Trait frame_support::storage::StoragePrefixedMap
source · pub trait StoragePrefixedMap<Value: FullCodec> {
fn module_prefix() -> &'static [u8] ⓘ;
fn storage_prefix() -> &'static [u8] ⓘ;
fn final_prefix() -> [u8; 32] { ... }
fn remove_all(limit: Option<u32>) -> KillStorageResult { ... }
fn clear(limit: u32, maybe_cursor: Option<&[u8]>) -> MultiRemovalResults { ... }
fn iter_values() -> PrefixIterator<Value> ⓘ { ... }
fn translate_values<OldValue: Decode, F: FnMut(OldValue) -> Option<Value>>(
f: F
) { ... }
}Expand description
Trait for maps that store all its value after a unique prefix.
By default the final prefix is:
Twox128(module_prefix) ++ Twox128(storage_prefix)
Required Methods§
sourcefn module_prefix() -> &'static [u8] ⓘ
fn module_prefix() -> &'static [u8] ⓘ
Module prefix. Used for generating final key.
sourcefn storage_prefix() -> &'static [u8] ⓘ
fn storage_prefix() -> &'static [u8] ⓘ
Storage prefix. Used for generating final key.
Provided Methods§
sourcefn final_prefix() -> [u8; 32]
fn final_prefix() -> [u8; 32]
Final full prefix that prefixes all keys.
Examples found in repository?
src/storage/mod.rs (line 1188)
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fn remove_all(limit: Option<u32>) -> sp_io::KillStorageResult {
unhashed::clear_prefix(&Self::final_prefix(), limit, None).into()
}
/// Attempt to remove all items from the map.
///
/// Returns [`MultiRemovalResults`](sp_io::MultiRemovalResults) to inform about the result. Once
/// the resultant `maybe_cursor` field is `None`, then no further items remain to be deleted.
///
/// NOTE: After the initial call for any given map, it is important that no further items
/// are inserted into the map. If so, then the map may not be empty when the resultant
/// `maybe_cursor` is `None`.
///
/// # Limit
///
/// A `limit` must always be provided through in order to cap the maximum
/// amount of deletions done in a single call. This is one fewer than the
/// maximum number of backend iterations which may be done by this operation and as such
/// represents the maximum number of backend deletions which may happen. A `limit` of zero
/// implies that no keys will be deleted, though there may be a single iteration done.
///
/// # Cursor
///
/// A *cursor* may be passed in to this operation with `maybe_cursor`. `None` should only be
/// passed once (in the initial call) for any given storage map. Subsequent calls
/// operating on the same map should always pass `Some`, and this should be equal to the
/// previous call result's `maybe_cursor` field.
fn clear(limit: u32, maybe_cursor: Option<&[u8]>) -> sp_io::MultiRemovalResults {
unhashed::clear_prefix(&Self::final_prefix(), Some(limit), maybe_cursor)
}
/// Iter over all value of the storage.
///
/// NOTE: If a value failed to decode because storage is corrupted then it is skipped.
fn iter_values() -> PrefixIterator<Value> {
let prefix = Self::final_prefix();
PrefixIterator {
prefix: prefix.to_vec(),
previous_key: prefix.to_vec(),
drain: false,
closure: |_raw_key, mut raw_value| Value::decode(&mut raw_value),
phantom: Default::default(),
}
}
/// Translate the values of all elements by a function `f`, in the map in no particular order.
/// By returning `None` from `f` for an element, you'll remove it from the map.
///
/// NOTE: If a value fail to decode because storage is corrupted then it is skipped.
///
/// # Warning
///
/// This function must be used with care, before being updated the storage still contains the
/// old type, thus other calls (such as `get`) will fail at decoding it.
///
/// # Usage
///
/// This would typically be called inside the module implementation of on_runtime_upgrade.
fn translate_values<OldValue: Decode, F: FnMut(OldValue) -> Option<Value>>(mut f: F) {
let prefix = Self::final_prefix();
let mut previous_key = prefix.clone().to_vec();
while let Some(next) =
sp_io::storage::next_key(&previous_key).filter(|n| n.starts_with(&prefix))
{
previous_key = next;
let maybe_value = unhashed::get::<OldValue>(&previous_key);
match maybe_value {
Some(value) => match f(value) {
Some(new) => unhashed::put::<Value>(&previous_key, &new),
None => unhashed::kill(&previous_key),
},
None => {
log::error!("old key failed to decode at {:?}", previous_key);
continue
},
}
}
}More examples
src/storage/types/map.rs (line 446)
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fn storage_info() -> Vec<StorageInfo> {
vec![StorageInfo {
pallet_name: Self::module_prefix().to_vec(),
storage_name: Self::storage_prefix().to_vec(),
prefix: Self::final_prefix().to_vec(),
max_values: MaxValues::get(),
max_size: Some(
Hasher::max_len::<Key>()
.saturating_add(Value::max_encoded_len())
.saturated_into(),
),
}]
}
}
/// It doesn't require to implement `MaxEncodedLen` and give no information for `max_size`.
impl<Prefix, Hasher, Key, Value, QueryKind, OnEmpty, MaxValues>
crate::traits::PartialStorageInfoTrait
for StorageMap<Prefix, Hasher, Key, Value, QueryKind, OnEmpty, MaxValues>
where
Prefix: StorageInstance,
Hasher: crate::hash::StorageHasher,
Key: FullCodec,
Value: FullCodec,
QueryKind: QueryKindTrait<Value, OnEmpty>,
OnEmpty: Get<QueryKind::Query> + 'static,
MaxValues: Get<Option<u32>>,
{
fn partial_storage_info() -> Vec<StorageInfo> {
vec![StorageInfo {
pallet_name: Self::module_prefix().to_vec(),
storage_name: Self::storage_prefix().to_vec(),
prefix: Self::final_prefix().to_vec(),
max_values: MaxValues::get(),
max_size: None,
}]
}src/storage/types/nmap.rs (line 586)
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fn storage_info() -> Vec<StorageInfo> {
vec![StorageInfo {
pallet_name: Self::module_prefix().to_vec(),
storage_name: Self::storage_prefix().to_vec(),
prefix: Self::final_prefix().to_vec(),
max_values: MaxValues::get(),
max_size: Some(
Key::key_max_encoded_len()
.saturating_add(Value::max_encoded_len())
.saturated_into(),
),
}]
}
}
/// It doesn't require to implement `MaxEncodedLen` and give no information for `max_size`.
