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//! Worker Pool for processing jobs
use std::sync::Arc;
use std::time::Duration;
use tokio::sync::Semaphore;
use tracing::{error, info, warn};
use crate::backend::QueueBackend;
use crate::job::{Job, JobResult, JobStatus};
#[derive(Clone, Copy)]
pub struct WorkerConfig {
pub max_concurrency: usize,
pub poll_interval: Duration,
}
impl Default for WorkerConfig {
fn default() -> Self {
Self {
max_concurrency: 5,
poll_interval: Duration::from_millis(100),
}
}
}
use serde::de::DeserializeOwned;
use std::sync::RwLock;
pub struct WorkerPool<B: QueueBackend + ?Sized> {
pub backend: Arc<B>,
config: WorkerConfig,
registry: Arc<JobRegistry>,
}
type JobFactory =
Box<dyn Fn(serde_json::Value) -> Result<Box<dyn Job>, serde_json::Error> + Send + Sync>;
struct JobRegistry {
factories: RwLock<std::collections::HashMap<String, JobFactory>>,
}
impl<B: QueueBackend + 'static> WorkerPool<B> {
pub fn new(backend: B, config: WorkerConfig) -> Self {
Self::new_with_arc(Arc::new(backend), config)
}
}
impl<B: QueueBackend + ?Sized + 'static> WorkerPool<B> {
/// Create new worker pool from existing Arc backend (supports dyn dispatch)
pub fn new_with_arc(backend: Arc<B>, config: WorkerConfig) -> Self {
Self {
backend,
config,
registry: Arc::new(JobRegistry {
factories: RwLock::new(std::collections::HashMap::new()),
}),
}
}
/// Register a job type handler
pub fn register_job_type<J: Job + DeserializeOwned + 'static>(&self, name: &str) {
let factory = Box::new(|payload: serde_json::Value| {
let job: J = serde_json::from_value(payload)?;
Ok(Box::new(job) as Box<dyn Job>)
});
self.registry
.factories
.write()
.expect("Job registry RwLock poisoned")
.insert(name.to_string(), factory);
}
/// Register a custom factory (useful for jobs with dependency injection)
pub fn register_job_factory<F>(&self, name: &str, factory: F)
where
F: Fn(serde_json::Value) -> Box<dyn Job> + Send + Sync + 'static,
{
self.registry
.factories
.write()
.expect("Job registry RwLock poisoned")
.insert(
name.to_string(),
Box::new(move |payload| Ok(factory(payload))),
);
}
pub async fn start(&self) {
let semaphore = Arc::new(Semaphore::new(self.config.max_concurrency));
info!(
"Worker pool started with concurrency {}",
self.config.max_concurrency
);
loop {
if semaphore.available_permits() > 0 {
match self.backend.dequeue().await {
Ok(Some(entry)) => {
let permit = semaphore
.clone()
.acquire_owned()
.await
.expect("Worker semaphore closed unexpectedly");
let backend = self.backend.clone();
let registry = self.registry.clone();
tokio::spawn(async move {
let job_opt = {
let factories = registry
.factories
.read()
.expect("Job registry RwLock poisoned");
factories
.get(&entry.job_type)
.map(|f| f(entry.payload.clone()))
};
match job_opt {
Some(Ok(mut job)) => {
info!("Processing job {} ({})", entry.id, entry.job_type);
let result = job.execute().await;
match result {
JobResult::Success(value) => {
if let Some(val) = value {
let _ = backend.set_result(entry.id, val).await;
}
let _ = backend
.update_status(
entry.id,
JobStatus::Completed,
None,
None,
)
.await;
}
JobResult::Retry(e) => {
let delay =
job.backoff_strategy().delay(entry.attempts);
let delay_secs = delay.as_secs();
info!(
job_id = %entry.id,
attempt = entry.attempts + 1,
delay_secs = delay_secs,
"Job failed, scheduling retry with backoff"
);
let _ = backend
.update_status(
entry.id,
JobStatus::Failed(entry.attempts + 1),
Some(e),
Some(delay_secs),
)
.await;
}
JobResult::Fatal(e) => {
let _ = backend
.update_status(
entry.id,
JobStatus::DeadLetter,
Some(e),
None,
)
.await;
}
}
}
Some(Err(e)) => {
error!(job_id = %entry.id, error = %e, "Job payload deserialization failed");
let _ = backend
.update_status(
entry.id,
JobStatus::DeadLetter,
Some(e.to_string()),
None,
)
.await;
}
None => {
warn!("No handler registered for job type: {}", entry.job_type);
let _ = backend
.update_status(
entry.id,
JobStatus::DeadLetter,
Some(format!("No handler for {}", entry.job_type)),
None,
)
.await;
}
}
drop(permit);
});
}
Ok(None) => {
// Queue empty
tokio::time::sleep(self.config.poll_interval).await;
}
Err(e) => {
error!("Queue error: {}", e);
tokio::time::sleep(Duration::from_secs(1)).await;
}
}
} else {
// Wait for permit availability
tokio::time::sleep(Duration::from_millis(50)).await;
}
}
}
}