diff --git a/substrate/frame/support/src/dispatch.rs b/substrate/frame/support/src/dispatch.rs
index 4287f2c1ceba39cc16c663845859fb182b39514d..31e3efb001a70824cd31f884de238d2b8914b773 100644
--- a/substrate/frame/support/src/dispatch.rs
+++ b/substrate/frame/support/src/dispatch.rs
@@ -46,10 +46,6 @@ pub type DispatchResult = Result<(), sp_runtime::DispatchError>;
pub type DispatchErrorWithPostInfo =
sp_runtime::DispatchErrorWithPostInfo<crate::weights::PostDispatchInfo>;
-
-/// A type that cannot be instantiated.
-pub enum Never {}
-
/// Serializable version of Dispatchable.
/// This value can be used as a "function" in an extrinsic.
pub trait Callable<T> {
@@ -1316,7 +1312,7 @@ macro_rules! decl_module {
{
#[doc(hidden)]
#[codec(skip)]
- __PhantomItem($crate::sp_std::marker::PhantomData<($trait_instance, $($instance)?)>, $crate::dispatch::Never),
+ __PhantomItem($crate::sp_std::marker::PhantomData<($trait_instance, $($instance)?)>, $crate::Never),
$( $generated_variants )*
}
};
diff --git a/substrate/frame/support/src/error.rs b/substrate/frame/support/src/error.rs
index a06f46889224dd7fb1ebcbe56426ce35e1ecb895..2fdba88156404a31ff7801f2d9532209a40a96a9 100644
--- a/substrate/frame/support/src/error.rs
+++ b/substrate/frame/support/src/error.rs
@@ -89,7 +89,7 @@ macro_rules! decl_error {
#[doc(hidden)]
__Ignore(
$crate::sp_std::marker::PhantomData<($generic, $( $inst_generic)?)>,
- $crate::dispatch::Never,
+ $crate::Never,
),
$(
$( #[doc = $doc_attr] )*
diff --git a/substrate/frame/support/src/lib.rs b/substrate/frame/support/src/lib.rs
index 8a88496eda0bab28a1eec585cdd971000446f60d..49ad802d07dc48624ac4c12e3b2e0a72731017cb 100644
--- a/substrate/frame/support/src/lib.rs
+++ b/substrate/frame/support/src/lib.rs
@@ -78,6 +78,10 @@ pub use self::storage::{
pub use self::dispatch::{Parameter, Callable, IsSubType};
pub use sp_runtime::{self, ConsensusEngineId, print, traits::Printable};
+/// A type that cannot be instantiated.
+#[derive(Debug)]
+pub enum Never {}
+
/// Macro for easily creating a new implementation of the `Get` trait. Use similarly to
/// how you would declare a `const`:
///
diff --git a/substrate/frame/support/src/storage/generator/double_map.rs b/substrate/frame/support/src/storage/generator/double_map.rs
index e23b332383c68b36b4b05c7950d1bd6d9473fdb9..c7e4c10017e706275727f687228516bb6e55aca0 100644
--- a/substrate/frame/support/src/storage/generator/double_map.rs
+++ b/substrate/frame/support/src/storage/generator/double_map.rs
@@ -17,7 +17,7 @@
use sp_std::prelude::*;
use sp_std::borrow::Borrow;
use codec::{Ref, FullCodec, FullEncode, Decode, Encode, EncodeLike, EncodeAppend};
-use crate::{storage::{self, unhashed}, traits::Len};
+use crate::{storage::{self, unhashed}, traits::Len, Never};
use crate::hash::{StorageHasher, Twox128, ReversibleStorageHasher};
/// Generator for `StorageDoubleMap` used by `decl_storage`.
