chore: remove or improve resharding TODOs (#12816)

- Removing a few TODOs which aren't valid anymore
- Adding more context to an existing TODO

chain/chain/src/resharding/resharding_actor.rs

@@ -38,7 +38,9 @@ impl HandlerWithContext<FlatStorageShardCatchupRequest> for ReshardingActor {
 
 impl Handler<MemtrieReloadRequest> for ReshardingActor {
     fn handle(&mut self, _msg: MemtrieReloadRequest) {
-        // TODO(resharding)
+        // TODO(resharding): implement memtrie reloading. At this stage the flat storage for
+        // `msg.shard_uid` should be ready. Construct a new memtrie in the background and replace
+        // with hybrid memtrie with it. Afterwards, the hybrid memtrie can be deleted.
     }
 }
 

chain/chain/src/resharding/resharding_v2.rs

@@ -236,8 +236,7 @@ impl Chain {
             let TrieUpdateBatch { entries } = batch;
             let (store_update, apply_time) = {
                 let timer = Instant::now();
-                // TODO(#9435): This is highly inefficient as for each key in the batch, we are parsing the account_id
-                // A better way would be to use the boundary account to construct the from and to key range for flat storage iterator
+                // A better way would be to use the boundary account to construct the from and to key range for flat storage iterator.
                 let (store_update, new_state_roots) = tries.add_values_to_children_states(
                     &state_roots,
                     entries,

chain/chunks/src/client.rs

@@ -122,7 +122,6 @@ impl ShardedTransactionPool {
     /// the new shard layout.
     /// It works by emptying the pools for old shard uids and re-inserting the
     /// transactions back to the pool with the new shard uids.
-    /// TODO(resharding) check if this logic works in resharding V3
     pub fn reshard(&mut self, old_shard_layout: &ShardLayout, new_shard_layout: &ShardLayout) {
         tracing::debug!(
             target: "resharding",

chain/client/src/client.rs

@@ -1800,7 +1800,6 @@ impl Client {
             // layout is changing we need to reshard the transaction pool.
             // TODO make sure transactions don't get added for the old shard
             // layout after the pool resharding
-            // TODO(resharding) check if this logic works in resharding V3
             if self.epoch_manager.is_next_block_epoch_start(&block_hash).unwrap_or(false) {
                 let new_shard_layout =
                     self.epoch_manager.get_shard_layout_from_prev_block(&block_hash);

core/store/src/flat/manager.rs

@@ -86,12 +86,8 @@ impl FlatStorageManager {
         }
         let original_value = flat_storages.insert(shard_uid, flat_storage);
         if original_value.is_some() {
-            // Generally speaking this shouldn't happen. It may only happen when
-            // the node is restarted in the middle of resharding.
-            //
-            // TODO(resharding) It would be better to detect when building state
-            // is finished for a shard and skip doing it again after restart. We
-            // can then assert that the flat storage is only created once.
+            // Generally speaking this shouldn't happen. Starting from resharding V3 it shouldn't
+            // happen even if the node is restarted.
             tracing::warn!(target: "store", ?shard_uid, "Creating flat storage for shard that already has flat storage.");
         }
         Ok(())