[][src]Struct sled::Tree

pub struct Tree(_);

A flash-sympathetic persistent lock-free B+ tree

Examples

use sled::{Db, IVec};

let t = Db::open("db").unwrap();
t.insert(b"yo!", b"v1".to_vec());
assert_eq!(t.get(b"yo!"), Ok(Some(IVec::from(b"v1"))));

// Atomic compare-and-swap.
t.compare_and_swap(
    b"yo!",      // key
    Some(b"v1"), // old value, None for not present
    Some(b"v2"), // new value, None for delete
)
.unwrap();

// Iterates over key-value pairs, starting at the given key.
let scan_key: &[u8] = b"a non-present key before yo!";
let mut iter = t.range(scan_key..);
assert_eq!(
    iter.next().unwrap(),
    Ok((IVec::from(b"yo!"), IVec::from(b"v2")))
);
assert_eq!(iter.next(), None);

t.remove(b"yo!");
assert_eq!(t.get(b"yo!"), Ok(None));

Methods

impl Tree[src]

pub fn insert<K, V>(&self, key: K, value: V) -> Result<Option<IVec>> where
    K: AsRef<[u8]>,
    IVec: From<V>, 
[src]

Insert a key to a new value, returning the last value if it was set.

Examples

use sled::{Config, IVec};
let config = Config::new().temporary(true);
let t = config.open().unwrap();

assert_eq!(t.insert(&[1, 2, 3], vec![0]), Ok(None));
assert_eq!(t.insert(&[1, 2, 3], vec![1]), Ok(Some(IVec::from(&[0]))));

pub fn transaction<F, A, E>(&self, f: F) -> TransactionResult<A, E> where
    F: Fn(&TransactionalTree) -> ConflictableTransactionResult<A, E>, 
[src]

Perform a multi-key serializable transaction.

Examples


let config = Config::new().temporary(true);
let db = config.open().unwrap();

// Use write-only transactions as a writebatch:
db.transaction(|db| {
    db.insert(b"k1", b"cats")?;
    db.insert(b"k2", b"dogs")?;
    Ok(())
})?;

// Atomically swap two items:
db.transaction(|db| {
    let v1_option = db.remove(b"k1")?;
    let v1 = v1_option.unwrap();
    let v2_option = db.remove(b"k2")?;
    let v2 = v2_option.unwrap();

    db.insert(b"k1", v2)?;
    db.insert(b"k2", v1)?;

    Ok(())
})?;

assert_eq!(&db.get(b"k1")?.unwrap(), b"dogs");
assert_eq!(&db.get(b"k2")?.unwrap(), b"cats");

A transaction may return information from an intentionally-cancelled transaction by using the abort function inside the closure in combination with the try operator.

use sled::{TransactionError, TransactionResult, Config, abort};

#[derive(Debug, PartialEq)]
struct MyBullshitError;

fn main() -> TransactionResult<(), MyBullshitError> {
    let config = Config::new().temporary(true);
    let db = config.open().unwrap();

    // Use write-only transactions as a writebatch:
    let res = db.transaction(|db| {
        db.insert(b"k1", b"cats")?;
        db.insert(b"k2", b"dogs")?;
        // aborting will cause all writes to roll-back.
        if true {
            abort(MyBullshitError)?;
        }
        Ok(42)
    }).unwrap_err();

    assert_eq!(res, TransactionError::Abort(MyBullshitError));
    assert_eq!(db.get(b"k1")?, None);
    assert_eq!(db.get(b"k2")?, None);

    Ok(())
}

Transactions also work on tuples of Trees, preserving serializable ACID semantics! In this example, we treat two trees like a work queue, atomically apply updates to data and move them from the unprocessed Tree to the processed Tree.

use sled::{Config, Transactional};

let config = Config::new().temporary(true);
let db = config.open().unwrap();

let unprocessed = db.open_tree(b"unprocessed items").unwrap();
let processed = db.open_tree(b"processed items").unwrap();

// An update somehow gets into the tree, which we
// later trigger the atomic processing of.
unprocessed.insert(b"k3", b"ligers").unwrap();

