Merge branch 'main' into yuchen/direct-io-delta-image-layer-write

libs/pageserver_api/src/controller_api.rs

@@ -245,6 +245,17 @@ impl From<NodeAvailability> for NodeAvailabilityWrapper {
     }
 }
 
+/// Scheduling policy enables us to selectively disable some automatic actions that the
+/// controller performs on a tenant shard. This is only set to a non-default value by
+/// human intervention, and it is reset to the default value (Active) when the tenant's
+/// placement policy is modified away from Attached.
+///
+/// The typical use of a non-Active scheduling policy is one of:
+/// - Pinnning a shard to a node (i.e. migrating it there & setting a non-Active scheduling policy)
+/// - Working around a bug (e.g. if something is flapping and we need to stop it until the bug is fixed)
+///
+/// If you're not sure which policy to use to pin a shard to its current location, you probably
+/// want Pause.
 #[derive(Serialize, Deserialize, Clone, Copy, Eq, PartialEq, Debug)]
 pub enum ShardSchedulingPolicy {
     // Normal mode: the tenant's scheduled locations may be updated at will, including

libs/pageserver_api/src/shard.rs

@@ -158,7 +158,8 @@ impl ShardIdentity {
         key_to_shard_number(self.count, self.stripe_size, key)
     }
 
-    /// Return true if the key should be ingested by this shard
+    /// Return true if the key is stored only on this shard. This does not include
+    /// global keys, see is_key_global().
     ///
     /// Shards must ingest _at least_ keys which return true from this check.
     pub fn is_key_local(&self, key: &Key) -> bool {
@@ -171,7 +172,7 @@ impl ShardIdentity {
     }
 
     /// Return true if the key should be stored on all shards, not just one.
-    fn is_key_global(&self, key: &Key) -> bool {
+    pub fn is_key_global(&self, key: &Key) -> bool {
         if key.is_slru_block_key() || key.is_slru_segment_size_key() || key.is_aux_file_key() {
             // Special keys that are only stored on shard 0
             false