add storage bumps

contracts/token/fungible/src/storage.rs

@@ -2,27 +2,50 @@ use soroban_sdk::{contracttype, panic_with_error, Address, Env};
 
 use crate::fungible::{emit_approve, emit_transfer, FungibleTokenError};
 
+// Same values as in Stellar Asset Contract (SAC) implementation:
+// https://github.com/stellar/rs-soroban-env/blob/main/soroban-env-host/src/builtin_contracts/stellar_asset_contract/storage_types.rs
+pub(crate) const DAY_IN_LEDGERS: u32 = 17280;
+
+pub(crate) const INSTANCE_EXTEND_AMOUNT: u32 = 7 * DAY_IN_LEDGERS;
+pub(crate) const INSTANCE_TTL_THRESHOLD: u32 = INSTANCE_EXTEND_AMOUNT - DAY_IN_LEDGERS;
+
+pub(crate) const BALANCE_EXTEND_AMOUNT: u32 = 30 * DAY_IN_LEDGERS;
+pub(crate) const BALANCE_TTL_THRESHOLD: u32 = BALANCE_EXTEND_AMOUNT - DAY_IN_LEDGERS;
+
+/// Storage key that maps to [`AllowanceData`]
 #[contracttype]
-struct AllowanceKey {
-    owner: Address,
-    spender: Address,
+pub struct AllowanceKey {
+    pub owner: Address,
+    pub spender: Address,
 }
 
-/// Contains the amount of tokens for which an allowance is granted and the
-/// ledger number at which this allowance expires.
+/// Storage container for the amount of tokens for which an allowance is granted
+/// and the ledger number at which this allowance expires.
 #[contracttype]
 pub struct AllowanceData {
     pub value: i128,
     pub live_until_ledger: u32,
 }
 
+/// Storage keys for the data associated with `FungibleToken`
 #[contracttype]
-enum StorageKey {
+pub enum StorageKey {
     TotalSupply,
     Balance(Address),
     Allowance(AllowanceKey),
 }
 
+/// Extends the Time-to-Live (TTL) value of the instance storage entry.
+///
+/// # Arguments
+///
+/// * `e` - Access to the Soroban environment.
+/// * `ttl_threshold` - The TTL threshold below which the entry can be extended.
+/// * `extend_amount` - The new TTL value.
+pub fn bump_instance(e: &Env, ttl_threshold: u32, extend_amount: u32) {
+    e.storage().instance().extend_ttl(ttl_threshold, extend_amount);
+}
+
 // ################## QUERY STATE ##################
 
 /// Returns the total amount of tokens in circulation. If no supply is recorded,
@@ -32,6 +55,7 @@ enum StorageKey {
 ///
 /// * `e` - Access to the Soroban environment.
 pub fn total_supply(e: &Env) -> i128 {
+    bump_instance(e, INSTANCE_TTL_THRESHOLD, INSTANCE_EXTEND_AMOUNT);
     e.storage().instance().get(&StorageKey::TotalSupply).unwrap_or(0)
 }
 
@@ -43,8 +67,13 @@ pub fn total_supply(e: &Env) -> i128 {
 /// * `e` - Access to the Soroban environment.
 /// * `account` - The address for which the balance is being queried.
 pub fn balance(e: &Env, account: &Address) -> i128 {
-    // TODO: extend persistent?
-    e.storage().persistent().get(&StorageKey::Balance(account.clone())).unwrap_or(0)
+    let key = StorageKey::Balance(account.clone());
+    if let Some(balance) = e.storage().persistent().get::<_, i128>(&key) {
+        e.storage().persistent().extend_ttl(&key, BALANCE_TTL_THRESHOLD, BALANCE_EXTEND_AMOUNT);
+        balance
+    } else {
+        0
+    }
 }
 
 /// Returns the amount of tokens a `spender` is allowed to spend on behalf of an

contracts/token/fungible/src/test.rs

@@ -4,13 +4,16 @@ extern crate std;
 
 use soroban_sdk::{
     contract, symbol_short,
-    testutils::{Address as _, Events, Ledger},
+    testutils::{
+        storage::{Instance, Persistent},
+        Address as _, Events, Ledger,
+    },
     vec, Address, Env, IntoVal,
 };
 
 use crate::storage::{
-    allowance, approve, balance, burn, mint, set_allowance, spend_allowance, total_supply,
-    transfer, transfer_from, update,
+    allowance, approve, balance, bump_instance, burn, mint, set_allowance, spend_allowance,
+    total_supply, transfer, transfer_from, update, StorageKey, BALANCE_EXTEND_AMOUNT,
 };
 
