Eth connector statistic

src/connector.rs

@@ -582,6 +582,12 @@ impl EthConnectorContract {
         sdk::return_output(0.to_string().as_bytes());
     }
 
+    /// Get accounts counter for statistics.
+    /// It represents total unique accounts (all-time, including accounts which now have zero balance).
+    pub fn get_accounts_counter(&self) {
+        sdk::return_output(self.ft.get_accounts_counter().to_string().as_bytes());
+    }
+
     /// Save eth-connector contract data
     fn save_ft_contract(&mut self) {
         sdk::save_contract(

src/fungible_token.rs

@@ -421,8 +421,24 @@ impl FungibleToken {
         }
     }
 
+    /// Insert account.
+    /// Calculate total unique accounts
     pub fn accounts_insert(&self, account_id: &str, amount: Balance) {
-        sdk::save_contract(&Self::account_to_key(account_id), &amount)
+        if !self.accounts_contains_key(account_id) {
+            let key = Self::get_statistic_key();
+            let accounts_counter = sdk::read_u64(&key)
+                .unwrap_or(0)
+                .checked_add(1)
+                .expect("ERR_ACCOUNTS_COUNTER_OVERFLOW");
+            sdk::write_storage(&key, &accounts_counter.to_le_bytes());
+        }
+        sdk::save_contract(&Self::account_to_key(account_id), &amount);
+    }
+
+    /// Get accounts counter for statistics
+    /// It represents total unique accounts.
+    pub fn get_accounts_counter(&self) -> u64 {
+        sdk::read_u64(&Self::get_statistic_key()).unwrap_or(0)
     }
 
     fn accounts_contains_key(&self, account_id: &str) -> bool {
@@ -446,4 +462,12 @@ impl FungibleToken {
         key.extend_from_slice(account_id.as_bytes());
         key
     }
+
+    /// Key for store contract statistics data
+    fn get_statistic_key() -> Vec<u8> {
+        storage::bytes_to_key(
+            storage::KeyPrefix::EthConnector,
+            &[storage::EthConnectorStorageId::StatisticsAuroraAccountsCounter as u8],
+        )
+    }
 }

src/lib.rs

@@ -447,6 +447,11 @@ mod contract {
         EthConnectorContract::get_instance().ft_on_transfer(&engine)
     }
 
+    #[no_mangle]
+    pub extern "C" fn get_accounts_counter() {
+        EthConnectorContract::get_instance().get_accounts_counter()
+    }
+
     #[cfg(feature = "integration-test")]
     #[no_mangle]
     pub extern "C" fn verify_log_entry() {

src/storage.rs

@@ -25,6 +25,7 @@ pub enum EthConnectorStorageId {
     Contract = 0x0,
     FungibleToken = 0x1,
     UsedEvent = 0x2,
+    StatisticsAuroraAccountsCounter = 0x3,
 }
 
 /// We can't use const generic over Enum, but we can do it over integral type

tests/test_connector.rs

@@ -585,3 +585,16 @@ fn test_ft_transfer_call_fee_greater_than_amount() {
     let balance = total_supply_eth(&master_account, CONTRACT_ACC);
     assert_eq!(balance, 0);
 }
+
+#[test]
+fn test_get_accounts_counter() {
+    let (master_account, contract) = init(CUSTODIAN_ADDRESS);
+    call_deposit_near(&contract, CONTRACT_ACC);
+
+    let counter = master_account.view(CONTRACT_ACC.into(), "get_accounts_counter", &[]);
+    let counter: u128 = String::from_utf8(counter.unwrap())
+        .unwrap()
+        .parse()
+        .unwrap();
+    assert_eq!(counter, 2);
+}