@@ -223,14 +223,24 @@ impl<K1, K2, V, G> storage::StorageDoubleMap<K1, K2, V> for G where
KArg1: EncodeLike<K1>,
KArg2: EncodeLike<K2>,
F: FnOnce(&mut Self::Query) -> R,
+ {
+ Self::try_mutate(k1, k2, |v| Ok::<R, Never>(f(v))).expect("`Never` can not be constructed; qed")
+ }
+
+ fn try_mutate<KArg1, KArg2, R, E, F>(k1: KArg1, k2: KArg2, f: F) -> Result<R, E> where
+ KArg1: EncodeLike<K1>,
+ KArg2: EncodeLike<K2>,
+ F: FnOnce(&mut Self::Query) -> Result<R, E>,
{
let final_key = Self::storage_double_map_final_key(k1, k2);
let mut val = G::from_optional_value_to_query(unhashed::get(final_key.as_ref()));
let ret = f(&mut val);
- match G::from_query_to_optional_value(val) {
- Some(ref val) => unhashed::put(final_key.as_ref(), val),
- None => unhashed::kill(final_key.as_ref()),
+ if ret.is_ok() {
+ match G::from_query_to_optional_value(val) {
+ Some(ref val) => unhashed::put(final_key.as_ref(), val),
+ None => unhashed::kill(final_key.as_ref()),
+ }
}
ret
}
diff --git a/substrate/frame/support/src/storage/generator/map.rs b/substrate/frame/support/src/storage/generator/map.rs
index c29a9a223aacf578d162864ef9a119aa015e78bc..cc871072f5f40f550464c33400978b53358970a8 100644
--- a/substrate/frame/support/src/storage/generator/map.rs
+++ b/substrate/frame/support/src/storage/generator/map.rs
@@ -18,7 +18,7 @@
use sp_std::prelude::*;
use sp_std::borrow::Borrow;
use codec::{FullCodec, FullEncode, Decode, Encode, EncodeLike, Ref, EncodeAppend};
-use crate::{storage::{self, unhashed}, traits::Len};
+use crate::{storage::{self, unhashed}, traits::Len, Never};
use crate::hash::{StorageHasher, Twox128, ReversibleStorageHasher};
/// Generator for `StorageMap` used by `decl_storage`.
@@ -229,27 +229,11 @@ impl<K: FullEncode, V: FullCodec, G: StorageMap<K, V>> storage::StorageMap<K, V>
}
fn mutate<KeyArg: EncodeLike<K>, R, F: FnOnce(&mut Self::Query) -> R>(key: KeyArg, f: F) -> R {
- let final_key = Self::storage_map_final_key(key);
- let mut val = G::from_optional_value_to_query(unhashed::get(final_key.as_ref()));
-
- let ret = f(&mut val);
- match G::from_query_to_optional_value(val) {
- Some(ref val) => unhashed::put(final_key.as_ref(), &val),
- None => unhashed::kill(final_key.as_ref()),
- }
- ret
+ Self::try_mutate(key, |v| Ok::<R, Never>(f(v))).expect("`Never` can not be constructed; qed")
}
fn mutate_exists<KeyArg: EncodeLike<K>, R, F: FnOnce(&mut Option<V>) -> R>(key: KeyArg, f: F) -> R {
- let final_key = Self::storage_map_final_key(key);
- let mut val = unhashed::get(final_key.as_ref());
-
- let ret = f(&mut val);
- match val {
- Some(ref val) => unhashed::put(final_key.as_ref(), &val),
- None => unhashed::kill(final_key.as_ref()),
- }
- ret
+ Self::try_mutate_exists(key, |v| Ok::<R, Never>(f(v))).expect("`Never` can not be constructed; qed")
}
fn try_mutate<KeyArg: EncodeLike<K>, R, E, F: FnOnce(&mut Self::Query) -> Result<R, E>>(
diff --git a/substrate/frame/support/src/storage/generator/mod.rs b/substrate/frame/support/src/storage/generator/mod.rs
index 687d8a3c9361ba1ca217ee22947a349ae9095955..07e75055f356a87435fc0ec700e5afdb0795c877 100644
--- a/substrate/frame/support/src/storage/generator/mod.rs
+++ b/substrate/frame/support/src/storage/generator/mod.rs
@@ -37,6 +37,7 @@ mod tests {
use sp_io::TestExternalities;
use codec::Encode;
use crate::storage::{unhashed, generator::StorageValue, IterableStorageMap};
+ use crate::{assert_noop, assert_ok};
struct Runtime {}
pub trait Trait {
@@ -57,6 +58,7 @@ mod tests {
trait Store for Module<T: Trait> as Runtime {
