From 250ec3f2a4d876de26f23b2b18ff5049fa161397 Mon Sep 17 00:00:00 2001
From: "Jeff Washington (jwash)" <jeff.washington@solana.com>
Date: Tue, 13 Dec 2022 16:40:12 -0600
Subject: [PATCH] improve write_version usage in geyser scan from snapshot
 (#29223)

---
 .../src/accounts_db/geyser_plugin_utils.rs    | 24 +++++++++++--------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/runtime/src/accounts_db/geyser_plugin_utils.rs b/runtime/src/accounts_db/geyser_plugin_utils.rs
index 4f669030d..ab301f13c 100644
--- a/runtime/src/accounts_db/geyser_plugin_utils.rs
+++ b/runtime/src/accounts_db/geyser_plugin_utils.rs
@@ -89,29 +89,33 @@ impl AccountsDb {
         let slot_stores = slot_stores.read().unwrap();
         let mut accounts_to_stream: HashMap<Pubkey, StoredAccountMeta> = HashMap::default();
         let mut measure_filter = Measure::start("accountsdb-plugin-filtering-accounts");
+        let mut previous_write_version = None;
         for (_, storage_entry) in slot_stores.iter() {
-            let mut accounts = storage_entry.all_accounts();
-            let account_len = accounts.len();
-            notify_stats.total_accounts += account_len;
-            accounts.drain(..).into_iter().for_each(|account| {
+            let accounts = storage_entry.accounts.account_iter();
+            let mut account_len = 0;
+            accounts.for_each(|account| {
+                account_len += 1;
+                if let Some(previous_write_version) = previous_write_version {
+                    assert!(previous_write_version < account.meta.write_version);
+                }
+                previous_write_version = Some(account.meta.write_version);
                 if notified_accounts.contains(&account.meta.pubkey) {
                     notify_stats.skipped_accounts += 1;
                     return;
                 }
                 match accounts_to_stream.entry(account.meta.pubkey) {
                     Entry::Occupied(mut entry) => {
-                        let existing_account = entry.get();
-                        if account.meta.write_version > existing_account.meta.write_version {
-                            entry.insert(account);
-                        } else {
-                            notify_stats.skipped_accounts += 1;
-                        }
+                        // later entries in the same slot are more recent and override earlier accounts for the same pubkey
+                        // We can pass an incrementing number here for write_version in the future, if the storage does not have a write_version.
+                        // As long as all accounts for this slot are in 1 append vec that can be itereated olest to newest.
+                        entry.insert(account);
                     }
                     Entry::Vacant(entry) => {
                         entry.insert(account);
                     }
                 }
             });
+            notify_stats.total_accounts += account_len;
         }
         measure_filter.stop();
         notify_stats.elapsed_filtering_us += measure_filter.as_us() as usize;