[db] Add the last_sync_time database entry

This will be used to store the height and timestamp after every sync.

src/database/mod.rs

@@ -64,6 +64,8 @@ pub trait BatchOperations {
     fn set_tx(&mut self, transaction: &TransactionDetails) -> Result<(), Error>;
     /// Store the last derivation index for a given keychain.
     fn set_last_index(&mut self, keychain: KeychainKind, value: u32) -> Result<(), Error>;
+    /// Store the sync time in terms of block height and timestamp
+    fn set_last_sync_time(&mut self, last_sync_time: ConfirmationTime) -> Result<(), Error>;
 
     /// Delete a script_pubkey given the keychain and its child number.
     fn del_script_pubkey_from_path(
@@ -89,6 +91,10 @@ pub trait BatchOperations {
     ) -> Result<Option<TransactionDetails>, Error>;
     /// Delete the last derivation index for a keychain.
     fn del_last_index(&mut self, keychain: KeychainKind) -> Result<Option<u32>, Error>;
+    /// Reset the last sync time to `None`
+    ///
+    /// Returns the removed value
+    fn del_last_sync_time(&mut self) -> Result<Option<ConfirmationTime>, Error>;
 }
 
 /// Trait for reading data from a database
@@ -134,6 +140,8 @@ pub trait Database: BatchOperations {
     fn get_tx(&self, txid: &Txid, include_raw: bool) -> Result<Option<TransactionDetails>, Error>;
     /// Return the last defivation index for a keychain.
     fn get_last_index(&self, keychain: KeychainKind) -> Result<Option<u32>, Error>;
+    /// Return the last sync time, if present
+    fn get_last_sync_time(&self) -> Result<Option<ConfirmationTime>, Error>;
 
     /// Increment the last derivation index for a keychain and return it
     ///
@@ -377,5 +385,23 @@ pub mod test {
         );
     }
 
+    pub fn test_last_sync_time<D: Database>(mut tree: D) {
+        assert!(tree.get_last_sync_time().unwrap().is_none());
+
+        tree.set_last_sync_time(ConfirmationTime {
+            height: 100,
+            timestamp: 1000,
+        })
+        .unwrap();
+
+        let extracted = tree.get_last_sync_time().unwrap();
+        assert!(extracted.is_some());
+        assert_eq!(extracted.as_ref().unwrap().height, 100);
+        assert_eq!(extracted.as_ref().unwrap().timestamp, 1000);
+
+        tree.del_last_sync_time().unwrap();
+        assert!(tree.get_last_sync_time().unwrap().is_none());
+    }
+
     // TODO: more tests...
 }