// Atomically process the new item and move it
// between `Tree`s.
(&unprocessed, &processed)
    .transaction(|(unprocessed, processed)| {
        let unprocessed_item = unprocessed.remove(b"k3")?.unwrap();
        let mut processed_item = b"yappin' ".to_vec();
        processed_item.extend_from_slice(&unprocessed_item);
        processed.insert(b"k3", processed_item)?;
        Ok(())
    })
    .unwrap();

assert_eq!(unprocessed.get(b"k3").unwrap(), None);
assert_eq!(&processed.get(b"k3").unwrap().unwrap(), b"yappin' ligers");

pub fn apply_batch(&self, batch: Batch) -> Result<()>[src]

Create a new batched update that can be atomically applied.

It is possible to apply a Batch in a transaction as well, which is the way you can apply a Batch to multiple Trees atomically.

Examples

use sled::{Batch, Db};

let db = Db::open("batch_db").unwrap();
db.insert("key_0", "val_0").unwrap();

let mut batch = Batch::default();
batch.insert("key_a", "val_a");
batch.insert("key_b", "val_b");
batch.insert("key_c", "val_c");
batch.remove("key_0");

db.apply_batch(batch).unwrap();
// key_0 no longer exists, and key_a, key_b, and key_c
// now do exist.

pub fn get<K: AsRef<[u8]>>(&self, key: K) -> Result<Option<IVec>>[src]

Retrieve a value from the Tree if it exists.

Examples

use sled::{Config, IVec};
let config = Config::new().temporary(true);
let t = config.open().unwrap();

t.insert(&[0], vec![0]).unwrap();
assert_eq!(t.get(&[0]), Ok(Some(IVec::from(vec![0]))));
assert_eq!(t.get(&[1]), Ok(None));

pub fn remove<K: AsRef<[u8]>>(&self, key: K) -> Result<Option<IVec>>[src]

Delete a value, returning the old value if it existed.

Examples

let config = sled::Config::new().temporary(true);
let t = config.open().unwrap();
t.insert(&[1], vec![1]);
assert_eq!(t.remove(&[1]), Ok(Some(sled::IVec::from(vec![1]))));
assert_eq!(t.remove(&[1]), Ok(None));

pub fn compare_and_swap<K, OV, NV>(
    &self,
    key: K,
    old: Option<OV>,
    new: Option<NV>
) -> CompareAndSwapResult where
    K: AsRef<[u8]>,
    OV: AsRef<[u8]>,
    IVec: From<NV>, 
[src]

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.

It returns Ok(Ok(())) if operation finishes successfully.

If it fails it returns: - Ok(Err(CompareAndSwapError(current, proposed))) if operation failed to setup a new value. CompareAndSwapError contains current and proposed values. - Err(Error::Unsupported) if the database is opened in read-only mode.

Examples

let config = sled::Config::new().temporary(true);
let t = config.open().unwrap();

// unique creation
assert_eq!(
    t.compare_and_swap(&[1], None as Option<&[u8]>, Some(&[10])),
    Ok(Ok(()))
);

// conditional modification
assert_eq!(
    t.compare_and_swap(&[1], Some(&[10]), Some(&[20])),
    Ok(Ok(()))
);

// failed conditional modification -- the current value is returned in
// the error variant
let operation = t.compare_and_swap(&[1], Some(&[30]), Some(&[40]));
assert!(operation.is_ok()); // the operation succeeded
let modification = operation.unwrap();
assert!(modification.is_err());
let actual_value = modification.unwrap_err();
assert_eq!(actual_value.current.map(|ivec| ivec.to_vec()), Some(vec![20]));

// conditional deletion
assert_eq!(
    t.compare_and_swap(&[1], Some(&[20]), None as Option<&[u8]>),
    Ok(Ok(()))
);
assert_eq!(t.get(&[1]), Ok(None));

pub fn update_and_fetch<K, V, F>(&self, key: K, f: F) -> Result<Option<IVec>> where
    K: AsRef<[u8]>,
    F: FnMut(Option<&[u8]>) -> Option<V>,
    IVec: From<V>, 
[src]

Fetch the value, apply a function to it and return the result.

