feat(dispatcher): add ability to wait for job completion

Author: kerwanp

src/contracts/adapter.ts

@@ -84,8 +84,14 @@ export interface Adapter {
    * @param jobId - The job ID to complete
    * @param queue - The queue the job belongs to
    * @param removeOnComplete - Optional retention policy for completed jobs
+   * @param output - Optional output returned by the job
    */
-  completeJob(jobId: string, queue: string, removeOnComplete?: JobRetention): Promise<void>
+  completeJob(
+    jobId: string,
+    queue: string,
+    removeOnComplete?: JobRetention,
+    output?: any
+  ): Promise<void>
 
   /**
    * Mark a job as failed permanently and remove it from the queue.

src/drivers/knex_adapter.ts

@@ -117,9 +117,7 @@ export class KnexAdapter implements Adapter {
 
       // Update job to active status
       // For SQLite (no SKIP LOCKED), add status='pending' guard to prevent double-claim
-      const updateQuery = trx(this.#jobsTable)
-        .where('id', job.id)
-        .where('queue', queue)
+      const updateQuery = trx(this.#jobsTable).where('id', job.id).where('queue', queue)
 
       if (!this.#supportsSkipLocked()) {
         updateQuery.where('status', 'pending')
@@ -178,19 +176,21 @@ export class KnexAdapter implements Adapter {
         const priority = jobData.priority ?? DEFAULT_PRIORITY
         const score = calculateScore(priority, now)
 
-        await trx(this.#jobsTable)
-          .where('id', job.id)
-          .where('queue', queue)
-          .update({
-            status: 'pending',
-            score,
-            execute_at: null,
-          })
+        await trx(this.#jobsTable).where('id', job.id).where('queue', queue).update({
+          status: 'pending',
+          score,
+          execute_at: null,
+        })
       }
     })
   }
 
-  async completeJob(jobId: string, queue: string, removeOnComplete?: JobRetention): Promise<void> {
+  async completeJob(
+    jobId: string,
+    queue: string,
+    removeOnComplete?: JobRetention,
+    output?: any
+  ): Promise<void> {
     const { keep, maxAge, maxCount } = resolveRetention(removeOnComplete)
 
     if (!keep) {
@@ -213,6 +213,7 @@ export class KnexAdapter implements Adapter {
         worker_id: null,
         acquired_at: null,
         finished_at: now,
+        output: output ? JSON.stringify(output) : null,
       })
 
     if (!updated) {
@@ -276,6 +277,7 @@ export class KnexAdapter implements Adapter {
       status: row.status as JobStatus,
       data: jobData,
       finishedAt: row.finished_at ? Number(row.finished_at) : undefined,
+      output: row.output ? JSON.parse(row.output) : undefined,
       error: row.error || undefined,
     }
   }
@@ -331,33 +333,27 @@ export class KnexAdapter implements Adapter {
 
     if (retryAt && retryAt.getTime() > now) {
       // Move to delayed
-      await this.#connection(this.#jobsTable)
-        .where('id', jobId)
-        .where('queue', queue)
-        .update({
-          status: 'delayed',
-          data: updatedData,
-          worker_id: null,
-          acquired_at: null,
-          score: null,
-          execute_at: retryAt.getTime(),
-        })
+      await this.#connection(this.#jobsTable).where('id', jobId).where('queue', queue).update({
+        status: 'delayed',
+        data: updatedData,
+        worker_id: null,
+        acquired_at: null,
+        score: null,
+        execute_at: retryAt.getTime(),
+      })
     } else {
       // Move back to pending
       const priority = jobData.priority ?? DEFAULT_PRIORITY
       const score = calculateScore(priority, now)
 
-      await this.#connection(this.#jobsTable)
-        .where('id', jobId)
-        .where('queue', queue)
-        .update({
-          status: 'pending',
-          data: updatedData,
-          worker_id: null,
-          acquired_at: null,
-          score,
-          execute_at: null,
-        })
+      await this.#connection(this.#jobsTable).where('id', jobId).where('queue', queue).update({
+        status: 'pending',
+        data: updatedData,
+        worker_id: null,
+        acquired_at: null,
+        score,
+        execute_at: null,
+      })
     }
   }
 
