#[cfg(feature = "iterator")]
use std::cmp::Ordering;
use std::collections::BTreeMap;
#[cfg(feature = "iterator")]
use std::iter;
#[cfg(feature = "iterator")]
use std::iter::Peekable;
#[cfg(feature = "iterator")]
use std::ops::{Bound, RangeBounds};
#[cfg(feature = "iterator")]
use cosmwasm_std::{Order, KV};
use cosmwasm_std::{ReadonlyStorage, StdResult, Storage};
#[cfg(feature = "iterator")]
type BTreeMapPairRef<'a, T = Vec<u8>> = (&'a Vec<u8>, &'a T);
pub struct StorageTransaction<'a, S: ReadonlyStorage> {
storage: &'a S,
local_state: BTreeMap<Vec<u8>, Delta>,
rep_log: RepLog,
}
impl<'a, S: ReadonlyStorage> StorageTransaction<'a, S> {
pub fn new(storage: &'a S) -> Self {
StorageTransaction {
storage,
local_state: BTreeMap::new(),
rep_log: RepLog::new(),
}
}
pub fn prepare(self) -> RepLog {
self.rep_log
}
pub fn rollback(self) {}
}
impl<'a, S: ReadonlyStorage> ReadonlyStorage for StorageTransaction<'a, S> {
fn get(&self, key: &[u8]) -> Option<Vec<u8>> {
match self.local_state.get(key) {
Some(val) => match val {
Delta::Set { value } => Some(value.clone()),
Delta::Delete {} => None,
},
None => self.storage.get(key),
}
}
#[cfg(feature = "iterator")]
fn range<'b>(
&'b self,
start: Option<&[u8]>,
end: Option<&[u8]>,
order: Order,
) -> Box<dyn Iterator<Item = KV> + 'b> {
let bounds = range_bounds(start, end);
let local: Box<dyn Iterator<Item = BTreeMapPairRef<Delta>>> =
match (bounds.start_bound(), bounds.end_bound()) {
(Bound::Included(start), Bound::Excluded(end)) if start > end => {
Box::new(iter::empty())
}
_ => {
let local_raw = self.local_state.range(bounds);
match order {
Order::Ascending => Box::new(local_raw),
Order::Descending => Box::new(local_raw.rev()),
}
}
};
let base = self.storage.range(start, end, order);
let merged = MergeOverlay::new(local, base, order);
Box::new(merged)
}
}
impl<'a, S: ReadonlyStorage> Storage for StorageTransaction<'a, S> {
fn set(&mut self, key: &[u8], value: &[u8]) {
let op = Op::Set {
key: key.to_vec(),
value: value.to_vec(),
};
self.local_state.insert(key.to_vec(), op.to_delta());
self.rep_log.append(op);
}
fn remove(&mut self, key: &[u8]) {
let op = Op::Delete { key: key.to_vec() };
self.local_state.insert(key.to_vec(), op.to_delta());
self.rep_log.append(op);
}
}
pub struct RepLog {
ops_log: Vec<Op>,
}
impl RepLog {
fn new() -> Self {
RepLog { ops_log: vec![] }
}
fn append(&mut self, op: Op) {
self.ops_log.push(op);
}
pub fn commit<S: Storage>(self, storage: &mut S) {
for op in self.ops_log {
op.apply(storage);
}
}
}
enum Op {
Set {
key: Vec<u8>,
value: Vec<u8>,
},
Delete {
key: Vec<u8>,
},
}
impl Op {
pub fn apply<S: Storage>(&self, storage: &mut S) {
match self {
Op::Set { key, value } => storage.set(&key, &value),
Op::Delete { key } => storage.remove(&key),
}
}
pub fn to_delta(&self) -> Delta {
match self {
Op::Set { value, .. } => Delta::Set {
value: value.clone(),
},
Op::Delete { .. } => Delta::Delete {},
}
}
}
enum Delta {
Set { value: Vec<u8> },
Delete {},
}
#[cfg(feature = "iterator")]
struct MergeOverlay<'a, L, R>
where
L: Iterator<Item = BTreeMapPairRef<'a, Delta>>,
R: Iterator<Item = KV>,
{
left: Peekable<L>,
right: Peekable<R>,
order: Order,
}
#[cfg(feature = "iterator")]
impl<'a, L, R> MergeOverlay<'a, L, R>
where
L: Iterator<Item = BTreeMapPairRef<'a, Delta>>,
R: Iterator<Item = KV>,
{
fn new(left: L, right: R, order: Order) -> Self {
MergeOverlay {
left: left.peekable(),
right: right.peekable(),
order,
}
}
fn pick_match(&mut self, lkey: Vec<u8>, rkey: Vec<u8>) -> Option<KV> {
let order = match self.order {
Order::Ascending => lkey.cmp(&rkey),
Order::Descending => rkey.cmp(&lkey),
};
match order {
Ordering::Less => self.take_left(),
Ordering::Equal => {
let _ = self.right.next();
self.take_left()
}
