Do not create worker query if it is not possible to add any new allocations

Author: Kobzol

crates/hyperqueue/src/server/autoalloc/process.rs

@@ -355,7 +355,14 @@ async fn perform_submits(
         return Ok(());
     }
 
-    // TODO: do not run the code below if all queues have full backlog anyway
+    // If there is no allocation that we could possibly create, then stop
+    if queues
+        .iter()
+        .all(|(_, queue)| !queue.has_space_for_submit())
+    {
+        return Ok(());
+    }
+
     let queries: Vec<WorkerTypeQuery> = queues
         .iter()
         .map(|(id, queue)| {
@@ -470,11 +477,7 @@ fn compute_submission_permit(
 ) -> SubmissionPermit {
     let info = queue.info();
 
-    // How many workers are currently already queued or running?
-    let active_workers = queue
-        .active_allocations()
-        .map(|allocation| allocation.target_worker_count as u32)
-        .sum::<u32>();
+    let active_workers = queue.active_worker_count();
     let queued_allocs = queue.queued_allocations().collect::<Vec<_>>();
 
     let mut max_remaining_workers_to_spawn = match info.max_worker_count() {

crates/hyperqueue/src/server/autoalloc/state.rs

@@ -252,6 +252,26 @@ impl AllocationQueue {
     pub fn get_worker_config(&self) -> Option<&WorkerConfiguration> {
         self.worker_config.as_ref()
     }
+
+    /// How many workers are currently queued or running?
+    pub fn active_worker_count(&self) -> u32 {
+        self.active_allocations()
+            .map(|allocation| allocation.target_worker_count as u32)
+            .sum::<u32>()
+    }
+
+    /// Returns true only if at least a single allocation could be added to this queue.
+    pub fn has_space_for_submit(&self) -> bool {
+        if self.queued_allocations().count() >= self.info.backlog() as usize {
+            return false;
+        }
+        if let Some(max_worker_count) = self.info.max_worker_count() {
+            if self.active_worker_count() >= max_worker_count {
+                return false;
+            }
+        }
+        true
+    }
 }
 
 // Allocation