wrap low-level client access in mapper

hll/dynamodb-mapper/dynamodb-mapper-codegen/src/main/kotlin/aws/sdk/kotlin/hll/dynamodbmapper/codegen/model/MapperPkg.kt

@@ -12,6 +12,7 @@ public object MapperPkg {
     public object Hl {
         public val Base: String = "aws.sdk.kotlin.hll.dynamodbmapper"
         public val Annotations: String = "$Base.annotations"
+        public val Internal: String = "$Base.internal"
         public val Items: String = "$Base.items"
         public val Model: String = "$Base.model"
         public val Ops: String = "$Base.operations"

hll/dynamodb-mapper/dynamodb-mapper-codegen/src/main/kotlin/aws/sdk/kotlin/hll/dynamodbmapper/codegen/model/MapperTypes.kt

@@ -22,6 +22,10 @@ public object MapperTypes {
         public val ManualPagination: TypeRef = TypeRef(MapperPkg.Hl.Annotations, "ManualPagination")
     }
 
+    public object Internal {
+        public val withWrappedClient: TypeRef = TypeRef(MapperPkg.Hl.Internal, "withWrappedClient")
+    }
+
     public object Items {
         public fun itemSchema(typeVar: String): TypeRef =
             TypeRef(MapperPkg.Hl.Items, "ItemSchema", genericArgs = listOf(TypeVar(typeVar)))

hll/dynamodb-mapper/dynamodb-mapper-ops-codegen/src/main/kotlin/aws/sdk/kotlin/hll/dynamodbmapper/codegen/operations/rendering/OperationRenderer.kt

@@ -70,7 +70,12 @@ internal class OperationRenderer(
                 }
                 write("schema) },")
 
-                write("lowLevelInvoke = spec.mapper.client::#L,", operation.methodName)
+                withBlock("lowLevelInvoke = { lowLevelReq ->", "},") {
+                    withBlock("spec.mapper.client.#T { client ->", "}", MapperTypes.Internal.withWrappedClient) {
+                        write("client.#L(lowLevelReq)", operation.methodName)
+                    }
+                }
+
                 write("deserialize = #L::convert,", operation.response.lowLevelName)
                 write("interceptors = spec.mapper.config.interceptors,")
             }

hll/dynamodb-mapper/dynamodb-mapper/common/src/aws/sdk/kotlin/hll/dynamodbmapper/DynamoDbMapper.kt

@@ -112,4 +112,4 @@ public interface DynamoDbMapper {
 public fun DynamoDbMapper(
     client: DynamoDbClient,
     config: DynamoDbMapper.Config.Builder.() -> Unit = { },
-): DynamoDbMapper = DynamoDbMapperImpl.wrapping(client, DynamoDbMapper.Config(config))
+): DynamoDbMapper = DynamoDbMapperImpl(client, DynamoDbMapper.Config(config))

hll/dynamodb-mapper/dynamodb-mapper/common/src/aws/sdk/kotlin/hll/dynamodbmapper/internal/DynamoDbMapperImpl.kt

@@ -19,16 +19,6 @@ internal data class DynamoDbMapperImpl(
     override val client: DynamoDbClient,
     override val config: DynamoDbMapper.Config,
 ) : DynamoDbMapper {
-    internal companion object {
-        /**
-         * Wraps a low-level [DynamoDbClient] to add additional features before instantiating a new
-         * [DynamoDbMapperImpl].
-         */
-        fun wrapping(client: DynamoDbClient, config: DynamoDbMapper.Config): DynamoDbMapperImpl {
-            val wrappedClient = client.withConfig { interceptors += DdbMapperMetricInterceptor }
-            return DynamoDbMapperImpl(wrappedClient, config)
-        }
-    }
     override fun <T, PK> getTable(name: String, schema: ItemSchema.PartitionKey<T, PK>) =
         tableImpl(this, name, schema)
 