Ordering::Greater => self.right.next(),
}
}
fn take_left(&mut self) -> Option<KV> {
let (lkey, lval) = self.left.next().unwrap();
match lval {
Delta::Set { value } => Some((lkey.clone(), value.clone())),
Delta::Delete {} => self.next(),
}
}
}
#[cfg(feature = "iterator")]
impl<'a, L, R> Iterator for MergeOverlay<'a, L, R>
where
L: Iterator<Item = BTreeMapPairRef<'a, Delta>>,
R: Iterator<Item = KV>,
{
type Item = KV;
fn next(&mut self) -> Option<Self::Item> {
let (left, right) = (self.left.peek(), self.right.peek());
match (left, right) {
(Some(litem), Some(ritem)) => {
let (lkey, _) = litem;
let (rkey, _) = ritem;
let (l, r) = (lkey.to_vec(), rkey.to_vec());
self.pick_match(l, r)
}
(Some(_), None) => self.take_left(),
(None, Some(_)) => self.right.next(),
(None, None) => None,
}
}
}
pub fn transactional<S, C, T>(storage: &mut S, callback: C) -> StdResult<T>
where
S: Storage,
C: FnOnce(&mut StorageTransaction<S>) -> StdResult<T>,
{
let mut stx = StorageTransaction::new(storage);
let res = callback(&mut stx)?;
stx.prepare().commit(storage);
Ok(res)
}
#[cfg(feature = "iterator")]
fn range_bounds(start: Option<&[u8]>, end: Option<&[u8]>) -> impl RangeBounds<Vec<u8>> {
(
start.map_or(Bound::Unbounded, |x| Bound::Included(x.to_vec())),
end.map_or(Bound::Unbounded, |x| Bound::Excluded(x.to_vec())),
)
}
#[cfg(test)]
mod test {
use super::*;
use cosmwasm_std::{MemoryStorage, StdError};
#[cfg(feature = "iterator")]
fn iterator_test_suite<S: Storage>(store: &mut S) {
assert_eq!(store.get(b"foo"), Some(b"bar".to_vec()));
assert_eq!(store.range(None, None, Order::Ascending).count(), 1);
store.set(b"ant", b"hill");
store.set(b"ze", b"bra");
store.set(b"bye", b"bye");
store.remove(b"bye");
{
let iter = store.range(None, None, Order::Ascending);
let elements: Vec<KV> = iter.collect();
assert_eq!(
elements,
vec![
(b"ant".to_vec(), b"hill".to_vec()),
(b"foo".to_vec(), b"bar".to_vec()),
(b"ze".to_vec(), b"bra".to_vec()),
]
);
}
{
let iter = store.range(None, None, Order::Descending);
let elements: Vec<KV> = iter.collect();
assert_eq!(
elements,
vec![
(b"ze".to_vec(), b"bra".to_vec()),
(b"foo".to_vec(), b"bar".to_vec()),
(b"ant".to_vec(), b"hill".to_vec()),
]
);
}
{
let iter = store.range(Some(b"f"), Some(b"n"), Order::Ascending);
let elements: Vec<KV> = iter.collect();
assert_eq!(elements, vec![(b"foo".to_vec(), b"bar".to_vec())]);
}
{
let iter = store.range(Some(b"air"), Some(b"loop"), Order::Descending);
let elements: Vec<KV> = iter.collect();
assert_eq!(
elements,
vec![
(b"foo".to_vec(), b"bar".to_vec()),
(b"ant".to_vec(), b"hill".to_vec()),
]
);
}
{
let iter = store.range(Some(b"foo"), Some(b"foo"), Order::Ascending);
let elements: Vec<KV> = iter.collect();
assert_eq!(elements, vec![]);
}
{
let iter = store.range(Some(b"foo"), Some(b"foo"), Order::Descending);
let elements: Vec<KV> = iter.collect();
assert_eq!(elements, vec![]);
}
{
let iter = store.range(Some(b"z"), Some(b"a"), Order::Ascending);
let elements: Vec<KV> = iter.collect();
assert_eq!(elements, vec![]);
}
{
let iter = store.range(Some(b"z"), Some(b"a"), Order::Descending);
let elements: Vec<KV> = iter.collect();
assert_eq!(elements, vec![]);
}
{
let iter = store.range(Some(b"f"), None, Order::Ascending);
let elements: Vec<KV> = iter.collect();
assert_eq!(
elements,
vec![
(b"foo".to_vec(), b"bar".to_vec()),
(b"ze".to_vec(), b"bra".to_vec()),
]
);
}
{
let iter = store.range(Some(b"f"), None, Order::Descending);
let elements: Vec<KV> = iter.collect();
assert_eq!(
elements,
vec![
(b"ze".to_vec(), b"bra".to_vec()),
(b"foo".to_vec(), b"bar".to_vec()),
]
);
}
{
let iter = store.range(None, Some(b"f"), Order::Ascending);
let elements: Vec<KV> = iter.collect();
assert_eq!(elements, vec![(b"ant".to_vec(), b"hill".to_vec()),]);
}
{
