Snapshot Packaging Service (#5262)

* Snapshot serialization and packaging

runtime/src/bank.rs

@@ -3,6 +3,7 @@
 //! on behalf of the caller, and a low-level API for when they have
 //! already been signed and verified.
 use crate::accounts::Accounts;
+use crate::accounts_db::AccountStorageEntry;
 use crate::accounts_db::{
     AppendVecId, ErrorCounters, InstructionAccounts, InstructionCredits, InstructionLoaders,
 };
@@ -83,6 +84,15 @@ impl BankRc {
         self.accounts.update_from_stream(stream)
     }
 
+    pub fn get_storage_entries(&self) -> Vec<Arc<AccountStorageEntry>> {
+        let r_storage = self.accounts.accounts_db.storage.read().unwrap();
+        r_storage
+            .0
+            .values()
+            .flat_map(|fork_store| fork_store.values().cloned())
+            .collect()
+    }
+
     fn get_io_error(error: &str) -> std::io::Error {
         warn!("BankRc error: {:?}", error);
         std::io::Error::new(std::io::ErrorKind::Other, error)
@@ -167,6 +177,10 @@ impl StatusCacheRc {
         let sc = status_cache_rc.status_cache.write().unwrap();
         self.status_cache.write().unwrap().append(&sc);
     }
+
+    pub fn purge_roots(&self) {
+        self.status_cache.write().unwrap().purge_roots();
+    }
 }
 
 /// Manager for the state of all accounts and programs after processing its entries.