refactor: change DEFAULT_PAGE_SIZE to 1536

src/common/meta/src/range_stream.rs

@@ -39,7 +39,16 @@ enum PaginationStreamState<K, V> {
     Error,
 }
 
-pub const DEFAULT_PAGE_SIZE: usize = 512;
+/// The Range Request's default page size.
+///
+/// It dependents on upstream KvStore server side grpc message size limitation.
+/// (e.g., etcd has default grpc message size limitation is 4MiB)
+///
+/// Generally, almost all metadata is smaller than is 2700 Byte.
+/// Therefore, We can set the [DEFAULT_PAGE_SIZE] to 1536 statically.
+///
+/// TODO(weny): Considers updating the default page size dynamically.
+pub const DEFAULT_PAGE_SIZE: usize = 1536;
 
 struct PaginationStreamFactory {
     kv: KvBackendRef,

src/meta-srv/src/handler/on_leader_start_handler.rs

@@ -35,8 +35,10 @@ impl HeartbeatHandler for OnLeaderStartHandler {
         if let Some(election) = &ctx.election {
             if election.in_infancy() {
                 ctx.is_infancy = true;
+                // TODO(weny): Unifies the multiple leader state between Context and MetaSrv.
+                // we can't ensure the in-memory kv has already been reset in the outside loop.
+                // We still use heartbeat requests to trigger resetting in-memory kv.
                 ctx.reset_in_memory();
-                ctx.reset_leader_cached_kv_backend();
             }
         }
         Ok(())

src/meta-srv/src/service/store/cached_kv.rs

@@ -96,7 +96,7 @@ impl LeaderCachedKvBackend {
         for prefix in &CACHE_KEY_PREFIXES[..] {
             let _timer = metrics::METRIC_META_LEADER_CACHED_KV_LOAD.with_label_values(&[prefix]);
 
-            // TODO(weny): Refactors PaginationStream's ouput to unary output.
+            // TODO(weny): Refactors PaginationStream's output to unary output.
             let stream = PaginationStream::new(
                 self.store.clone(),
                 RangeRequest::new().with_prefix(prefix.as_bytes()),