Introduces account existence providers reference counting (#7363)

* Initial draft * Latest changes * Final bits. * Fixes * Fixes * Test fixes * Fix tests * Fix babe tests * Fix * Fix * Fix * Fix * Fix * fix warnings in assets * Fix UI tests * fix line width * Fix * Update frame/system/src/lib.rs Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com> * Update frame/system/src/lib.rs Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com> * Fix * fix unused warnings * Fix * Update frame/system/src/lib.rs Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com> * Update frame/system/src/lib.rs Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com> * Fix * fix slash and comprehensive slash test * fix reserved slash and comprehensive tests * check slash on non-existent account * Revert "Fix UI tests" This reverts commit e0002c0f13442f7d0c95a054a6c515536328a4a0. * Fix * Fix utility tests * keep dispatch error backwards compatible * Fix * Fix * fix ui test * Companion checker shouldn't be so anal. * Fix * Fix * Fix * Apply suggestions from code review Co-authored-by: Alexander Popiak <alexander.popiak@parity.io> * Update frame/balances/src/lib.rs Co-authored-by: Alexander Popiak <alexander.popiak@parity.io> * return correct slash info when failing gracefully * fix missing import * Update frame/system/src/lib.rs Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com> * Fix * Update frame/balances/src/tests_local.rs Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com> * Fixes Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com> Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com> Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com> Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>
2026-04-27 17:28:00 +00:00 · 2021-01-16 18:47:28 +01:00
parent 660cf13e6d
commit f1d36a7103
34 changed files with 814 additions and 447 deletions
@@ -27,7 +27,7 @@ use sp_runtime::{
 	traits::{
 		MaybeSerializeDeserialize, AtLeast32Bit, Saturating, TrailingZeroInput, Bounded, Zero,
 		BadOrigin, AtLeast32BitUnsigned, UniqueSaturatedFrom, UniqueSaturatedInto,
-		SaturatedConversion,
+		SaturatedConversion, StoredMapError,
 	},
 };
 use crate::dispatch::Parameter;
@@ -300,41 +300,60 @@ mod test_impl_filter_stack {

 /// An abstraction of a value stored within storage, but possibly as part of a larger composite
 /// item.
-pub trait StoredMap<K, T> {
+pub trait StoredMap<K, T: Default> {
 	/// Get the item, or its default if it doesn't yet exist; we make no distinction between the
 	/// two.
 	fn get(k: &K) -> T;
-	/// Get whether the item takes up any storage. If this is `false`, then `get` will certainly
-	/// return the `T::default()`. If `true`, then there is no implication for `get` (i.e. it
-	/// may return any value, including the default).
-	///
-	/// NOTE: This may still be `true`, even after `remove` is called. This is the case where
-	/// a single storage entry is shared between multiple `StoredMap` items single, without
-	/// additional logic to enforce it, deletion of any one them doesn't automatically imply
-	/// deletion of them all.
-	fn is_explicit(k: &K) -> bool;
-	/// Mutate the item.
-	fn mutate<R>(k: &K, f: impl FnOnce(&mut T) -> R) -> R;
-	/// Mutate the item, removing or resetting to default value if it has been mutated to `None`.
-	fn mutate_exists<R>(k: &K, f: impl FnOnce(&mut Option<T>) -> R) -> R;
+
 	/// Maybe mutate the item only if an `Ok` value is returned from `f`. Do nothing if an `Err` is
 	/// returned. It is removed or reset to default value if it has been mutated to `None`
-	fn try_mutate_exists<R, E>(k: &K, f: impl FnOnce(&mut Option<T>) -> Result<R, E>) -> Result<R, E>;
+	fn try_mutate_exists<R, E: From<StoredMapError>>(
+		k: &K,
+		f: impl FnOnce(&mut Option<T>) -> Result<R, E>,
+	) -> Result<R, E>;
+
+	// Everything past here has a default implementation.
+
+	/// Mutate the item.
+	fn mutate<R>(k: &K, f: impl FnOnce(&mut T) -> R) -> Result<R, StoredMapError> {
+		Self::mutate_exists(k, |maybe_account| match maybe_account {
+			Some(ref mut account) => f(account),
+			x @ None => {
+				let mut account = Default::default();
+				let r = f(&mut account);
+				*x = Some(account);
+				r
+			}
+		})
+	}
+
+	/// Mutate the item, removing or resetting to default value if it has been mutated to `None`.
+	///
+	/// This is infallible as long as the value does not get destroyed.
+	fn mutate_exists<R>(
+		k: &K,
+		f: impl FnOnce(&mut Option<T>) -> R,
+	) -> Result<R, StoredMapError> {
+		Self::try_mutate_exists(k, |x| -> Result<R, StoredMapError> { Ok(f(x)) })
+	}
+
 	/// Set the item to something new.
-	fn insert(k: &K, t: T) { Self::mutate(k, |i| *i = t); }
+	fn insert(k: &K, t: T) -> Result<(), StoredMapError> { Self::mutate(k, |i| *i = t) }
+
 	/// Remove the item or otherwise replace it with its default value; we don't care which.
-	fn remove(k: &K);
+	fn remove(k: &K) -> Result<(), StoredMapError> { Self::mutate_exists(k, |x| *x = None) }
 }

 /// A simple, generic one-parameter event notifier/handler.
-pub trait Happened<T> {
-	/// The thing happened.
-	fn happened(t: &T);
+pub trait HandleLifetime<T> {
+	/// An account was created.
+	fn created(_t: &T) -> Result<(), StoredMapError> { Ok(()) }
+
+	/// An account was killed.
+	fn killed(_t: &T) -> Result<(), StoredMapError> { Ok(()) }
 }

