cleanup get_snapshot_storages (#29488)

* cleanup get_snapshot_storages

* pr feedback

runtime/src/accounts_db.rs

@@ -8513,7 +8513,7 @@ impl AccountsDb {
         ancestors: Option<&Ancestors>,
     ) -> (SnapshotStorages, Vec<Slot>) {
         let mut m = Measure::start("get slots");
-        let slots = self
+        let slots_and_storages = self
             .storage
             .iter()
             .filter_map(|entry| {
@@ -8528,32 +8528,26 @@ impl AccountsDb {
 
         let chunk_size = 5_000;
         let wide = self.thread_pool_clean.install(|| {
-            slots
+            slots_and_storages
                 .par_chunks(chunk_size)
-                .map(|slots| {
-                    slots
+                .map(|slots_and_storages| {
+                    slots_and_storages
                         .iter()
-                        .filter_map(|(slot, storages)| {
-                            if self.accounts_index.is_alive_root(*slot)
+                        .filter(|(slot, _)| {
+                            self.accounts_index.is_alive_root(*slot)
                                 || ancestors
                                     .map(|ancestors| ancestors.contains_key(slot))
                                     .unwrap_or_default()
-                            {
-                                let storages = storages
-                                    .read()
-                                    .unwrap()
-                                    .values()
-                                    .filter(|x| x.has_accounts())
-                                    .cloned()
-                                    .collect::<Vec<_>>();
-                                if !storages.is_empty() {
-                                    Some((storages, *slot))
-                                } else {
-                                    None
-                                }
-                            } else {
-                                None
-                            }
+                        })
+                        .filter_map(|(slot, storages)| {
+                            let storages = storages
+                                .read()
+                                .unwrap()
+                                .values()
+                                .filter(|x| x.has_accounts())
+                                .cloned()
+                                .collect::<Vec<_>>();
+                            (!storages.is_empty()).then_some((storages, *slot))
                         })
                         .collect::<Vec<(SnapshotStorage, Slot)>>()
                 })
@@ -8563,7 +8557,7 @@ impl AccountsDb {
         let mut m3 = Measure::start("flatten");
         // some slots we found above may not have been a root or met the slot # constraint.
         // So the resulting 'slots' vector we return will be a subset of the raw keys we got initially.
-        let mut slots = Vec::with_capacity(slots.len());
+        let mut slots = Vec::with_capacity(slots_and_storages.len());
         let result = wide
             .into_iter()
             .flatten()

validator/src/cli.rs

@@ -1181,13 +1181,6 @@ pub fn app<'a>(version: &'a str, default_args: &'a DefaultArgs) -> App<'a, 'a> {
                 .help("Enables faster starting of validators by skipping shrink. \
                       This option is for use during testing."),
         )
-        .arg(
-            Arg::with_name("accounts_db_skip_rewrites")
-                .long("accounts-db-skip-rewrites")
-                .help("Accounts that are rent exempt and have no changes are not rewritten. \
-                      This produces snapshots that older versions cannot read.")
-                .hidden(true),
-        )
         .arg(
             Arg::with_name("accounts_db_ancient_append_vecs")
                 .long("accounts-db-ancient-append-vecs")