Note

This may call the function multiple times if the value has been changed from other threads in the meantime.

Examples

use sled::{Config, Error, IVec};
use std::convert::TryInto;

let config = Config::new().temporary(true);
let tree = config.open().unwrap();

fn u64_to_ivec(number: u64) -> IVec {
    IVec::from(number.to_be_bytes().to_vec())
}

let zero = u64_to_ivec(0);
let one = u64_to_ivec(1);
let two = u64_to_ivec(2);
let three = u64_to_ivec(3);

fn increment(old: Option<&[u8]>) -> Option<Vec<u8>> {
    let number = match old {
        Some(bytes) => {
            let array: [u8; 8] = bytes.try_into().unwrap();
            let number = u64::from_be_bytes(array);
            number + 1
        }
        None => 0,
    };

    Some(number.to_be_bytes().to_vec())
}

assert_eq!(tree.update_and_fetch("counter", increment), Ok(Some(zero)));
assert_eq!(tree.update_and_fetch("counter", increment), Ok(Some(one)));
assert_eq!(tree.update_and_fetch("counter", increment), Ok(Some(two)));
assert_eq!(tree.update_and_fetch("counter", increment), Ok(Some(three)));

pub fn fetch_and_update<K, V, F>(&self, key: K, f: F) -> Result<Option<IVec>> where
    K: AsRef<[u8]>,
    F: FnMut(Option<&[u8]>) -> Option<V>,
    IVec: From<V>, 
[src]

Fetch the value, apply a function to it and return the previous value.

Note

This may call the function multiple times if the value has been changed from other threads in the meantime.

Examples

use sled::{Config, Error, IVec};
use std::convert::TryInto;

let config = Config::new().temporary(true);
let tree = config.open().unwrap();

fn u64_to_ivec(number: u64) -> IVec {
    IVec::from(number.to_be_bytes().to_vec())
}

let zero = u64_to_ivec(0);
let one = u64_to_ivec(1);
let two = u64_to_ivec(2);

fn increment(old: Option<&[u8]>) -> Option<Vec<u8>> {
    let number = match old {
        Some(bytes) => {
            let array: [u8; 8] = bytes.try_into().unwrap();
            let number = u64::from_be_bytes(array);
            number + 1
        }
        None => 0,
    };

    Some(number.to_be_bytes().to_vec())
}

assert_eq!(tree.fetch_and_update("counter", increment), Ok(None));
assert_eq!(tree.fetch_and_update("counter", increment), Ok(Some(zero)));
assert_eq!(tree.fetch_and_update("counter", increment), Ok(Some(one)));
assert_eq!(tree.fetch_and_update("counter", increment), Ok(Some(two)));

Important traits for Subscriber
pub fn watch_prefix<P: AsRef<[u8]>>(&self, prefix: P) -> Subscriber[src]

Subscribe to Events that happen to keys that have the specified prefix. Events for particular keys are guaranteed to be witnessed in the same order by all threads, but threads may witness different interleavings of Events across different keys. If subscribers don't keep up with new writes, they will cause new writes to block. There is a buffer of 1024 items per Subscriber. This can be used to build reactive and replicated systems.

Examples

use sled::{Config, Event};
let config = Config::new().temporary(true);

let tree = config.open().unwrap();

// watch all events by subscribing to the empty prefix
let mut events = tree.watch_prefix(vec![]);

let tree_2 = tree.clone();
let thread = std::thread::spawn(move || {
    tree.insert(vec![0], vec![1]).unwrap();
});

// events is a blocking `Iterator` over `Event`s
for event in events.take(1) {
    match event {
        Event::Insert(key, value) => assert_eq!(key.as_ref(), &[0]),
        Event::Remove(key) => {}
    }
}

thread.join().unwrap();

pub fn flush(&self) -> Result<usize>[src]

Synchronously flushes all dirty IO buffers and calls fsync. If this succeeds, it is guaranteed that all previous writes will be recovered if the system crashes. Returns the number of bytes flushed during this call.