-impl<T> Happened<T> for () {
-	fn happened(_: &T) {}
-}
+impl<T> HandleLifetime<T> for () {}

 /// A shim for placing around a storage item in order to use it as a `StoredValue`. Ideally this
 /// wouldn't be needed as `StorageValue`s should blanket implement `StoredValue`s, however this
@@ -347,68 +366,63 @@ impl<T> Happened<T> for () {
 /// be the default value), or where the account is being removed or reset back to the default value
 /// where previously it did exist (though may have been in a default state). This works well with
 /// system module's `CallOnCreatedAccount` and `CallKillAccount`.
-pub struct StorageMapShim<
-	S,
-	Created,
-	Removed,
-	K,
-	T
->(sp_std::marker::PhantomData<(S, Created, Removed, K, T)>);
+pub struct StorageMapShim<S, L, K, T>(sp_std::marker::PhantomData<(S, L, K, T)>);
 impl<
 	S: StorageMap<K, T, Query=T>,
-	Created: Happened<K>,
-	Removed: Happened<K>,
+	L: HandleLifetime<K>,
 	K: FullCodec,
-	T: FullCodec,
-> StoredMap<K, T> for StorageMapShim<S, Created, Removed, K, T> {
+	T: FullCodec + Default,
+> StoredMap<K, T> for StorageMapShim<S, L, K, T> {
 	fn get(k: &K) -> T { S::get(k) }
-	fn is_explicit(k: &K) -> bool { S::contains_key(k) }
-	fn insert(k: &K, t: T) {
-		let existed = S::contains_key(&k);
+	fn insert(k: &K, t: T) -> Result<(), StoredMapError> {
+		if !S::contains_key(&k) {
+			L::created(k)?;
+		}
 		S::insert(k, t);
-		if !existed {
-			Created::happened(k);
-		}
+		Ok(())
 	}
-	fn remove(k: &K) {
-		let existed = S::contains_key(&k);
-		S::remove(k);
-		if existed {
-			Removed::happened(&k);
+	fn remove(k: &K) -> Result<(), StoredMapError> {
+		if S::contains_key(&k) {
+			L::killed(&k)?;
+			S::remove(k);
 		}
+		Ok(())
 	}
-	fn mutate<R>(k: &K, f: impl FnOnce(&mut T) -> R) -> R {
-		let existed = S::contains_key(&k);
-		let r = S::mutate(k, f);
-		if !existed {
-			Created::happened(k);
+	fn mutate<R>(k: &K, f: impl FnOnce(&mut T) -> R) -> Result<R, StoredMapError> {
+		if !S::contains_key(&k) {
+			L::created(k)?;
 		}
-		r
+		Ok(S::mutate(k, f))
 	}
-	fn mutate_exists<R>(k: &K, f: impl FnOnce(&mut Option<T>) -> R) -> R {
-		let (existed, exists, r) = S::mutate_exists(k, |maybe_value| {
-			let existed = maybe_value.is_some();
-			let r = f(maybe_value);
-			(existed, maybe_value.is_some(), r)
-		});
-		if !existed && exists {
-			Created::happened(k);
-		} else if existed && !exists {
-			Removed::happened(k);
-		}
-		r
-	}
-	fn try_mutate_exists<R, E>(k: &K, f: impl FnOnce(&mut Option<T>) -> Result<R, E>) -> Result<R, E> {
+	fn mutate_exists<R>(k: &K, f: impl FnOnce(&mut Option<T>) -> R) -> Result<R, StoredMapError> {
 		S::try_mutate_exists(k, |maybe_value| {
 			let existed = maybe_value.is_some();
-			f(maybe_value).map(|v| (existed, maybe_value.is_some(), v))
-		}).map(|(existed, exists, v)| {
+			let r = f(maybe_value);
+			let exists = maybe_value.is_some();
+
 			if !existed && exists {
-				Created::happened(k);
+				L::created(k)?;
 			} else if existed && !exists {
-				Removed::happened(k);
+				L::killed(k)?;
 			}
-			v
+			Ok(r)
+		})
+	}
+	fn try_mutate_exists<R, E: From<StoredMapError>>(
+		k: &K,
+		f: impl FnOnce(&mut Option<T>) -> Result<R, E>,
+	) -> Result<R, E> {
+		S::try_mutate_exists(k, |maybe_value| {
+			let existed = maybe_value.is_some();
+			let r = f(maybe_value)?;
+			let exists = maybe_value.is_some();
+
+			if !existed && exists {
+				L::created(k).map_err(E::from)?;
+			} else if existed && !exists {
+				L::killed(k).map_err(E::from)?;
+			}
+			Ok(r)
 		})
 	}
 }
@@ -507,18 +521,6 @@ pub trait ContainsLengthBound {
 	fn max_len() -> usize;
 }

-/// Determiner to say whether a given account is unused.
-pub trait IsDeadAccount<AccountId> {
-	/// Is the given account dead?
-	fn is_dead_account(who: &AccountId) -> bool;
-}
-
-impl<AccountId> IsDeadAccount<AccountId> for () {
-	fn is_dead_account(_who: &AccountId) -> bool {
-		true
-	}
-}
-
 /// Handler for when a new account has been created.
 #[impl_for_tuples(30)]
 pub trait OnNewAccount<AccountId> {