 #[contract]
@@ -27,6 +30,34 @@ fn initial_state() {
     });
 }
 
+#[test]
+fn bump_instance_works() {
+    let e = Env::default();
+
+    e.ledger().with_mut(|l| {
+        // Minimum TTL for persistent entries - new persistent (and instance)
+        // entries will have this TTL when created.
+        l.min_persistent_entry_ttl = 500;
+    });
+
+    let address = e.register(MockContract, ());
+
+    e.as_contract(&address, || {
+        let ttl = e.storage().instance().get_ttl();
+        // Note, that TTL doesn't include the current ledger, but when entry
+        // is created the current ledger is counted towards the number of
+        // ledgers specified by `min_persistent_entry_ttl`, thus
+        // the TTL is 1 ledger less than the respective setting.
+        assert_eq!(ttl, 499);
+
+        let current = e.ledger().sequence();
+        e.ledger().set_sequence_number(current + ttl);
+
+        bump_instance(&e, 400, 500);
+        assert_eq!(e.storage().instance().get_ttl(), 500);
+    });
+}
+
 #[test]
 fn mint_works() {
     let e = Env::default();
@@ -191,6 +222,29 @@ fn transfer_works() {
     });
 }
 
+#[test]
+fn extend_balance_ttl_thru_transfer() {
+    let e = Env::default();
+    e.mock_all_auths();
+    let address = e.register(MockContract, ());
+    let from = Address::generate(&e);
+    let recipient = Address::generate(&e);
+
+    e.as_contract(&address, || {
+        mint(&e, &from, 100);
+
+        let key = StorageKey::Balance(from.clone());
+
+        let ttl = e.storage().persistent().get_ttl(&key);
+        e.ledger().with_mut(|l| {
+            l.sequence_number += ttl;
+        });
+        transfer(&e, &from, &recipient, 50);
+        let ttl = e.storage().persistent().get_ttl(&key);
+        assert_eq!(ttl, BALANCE_EXTEND_AMOUNT);
+    });
+}
+
 #[test]
 fn approve_and_transfer_from() {
     let e = Env::default();

contracts/token/fungible/test_snapshots/test/approve_and_transfer_from.1.json

@@ -188,7 +188,7 @@
             },
             "ext": "v0"
           },
-          4095
+          518400
         ]
       ],
       [
@@ -236,7 +236,7 @@
             },
             "ext": "v0"
           },
-          4095
+          518400
         ]
       ],
       [
@@ -284,7 +284,7 @@
             },
             "ext": "v0"
           },
-          4095
+          120960
         ]
       ],
       [
@@ -371,7 +371,7 @@
             },
             "ext": "v0"
           },
-          4095
+          120960
         ]
       ]
     ]

contracts/token/fungible/test_snapshots/test/bump_instance_works.1.json

@@ -0,0 +1,76 @@
+{
+  "generators": {
+    "address": 1,
+    "nonce": 0
+  },
+  "auth": [
+    [],
+    []
+  ],
+  "ledger": {
+    "protocol_version": 22,
+    "sequence_number": 499,
+    "timestamp": 0,
+    "network_id": "0000000000000000000000000000000000000000000000000000000000000000",
+    "base_reserve": 0,
+    "min_persistent_entry_ttl": 500,
+    "min_temp_entry_ttl": 16,
+    "max_entry_ttl": 6312000,
+    "ledger_entries": [
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM",
+            "key": "ledger_key_contract_instance",
+            "durability": "persistent"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM",
+                "key": "ledger_key_contract_instance",
+                "durability": "persistent",
+                "val": {
+                  "contract_instance": {
+                    "executable": {
+                      "wasm": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+                    },
+                    "storage": null
+                  }
+                }
+              }
+            },
+            "ext": "v0"
+          },
+          999
+        ]
+      ],
+      [
+        {
+          "contract_code": {
+            "hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_code": {
+                "ext": "v0",
+                "hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
+                "code": ""
+              }
+            },
+            "ext": "v0"
+          },
+          999
+        ]
+      ]
+    ]
+  },
+  "events": []
+}

contracts/token/fungible/test_snapshots/test/burn_works.1.json

@@ -62,7 +62,7 @@
             },
             "ext": "v0"
           },
-          4095
+          518400
         ]
       ],
       [
@@ -110,7 +110,7 @@
             },
             "ext": "v0"
           },
-          4095
+          120960
         ]
       ],
       [
@@ -131,7 +131,7 @@
             },
             "ext": "v0"
           },
-          4095
+          120960
         ]
       ]
     ]