Struct GrausDb

pub struct GrausDb { /* private fields */ }

The GrausDb stores string key/value pairs.

Key/value pairs are persisted to disk in log files. Log files are named after monotonically increasing generation numbers with a log extension name. A SkipMap in memory stores the keys and the value locations for fast query.

GrausDb is thead-safe. It can be cloned to use it on new threads.

use std::env::current_dir;
let store = GrausDb::open(current_dir()?)?;
store.set("key".to_owned(), "value".to_owned())?;
let val = store.get("key".to_owned())?;
assert_eq!(val, Some("value".to_owned()));

Implementations

impl GrausDb

pub fn open(path: impl Into<PathBuf>) -> Result<GrausDb>

Opens a GrausDb with the given path.

This will create a new directory if the given one does not exist.

Errors

It propagates I/O or deserialization errors during the log replay.

pub fn set(&self, key: String, value: String) -> Result<()>

Sets the value of a string key to a string.

If the key already exists, the previous value will be overwritten.

pub fn get(&self, key: String) -> Result<Option<String>>

Gets the string value of a given string key.

Returns None if the given key does not exist.

pub fn remove(&self, key: String) -> Result<()>

Removes a given key.

Returns GrausError::KeyNotFound if the key does not exist.

pub fn update_if<F, P>( &self, key: String, update_fn: F, predicate_key: Option<String>, predicate: Option<P>, ) -> Result<()>

where F: FnOnce(String) -> String, P: FnOnce(String) -> bool,

Updates atomically an existing value.

If predicate_key and predicate are provided, it won´t update the value if the predicate is not satisfied for predicate_key.

Trait Implementations

impl Clone for GrausDb

fn clone(&self) -> GrausDb

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.