let iter = store.range(None, Some(b"no"), Order::Descending);
let elements: Vec<KV> = iter.collect();
assert_eq!(
elements,
vec![
(b"foo".to_vec(), b"bar".to_vec()),
(b"ant".to_vec(), b"hill".to_vec()),
]
);
}
}
#[test]
fn delete_local() {
let mut base = MemoryStorage::new();
let mut check = StorageTransaction::new(&base);
check.set(b"foo", b"bar");
check.set(b"food", b"bank");
check.remove(b"foo");
assert_eq!(check.get(b"foo"), None);
assert_eq!(check.get(b"food"), Some(b"bank".to_vec()));
check.prepare().commit(&mut base);
assert_eq!(base.get(b"foo"), None);
assert_eq!(base.get(b"food"), Some(b"bank".to_vec()));
}
#[test]
fn delete_from_base() {
let mut base = MemoryStorage::new();
base.set(b"foo", b"bar");
let mut check = StorageTransaction::new(&base);
check.set(b"food", b"bank");
check.remove(b"foo");
assert_eq!(check.get(b"foo"), None);
assert_eq!(check.get(b"food"), Some(b"bank".to_vec()));
check.prepare().commit(&mut base);
assert_eq!(base.get(b"foo"), None);
assert_eq!(base.get(b"food"), Some(b"bank".to_vec()));
}
#[test]
#[cfg(feature = "iterator")]
fn storage_transaction_iterator_empty_base() {
let base = MemoryStorage::new();
let mut check = StorageTransaction::new(&base);
check.set(b"foo", b"bar");
iterator_test_suite(&mut check);
}
#[test]
#[cfg(feature = "iterator")]
fn storage_transaction_iterator_with_base_data() {
let mut base = MemoryStorage::new();
base.set(b"foo", b"bar");
let mut check = StorageTransaction::new(&base);
iterator_test_suite(&mut check);
}
#[test]
#[cfg(feature = "iterator")]
fn storage_transaction_iterator_removed_items_from_base() {
let mut base = MemoryStorage::new();
base.set(b"foo", b"bar");
base.set(b"food", b"bank");
let mut check = StorageTransaction::new(&base);
check.remove(b"food");
iterator_test_suite(&mut check);
}
#[test]
fn commit_writes_through() {
let mut base = MemoryStorage::new();
base.set(b"foo", b"bar");
let mut check = StorageTransaction::new(&base);
assert_eq!(check.get(b"foo"), Some(b"bar".to_vec()));
check.set(b"subtx", b"works");
check.prepare().commit(&mut base);
assert_eq!(base.get(b"subtx"), Some(b"works".to_vec()));
}
#[test]
fn storage_remains_readable() {
let mut base = MemoryStorage::new();
base.set(b"foo", b"bar");
let mut stxn1 = StorageTransaction::new(&base);
assert_eq!(stxn1.get(b"foo"), Some(b"bar".to_vec()));
stxn1.set(b"subtx", b"works");
assert_eq!(stxn1.get(b"subtx"), Some(b"works".to_vec()));
assert_eq!(base.get(b"subtx"), None);
stxn1.prepare().commit(&mut base);
assert_eq!(base.get(b"subtx"), Some(b"works".to_vec()));
}
#[test]
fn rollback_has_no_effect() {
let mut base = MemoryStorage::new();
base.set(b"foo", b"bar");
let mut check = StorageTransaction::new(&base);
assert_eq!(check.get(b"foo"), Some(b"bar".to_vec()));
check.set(b"subtx", b"works");
check.rollback();
assert_eq!(base.get(b"subtx"), None);
}
#[test]
fn ignore_same_as_rollback() {
let mut base = MemoryStorage::new();
base.set(b"foo", b"bar");
let mut check = StorageTransaction::new(&base);
assert_eq!(check.get(b"foo"), Some(b"bar".to_vec()));
check.set(b"subtx", b"works");
assert_eq!(base.get(b"subtx"), None);
}
#[test]
fn transactional_works() {
let mut base = MemoryStorage::new();
base.set(b"foo", b"bar");
let res: StdResult<i32> = transactional(&mut base, |store| {
assert_eq!(store.get(b"foo"), Some(b"bar".to_vec()));
store.set(b"good", b"one");
Ok(5)
});
assert_eq!(res.unwrap(), 5);
assert_eq!(base.get(b"good"), Some(b"one".to_vec()));
let res: StdResult<i32> = transactional(&mut base, |store| {
assert_eq!(store.get(b"foo"), Some(b"bar".to_vec()));
assert_eq!(store.get(b"good"), Some(b"one".to_vec()));
store.set(b"bad", b"value");
Err(StdError::underflow(8, 65))
});
assert!(res.is_err());
assert_eq!(base.get(b"bad"), None);
}
}