scheduler: appropriately unblock evals with quotas

.changelog/18838.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+scheduler (Enterprise): auto-unblock evals with associated quotas when node resources are freed up
+```

nomad/blocked_evals.go

@@ -567,10 +567,13 @@ func (b *BlockedEvals) unblock(computedClass, quota string, index uint64) {
 	// never saw a node with the given computed class and thus needs to be
 	// unblocked for correctness.
 	for id, wrapped := range b.captured {
-		if quota != "" && wrapped.eval.QuotaLimitReached != quota {
+		if quota != "" &&
+			wrapped.eval.QuotaLimitReached != "" &&
+			wrapped.eval.QuotaLimitReached != quota {
 			// We are unblocking based on quota and this eval doesn't match
 			continue
-		} else if elig, ok := wrapped.eval.ClassEligibility[computedClass]; ok && !elig {
+		}
+		if elig, ok := wrapped.eval.ClassEligibility[computedClass]; ok && !elig {
 			// Can skip because the eval has explicitly marked the node class
 			// as ineligible.
 			continue

nomad/blocked_evals_test.go

@@ -13,6 +13,7 @@ import (
 	"github.com/hashicorp/nomad/nomad/mock"
 	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/hashicorp/nomad/testutil"
+	"github.com/shoenig/test/must"
 	"github.com/stretchr/testify/require"
 )
 
@@ -322,6 +323,33 @@ func TestBlockedEvals_UnblockEligible_Quota(t *testing.T) {
 	requireBlockedEvalsEnqueued(t, blocked, broker, 1)
 }
 
+// The quota here is incidental. The eval is blocked due to something else,
+// e.g. cpu exhausted, but there happens to also be a quota on the namespace.
+func TestBlockedEvals_UnblockEligible_IncidentalQuota(t *testing.T) {
+	ci.Parallel(t)
+
+	blocked, broker := testBlockedEvals(t)
+
+	e := mock.BlockedEval()
+	e.Status = structs.EvalStatusBlocked
+	e.QuotaLimitReached = "" // explicitly not blocked due to quota limit
+	blocked.Block(e)
+
+	// Verify block caused the eval to be tracked.
+	blockedStats := blocked.Stats()
+	must.Eq(t, 1, blockedStats.TotalBlocked)
+	must.MapLen(t, 1, blockedStats.BlockedResources.ByJob)
+	// but not due to quota.
+	must.Eq(t, 0, blockedStats.TotalQuotaLimit)
+
+	// When unblocking, the quota name from the alloc is passed in,
+	// regardless of the cause of the initial blockage.
+	// Since the initial block in this test was due to something else,
+	// it should be unblocked without regard to quota.
+	blocked.UnblockQuota("foo", 1000)
+	requireBlockedEvalsEnqueued(t, blocked, broker, 1)
+}
+
 func TestBlockedEvals_UnblockIneligible_Quota(t *testing.T) {
 	ci.Parallel(t)
 	require := require.New(t)