redis: Allow customizing the processing queue key (#81)

omniqueue/src/backends/redis/mod.rs

@@ -197,6 +197,7 @@ impl<R: RedisConnection> QueueBackend for RedisBackend<R> {
 pub struct RedisBackendBuilder<R = RedisConnectionManager, S = Static> {
     config: RedisConfig,
     use_redis_streams: bool,
+    processing_queue_key: Option<String>,
     _phantom: PhantomData<fn() -> (R, S)>,
 }
 
@@ -208,6 +209,7 @@ impl<R: RedisConnection> RedisBackendBuilder<R> {
         Self {
             config,
             use_redis_streams: true,
+            processing_queue_key: None,
             _phantom: PhantomData,
         }
     }
@@ -216,6 +218,7 @@ impl<R: RedisConnection> RedisBackendBuilder<R> {
         RedisBackendBuilder {
             config: self.config,
             use_redis_streams: self.use_redis_streams,
+            processing_queue_key: self.processing_queue_key,
             _phantom: PhantomData,
         }
     }
@@ -249,6 +252,24 @@ impl<R: RedisConnection> RedisBackendBuilder<R> {
         self
     }
 
+    /// Set a custom redis key for the processing queue.
+    ///
+    /// This secondary queue is only used if you set
+    /// <code>[`use_redis_streams`][Self::use_redis_streams](false)</code>.
+    /// If you don't set a custom key, one will be selected based on the main
+    /// queue key. You only have to call this if you need precise control over
+    /// which keys omniqueue uses in redis.
+    pub fn processing_queue_key(mut self, value: String) -> Self {
+        self.processing_queue_key = Some(value);
+        self
+    }
+
+    fn get_processing_queue_key(&self) -> String {
+        self.processing_queue_key
+            .clone()
+            .unwrap_or_else(|| format!("{}_processing", self.config.queue_key))
+    }
+
     pub async fn build_pair(self) -> Result<(RedisProducer<R>, RedisConsumer<R>)> {
         let redis = R::from_dsn(&self.config.dsn)?;
         let redis = bb8::Pool::builder()
@@ -258,7 +279,7 @@ impl<R: RedisConnection> RedisBackendBuilder<R> {
             .map_err(QueueError::generic)?;
 
         let background_tasks = self.start_background_tasks(redis.clone()).await;
-        let processing_queue_key = format!("{}_processing", self.config.queue_key);
+        let processing_queue_key = self.get_processing_queue_key();
 
         Ok((
             RedisProducer {
@@ -310,7 +331,7 @@ impl<R: RedisConnection> RedisBackendBuilder<R> {
             .map_err(QueueError::generic)?;
 
         let _background_tasks = self.start_background_tasks(redis.clone()).await;
-        let processing_queue_key = format!("{}_processing", self.config.queue_key);
+        let processing_queue_key = self.get_processing_queue_key();
 
         Ok(RedisConsumer {
             redis,
@@ -388,7 +409,7 @@ impl<R: RedisConnection> RedisBackendBuilder<R> {
             join_set.spawn(fallback::background_task_processing(
                 redis.clone(),
                 self.config.queue_key.to_owned(),
-                format!("{}_processing", self.config.queue_key),
+                self.get_processing_queue_key(),
                 self.config.ack_deadline_ms,
             ));
         }