+}
+
+/**
+ * Task performance.
+ *
+ * @internal
+ */
+export interface TaskPerformance {
+ /**
+ * Task performance timestamp.
+ */
+ readonly timestamp: number
+ /**
+ * Task runtime.
+ */
+ readonly runTime?: number
+ /**
+ * Task event loop utilization.
+ */
+ readonly elu?: EventLoopUtilization
+}
+
+/**
+ * Performance statistics computation.
+ *
+ * @internal
+ */
+export interface WorkerStatistics {
+ runTime: boolean
+ elu: boolean
+}
+
+/**
+ * Message object that is passed between main worker and worker.
+ *
+ * @typeParam Data - Type of data sent to the worker or execution response. This can only be structured-cloneable data.
+ * @typeParam ErrorData - Type of data sent to the worker triggering an error. This can only be structured-cloneable data.
+ * @internal
+ */
+export interface MessageValue<Data = unknown, ErrorData = unknown>
+ extends Task<Data> {
+ /**
+ * Kill code.
+ */
+ readonly kill?: KillBehavior | true
+ /**
+ * Task error.
+ */
+ readonly taskError?: TaskError<ErrorData>
+ /**
+ * Task performance.
+ */
+ readonly taskPerformance?: TaskPerformance
+ /**
+ * Whether the worker computes the given statistics or not.
+ */
+ readonly statistics?: WorkerStatistics
+ /**
+ * Whether the worker is ready or not.
+ */
+ readonly ready?: boolean
+ /**
+ * Whether the worker starts or stops its aliveness check.
+ */
+ readonly checkAlive?: boolean
+}
+
+/**
+ * An object holding the execution response promise resolve/reject callbacks.
+ *
+ * @typeParam Worker - Type of worker.
+ * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
+ * @internal
+ */
+export interface PromiseResponseWrapper<
+ Worker extends IWorker,
+ Response = unknown
+> {
+ /**
+ * Resolve callback to fulfill the promise.
+ */
+ readonly resolve: (value: Response) => void
+ /**
+ * Reject callback to reject the promise.
+ */
+ readonly reject: (reason?: string) => void
+ /**
+ * The worker handling the execution.
+ */
+ readonly worker: Worker