Struct sled::Tree
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pub struct Tree { /* fields omitted */ }
A flash-sympathetic persistent lock-free B+ tree
Methods
impl Tree
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fn start(config: Config) -> DbResult<Tree, ()>
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Load existing or create a new Tree
.
fn flush(&self) -> CacheResult<(), ()>
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Flushes any pending IO buffers to disk to ensure durability.
fn get(&self, key: &[u8]) -> DbResult<Option<Vec<u8>>, ()>
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Retrieve a value from the Tree
if it exists.
fn cas(
&self,
key: Vec<u8>,
old: Option<Vec<u8>>,
new: Option<Vec<u8>>
) -> DbResult<(), Option<Vec<u8>>>
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&self,
key: Vec<u8>,
old: Option<Vec<u8>>,
new: Option<Vec<u8>>
) -> DbResult<(), 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. If Tree is read-only, will do nothing.
Examples
use sled::{ConfigBuilder, Error}; let config = ConfigBuilder::new().temporary(true).build(); let t = sled::Tree::start(config).unwrap(); // unique creation assert_eq!(t.cas(vec![1], None, Some(vec![1])), Ok(())); assert_eq!(t.cas(vec![1], None, Some(vec![1])), Err(Error::CasFailed(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(Error::CasFailed(Some(vec![2])))); // conditional deletion assert_eq!(t.cas(vec![1], Some(vec![2]), None), Ok(())); assert_eq!(t.get(&*vec![1]), Ok(None));
fn set(&self, key: Vec<u8>, value: Vec<u8>) -> DbResult<(), ()>
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Set a key to a new value.
fn del(&self, key: &[u8]) -> DbResult<Option<Vec<u8>>, ()>
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Delete a value, returning the last result if it existed.
Examples
let config = sled::ConfigBuilder::new().temporary(true).build(); let t = sled::Tree::start(config).unwrap(); t.set(vec![1], vec![1]); assert_eq!(t.del(&*vec![1]), Ok(Some(vec![1]))); assert_eq!(t.del(&*vec![1]), Ok(None));
fn scan(&self, key: &[u8]) -> Iter
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Iterate over tuples of keys and values, starting at the provided key.
Examples
let config = sled::ConfigBuilder::new().temporary(true).build(); let t = sled::Tree::start(config).unwrap(); 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(Ok((vec![2], vec![20])))); assert_eq!(iter.next(), Some(Ok((vec![3], vec![30])))); assert_eq!(iter.next(), None);
fn iter(&self) -> Iter
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Iterate over the tuples of keys and values in this tree.
Examples
let config = sled::ConfigBuilder::new().temporary(true).build(); let t = sled::Tree::start(config).unwrap(); 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(Ok((vec![1], vec![10])))); assert_eq!(iter.next(), Some(Ok((vec![2], vec![20])))); assert_eq!(iter.next(), Some(Ok((vec![3], vec![30])))); assert_eq!(iter.next(), None);
Trait Implementations
impl<'a> IntoIterator for &'a Tree
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type Item = DbResult<(Vec<u8>, Vec<u8>), ()>
The type of the elements being iterated over.
type IntoIter = Iter<'a>
Which kind of iterator are we turning this into?
fn into_iter(self) -> Iter<'a>
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Creates an iterator from a value. Read more
impl Clone for Tree
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fn clone(&self) -> Tree
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Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
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Performs copy-assignment from source
. Read more