modify geyser account iter at snapshot load (solana-labs#960)

accounts-db/src/accounts_db/geyser_plugin_utils.rs

@@ -89,40 +89,65 @@ impl AccountsDb {
     ) {
         let storage_entry = self.storage.get_slot_storage_entry(slot).unwrap();
 
-        let mut accounts_to_stream: HashMap<Pubkey, StoredAccountMeta> = HashMap::default();
+        let mut accounts_duplicate: HashMap<Pubkey, usize> = HashMap::default();
         let mut measure_filter = Measure::start("accountsdb-plugin-filtering-accounts");
-        let accounts = storage_entry.accounts.account_iter();
         let mut account_len = 0;
-        accounts.for_each(|account| {
+        let mut pubkeys = HashSet::new();
+
+        // populate `accounts_duplicate` for any pubkeys that are in this storage twice.
+        // Storages cannot return `StoredAccountMeta<'_>` for more than 1 account at a time, so we have to do 2 passes to make sure
+        // we don't have duplicate pubkeys.
+        let mut i = 0;
+        storage_entry.accounts.scan_pubkeys(|pubkey| {
+            i += 1; // pre-increment to most easily match early returns in next loop
+            if !pubkeys.insert(*pubkey) {
+                accounts_duplicate.insert(*pubkey, i); // remember the highest index entry in this slot
+            }
+        });
+
+        // now, actually notify geyser
+        let mut i = 0;
+        storage_entry.accounts.scan_accounts(|account| {
+            i += 1;
             account_len += 1;
             if notified_accounts.contains(account.pubkey()) {
                 notify_stats.skipped_accounts += 1;
                 return;
             }
+            if let Some(highest_i) = accounts_duplicate.get(account.pubkey()) {
+                if highest_i != &i {
+                    // this pubkey is in this storage twice and the current instance is not the last one, so we skip it.
+                    // We only send unique accounts in this slot to `notify_filtered_accounts`
+                    return;
+                }
+            }
 
             // 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.
-            accounts_to_stream.insert(*account.pubkey(), account);
+            self.notify_filtered_accounts(
+                slot,
+                notified_accounts,
+                std::iter::once(account),
+                notify_stats,
+            );
         });
         notify_stats.total_accounts += account_len;
         measure_filter.stop();
         notify_stats.elapsed_filtering_us += measure_filter.as_us() as usize;
-
-        self.notify_filtered_accounts(slot, notified_accounts, accounts_to_stream, notify_stats);
     }
 
-    fn notify_filtered_accounts(
+    fn notify_filtered_accounts<'a>(
         &self,
         slot: Slot,
         notified_accounts: &mut HashSet<Pubkey>,
-        mut accounts_to_stream: HashMap<Pubkey, StoredAccountMeta>,
+        accounts_to_stream: impl Iterator<Item = StoredAccountMeta<'a>>,
         notify_stats: &mut GeyserPluginNotifyAtSnapshotRestoreStats,
     ) {
         let notifier = self.accounts_update_notifier.as_ref().unwrap();
         let mut measure_notify = Measure::start("accountsdb-plugin-notifying-accounts");
         let local_write_version = 0;
-        for (_, mut account) in accounts_to_stream.drain() {
+        for mut account in accounts_to_stream {
             // We do not need to rely on the specific write_version read from the append vec.
             // So, overwrite the write_version with something that works.
             // 'accounts_to_stream' is already a hashmap, so there is already only entry per pubkey.
@@ -143,8 +168,9 @@ impl AccountsDb {
             notified_accounts.insert(*account.pubkey());
             measure_bookkeep.stop();
             notify_stats.total_pure_bookeeping += measure_bookkeep.as_us() as usize;
+
+            notify_stats.notified_accounts += 1;
         }
-        notify_stats.notified_accounts += accounts_to_stream.len();
         measure_notify.stop();
         notify_stats.elapsed_notifying_us += measure_notify.as_us() as usize;
     }