Struct cw_storage_plus::SnapshotItem

pub struct SnapshotItem<T> { /* private fields */ }

Item that maintains a snapshot of one or more checkpoints. We can query historical data as well as current state. What data is snapshotted depends on the Strategy.

Implementations

impl<T> SnapshotItem<T>

pub const fn new( storage_key: &'static str, checkpoints: &'static str, changelog: &'static str, strategy: Strategy ) -> Self

Creates a new SnapshotItem with the given storage keys and strategy. This is a const fn only suitable when all the storage keys provided are static strings.

Example:

use cw_storage_plus::{SnapshotItem, Strategy};

SnapshotItem::<u64>::new(
    "every",
    "every__check",
    "every__change",
    Strategy::EveryBlock);

pub fn new_dyn( storage_key: impl Into<Namespace>, checkpoints: impl Into<Namespace>, changelog: impl Into<Namespace>, strategy: Strategy ) -> Self

Creates a new SnapshotItem with the given storage keys and strategy. Use this if you might need to handle dynamic strings. Otherwise, you might prefer SnapshotItem::new.

Example:

use cw_storage_plus::{SnapshotItem, Strategy};

let key = "every";
let checkpoints_key = format!("{}_check", key);
let changelog_key = format!("{}_change", key);

SnapshotItem::<u64>::new_dyn(
    key,
    checkpoints_key,
    changelog_key,
    Strategy::EveryBlock);

pub fn add_checkpoint( &self, store: &mut dyn Storage, height: u64 ) -> StdResult<()>

pub fn remove_checkpoint( &self, store: &mut dyn Storage, height: u64 ) -> StdResult<()>

pub fn changelog(&self) -> Map<u64, ChangeSet<T>>

impl<T> SnapshotItem<T>

where T: Serialize + DeserializeOwned + Clone,

pub fn save( &self, store: &mut dyn Storage, data: &T, height: u64 ) -> StdResult<()>

pub fn remove(&self, store: &mut dyn Storage, height: u64) -> StdResult<()>

pub fn load(&self, store: &dyn Storage) -> StdResult<T>

load will return an error if no data is set, or on parse error

pub fn may_load(&self, store: &dyn Storage) -> StdResult<Option<T>>

may_load will parse the data stored if present, returns Ok(None) if no data there. returns an error on parsing issues

pub fn may_load_at_height( &self, store: &dyn Storage, height: u64 ) -> StdResult<Option<T>>

pub fn assert_checkpointed( &self, store: &dyn Storage, height: u64 ) -> StdResult<()>

pub fn update<A, E>( &self, store: &mut dyn Storage, height: u64, action: A ) -> Result<T, E>

where A: FnOnce(Option<T>) -> Result<T, E>, E: From<StdError>,

Loads the data, perform the specified action, and store the result in the database. This is a shorthand for some common sequences, which may be useful.

If the data exists, action(Some(value)) is called. Otherwise action(None) is called.

This is a bit more customized than needed to only read “old” value 1 time, not 2 per naive approach