Value get(fn value) config(): (u64, u64);
NumberMap: map hasher(identity) u32 => u64;
+ DoubleMap: double_map hasher(identity) u32, hasher(identity) u32 => u64;
}
}
@@ -102,4 +104,54 @@ mod tests {
);
})
}
+
+ #[test]
+ fn try_mutate_works() {
+ let t = GenesisConfig::default().build_storage().unwrap();
+ TestExternalities::new(t).execute_with(|| {
+ assert_eq!(Value::get(), (0, 0));
+ assert_eq!(NumberMap::get(0), 0);
+ assert_eq!(DoubleMap::get(0, 0), 0);
+
+ // `assert_noop` ensures that the state does not change
+ assert_noop!(Value::try_mutate(|value| -> Result<(), &'static str> {
+ *value = (2, 2);
+ Err("don't change value")
+ }), "don't change value");
+
+ assert_noop!(NumberMap::try_mutate(0, |value| -> Result<(), &'static str> {
+ *value = 4;
+ Err("don't change value")
+ }), "don't change value");
+
+ assert_noop!(DoubleMap::try_mutate(0, 0, |value| -> Result<(), &'static str> {
+ *value = 6;
+ Err("don't change value")
+ }), "don't change value");
+
+ // Showing this explicitly for clarity
+ assert_eq!(Value::get(), (0, 0));
+ assert_eq!(NumberMap::get(0), 0);
+ assert_eq!(DoubleMap::get(0, 0), 0);
+
+ assert_ok!(Value::try_mutate(|value| -> Result<(), &'static str> {
+ *value = (2, 2);
+ Ok(())
+ }));
+
+ assert_ok!(NumberMap::try_mutate(0, |value| -> Result<(), &'static str> {
+ *value = 4;
+ Ok(())
+ }));
+
+ assert_ok!(DoubleMap::try_mutate(0, 0, |value| -> Result<(), &'static str> {
+ *value = 6;
+ Ok(())
+ }));
+
+ assert_eq!(Value::get(), (2, 2));
+ assert_eq!(NumberMap::get(0), 4);
+ assert_eq!(DoubleMap::get(0, 0), 6);
+ });
+ }
}
diff --git a/substrate/frame/support/src/storage/generator/value.rs b/substrate/frame/support/src/storage/generator/value.rs
index 9e26131f48949637be4a8779169e97bddc9396a0..dd9bbded4b8ebb10f8553a24db37099935a15290 100644
--- a/substrate/frame/support/src/storage/generator/value.rs
+++ b/substrate/frame/support/src/storage/generator/value.rs
@@ -17,7 +17,12 @@
#[cfg(not(feature = "std"))]
use sp_std::prelude::*;
use codec::{FullCodec, Encode, EncodeAppend, EncodeLike, Decode};
-use crate::{storage::{self, unhashed}, hash::{Twox128, StorageHasher}, traits::Len};
+use crate::{
+ Never,
+ storage::{self, unhashed},
+ hash::{Twox128, StorageHasher},
+ traits::Len
+};
/// Generator for `StorageValue` used by `decl_storage`.
///
@@ -104,12 +109,18 @@ impl<T: FullCodec, G: StorageValue<T>> storage::StorageValue<T> for G {
}
fn mutate<R, F: FnOnce(&mut G::Query) -> R>(f: F) -> R {
+ Self::try_mutate(|v| Ok::<R, Never>(f(v))).expect("`Never` can not be constructed; qed")
+ }
+
+ fn try_mutate<R, E, F: FnOnce(&mut G::Query) -> Result<R, E>>(f: F) -> Result<R, E> {
let mut val = G::get();
let ret = f(&mut val);
- match G::from_query_to_optional_value(val) {
- Some(ref val) => G::put(val),
- None => G::kill(),
+ if ret.is_ok() {
+ match G::from_query_to_optional_value(val) {
+ Some(ref val) => G::put(val),
+ None => G::kill(),
+ }
}
ret
}
diff --git a/substrate/frame/support/src/storage/mod.rs b/substrate/frame/support/src/storage/mod.rs
index 47201e22e602e9a8510de35ccf2de8eaa0181633..3a811c20e364433f9ea6bd542b95a9acddef2b01 100644
--- a/substrate/frame/support/src/storage/mod.rs
+++ b/substrate/frame/support/src/storage/mod.rs
@@ -80,6 +80,9 @@ pub trait StorageValue<T: FullCodec> {
/// Mutate the value
fn mutate<R, F: FnOnce(&mut Self::Query) -> R>(f: F) -> R;
+ /// Mutate the value if closure returns `Ok`
+ fn try_mutate<R, E, F: FnOnce(&mut Self::Query) -> Result<R, E>>(f: F) -> Result<R, E>;
+
/// Clear the storage value.