Flushing can take quite a lot of time, and you should measure the performance impact of using it on realistic sustained workloads running on realistic hardware.

pub fn flush_async(&self) -> impl Future<Output = Result<usize>>[src]

Asynchronously flushes all dirty IO buffers and calls fsync. If this succeeds, it is guaranteed that all previous writes will be recovered if the system crashes. Returns the number of bytes flushed during this call.

Flushing can take quite a lot of time, and you should measure the performance impact of using it on realistic sustained workloads running on realistic hardware.

pub fn contains_key<K: AsRef<[u8]>>(&self, key: K) -> Result<bool>[src]

Returns true if the Tree contains a value for the specified key.

Examples

let config = sled::Config::new().temporary(true);
let t = config.open().unwrap();

t.insert(&[0], vec![0]).unwrap();
assert!(t.contains_key(&[0]).unwrap());
assert!(!t.contains_key(&[1]).unwrap());

pub fn get_lt<K>(&self, key: K) -> Result<Option<(IVec, IVec)>> where
    K: AsRef<[u8]>, 
[src]

Retrieve the key and value before the provided key, if one exists.

Examples

use sled::{Config, IVec};
let config = Config::new().temporary(true);
let tree = config.open().unwrap();

for i in 0..10 {
    tree.insert(&[i], vec![i])
        .expect("should write successfully");
}

assert_eq!(tree.get_lt(&[]), Ok(None));
assert_eq!(tree.get_lt(&[0]), Ok(None));
assert_eq!(
    tree.get_lt(&[1]),
    Ok(Some((IVec::from(&[0]), IVec::from(&[0]))))
);
assert_eq!(
    tree.get_lt(&[9]),
    Ok(Some((IVec::from(&[8]), IVec::from(&[8]))))
);
assert_eq!(
    tree.get_lt(&[10]),
    Ok(Some((IVec::from(&[9]), IVec::from(&[9]))))
);
assert_eq!(
    tree.get_lt(&[255]),
    Ok(Some((IVec::from(&[9]), IVec::from(&[9]))))
);

pub fn get_gt<K>(&self, key: K) -> Result<Option<(IVec, IVec)>> where
    K: AsRef<[u8]>, 
[src]

Retrieve the next key and value from the Tree after the provided key.

Note

The order follows the Ord implementation for Vec<u8>:

[] < [0] < [255] < [255, 0] < [255, 255] ...

To retain the ordering of numerical types use big endian reprensentation

Examples

use sled::{Config, IVec};
let config = Config::new().temporary(true);
let tree = config.open().unwrap();

for i in 0..10 {
    tree.insert(&[i], vec![i])
        .expect("should write successfully");
}

assert_eq!(
    tree.get_gt(&[]),
    Ok(Some((IVec::from(&[0]), IVec::from(&[0]))))
);
assert_eq!(
    tree.get_gt(&[0]),
    Ok(Some((IVec::from(&[1]), IVec::from(&[1]))))
);
assert_eq!(
    tree.get_gt(&[1]),
    Ok(Some((IVec::from(&[2]), IVec::from(&[2]))))
);
assert_eq!(
    tree.get_gt(&[8]),
    Ok(Some((IVec::from(&[9]), IVec::from(&[9]))))
);
assert_eq!(tree.get_gt(&[9]), Ok(None));

tree.insert(500u16.to_be_bytes(), vec![10]);
assert_eq!(
    tree.get_gt(&499u16.to_be_bytes()),
    Ok(Some((IVec::from(&500u16.to_be_bytes()), IVec::from(&[10]))))
);

pub fn merge<K, V>(&self, key: K, value: V) -> Result<Option<IVec>> where
    K: AsRef<[u8]>,
    V: AsRef<[u8]>, 
[src]

Merge state directly into a given key's value using the configured merge operator. This allows state to be written into a value directly, without any read-modify-write steps. Merge operators can be used to implement arbitrary data structures.

Panics

Calling merge will panic if no merge operator has been configured.

