Trait tetsy_kvdb::KeyValueDB

pub trait KeyValueDB: Sync + Send + MallocSizeOf {
    fn get(&self, col: u32, key: &[u8]) -> Result<Option<DBValue>>;
    fn get_by_prefix(&self, col: u32, prefix: &[u8]) -> Option<Box<[u8]>>;
    fn write(&self, transaction: DBTransaction) -> Result<()>;
    fn iter<'a>(
        &'a self, 
        col: u32
    ) -> Box<dyn Iterator<Item = (Box<[u8]>, Box<[u8]>)> + 'a>;
    fn iter_with_prefix<'a>(
        &'a self, 
        col: u32, 
        prefix: &'a [u8]
    ) -> Box<dyn Iterator<Item = (Box<[u8]>, Box<[u8]>)> + 'a>;
    fn restore(&self, new_db: &str) -> Result<()>;

    fn transaction(&self) -> DBTransaction { ... }
    fn io_stats(&self, _kind: IoStatsKind) -> IoStats { ... }
    fn has_key(&self, col: u32, key: &[u8]) -> Result<bool> { ... }
    fn has_prefix(&self, col: u32, prefix: &[u8]) -> bool { ... }
}

Generic key-value database.

The KeyValueDB deals with “column families”, which can be thought of as distinct stores within a database. Keys written in one column family will not be accessible from any other. The number of column families must be specified at initialization, with a differing interface for each database.

The API laid out here, along with the Sync bound implies interior synchronization for implementation.

Required methods

fn get(&self, col: u32, key: &[u8]) -> Result<Option<DBValue>>

Get a value by key.

fn get_by_prefix(&self, col: u32, prefix: &[u8]) -> Option<Box<[u8]>>

Get the first value matching the given prefix.

fn write(&self, transaction: DBTransaction) -> Result<()>

Write a transaction of changes to the backing store.

fn iter<'a>(
    &'a self,
    col: u32
) -> Box<dyn Iterator<Item = (Box<[u8]>, Box<[u8]>)> + 'a>

Iterate over the data for a given column.

fn iter_with_prefix<'a>(
    &'a self,
    col: u32,
    prefix: &'a [u8]
) -> Box<dyn Iterator<Item = (Box<[u8]>, Box<[u8]>)> + 'a>

Iterate over the data for a given column, returning all key/value pairs where the key starts with the given prefix.

fn restore(&self, new_db: &str) -> Result<()>

Attempt to replace this database with a new one located at the given path.

Provided methods

fn transaction(&self) -> DBTransaction

Helper to create a new transaction.

fn io_stats(&self, _kind: IoStatsKind) -> IoStats

Query statistics.

Not all tetsy-kvdb implementations are able or expected to implement this, so by default, empty statistics is returned. Also, not all tetsy-kvdb implementation can return every statistic or configured to do so (some statistics gathering may impede the performance and might be off by default).

fn has_key(&self, col: u32, key: &[u8]) -> Result<bool>

Check for the existence of a value by key.

fn has_prefix(&self, col: u32, prefix: &[u8]) -> bool

Check for the existence of a value by prefix.

Implementors