@@ -458,10 +454,7 @@ export class KnexAdapter implements Adapter {
 
         if (currentStalledCount >= maxStalledCount) {
           // Fail permanently - remove the job
-          await trx(this.#jobsTable)
-            .where('id', row.id)
-            .where('queue', queue)
-            .delete()
+          await trx(this.#jobsTable).where('id', row.id).where('queue', queue).delete()
         } else {
           // Recover: increment stalledCount and put back in pending
           jobData.stalledCount = currentStalledCount + 1
@@ -534,9 +527,9 @@ export class KnexAdapter implements Adapter {
   }
 
   async getSchedule(id: string): Promise<ScheduleData | null> {
-    const row = (await this.#connection(this.#schedulesTable)
-      .where('id', id)
-      .first()) as ScheduleRow | undefined
+    const row = (await this.#connection(this.#schedulesTable).where('id', id).first()) as
+      | ScheduleRow
+      | undefined
     if (!row) return null
 
     return this.#rowToScheduleData(row)
@@ -565,16 +558,12 @@ export class KnexAdapter implements Adapter {
     if (updates.runCount !== undefined) data.run_count = updates.runCount
 
     if (Object.keys(data).length > 0) {
-      await this.#connection(this.#schedulesTable)
-        .where('id', id)
-        .update(data)
+      await this.#connection(this.#schedulesTable).where('id', id).update(data)
     }
   }
 
   async deleteSchedule(id: string): Promise<void> {
-    await this.#connection(this.#schedulesTable)
-      .where('id', id)
-      .delete()
+    await this.#connection(this.#schedulesTable).where('id', id).delete()
   }
 
   async claimDueSchedule(): Promise<ScheduleData | null> {
@@ -629,13 +618,11 @@ export class KnexAdapter implements Adapter {
       }
 
       // Update atomically
-      await trx(this.#schedulesTable)
-        .where('id', row.id)
-        .update({
-          next_run_at: nextRunAt,
-          last_run_at: now,
-          run_count: newRunCount,
-        })
+      await trx(this.#schedulesTable).where('id', row.id).update({
+        next_run_at: nextRunAt,
+        last_run_at: now,
+        run_count: newRunCount,
+      })
 
       // Return schedule data (before update state for payload)
       return this.#rowToScheduleData(row)

src/exceptions.ts

@@ -35,6 +35,16 @@ export const E_JOB_NOT_FOUND = createError<[jobName: string]>(
   'E_JOB_NOT_FOUND'
 )
 
+export const E_JOB_EXECUTION_NOT_FOUND = createError<[jobId: string]>(
+  'The job execution "%s" could not be found',
+  'E_JOB_EXECUTION_NOT_FOUND'
+)
+
+export const E_JOB_EXECUTION_FAILED = createError<[jobId: string]>(
+  'The job execution "%s" failed',
+  'E_JOB_EXECUTION_FAILED'
+)
+
 export const E_JOB_MAX_ATTEMPTS_REACHED = createError<[jobName: string]>(
   'The job "%s" has reached the maximum number of retry attempts',
   'E_JOB_MAX_ATTEMPTS_REACHED'

src/job.ts

@@ -46,7 +46,7 @@ import type { JobContext, JobOptions } from './types/main.js'
  * }
  * ```
  */
-export abstract class Job<Payload = any> {
+export abstract class Job<Payload = any, Output = any> {
   #payload!: Payload
   #context!: JobContext
   #signal?: AbortSignal
@@ -173,12 +173,15 @@ export abstract class Job<Payload = any> {
   static dispatch<T extends Job>(
     this: abstract new (...args: any[]) => T,
     payload: T extends Job<infer P> ? P : never
-  ): JobDispatcher<T extends Job<infer P> ? P : never> {
+  ): JobDispatcher<T extends Job<infer P> ? P : never, T extends Job<any, infer O> ? O : never> {
     const jobClass = this as unknown as { options?: JobOptions; name: string }
     const options = jobClass.options || {}
     const jobName = options.name || this.name
 
-    const dispatcher = new JobDispatcher<T extends Job<infer P> ? P : never>(jobName, payload)
+    const dispatcher = new JobDispatcher<
+      T extends Job<infer P> ? P : never,
+      T extends Job<any, infer O> ? O : never
+    >(jobName, payload)
 
     if (options.queue) {
       dispatcher.toQueue(options.queue)
@@ -305,7 +308,7 @@ export abstract class Job<Payload = any> {
    * }
    * ```
    */
-  abstract execute(): Promise<void>
+  abstract execute(): Promise<Output>
 
   /**
    * Called when the job has permanently failed (after all retries exhausted).

src/job_dispatcher.ts

@@ -5,7 +5,9 @@ import { dispatchChannel } from './tracing_channels.js'
 import type { Adapter } from './contracts/adapter.js'
 import type { DispatchResult, Duration } from './types/main.js'
 import type { JobDispatchMessage } from './types/tracing_channels.js'
+import { setTimeout } from 'node:timers/promises'
 import { parse } from './utils.js'
+import { E_JOB_EXECUTION_FAILED, E_JOB_EXECUTION_NOT_FOUND } from './exceptions.ts'
 
 /**
  * Fluent builder for dispatching jobs to the queue.
@@ -39,9 +41,9 @@ import { parse } from './utils.js'
  * await ReminderJob.dispatch({ userId: 123 }).in('24h')
  * ```
  */
-export class JobDispatcher<T> {
+export class JobDispatcher<TPayload, TOutput> {
   readonly #name: string
-  readonly #payload: T
+  readonly #payload: TPayload
   #queue: string = 'default'
   #adapter?: string | (() => Adapter)
   #delay?: Duration
@@ -54,7 +56,7 @@ export class JobDispatcher<T> {
    * @param name - The job class name (used to locate the class at runtime)
    * @param payload - The data to pass to the job
    */
-  constructor(name: string, payload: T) {
+  constructor(name: string, payload: TPayload) {
     this.#name = name
     this.#payload = payload
   }
@@ -211,6 +213,39 @@ export class JobDispatcher<T> {
     return { jobId: id }
   }
 