Examples

use sled::{Config, IVec};

fn concatenate_merge(
  _key: &[u8],               // the key being merged
  old_value: Option<&[u8]>,  // the previous value, if one existed
  merged_bytes: &[u8]        // the new bytes being merged in
) -> Option<Vec<u8>> {       // set the new value, return None to delete
  let mut ret = old_value
    .map(|ov| ov.to_vec())
    .unwrap_or_else(|| vec![]);

  ret.extend_from_slice(merged_bytes);

  Some(ret)
}

let config = Config::new()
  .temporary(true);

let tree = config.open().unwrap();
tree.set_merge_operator(concatenate_merge);

let k = b"k1";

tree.insert(k, vec![0]);
tree.merge(k, vec![1]);
tree.merge(k, vec![2]);
assert_eq!(tree.get(k), Ok(Some(IVec::from(vec![0, 1, 2]))));

// Replace previously merged data. The merge function will not be called.
tree.insert(k, vec![3]);
assert_eq!(tree.get(k), Ok(Some(IVec::from(vec![3]))));

// Merges on non-present values will cause the merge function to be called
// with `old_value == None`. If the merge function returns something (which it
// does, in this case) a new value will be inserted.
tree.remove(k);
tree.merge(k, vec![4]);
assert_eq!(tree.get(k), Ok(Some(IVec::from(vec![4]))));

pub fn set_merge_operator(&self, merge_operator: MergeOperator)[src]

Sets a merge operator for use with the merge function.

Merge state directly into a given key's value using the configured merge operator. This allows state to be written into a value directly, without any read-modify-write steps. Merge operators can be used to implement arbitrary data structures.

Panics

Calling merge will panic if no merge operator has been configured.

Examples

use sled::{Config, IVec};

fn concatenate_merge(
  _key: &[u8],               // the key being merged
  old_value: Option<&[u8]>,  // the previous value, if one existed
  merged_bytes: &[u8]        // the new bytes being merged in
) -> Option<Vec<u8>> {       // set the new value, return None to delete
  let mut ret = old_value
    .map(|ov| ov.to_vec())
    .unwrap_or_else(|| vec![]);

  ret.extend_from_slice(merged_bytes);

  Some(ret)
}

let config = Config::new()
  .temporary(true);

let tree = config.open().unwrap();
tree.set_merge_operator(concatenate_merge);

let k = b"k1";

tree.insert(k, vec![0]);
tree.merge(k, vec![1]);
tree.merge(k, vec![2]);
assert_eq!(tree.get(k), Ok(Some(IVec::from(vec![0, 1, 2]))));

// Replace previously merged data. The merge function will not be called.
tree.insert(k, vec![3]);
assert_eq!(tree.get(k), Ok(Some(IVec::from(vec![3]))));

// Merges on non-present values will cause the merge function to be called
// with `old_value == None`. If the merge function returns something (which it
// does, in this case) a new value will be inserted.
tree.remove(k);
tree.merge(k, vec![4]);
assert_eq!(tree.get(k), Ok(Some(IVec::from(vec![4]))));

Important traits for Iter
pub fn iter(&self) -> Iter[src]

Create a double-ended iterator over the tuples of keys and values in this tree.

Examples

use sled::{Config, IVec};
let config = Config::new().temporary(true);
let t = config.open().unwrap();
t.insert(&[1], vec![10]);
t.insert(&[2], vec![20]);
t.insert(&[3], vec![30]);
let mut iter = t.iter();
assert_eq!(
    iter.next().unwrap(),
    Ok((IVec::from(&[1]), IVec::from(&[10])))
);
assert_eq!(
    iter.next().unwrap(),
    Ok((IVec::from(&[2]), IVec::from(&[20])))
);
assert_eq!(
    iter.next().unwrap(),
    Ok((IVec::from(&[3]), IVec::from(&[30])))
);
assert_eq!(iter.next(), None);

Important traits for Iter
pub fn range<K, R>(&self, range: R) -> Iter where
    K: AsRef<[u8]>,
    R: RangeBounds<K>, 
[src]

Create a double-ended iterator over tuples of keys and values, where the keys fall within the specified range.

