IndexLimitMb option adds 'Unspecified' state (#24249)

runtime/src/accounts_index.rs

@@ -50,7 +50,7 @@ pub const ACCOUNTS_INDEX_CONFIG_FOR_TESTING: AccountsIndexConfig = AccountsIndex
     bins: Some(BINS_FOR_TESTING),
     flush_threads: Some(FLUSH_THREADS_TESTING),
     drives: None,
-    index_limit_mb: None,
+    index_limit_mb: IndexLimitMb::Unspecified,
     ages_to_stay_in_cache: None,
     scan_results_limit_bytes: None,
     started_from_validator: false,
@@ -59,7 +59,7 @@ pub const ACCOUNTS_INDEX_CONFIG_FOR_BENCHMARKS: AccountsIndexConfig = AccountsIn
     bins: Some(BINS_FOR_BENCHMARKS),
     flush_threads: Some(FLUSH_THREADS_TESTING),
     drives: None,
-    index_limit_mb: None,
+    index_limit_mb: IndexLimitMb::Unspecified,
     ages_to_stay_in_cache: None,
     scan_results_limit_bytes: None,
     started_from_validator: false,
@@ -157,12 +157,29 @@ pub struct AccountSecondaryIndexesIncludeExclude {
     pub keys: HashSet<Pubkey>,
 }
 
+/// specification of how much memory in-mem portion of account index can use
+#[derive(Debug, Clone)]
+pub enum IndexLimitMb {
+    /// nothing explicit specified, so default
+    Unspecified,
+    /// limit was specified, use disk index for rest
+    Limit(usize),
+    /// in-mem-only was specified, no disk index
+    InMemOnly,
+}
+
+impl Default for IndexLimitMb {
+    fn default() -> Self {
+        Self::Unspecified
+    }
+}
+
 #[derive(Debug, Default, Clone)]
 pub struct AccountsIndexConfig {
     pub bins: Option<usize>,
     pub flush_threads: Option<usize>,
     pub drives: Option<Vec<PathBuf>>,
-    pub index_limit_mb: Option<usize>,
+    pub index_limit_mb: IndexLimitMb,
     pub ages_to_stay_in_cache: Option<Age>,
     pub scan_results_limit_bytes: Option<usize>,
     /// true if the accounts index is being created as a result of being started as a validator (as opposed to test, etc.)

runtime/src/bucket_map_holder.rs

@@ -1,6 +1,6 @@
 use {
     crate::{
-        accounts_index::{AccountsIndexConfig, IndexValue},
+        accounts_index::{AccountsIndexConfig, IndexLimitMb, IndexValue},
         bucket_map_holder_stats::BucketMapHolderStats,
         in_mem_accounts_index::{InMemAccountsIndex, SlotT},
         waitable_condvar::WaitableCondvar,
@@ -153,7 +153,13 @@ impl<T: IndexValue> BucketMapHolder<T> {
 
         let mut bucket_config = BucketMapConfig::new(bins);
         bucket_config.drives = config.as_ref().and_then(|config| config.drives.clone());
-        let mut mem_budget_mb = config.as_ref().and_then(|config| config.index_limit_mb);
+        let mut mem_budget_mb = config.as_ref().and_then(|config| {
+            if let IndexLimitMb::Limit(mb) = config.index_limit_mb {
+                Some(mb)
+            } else {
+                None
+            }
+        });
         let bucket_map_tests_allowed = mem_budget_mb.is_none()
             && !config
                 .as_ref()
@@ -391,7 +397,7 @@ pub mod tests {
     fn test_disk_index_enabled() {
         let bins = 1;
         let config = AccountsIndexConfig {
-            index_limit_mb: Some(0),
+            index_limit_mb: IndexLimitMb::Limit(0),
             ..AccountsIndexConfig::default()
         };
         let test = BucketMapHolder::<u64>::new(bins, &Some(config), 1);

runtime/src/in_mem_accounts_index.rs

@@ -1263,7 +1263,7 @@ impl Drop for FlushGuard<'_> {
 mod tests {
     use {
         super::*,
-        crate::accounts_index::{AccountsIndexConfig, BINS_FOR_TESTING},
+        crate::accounts_index::{AccountsIndexConfig, IndexLimitMb, BINS_FOR_TESTING},
         itertools::Itertools,
     };
 
@@ -1281,7 +1281,7 @@ mod tests {
         let holder = Arc::new(BucketMapHolder::new(
             BINS_FOR_TESTING,
             &Some(AccountsIndexConfig {
-                index_limit_mb: Some(1),
+                index_limit_mb: IndexLimitMb::Limit(1),
                 ..AccountsIndexConfig::default()
             }),
             1,