnabled())
+    }
+
+    @Test
+    fun `should track reload statistics`() {
+        val mockProvider = mockk<ReloadableDgsDataLoaderProvider>()
+        every { mockProvider.forceReload() } returns true
+
+        val controller = DefaultDgsDataLoaderReloadController(mockProvider)
+
+        // Initial stats
+        val initialStats = controller.getReloadStats()
+        assertEquals(0L, initialStats.totalReloads)
+        assertNull(initialStats.lastReloadTime)
+        assertNull(initialStats.lastReloadDuration)
+        assertTrue(initialStats.isEnabled)
+
+        // Perform some reloads
+        controller.reloadDataLoaders()
+        Thread.sleep(1) // Ensure different timestamp
+        controller.reloadDataLoaders()
+
+        val finalStats = controller.getReloadStats()
+        assertEquals(2L, finalStats.totalReloads)
+        assertNotNull(finalStats.lastReloadTime)
+        assertNotNull(finalStats.lastReloadDuration)
+        assertTrue(finalStats.isEnabled)
+
+        verify(exactly = 2) { mockProvider.forceReload() }
+    }
+
+    @Test
+    fun `should update last reload time only on success`() {
+        val mockProvider = mockk<ReloadableDgsDataLoaderProvider>()
+        val controller = DefaultDgsDataLoaderReloadController(mockProvider)
+
+        // First reload succeeds
+        every { mockProvider.forceReload() } returns true
+        controller.reloadDataLoaders()
+        val firstReloadTime = controller.getLastReloadTime()
+        assertNotNull(firstReloadTime)
+
+        Thread.sleep(1) // Ensure different timestamp
+
+        // Second reload fails
+        every { mockProvider.forceReload() } returns false
+        controller.reloadDataLoaders()
+        val secondReloadTime = controller.getLastReloadTime()
+
+        // Time should remain the same as the first successful reload
+        assertEquals(firstReloadTime, secondReloadTime)
+
+        val stats = controller.getReloadStats()
+        assertEquals(1L, stats.totalReloads) // Only one successful reload
+    }
+}