impl<Prefix, Key, Value, QueryKind, OnEmpty, MaxValues> crate::traits::PartialStorageInfoTrait
for StorageNMap<Prefix, Key, Value, QueryKind, OnEmpty, MaxValues>
where
Prefix: StorageInstance,
Key: super::key::KeyGenerator,
Value: FullCodec,
QueryKind: QueryKindTrait<Value, OnEmpty>,
OnEmpty: Get<QueryKind::Query> + 'static,
MaxValues: Get<Option<u32>>,
{
fn partial_storage_info() -> Vec<StorageInfo> {
vec![StorageInfo {
pallet_name: Self::module_prefix().to_vec(),
storage_name: Self::storage_prefix().to_vec(),
prefix: Self::final_prefix().to_vec(),
max_values: MaxValues::get(),
max_size: None,
}]
}src/storage/types/double_map.rs (line 696)
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fn storage_info() -> Vec<StorageInfo> {
vec![StorageInfo {
pallet_name: Self::module_prefix().to_vec(),
storage_name: Self::storage_prefix().to_vec(),
prefix: Self::final_prefix().to_vec(),
max_values: MaxValues::get(),
max_size: Some(
Hasher1::max_len::<Key1>()
.saturating_add(Hasher2::max_len::<Key2>())
.saturating_add(Value::max_encoded_len())
.saturated_into(),
),
}]
}
}
/// It doesn't require to implement `MaxEncodedLen` and give no information for `max_size`.
impl<Prefix, Hasher1, Hasher2, Key1, Key2, Value, QueryKind, OnEmpty, MaxValues>
crate::traits::PartialStorageInfoTrait
for StorageDoubleMap<Prefix, Hasher1, Key1, Hasher2, Key2, Value, QueryKind, OnEmpty, MaxValues>
where
Prefix: StorageInstance,
Hasher1: crate::hash::StorageHasher,
Hasher2: crate::hash::StorageHasher,
Key1: FullCodec,
Key2: FullCodec,
Value: FullCodec,
QueryKind: QueryKindTrait<Value, OnEmpty>,
OnEmpty: Get<QueryKind::Query> + 'static,
MaxValues: Get<Option<u32>>,
{
fn partial_storage_info() -> Vec<StorageInfo> {
vec![StorageInfo {
pallet_name: Self::module_prefix().to_vec(),
storage_name: Self::storage_prefix().to_vec(),
prefix: Self::final_prefix().to_vec(),
max_values: MaxValues::get(),
max_size: None,
}]
}sourcefn remove_all(limit: Option<u32>) -> KillStorageResult
fn remove_all(limit: Option<u32>) -> KillStorageResult
👎Deprecated: Use
clear insteadRemove all values in the overlay and up to limit in the backend.
All values in the client overlay will be deleted, if there is some limit then up to
limit values are deleted from the client backend, if limit is none then all values in
the client backend are deleted.
Note
Calling this multiple times per block with a limit set leads always to the same keys being
removed and the same result being returned. This happens because the keys to delete in the
overlay are not taken into account when deleting keys in the backend.
Examples found in repository?
More examples
sourcefn clear(limit: u32, maybe_cursor: Option<&[u8]>) -> MultiRemovalResults
fn clear(limit: u32, maybe_cursor: Option<&[u8]>) -> MultiRemovalResults
Attempt to remove all items from the map.
Returns MultiRemovalResults to inform about the result. Once
the resultant maybe_cursor field is None, then no further items remain to be deleted.
NOTE: After the initial call for any given map, it is important that no further items
are inserted into the map. If so, then the map may not be empty when the resultant
maybe_cursor is None.
Limit
A limit must always be provided through in order to cap the maximum
amount of deletions done in a single call. This is one fewer than the
maximum number of backend iterations which may be done by this operation and as such
represents the maximum number of backend deletions which may happen. A limit of zero
implies that no keys will be deleted, though there may be a single iteration done.
Cursor
A cursor may be passed in to this operation with maybe_cursor. None should only be
passed once (in the initial call) for any given storage map. Subsequent calls
operating on the same map should always pass Some, and this should be equal to the
previous call result’s maybe_cursor field.
Examples found in repository?
More examples
sourcefn iter_values() -> PrefixIterator<Value> ⓘ
fn iter_values() -> PrefixIterator<Value> ⓘ
Iter over all value of the storage.
NOTE: If a value failed to decode because storage is corrupted then it is skipped.
Examples found in repository?
More examples
sourcefn translate_values<OldValue: Decode, F: FnMut(OldValue) -> Option<Value>>(f: F)
fn translate_values<OldValue: Decode, F: FnMut(OldValue) -> Option<Value>>(f: F)
Translate the values of all elements by a function f, in the map in no particular order.
By returning None from f for an element, you’ll remove it from the map.
NOTE: If a value fail to decode because storage is corrupted then it is skipped.
Warning
This function must be used with care, before being updated the storage still contains the
old type, thus other calls (such as get) will fail at decoding it.
Usage
This would typically be called inside the module implementation of on_runtime_upgrade.