Adds cache hash data deletion policy enum (#34956)

(cherry picked from commit e155d9c)

accounts-db/src/accounts_db.rs

@@ -58,7 +58,9 @@ use {
         append_vec::{
             aligned_stored_size, AppendVec, APPEND_VEC_MMAPPED_FILES_OPEN, STORE_META_OVERHEAD,
         },
-        cache_hash_data::{CacheHashData, CacheHashDataFileReference},
+        cache_hash_data::{
+            CacheHashData, CacheHashDataFileReference, DeletionPolicy as CacheHashDeletionPolicy,
+        },
         contains::Contains,
         epoch_accounts_hash::EpochAccountsHashManager,
         in_mem_accounts_index::StartupStats,
@@ -7549,10 +7551,13 @@ impl AccountsDb {
             _ = std::fs::remove_dir_all(&failed_dir);
             failed_dir
         };
-        CacheHashData::new(
-            accounts_hash_cache_path,
-            (kind == CalcAccountsHashKind::Incremental).then_some(storages_start_slot),
-        )
+        let deletion_policy = match kind {
+            CalcAccountsHashKind::Full => CacheHashDeletionPolicy::AllUnused,
+            CalcAccountsHashKind::Incremental => {
+                CacheHashDeletionPolicy::UnusedAtLeast(storages_start_slot)
+            }
+        };
+        CacheHashData::new(accounts_hash_cache_path, deletion_policy)
     }
 
     // modeled after calculate_accounts_delta_hash
@@ -9775,7 +9780,7 @@ pub mod tests {
             let temp_dir = TempDir::new().unwrap();
             let accounts_hash_cache_path = temp_dir.path().to_path_buf();
             self.scan_snapshot_stores_with_cache(
-                &CacheHashData::new(accounts_hash_cache_path, None),
+                &CacheHashData::new(accounts_hash_cache_path, CacheHashDeletionPolicy::AllUnused),
                 storage,
                 stats,
                 bins,
@@ -10843,7 +10848,7 @@ pub mod tests {
         };
 
         let result = accounts_db.scan_account_storage_no_bank(
-            &CacheHashData::new(accounts_hash_cache_path, None),
+            &CacheHashData::new(accounts_hash_cache_path, CacheHashDeletionPolicy::AllUnused),
             &CalcAccountsHashConfig::default(),
             &get_storage_refs(&[storage]),
             test_scan,

accounts-db/src/cache_hash_data.rs

@@ -193,8 +193,7 @@ impl CacheHashDataFile {
 pub(crate) struct CacheHashData {
     cache_dir: PathBuf,
     pre_existing_cache_files: Arc<Mutex<HashSet<PathBuf>>>,
-    /// Decides which old cache files to delete.  See `delete_old_cache_files()` for more info.
-    storages_start_slot: Option<Slot>,
+    deletion_policy: DeletionPolicy,
     pub stats: Arc<CacheHashDataStats>,
 }
 
@@ -206,15 +205,15 @@ impl Drop for CacheHashData {
 }
 
 impl CacheHashData {
-    pub(crate) fn new(cache_dir: PathBuf, storages_start_slot: Option<Slot>) -> CacheHashData {
+    pub(crate) fn new(cache_dir: PathBuf, deletion_policy: DeletionPolicy) -> CacheHashData {
         std::fs::create_dir_all(&cache_dir).unwrap_or_else(|err| {
             panic!("error creating cache dir {}: {err}", cache_dir.display())
         });
 
         let result = CacheHashData {
             cache_dir,
             pre_existing_cache_files: Arc::new(Mutex::new(HashSet::default())),
-            storages_start_slot,
+            deletion_policy,
             stats: Arc::default(),
         };
 
@@ -229,21 +228,24 @@ impl CacheHashData {
         let mut old_cache_files =
             std::mem::take(&mut *self.pre_existing_cache_files.lock().unwrap());
 
-        // If `storages_start_slot` is None, we're doing a full accounts hash calculation, and thus
-        // all unused cache files can be deleted.
-        // If `storages_start_slot` is Some, we're doing an incremental accounts hash calculation,
-        // and we only want to delete the unused cache files *that IAH considered*.
-        if let Some(storages_start_slot) = self.storages_start_slot {
-            old_cache_files.retain(|old_cache_file| {
-                let Some(parsed_filename) = parse_filename(old_cache_file) else {
-                    // if parsing the cache filename fails, we *do* want to delete it
-                    return true;
-                };
-
-                // if the old cache file is in the incremental accounts hash calculation range,
-                // then delete it
-                parsed_filename.slot_range_start >= storages_start_slot
-            });
+        match self.deletion_policy {
+            DeletionPolicy::AllUnused => {
+                // no additional work to do here; we will delete everything in `old_cache_files`
+            }
+            DeletionPolicy::UnusedAtLeast(storages_start_slot) => {
+                // when calculating an incremental accounts hash, we only want to delete the unused
+                // cache files *that IAH considered*
+                old_cache_files.retain(|old_cache_file| {
+                    let Some(parsed_filename) = parse_filename(old_cache_file) else {
+                        // if parsing the cache filename fails, we *do* want to delete it
+                        return true;
+                    };
+
+                    // if the old cache file is in the incremental accounts hash calculation range,
+                    // then delete it
+                    parsed_filename.slot_range_start >= storages_start_slot
+                });
+            }
         }
 
         if !old_cache_files.is_empty() {
@@ -410,6 +412,19 @@ fn parse_filename(cache_filename: impl AsRef<Path>) -> Option<ParsedFilename> {
     })
 }
 
+/// Decides which old cache files to delete
+///
+/// See `delete_old_cache_files()` for more info.
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub enum DeletionPolicy {
+    /// Delete *all* the unused cache files
+    /// Should be used when calculating full accounts hash
+    AllUnused,
+    /// Delete *only* the unused cache files with starting slot range *at least* this slot
+    /// Should be used when calculating incremental accounts hash
+    UnusedAtLeast(Slot),
+}
+
 #[cfg(test)]
 mod tests {
     use {super::*, crate::accounts_hash::AccountHash, rand::Rng};
@@ -477,7 +492,8 @@ mod tests {
                                 data_this_pass.push(this_bin_data);
                             }
                         }
-                        let cache = CacheHashData::new(cache_dir.clone(), None);
+                        let cache =
+                            CacheHashData::new(cache_dir.clone(), DeletionPolicy::AllUnused);
                         let file_name = PathBuf::from("test");
                         cache.save(&file_name, &data_this_pass).unwrap();
                         cache.get_cache_files();