feat: continuous task stealing

[poolifier.git] / src / pools / worker.ts

diff --git a/src/pools/worker.ts b/src/pools/worker.ts
index 09253242f7d0af88204ba9989fb37a7fa12cc287..52b56a2411f0f41f7c56452270b2c63be7ecd0a5 100644 (file)
--- a/src/pools/worker.ts
+++ b/src/pools/worker.ts
@@ -2,6 +2,11 @@ import type { MessageChannel } from 'node:worker_threads'
 import type { CircularArray } from '../circular-array'
 import type { Task } from '../utility-types'
 
+/**
+ * Callback invoked when the worker has started successfully.
+ */
+export type OnlineHandler<Worker extends IWorker> = (this: Worker) => void
+
 /**
  * Callback invoked if the worker has received a message.
  */
@@ -18,11 +23,6 @@ export type ErrorHandler<Worker extends IWorker> = (
   error: Error
 ) => void
 
-/**
- * Callback invoked when the worker has started successfully.
- */
-export type OnlineHandler<Worker extends IWorker> = (this: Worker) => void
-
 /**
  * Callback invoked when the worker exits successfully.
  */
@@ -96,6 +96,10 @@ export interface TaskStatistics {
    * Maximum number of queued tasks.
    */
   readonly maxQueued?: number
+  /**
+   * Number of stolen tasks.
+   */
+  stolen: number
   /**
    * Number of failed tasks.
    */
@@ -189,7 +193,7 @@ export interface IWorker {
   /**
    * Registers a listener to the exit event that will only be performed once.
    *
-   * @param event - `'exit'`.
+   * @param event - The `'exit'` event.
    * @param handler - The exit handler.
    */
   readonly once: (event: 'exit', handler: ExitHandler<this>) => void
@@ -212,13 +216,30 @@ export interface IWorkerNode<Worker extends IWorker, Data = unknown> {
    */
   readonly info: WorkerInfo
   /**
-   * Message channel.
+   * Message channel (worker_threads only).
    */
   readonly messageChannel?: MessageChannel
   /**
    * Worker usage statistics.
    */
   usage: WorkerUsage
+  /**
+   * Tasks queue back pressure size.
+   * This is the number of tasks that can be enqueued before the worker node has back pressure.
+   */
+  tasksQueueBackPressureSize: number
+  /**
+   * Callback invoked when worker node tasks queue is back pressured.
+   *
+   * @param workerId - The worker id.
+   */
+  onBackPressure?: (workerId: number) => void
+  /**
+   * Callback invoked when worker node tasks queue is empty.
+   *
+   * @param workerId - The worker id.
+   */
+  onEmptyQueue?: (workerId: number) => void
   /**
    * Tasks queue size.
    *
@@ -229,21 +250,40 @@ export interface IWorkerNode<Worker extends IWorker, Data = unknown> {
    * Enqueue task.
    *
    * @param task - The task to queue.
-   * @returns The task queue size.
+   * @returns The tasks queue size.
    */
   readonly enqueueTask: (task: Task<Data>) => number
+  /**
+   * Prepends a task to the tasks queue.
+   *
+   * @param task - The task to prepend.
+   * @returns The tasks queue size.
+   */
+  readonly unshiftTask: (task: Task<Data>) => number
   /**
    * Dequeue task.
    *
    * @returns The dequeued task.
    */
   readonly dequeueTask: () => Task<Data> | undefined
+  /**
+   * Pops a task from the tasks queue.
+   *
+   * @returns The popped task.
+   */
+  readonly popTask: () => Task<Data> | undefined
   /**
    * Clears tasks queue.
    */
   readonly clearTasksQueue: () => void
   /**
-   * Resets usage statistics .
+   * Whether the worker node has back pressure (i.e. its tasks queue is full).
+   *
+   * @returns `true` if the worker node has back pressure, `false` otherwise.
+   */
+  readonly hasBackPressure: () => boolean
+  /**
+   * Resets usage statistics.
    */
   readonly resetUsage: () => void
   /**
@@ -251,7 +291,10 @@ export interface IWorkerNode<Worker extends IWorker, Data = unknown> {
    */
   readonly closeChannel: () => void
   /**
-   * Gets task worker usage statistics.
+   * Gets task function worker usage statistics.
+   *
+   * @param name - The task function name.
+   * @returns The task function worker usage statistics if the task function worker usage statistics are initialized, `undefined` otherwise.
    */
-  readonly getTaskWorkerUsage: (name: string) => WorkerUsage | undefined
+  readonly getTaskFunctionWorkerUsage: (name: string) => WorkerUsage | undefined
 }