Contracts | Gas-Efficient Storage: Bump Ledger Expiration

README.md

@@ -10,6 +10,19 @@ This repository contains smart contracts for the StellarFlow Network with a time
 - **Admin-Only Operations**: Only contract administrators can propose and execute upgrades
 - **Upgrade Cancellation**: Ability to cancel pending upgrades before execution
 - **Timelock Monitoring**: Functions to check remaining timelock time
+- **State Expiration Management**: Automatic TTL extension to prevent data deletion
+
+## State Expiration Management
+
+To ensure contract data is never deleted due to Soroban's state expiration mechanism, the contract uses persistent storage and automatically extends TTL (Time-To-Live) for all storage entries. TTL is extended to approximately 1 year (535,000 ledgers) whenever data is accessed or modified.
+
+### Implementation Details
+
+- **Persistent Storage**: All contract state is stored in persistent storage to survive contract upgrades
+- **Automatic TTL Extension**: `env.storage().persistent().extend_ttl()` is called in all update functions
+- **TTL Parameters**: 
+  - Minimum ledgers: 535,000 (≈1 year)
+  - Maximum ledgers: 1,000,000 (≈2 years)
 
 ## Architecture
 
@@ -90,6 +103,7 @@ cargo test
 ✅ **Pending State Storage**: New WASM hash stored in pending state before commitment  
 ✅ **48-Hour Delay**: Enforced delay between proposal and execution  
 ✅ **Flash Upgrade Prevention**: Complete protection against immediate upgrades  
+✅ **State Expiration Management**: Uses `env.storage().persistent().extend_ttl()` to keep data alive  
 
 ## Build and Deploy
 

src/lib.rs

@@ -5,6 +5,10 @@ const DATA_KEY: Symbol = Symbol::short("DATA");
 const PENDING_UPGRADE_KEY: Symbol = Symbol::short("PENDING");
 const UPGRADE_DELAY_SECONDS: u64 = 48 * 60 * 60; // 48 hours in seconds
 
+// TTL extension parameters (approximately 1 year in ledgers)
+const MIN_LEDGERS_TTL: u32 = 535_000;
+const MAX_LEDGERS_TTL: u32 = 1_000_000;
+
 #[contracttype]
 pub struct PendingUpgrade {
     pub new_wasm_hash: BytesN<32>,
@@ -26,7 +30,7 @@ pub struct TimeLockedUpgradeContract;
 impl TimeLockedUpgradeContract {
     /// Initialize the contract with an admin address
     pub fn initialize(env: Env, admin: Address) {
-        if env.storage().instance().has(&DATA_KEY) {
+        if env.storage().persistent().has(&DATA_KEY) {
             panic!("contract already initialized");
         }
 
@@ -37,15 +41,18 @@ impl TimeLockedUpgradeContract {
             value: 0,
         };
 
-        env.storage().instance().set(&DATA_KEY, &data);
+        env.storage().persistent().set(&DATA_KEY, &data);
+        env.storage().persistent().extend_ttl(MIN_LEDGERS_TTL, MAX_LEDGERS_TTL, &DATA_KEY);
     }
 
     /// Get the current contract data
     pub fn get_data(env: Env) -> ContractData {
-        env.storage()
-            .instance()
+        let data = env.storage()
+            .persistent()
             .get(&DATA_KEY)
-            .unwrap_or_else(|| panic!("contract not initialized"))
+            .unwrap_or_else(|| panic!("contract not initialized"));
+        env.storage().persistent().extend_ttl(MIN_LEDGERS_TTL, MAX_LEDGERS_TTL, &DATA_KEY);
+        data
     }
 
     /// Propose an upgrade with a new WASM hash
@@ -68,7 +75,8 @@ impl TimeLockedUpgradeContract {
             proposer: proposer.clone(),
         };
 
-        env.storage().instance().set(&PENDING_UPGRADE_KEY, &pending_upgrade);
+        env.storage().persistent().set(&PENDING_UPGRADE_KEY, &pending_upgrade);
+        env.storage().persistent().extend_ttl(MIN_LEDGERS_TTL, MAX_LEDGERS_TTL, &PENDING_UPGRADE_KEY);
     }
 
     /// Execute a pending upgrade if the timelock period has passed
@@ -84,7 +92,7 @@ impl TimeLockedUpgradeContract {
 
         let pending_upgrade: PendingUpgrade = env
             .storage()
-            .instance()
+            .persistent()
             .get(&PENDING_UPGRADE_KEY)
             .unwrap_or_else(|| panic!("no pending upgrade"));
 
@@ -104,7 +112,7 @@ impl TimeLockedUpgradeContract {
             .update_current_contract(pending_upgrade.new_wasm_hash);
 
         // Clear the pending upgrade
-        env.storage().instance().remove(&PENDING_UPGRADE_KEY);
+        env.storage().persistent().remove(&PENDING_UPGRADE_KEY);
     }
 
     /// Cancel a pending upgrade
@@ -118,16 +126,21 @@ impl TimeLockedUpgradeContract {
 
         canceller.require_auth();
 
-        if !env.storage().instance().has(&PENDING_UPGRADE_KEY) {
+        if !env.storage().persistent().has(&PENDING_UPGRADE_KEY) {
             panic!("no pending upgrade to cancel");
         }
 
-        env.storage().instance().remove(&PENDING_UPGRADE_KEY);
+        env.storage().persistent().remove(&PENDING_UPGRADE_KEY);
     }
 
     /// Get the current pending upgrade information
     pub fn get_pending_upgrade(env: Env) -> Option<PendingUpgrade> {
-        env.storage().instance().get(&PENDING_UPGRADE_KEY)
+        if let Some(pending) = env.storage().persistent().get(&PENDING_UPGRADE_KEY) {
+            env.storage().persistent().extend_ttl(MIN_LEDGERS_TTL, MAX_LEDGERS_TTL, &PENDING_UPGRADE_KEY);
+            Some(pending)
+        } else {
+            None
+        }
     }
 
     /// Get the remaining time before an upgrade can be executed
@@ -158,7 +171,8 @@ impl TimeLockedUpgradeContract {
         setter.require_auth();
 
         data.value = value;
-        env.storage().instance().set(&DATA_KEY, &data);
+        env.storage().persistent().set(&DATA_KEY, &data);
+        env.storage().persistent().extend_ttl(MIN_LEDGERS_TTL, MAX_LEDGERS_TTL, &DATA_KEY);
     }
 }