Be clearer about what property values workers are missing (#2121)

Author: palfrey

nativelink-scheduler/src/worker_capability_index.rs

@@ -134,18 +134,18 @@ impl WorkerCapabilityIndex {
         action_properties: &PlatformProperties,
         full_worker_logging: bool,
     ) -> HashSet<WorkerId> {
-        if action_properties.properties.is_empty() {
-            // No properties required, all workers match
-            return self.all_workers.clone();
-        }
-
         if self.all_workers.is_empty() {
             if full_worker_logging {
                 info!("No workers available to match!");
             }
             return HashSet::new();
         }
 
+        if action_properties.properties.is_empty() {
+            // No properties required, all workers match
+            return self.all_workers.clone();
+        }
+
         let mut candidates: Option<HashSet<WorkerId>> = None;
 
         for (name, value) in &action_properties.properties {
@@ -167,8 +167,14 @@ impl WorkerCapabilityIndex {
                     // Early exit if no candidates
                     if internal_candidates.is_empty() {
                         if full_worker_logging {
+                            let values: Vec<_> = self
+                                .exact_index
+                                .iter()
+                                .filter(|pk| &pk.0.name == name)
+                                .map(|pk| pk.0.value.clone())
+                                .collect();
                             info!(
-                                "No candidate workers due to a lack of matching {name} = {value:?}"
+                                "No candidate workers due to a lack of matching '{name}' = {value:?}. Workers have: {values:?}"
                             );
                         }
                         return HashSet::new();
@@ -196,7 +202,9 @@ impl WorkerCapabilityIndex {
 
                     if internal_candidates.is_empty() {
                         if full_worker_logging {
-                            info!("No candidate workers due to a lack of key {name}");
+                            info!(
+                                "No candidate workers due to a lack of key '{name}'. Job asked for {value:?}"
+                            );
                         }
                         return HashSet::new();
                     }

nativelink-scheduler/tests/worker_capability_index_test.rs

@@ -33,11 +33,14 @@ fn make_properties(props: &[(&str, PlatformPropertyValue)]) -> PlatformPropertie
 }
 
 #[test]
+#[tracing_test::traced_test]
 fn test_empty_index() {
     let index = WorkerCapabilityIndex::new();
     let props = make_properties(&[]);
     let result = index.find_matching_workers(&props, true);
     assert!(result.is_empty());
+
+    assert!(logs_contain("No workers available to match!"));
 }
 
 #[test]
@@ -236,3 +239,38 @@ fn test_ignore_property() {
     let result = index.find_matching_workers(&props, true);
     assert_eq!(result.len(), 2);
 }
+
+#[test]
+#[tracing_test::traced_test]
+fn test_no_exact_property_match() {
+    let mut index = WorkerCapabilityIndex::new();
+    let worker1 = make_worker_id("worker1");
+    index.add_worker(
+        &worker1,
+        &make_properties(&[("os", PlatformPropertyValue::Exact("windows".to_string()))]),
+    );
+
+    let props = make_properties(&[("os", PlatformPropertyValue::Exact("linux".to_string()))]);
+    let result = index.find_matching_workers(&props, true);
+    assert_eq!(result.len(), 0);
+
+    assert!(logs_contain(
+        "No candidate workers due to a lack of matching 'os' = Exact(\"linux\"). Workers have: [Exact(\"windows\")]"
+    ));
+}
+
+#[test]
+#[tracing_test::traced_test]
+fn test_no_priority_property_match() {
+    let mut index = WorkerCapabilityIndex::new();
+    let worker1 = make_worker_id("worker1");
+    index.add_worker(&worker1, &make_properties(&[]));
+
+    let props = make_properties(&[("os", PlatformPropertyValue::Priority("linux".to_string()))]);
+    let result = index.find_matching_workers(&props, true);
+    assert_eq!(result.len(), 0);
+
+    assert!(logs_contain(
+        "No candidate workers due to a lack of key 'os'. Job asked for Priority(\"linux\")"
+    ));
+}