Struct Metadata 

pub struct Metadata<E: Context, K: Span, V: Codec>(/* private fields */);

Implementation of Metadata storage.

Storage-mutating functions consume the store and return it only on success: an error (or a dropped future) destroys the handle.

Implementations

impl<E: Context, K: Span, V: Codec> Metadata<E, K, V>

pub async fn init(context: E, cfg: Config<V::Cfg>) -> Result<Self, Error>

Initialize a new Metadata instance.

pub fn get(&self, key: &K) -> Option<&V>

Get a value from Metadata (if it exists).

pub fn get_mut(&mut self, key: &K) -> Option<&mut V>

Get a mutable reference to a value from Metadata (if it exists).

pub fn clear(&mut self)

Clear all values from Metadata. The new state will not be persisted until Self::sync is called.

pub fn put(&mut self, key: K, value: V) -> Option<V>

Put a value into Metadata.

If the key already exists, the value will be overwritten and the previous value is returned. The value stored will not be persisted until Self::sync is called.

pub async fn put_sync(self, key: K, value: V) -> Result<Self, Error>

Perform a Self::put and Self::sync in a single operation.

Like calling Self::sync directly, this commits all pending metadata changes, not just the provided key.

pub fn upsert(&mut self, key: K, f: impl FnOnce(&mut V))

where V: Default,

Update (or insert) a value in Metadata using a closure.

pub async fn upsert_sync( self, key: K, f: impl FnOnce(&mut V), ) -> Result<Self, Error>

where V: Default,

Update (or insert) a value in Metadata using a closure and sync immediately.

pub fn remove(&mut self, key: &K) -> Option<V>

Remove a value from Metadata (if it exists).

pub fn keys(&self) -> impl Iterator<Item = &K>

Iterate over all keys in metadata.

pub fn retain(&mut self, f: impl FnMut(&K, &V) -> bool)

Retain only the keys that satisfy the predicate.

pub async fn sync(self) -> Result<Self, Error>

Atomically commit the current state of Metadata.

pub async fn start_sync(self) -> Result<(Self, Handle<()>), Error>

Atomically begin committing the current state of Metadata, returning a completion handle.

Awaiting the returned Handle provides the same guarantee as Self::sync. A started sync’s failure surfaces on the handle and again on the next sync, which fails (destroying the store) without writing. At most one sync is in flight: a new call writes nothing until the prior sync completes. Dropping the handle neither cancels the sync nor loses a failure.

pub async fn destroy(self) -> Result<(), Error>

Remove the underlying blobs for this Metadata.

Trait Implementations

impl<E: Context, K: Span, V: Codec> Debug for Metadata<E, K, V>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.