@@ -54,9 +44,12 @@ internal class MapperConfigBuilderImpl : DynamoDbMapper.Config.Builder {
 /**
  * An interceptor that emits the DynamoDB Mapper business metric
  */
-private object DdbMapperMetricInterceptor : HttpInterceptor {
+private object BusinessMetricInterceptor : HttpInterceptor {
     override suspend fun modifyBeforeSerialization(context: RequestInterceptorContext<Any>): Any {
         context.executionContext.emitBusinessMetric(AwsBusinessMetric.DDB_MAPPER)
         return context.request
     }
 }
+
+internal inline fun <T> DynamoDbClient.withWrappedClient(block: (DynamoDbClient) -> T): T =
+    withConfig { interceptors += BusinessMetricInterceptor }.use(block)

hll/dynamodb-mapper/dynamodb-mapper/common/test/aws/sdk/kotlin/hll/dynamodbmapper/DynamoDbMapperTest.kt

@@ -51,11 +51,11 @@ class DynamoDbMapperTest : DdbLocalTest() {
     fun testBusinessMetricEmission() = runTest {
         val interceptor = MetricCapturingInterceptor()
 
-        val ddb = super.ddb.withConfig { interceptors += interceptor }
+        val ddb = lowLevelAccess { withConfig { interceptors += interceptor } }
         interceptor.assertEmpty()
 
         // No metric for low-level client
-        ddb.scan { tableName = TABLE_NAME }
+        lowLevelAccess { scan { tableName = TABLE_NAME } }
         interceptor.assertMetric(AwsBusinessMetric.DDB_MAPPER, exists = false)
         interceptor.reset()
 
@@ -67,12 +67,12 @@ class DynamoDbMapperTest : DdbLocalTest() {
         interceptor.reset()
 
         // Still no metric for low-level client (i.e., LL wasn't modified by HL)
-        ddb.scan { tableName = TABLE_NAME }
+        lowLevelAccess { scan { tableName = TABLE_NAME } }
         interceptor.assertMetric(AwsBusinessMetric.DDB_MAPPER, exists = false)
         interceptor.reset()
 
         // Original client can be closed, mapper is unaffected
-        ddb.close()
+        lowLevelAccess { close() }
         table.scanPaginated { }.collect()
         interceptor.assertMetric(AwsBusinessMetric.DDB_MAPPER)
     }

hll/dynamodb-mapper/dynamodb-mapper/common/test/aws/sdk/kotlin/hll/dynamodbmapper/operations/PutItemTest.kt

@@ -43,7 +43,7 @@ class PutItemTest : DdbLocalTest() {
 
         table.putItem { item = Item(id = "foo", value = 42) }
 
-        val resp = ddb.getItem(TABLE_NAME, "id" to "foo")
+        val resp = lowLevelAccess { getItem(TABLE_NAME, "id" to "foo") }
 
         val item = assertNotNull(resp.item)
         assertEquals("foo", item["id"]?.asSOrNull())

hll/dynamodb-mapper/dynamodb-mapper/common/test/aws/sdk/kotlin/hll/dynamodbmapper/testutils/DdbLocalTest.kt

@@ -8,14 +8,19 @@ import aws.sdk.kotlin.hll.dynamodbmapper.DynamoDbMapper
 import aws.sdk.kotlin.hll.dynamodbmapper.items.ItemSchema
 import aws.sdk.kotlin.hll.dynamodbmapper.model.Item
 import aws.sdk.kotlin.runtime.auth.credentials.StaticCredentialsProvider
+import aws.sdk.kotlin.runtime.http.interceptors.AwsBusinessMetric
 import aws.sdk.kotlin.services.dynamodb.DynamoDbClient
 import aws.sdk.kotlin.services.dynamodb.deleteTable
 import aws.sdk.kotlin.services.dynamodb.waiters.waitUntilTableNotExists
+import aws.smithy.kotlin.runtime.client.ProtocolRequestInterceptorContext
+import aws.smithy.kotlin.runtime.http.interceptors.HttpInterceptor
+import aws.smithy.kotlin.runtime.http.request.HttpRequest
 import aws.smithy.kotlin.runtime.net.Host
 import aws.smithy.kotlin.runtime.net.Scheme
 import aws.smithy.kotlin.runtime.net.url.Url
 import io.kotest.core.spec.style.AnnotationSpec
 import kotlinx.coroutines.runBlocking
+import kotlin.test.assertContains
 import kotlin.test.assertEquals
 import kotlin.test.assertNotNull
 
