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KvReader

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Trait KvReader 

Source 
pub trait KvReader: Send + Sync {
    // Required methods
    fn get<'life0, 'life1, 'async_trait>(
        &'life0 self,
        key: &'life1 str,
    ) -> Pin<Box<dyn Future<Output = Result<Option<KvEntry>, KvError>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait;
    fn keys<'life0, 'life1, 'async_trait>(
        &'life0 self,
        prefix: &'life1 str,
    ) -> Pin<Box<dyn Future<Output = Result<Vec<String>, KvError>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait;
    fn scan<'life0, 'life1, 'async_trait>(
        &'life0 self,
        prefix: &'life1 str,
    ) -> Pin<Box<dyn Future<Output = Result<Vec<KvEntry>, KvError>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait;

    // Provided method
    fn entry<'life0, 'life1, 'async_trait>(
        &'life0 self,
        key: &'life1 str,
    ) -> Pin<Box<dyn Future<Output = Result<Option<KvEntry>, KvError>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait { ... }
}
Expand description

Core read-only KV operations - the minimal interface every store must implement.

Required Methods§

Source

fn get<'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 str, ) -> Pin<Box<dyn Future<Output = Result<Option<KvEntry>, KvError>> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Get a value by key. Returns None if the key doesn’t exist.

Backends that use empty-value tombstones (NATS: delete_with_version writes an empty-value Put so concurrent CAS writers still conflict) also return None for a stored empty value — get() cannot tell a real b"" apart from a tombstone. A caller using zero-length values as a presence signal (locks, feature flags) must use entry, which exposes the raw record including empty-value Puts.

Source

fn keys<'life0, 'life1, 'async_trait>( &'life0 self, prefix: &'life1 str, ) -> Pin<Box<dyn Future<Output = Result<Vec<String>, KvError>> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Get all keys matching a prefix. Returns keys only, not values.

Source

fn scan<'life0, 'life1, 'async_trait>( &'life0 self, prefix: &'life1 str, ) -> Pin<Box<dyn Future<Output = Result<Vec<KvEntry>, KvError>> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Get multiple entries by prefix. Useful for bulk loading.

Provided Methods§

Source

fn entry<'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 str, ) -> Pin<Box<dyn Future<Output = Result<Option<KvEntry>, KvError>> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Get the raw entry for a key, including tombstones (empty-value Put entries written by delete_with_version). Most callers should use get() instead, which filters tombstones for consistency with scan().

Override in backends where tombstone version access is needed for CAS conflict detection.

Dyn Compatibility§

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors§