feat(storage): add db table iterator

crates/papyrus_storage/src/db/db_test.rs

@@ -2,7 +2,7 @@ use libmdbx::PageSize;
 use pretty_assertions::assert_eq;
 use tempfile::TempDir;
 
-use crate::db::{get_page_size, open_env, DbReader, DbWriter};
+use crate::db::{get_page_size, open_env, DbIter, DbReader, DbResult, DbWriter};
 use crate::test_utils::get_test_config;
 
 fn get_test_env() -> ((DbReader, DbWriter), TempDir) {
@@ -115,3 +115,38 @@ fn get_page_size_test() {
     assert_eq!(get_page_size(1025), PageSize::Set(1024));
     assert_eq!(get_page_size(2047), PageSize::Set(1024));
 }
+
+#[test]
+fn test_iter() {
+    // Create an environment and a table.
+    let ((reader, mut writer), _temp_dir) = get_test_env();
+    let table_id = writer.create_table::<[u8; 4], [u8; 4]>("table").unwrap();
+
+    // Insert some values.
+    let items = vec![
+        (*b"key1", *b"val1"),
+        (*b"key2", *b"val2"),
+        (*b"key3", *b"val3"),
+        (*b"key5", *b"val5"),
+    ];
+    let wtxn = writer.begin_rw_txn().unwrap();
+    let table = wtxn.open_table(&table_id).unwrap();
+    for (k, v) in &items {
+        table.insert(&wtxn, k, v).unwrap();
+    }
+    wtxn.commit().unwrap();
+
+    // Use the iterator.
+    let txn = reader.begin_ro_txn().unwrap();
+    let mut cursor = txn.open_table(&table_id).unwrap().cursor(&txn).unwrap();
+    let iter = DbIter::new(&mut cursor);
+    assert_eq!(items, iter.collect::<DbResult<Vec<_>>>().unwrap());
+
+    let mut cursor = txn.open_table(&table_id).unwrap().cursor(&txn).unwrap();
+    let mut iter = DbIter::new(&mut cursor);
+    let mut index = 0;
+    while let Some(Ok((k, v))) = iter.next() {
+        assert_eq!(items[index], (k, v));
+        index += 1;
+    }
+}

crates/papyrus_storage/src/db/mod.rs

@@ -380,6 +380,33 @@ impl<'txn, Mode: TransactionKind, K: StorageSerde, V: StorageSerde> DbCursor<'tx
     }
 }
 
+/// A wrapper around a cursor that allows iterating over a table.
+pub(crate) struct DbIter<'cursor, 'txn, Mode: TransactionKind, K: StorageSerde, V: StorageSerde> {
+    cursor: &'cursor mut DbCursor<'txn, Mode, K, V>,
+    _key_type: PhantomData<K>,
+    _value_type: PhantomData<V>,
+}
+
+impl<'cursor, 'txn, Mode: TransactionKind, K: StorageSerde, V: StorageSerde>
+    DbIter<'cursor, 'txn, Mode, K, V>
+{
+    #[allow(dead_code)]
+    pub(crate) fn new(cursor: &'cursor mut DbCursor<'txn, Mode, K, V>) -> Self {
+        Self { cursor, _key_type: PhantomData {}, _value_type: PhantomData {} }
+    }
+}
+
+impl<'cursor, 'txn, Mode: TransactionKind, K: StorageSerde, V: StorageSerde> Iterator
+    for DbIter<'cursor, 'txn, Mode, K, V>
+{
+    type Item = DbResult<(K, V)>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let prev_cursor_res = self.cursor.next().transpose()?;
+        Some(prev_cursor_res)
+    }
+}
+
 #[doc(hidden)]
 pub struct RO {}