Struct sled::Tree

pub struct Tree { /* fields omitted */ }

A flash-sympathetic persistent lock-free B+ tree

Methods

impl Tree

fn new(config: Config) -> Tree

Load existing or create a new Tree.

fn config(&self) -> &Config

Returns a ref to the current Config in use by the system.

fn get(&self, key: &[u8]) -> Option<Vec<u8>>

Retrieve a value from the Tree if it exists.

fn cas(
    &self,
    key: Vec<u8>,
    old: Option<Vec<u8>>,
    new: Option<Vec<u8>>
) -> Result<(), Option<Vec<u8>>>

Compare and swap. Capable of unique creation, conditional modification, or deletion. If old is None, this will only set the value if it doesn't exist yet. If new is None, will delete the value if old is correct. If both old and new are Some, will modify the value if old is correct.

Examples

use sled::Config;
let t = Config::default().tree();

// unique creation
assert_eq!(t.cas(vec![1], None, Some(vec![1])), Ok(()));
assert_eq!(t.cas(vec![1], None, Some(vec![1])), Err(Some(vec![1])));

// conditional modification
assert_eq!(t.cas(vec![1], Some(vec![1]), Some(vec![2])), Ok(()));
assert_eq!(t.cas(vec![1], Some(vec![1]), Some(vec![2])), Err(Some(vec![2])));

// conditional deletion
assert_eq!(t.cas(vec![1], Some(vec![2]), None), Ok(()));
assert_eq!(t.get(&*vec![1]), None);

fn set(&self, key: Vec<u8>, value: Vec<u8>)

Set a key to a new value.

fn del(&self, key: &[u8]) -> Option<Vec<u8>>

Delete a value, returning the last result if it existed.

Examples

use sled::Config;
let t = Config::default().tree();
t.set(vec![1], vec![1]);
assert_eq!(t.del(&*vec![1]), Some(vec![1]));
assert_eq!(t.del(&*vec![1]), None);

fn scan(&self, key: &[u8]) -> TreeIter

Iterate over tuples of keys and values, starting at the provided key.

Examples

use sled::Config;
let t = Config::default().tree();
t.set(vec![1], vec![10]);
t.set(vec![2], vec![20]);
t.set(vec![3], vec![30]);
let mut iter = t.scan(&*vec![2]);
assert_eq!(iter.next(), Some((vec![2], vec![20])));
assert_eq!(iter.next(), Some((vec![3], vec![30])));
assert_eq!(iter.next(), None);

fn iter(&self) -> TreeIter

Iterate over the tuples of keys and values in this tree.

Examples

use sled::Config;
let t = Config::default().tree();
t.set(vec![1], vec![10]);
t.set(vec![2], vec![20]);
t.set(vec![3], vec![30]);
let mut iter = t.iter();
assert_eq!(iter.next(), Some((vec![1], vec![10])));
assert_eq!(iter.next(), Some((vec![2], vec![20])));
assert_eq!(iter.next(), Some((vec![3], vec![30])));
assert_eq!(iter.next(), None);

Trait Implementations

impl Send for Tree

impl Sync for Tree

impl Debug for Tree

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

Formats the value using the given formatter.

impl<'a> IntoIterator for &'a Tree

type Item = (Vec<u8>, Vec<u8>)

The type of the elements being iterated over.

type IntoIter = TreeIter<'a>

Which kind of iterator are we turning this into?

fn into_iter(self) -> TreeIter<'a>

Creates an iterator from a value.