@@ -41,6 +46,9 @@ abstract class DdbLocalTest : AnnotationSpec() {
         }
     }
 
+    private val requests = mutableListOf<HttpRequest>()
+    private val requestInterceptor = RequestCapturingInterceptor(this@DdbLocalTest.requests)
+
     private val ddbHolder = lazy {
         DynamoDbClient {
             endpointUrl = Url {
@@ -55,15 +63,20 @@ abstract class DdbLocalTest : AnnotationSpec() {
                 accessKeyId = "DUMMY"
                 secretAccessKey = "DUMMY"
             }
+
+            interceptors += requestInterceptor
         }
     }
 
     /**
      * An instance of a low-level [DynamoDbClient] utilizing the DynamoDB Local instance which may be used for setting
      * up or verifying various mapper tests. If this is the first time accessing the value, the client will be
      * initialized.
+     *
+     * **Important**: This low-level client should only be accessed via [lowLevelAccess] to ensure that User-Agent
+     * header verification succeeds.
      */
-    val ddb by ddbHolder
+    private val ddb by ddbHolder
 
     private val tempTables = mutableListOf<String>()
 
@@ -95,9 +108,11 @@ abstract class DdbLocalTest : AnnotationSpec() {
         lsis: Map<String, ItemSchema<*>>,
         items: List<Item>,
     ) {
-        ddb.createTable(name, schema, gsis, lsis)
-        tempTables += name
-        ddb.putItems(name, items)
+        lowLevelAccess {
+            createTable(name, schema, gsis, lsis)
+            tempTables += name
+            putItems(name, items)
+        }
     }
 
     /**
@@ -109,6 +124,43 @@ abstract class DdbLocalTest : AnnotationSpec() {
         config: DynamoDbMapper.Config.Builder.() -> Unit = { },
     ) = DynamoDbMapper(ddb ?: this.ddb, config)
 
+    @BeforeEach
+    fun initializeTest() {
+        requestInterceptor.enabled = true
+    }
+
+    /**
+     * Executes requests on a low-level [DynamoDbClient] and _does not_ log any requests executed in [block]. (This
+     * skips verifying that low-level requests contain the [AwsBusinessMetric.DDB_MAPPER] metric.)
+     */
+    protected suspend fun <T> lowLevelAccess(block: suspend DynamoDbClient.() -> T): T {
+        requestInterceptor.enabled = false
+        return block(ddb).also { requestInterceptor.enabled = true }
+    }
+
+    @AfterEach
+    fun postVerify() {
+        requests.forEach { req ->
+            val uaString = requireNotNull(req.headers["User-Agent"]) {
+                "Missing User-Agent header for request $req"
+            }
+
+            val components = uaString.split(" ")
+
+            val metricsComponent = requireNotNull(components.find { it.startsWith("m/") }) {
+                """User-Agent header "$uaString" doesn't contain business metrics for request $req"""
+            }
+
+            val metrics = metricsComponent.removePrefix("m/").split(",")
+
+            assertContains(
+                metrics,
+                AwsBusinessMetric.DDB_MAPPER.identifier,
+                """Mapper business metric not present in User-Agent header "$uaString" for request $req""",
+            )
+        }
+    }
+
     @AfterAll
     fun cleanUp() {
         if (ddbHolder.isInitialized()) {
@@ -123,3 +175,13 @@ abstract class DdbLocalTest : AnnotationSpec() {
         }
     }
 }
+
+private class RequestCapturingInterceptor(val requests: MutableList<HttpRequest>) : HttpInterceptor {
+    var enabled = true
+
+    override fun readBeforeTransmit(context: ProtocolRequestInterceptorContext<Any, HttpRequest>) {
+        if (enabled) {
+            requests += context.protocolRequest
+        }
+    }
+}