rust 54 lines · 9 steps

An async job queue handler in Axum

An Axum handler accepts an export request, spawns the work in the background, and immediately returns 202 with a status URL.

Explained by highlit
Axum Intermediate background-jobs async http-202 task-spawning shared-state
1use axum::{
2 extract::State,
3 http::StatusCode,
4 response::IntoResponse,
5 Json,
6};
7use serde::{Deserialize, Serialize};
8use std::sync::Arc;
9use uuid::Uuid;
10 
11#[derive(Deserialize)]
12pub struct ExportRequest {
13 pub dataset_id: Uuid,
14 pub format: String,
15}
16 
17#[derive(Serialize)]
18pub struct ExportAccepted {
19 pub job_id: Uuid,
20 pub status: &'static str,
21}
22 
23pub async fn enqueue_export(
24 State(state): State<Arc<AppState>>,
25 Json(req): Json<ExportRequest>,
26) -> impl IntoResponse {
27 let job_id = Uuid::new_v4();
28 state.jobs.mark_pending(job_id).await;
29 
30 let state = state.clone();
31 tokio::spawn(async move {
32 if let Err(err) = run_export(&state, job_id, &req).await {
33 tracing::error!(%job_id, %err, "export job failed");
34 state.jobs.mark_failed(job_id, err.to_string()).await;
35 }
36 });
37 
38 (
39 StatusCode::ACCEPTED,
40 [("Location", format!("/exports/{job_id}"))],
41 Json(ExportAccepted { job_id, status: "pending" }),
42 )
43}
44 
45async fn run_export(
46 state: &AppState,
47 job_id: Uuid,
48 req: &ExportRequest,
49) -> anyhow::Result<()> {
50 let rows = state.repo.load_dataset(req.dataset_id).await?;
51 let url = state.storage.write_report(&rows, &req.format).await?;
52 state.jobs.mark_complete(job_id, url).await;
53 Ok(())
54}
01 / 01
STEP 01

Walkthrough

Space play ←→ step click any line
Three takeaways
  1. 1Returning 202 Accepted with a Location header lets clients poll a long-running job instead of blocking on the response.
  2. 2Spawning work with tokio::spawn detaches it from the request lifecycle, so the handler returns before the job finishes.
  3. 3Cloning an Arc state before moving it into a spawned task keeps shared resources available to the background work.

Related explainers

rust 
use std::collections::HashMap;
use std::sync::{Arc, Mutex};
use std::thread;
 

Aggregating metrics across threads in Rust

concurrency shared-state mutex
Intermediate 7 steps
rust 
use std::sync::{mpsc, Arc, Mutex};
use std::thread;
use std::time::Duration;
 

Building a thread pool in Rust

concurrency channels thread-pool
Advanced 9 steps
rust 
use std::time::Instant;
use tracing::info;
 
pub struct Timer {

A scope-guard timer with Drop in Rust

raii drop-guard timing
Intermediate 7 steps
rust 
use std::collections::HashMap;
 
pub struct Memoizer<K, V, F> {
    cache: HashMap<K, V>,

A generic memoizer in Rust

memoization generics caching
Intermediate 6 steps
ruby 
class ReportBatcher
  BATCH_SIZE = 500
 
  def initialize(account)

Batching monthly email summaries in Rails

batching service-object background-jobs
Intermediate 7 steps
rust 
use std::collections::HashMap;
 
#[derive(Debug, Clone)]
struct Order {

Aggregating Rust data with fold and entry

fold hashmap ownership
Intermediate 6 steps

Share this explainer

Here's the card — post it anywhere.

An async job queue handler in Axum — share card
Made with highlit — turn any snippet into a walkthrough like this in about a minute.
Explain your code