refactor: accept error in failed callback (#48)

server.go

@@ -57,8 +57,8 @@ type TaskOpts struct {
 	Queue        string
 	SuccessCB    func(JobCtx)
 	ProcessingCB func(JobCtx)
-	RetryingCB   func(JobCtx)
-	FailedCB     func(JobCtx)
+	RetryingCB   func(JobCtx, error)
+	FailedCB     func(JobCtx, error)
 }
 
 // RegisterTask maps a new task against the tasks map on the server.
@@ -295,7 +295,7 @@ func (s *Server) process(ctx context.Context, w chan []byte) {
 
 			if err := s.execJob(ctx, msg, task); err != nil {
 				s.spanError(span, err)
-				s.log.Error("could not execute job. err", "error", err)
+				s.log.Error("could not execute job", "error", err)
 			}
 		}
 	}
@@ -358,12 +358,12 @@ func (s *Server) execJob(ctx context.Context, msg JobMessage, task Task) error {
 		// Try queueing the job again.
 		if msg.MaxRetry != msg.Retried {
 			if task.opts.RetryingCB != nil {
-				task.opts.RetryingCB(taskCtx)
+				task.opts.RetryingCB(taskCtx, err)
 			}
 			return s.retryJob(ctx, msg)
 		} else {
 			if task.opts.FailedCB != nil {
-				task.opts.FailedCB(taskCtx)
+				task.opts.FailedCB(taskCtx, err)
 			}
 			// If we hit max retries, set the task status as failed.
 			return s.statusFailed(ctx, msg)
@@ -382,13 +382,13 @@ func (s *Server) execJob(ctx context.Context, msg JobMessage, task Task) error {
 		meta := DefaultMeta(nj.Opts)
 		meta.PrevJobResult, err = s.GetResult(ctx, msg.ID)
 		if err != nil {
-			return err
+			return fmt.Errorf("could not get result for id (%s) : %w", msg.ID, err)
 		}
 
 		// Set the ID of the next job in the chain
 		msg.OnSuccessID, err = s.enqueueWithMeta(ctx, nj, meta)
 		if err != nil {
-			return err
+			return fmt.Errorf("could not enqueue job id (%s) : %w", msg.ID, err)
 		}
 	}