From 25f3ca7592dd837e1a1449b110c5537222bcb08b Mon Sep 17 00:00:00 2001
From: HaoranYi <haoran.yi@solana.com>
Date: Wed, 28 Feb 2024 18:58:17 +0000
Subject: [PATCH] add finalize for lt hash

---
 accounts-db/src/accounts_hash.rs | 38 ++++++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/accounts-db/src/accounts_hash.rs b/accounts-db/src/accounts_hash.rs
index d6bfd4947855fc..4dfe32c316a096 100644
--- a/accounts-db/src/accounts_hash.rs
+++ b/accounts-db/src/accounts_hash.rs
@@ -1311,6 +1311,26 @@ impl AccountLTHash {
             self.0[i] = self.0[i].wrapping_sub(other.0[i]);
         }
     }
+
+    pub fn finalize(&self) -> AccountHash {
+        let mut hasher = blake3::Hasher::new();
+        hasher.update(self.as_ref());
+
+        AccountHash(Hash::new_from_array(hasher.finalize().into()))
+    }
+}
+
+impl AsRef<[u8]> for AccountLTHash {
+    fn as_ref(&self) -> &[u8] {
+        let ptr = unsafe { slice::from_raw_parts(self.0.as_ptr() as *mut u8, LT_HASH_BYTES) };
+        ptr
+    }
+}
+
+impl AsRef<[u16]> for AccountLTHash {
+    fn as_ref(&self) -> &[u16] {
+        &self.0[..]
+    }
 }
 
 /// Hash of accounts
@@ -2642,7 +2662,7 @@ mod tests {
             0x9924,
         ];
         let lt_hash_hello = get_lt_hash("hello".as_bytes());
-        assert_eq!(lt_hash_hello.to_u16(), LTHASH_HELLO);
+        assert_eq!(AsRef::<[u16]>::as_ref(&lt_hash_hello), &LTHASH_HELLO);
 
         // lt hash for "world!"
         const LTHASH_WORLD: [u16; 1024] = [
@@ -2742,7 +2762,7 @@ mod tests {
             0x171f,
         ];
         let lt_hash_world = get_lt_hash("world!".as_bytes());
-        assert_eq!(lt_hash_world.to_u16(), LTHASH_WORLD);
+        assert_eq!(AsRef::<[u16]>::as_ref(&lt_hash_world), &LTHASH_WORLD);
 
         // add "hello" and "world!"
         let mut expected_sum = [0_u16; LT_HASH_ELEMENT];
@@ -2765,4 +2785,18 @@ mod tests {
 
         assert_eq!(lt_hash.to_u16(), LTHASH_HELLO);
     }
+
+    #[test]
+    fn test_lt_hash_finalize() {
+        let get_lt_hash = |input: &[u8]| -> AccountLTHash {
+            let mut hasher = blake3::Hasher::new();
+            hasher.update(input);
+            AccountLTHash::new_from_reader(hasher.finalize_xof())
+        };
+
+        let lt_hash_hello = get_lt_hash("hello".as_bytes());
+        let final_hash = lt_hash_hello.finalize();
+        let expected = Hash::from_str("6MmGXJNfa8JKF5XhtHuKEhnLmr38vcyqBCwEXCCFnRVN").unwrap();
+        assert_eq!(final_hash.0, expected);
+    }
 }