Order NextItem subquery results predictably

- Fixes #5055 - Add a new column, `index` to the `NextItem` subquery, which indexes the shifts from 0..n. - Add an `ORDER BY index` clause to guarantee order. - Add test
oxidecomputer · Feb 14, 2024 · 604b19b · 604b19b
1 parent a93462f
commit 604b19b
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Showing 4 changed files with 240 additions and 43 deletions.
diff --git a/nexus/db-queries/src/db/queries/disk.rs b/nexus/db-queries/src/db/queries/disk.rs
@@ -46,11 +46,12 @@ struct NextDiskSlot {
 
 impl NextDiskSlot {
     fn new(instance_id: Uuid) -> Self {
-        let generator = DefaultShiftGenerator {
-            base: 0,
-            max_shift: i64::try_from(MAX_DISKS_PER_INSTANCE).unwrap(),
-            min_shift: 0,
-        };
+        let generator = DefaultShiftGenerator::new(
+            0,
+            i64::try_from(MAX_DISKS_PER_INSTANCE).unwrap(),
+            0,
+        )
+        .expect("invalid min/max shift");
         Self { inner: NextItem::new_scoped(generator, instance_id) }
     }
 }

diff --git a/nexus/db-queries/src/db/queries/network_interface.rs b/nexus/db-queries/src/db/queries/network_interface.rs
@@ -504,8 +504,8 @@ impl NextIpv4Address {
         let subnet = IpNetwork::from(subnet);
         let net = IpNetwork::from(first_available_address(&subnet));
         let max_shift = i64::from(last_address_offset(&subnet));
-        let generator =
-            DefaultShiftGenerator { base: net, max_shift, min_shift: 0 };
+        let generator = DefaultShiftGenerator::new(net, max_shift, 0)
+            .expect("invalid min/max shift");
         Self { inner: NextItem::new_scoped(generator, subnet_id) }
     }
 }
@@ -563,12 +563,12 @@ pub struct NextNicSlot {
 
 impl NextNicSlot {
     pub fn new(parent_id: Uuid) -> Self {
-        let generator = DefaultShiftGenerator {
-            base: 0,
-            max_shift: i64::try_from(MAX_NICS)
-                .expect("Too many network interfaces"),
-            min_shift: 0,
-        };
+        let generator = DefaultShiftGenerator::new(
+            0,
+            i64::try_from(MAX_NICS).expect("Too many network interfaces"),
+            0,
+        )
+        .expect("invalid min/max shift");
         Self { inner: NextItem::new_scoped(generator, parent_id) }
     }
 }
@@ -613,7 +613,8 @@ impl NextMacAddress {
                 (base.into(), max_shift, min_shift)
             }
         };
-        let generator = DefaultShiftGenerator { base, max_shift, min_shift };
+        let generator = DefaultShiftGenerator::new(base, max_shift, min_shift)
+            .expect("invalid min/max shift");
         Self { inner: NextItem::new_scoped(generator, vpc_id) }
     }
 }