+  /**
+   * Dispatch the job to the queue and
+   * await for job to complete or fail.
+   *
+   * @param pollingInterval - Interval between each check
+   * @param signal - Optional signal to abort waiting
+   * @returns The job output
+   */
+  async wait(pollingInterval: Duration = 2000, signal?: AbortSignal): Promise<TOutput> {
+    const adapter = this.#getAdapterInstance()
+    const dispatchResult = await this.run()
+
+    while (true) {
+      signal?.throwIfAborted()
+
+      await setTimeout(parse(pollingInterval))
+
+      const job = await adapter.getJob(dispatchResult.jobId, this.#queue)
+
+      if (!job) {
+        throw new E_JOB_EXECUTION_NOT_FOUND([dispatchResult.jobId])
+      }
+
+      if (job.status === 'completed') {
+        return job.output
+      }
+
+      if (job.status === 'failed') {
+        throw new E_JOB_EXECUTION_FAILED([dispatchResult.jobId], { cause: job.error })
+      }
+    }
+  }
+
   /**
    * Thenable implementation for auto-dispatch when awaited.
    *

src/job_runtime.ts

@@ -75,7 +75,7 @@ export class JobExecutionRuntime {
   /**
    * Execute a hydrated job instance and enforce the configured timeout.
    */
-  async execute(instance: Job, payload: unknown, context: JobContext): Promise<void> {
+  async execute(instance: Job, payload: unknown, context: JobContext): Promise<unknown> {
     if (this.#timeout === undefined) {
       instance.$hydrate(payload, context)
       return instance.execute()
@@ -90,7 +90,7 @@ export class JobExecutionRuntime {
     )
 
     try {
-      await Promise.race([instance.execute(), abortPromise])
+      return Promise.race([instance.execute(), abortPromise])
     } finally {
       cleanupAbortListener()
     }

src/services/queue_schema.ts

@@ -20,6 +20,7 @@ export class QueueSchemaService {
       table.string('queue', 255).notNullable()
       table.enu('status', ['pending', 'active', 'delayed', 'completed', 'failed']).notNullable()
       table.text('data').notNullable()
+      table.text('output').nullable()
       table.bigint('score').unsigned().nullable()
       table.string('worker_id', 255).nullable()
       table.bigint('acquired_at').unsigned().nullable()
@@ -57,10 +58,7 @@ export class QueueSchemaService {
       table.integer('run_count').unsigned().notNullable().defaultTo(0)
       table.timestamp('next_run_at').nullable()
       table.timestamp('last_run_at').nullable()
-      table
-        .timestamp('created_at')
-        .notNullable()
-        .defaultTo(this.#connection.fn.now())
+      table.timestamp('created_at').notNullable().defaultTo(this.#connection.fn.now())
       table.index(['status', 'next_run_at'])
 
       extend?.(table)

src/types/main.ts

@@ -141,6 +141,8 @@ export interface JobRecord {
   finishedAt?: number
   /** Error message (for failed jobs) */
   error?: string
+  /** Serialized job output */
+  output?: any
 }
 
 /**