fn kill();
@@ -280,21 +283,25 @@ pub trait StorageDoubleMap<K1: FullEncode, K2: FullEncode, V: FullCodec> {
/// The type that get/take returns.
type Query;
+ /// Get the storage key used to fetch a value corresponding to a specific key.
fn hashed_key_for<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Vec<u8>
where
KArg1: EncodeLike<K1>,
KArg2: EncodeLike<K2>;
+ /// Does the value (explicitly) exist in storage?
fn contains_key<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> bool
where
KArg1: EncodeLike<K1>,
KArg2: EncodeLike<K2>;
+ /// Load the value associated with the given key from the double map.
fn get<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Self::Query
where
KArg1: EncodeLike<K1>,
KArg2: EncodeLike<K2>;
+ /// Take a value from storage, removing it afterwards.
fn take<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Self::Query
where
KArg1: EncodeLike<K1>,
@@ -308,28 +315,43 @@ pub trait StorageDoubleMap<K1: FullEncode, K2: FullEncode, V: FullCodec> {
YKArg1: EncodeLike<K1>,
YKArg2: EncodeLike<K2>;
+ /// Store a value to be associated with the given keys from the double map.
fn insert<KArg1, KArg2, VArg>(k1: KArg1, k2: KArg2, val: VArg)
where
KArg1: EncodeLike<K1>,
KArg2: EncodeLike<K2>,
VArg: EncodeLike<V>;
+ /// Remove the value under the given keys.
fn remove<KArg1, KArg2>(k1: KArg1, k2: KArg2)
where
KArg1: EncodeLike<K1>,
KArg2: EncodeLike<K2>;
+ /// Remove all values under the first key.
fn remove_prefix<KArg1>(k1: KArg1) where KArg1: ?Sized + EncodeLike<K1>;
+ /// Iterate over values that share the first key.
fn iter_prefix_values<KArg1>(k1: KArg1) -> PrefixIterator<V>
where KArg1: ?Sized + EncodeLike<K1>;
+ /// Mutate the value under the given keys.
fn mutate<KArg1, KArg2, R, F>(k1: KArg1, k2: KArg2, f: F) -> R
where
KArg1: EncodeLike<K1>,
KArg2: EncodeLike<K2>,
F: FnOnce(&mut Self::Query) -> R;
+ /// Mutate the value under the given keys when the closure returns `Ok`.
+ fn try_mutate<KArg1, KArg2, R, E, F>(k1: KArg1, k2: KArg2, f: F) -> Result<R, E>
+ where
+ KArg1: EncodeLike<K1>,
+ KArg2: EncodeLike<K2>,
+ F: FnOnce(&mut Self::Query) -> Result<R, E>;
+
+ /// Append the given item to the value in the storage.
+ ///
+ /// `V` is required to implement `codec::EncodeAppend`.
fn append<Items, Item, EncodeLikeItem, KArg1, KArg2>(
k1: KArg1,
k2: KArg2,
@@ -344,6 +366,10 @@ pub trait StorageDoubleMap<K1: FullEncode, K2: FullEncode, V: FullCodec> {
Items: IntoIterator<Item=EncodeLikeItem>,
Items::IntoIter: ExactSizeIterator;
+ /// Safely append the given items to the value in the storage. If a codec error occurs, then the
+ /// old (presumably corrupt) value is replaced with the given `items`.
+ ///
+ /// `V` is required to implement `codec::EncodeAppend`.
fn append_or_insert<Items, Item, EncodeLikeItem, KArg1, KArg2>(
k1: KArg1,
k2: KArg2,