Examples

use sled::{Config, IVec};
let config = Config::new().temporary(true);
let t = config.open().unwrap();

t.insert(&[0], vec![0]).unwrap();
t.insert(&[1], vec![10]).unwrap();
t.insert(&[2], vec![20]).unwrap();
t.insert(&[3], vec![30]).unwrap();
t.insert(&[4], vec![40]).unwrap();
t.insert(&[5], vec![50]).unwrap();

let start: &[u8] = &[2];
let end: &[u8] = &[4];
let mut r = t.range(start..end);
assert_eq!(r.next().unwrap(), Ok((IVec::from(&[2]), IVec::from(&[20]))));
assert_eq!(r.next().unwrap(), Ok((IVec::from(&[3]), IVec::from(&[30]))));
assert_eq!(r.next(), None);

let mut r = t.range(start..end).rev();
assert_eq!(r.next().unwrap(), Ok((IVec::from(&[3]), IVec::from(&[30]))));
assert_eq!(r.next().unwrap(), Ok((IVec::from(&[2]), IVec::from(&[20]))));
assert_eq!(r.next(), None);

Important traits for Iter
pub fn scan_prefix<P>(&self, prefix: P) -> Iter where
    P: AsRef<[u8]>, 
[src]

Create an iterator over tuples of keys and values, where the all the keys starts with the given prefix.

Examples

use sled::{Config, IVec};
let config = Config::new().temporary(true);
let t = config.open().unwrap();

t.insert(&[0, 0, 0], vec![0, 0, 0]).unwrap();
t.insert(&[0, 0, 1], vec![0, 0, 1]).unwrap();
t.insert(&[0, 0, 2], vec![0, 0, 2]).unwrap();
t.insert(&[0, 0, 3], vec![0, 0, 3]).unwrap();
t.insert(&[0, 1, 0], vec![0, 1, 0]).unwrap();
t.insert(&[0, 1, 1], vec![0, 1, 1]).unwrap();

let prefix: &[u8] = &[0, 0];
let mut r = t.scan_prefix(prefix);
assert_eq!(
    r.next(),
    Some(Ok((IVec::from(&[0, 0, 0]), IVec::from(&[0, 0, 0]))))
);
assert_eq!(
    r.next(),
    Some(Ok((IVec::from(&[0, 0, 1]), IVec::from(&[0, 0, 1]))))
);
assert_eq!(
    r.next(),
    Some(Ok((IVec::from(&[0, 0, 2]), IVec::from(&[0, 0, 2]))))
);
assert_eq!(
    r.next(),
    Some(Ok((IVec::from(&[0, 0, 3]), IVec::from(&[0, 0, 3]))))
);
assert_eq!(r.next(), None);

pub fn pop_max(&self) -> Result<Option<(IVec, IVec)>>[src]

Atomically removes the maximum item in the Tree instance.

Examples

use sled::{Config, IVec};
let config = Config::new().temporary(true);
let t = config.open().unwrap();

t.insert(&[0], vec![0]).unwrap();
t.insert(&[1], vec![10]).unwrap();
t.insert(&[2], vec![20]).unwrap();
t.insert(&[3], vec![30]).unwrap();
t.insert(&[4], vec![40]).unwrap();
t.insert(&[5], vec![50]).unwrap();

assert_eq!(&t.pop_max().unwrap().unwrap().0, &[5]);
assert_eq!(&t.pop_max().unwrap().unwrap().0, &[4]);
assert_eq!(&t.pop_max().unwrap().unwrap().0, &[3]);
assert_eq!(&t.pop_max().unwrap().unwrap().0, &[2]);
assert_eq!(&t.pop_max().unwrap().unwrap().0, &[1]);
assert_eq!(&t.pop_max().unwrap().unwrap().0, &[0]);
assert_eq!(t.pop_max().unwrap(), None);

pub fn pop_min(&self) -> Result<Option<(IVec, IVec)>>[src]

Atomically removes the minimum item in the Tree instance.

Examples

use sled::{Config, IVec};
let config = Config::new().temporary(true);
let t = config.open().unwrap();

t.insert(&[0], vec![0]).unwrap();
t.insert(&[1], vec![10]).unwrap();
t.insert(&[2], vec![20]).unwrap();
t.insert(&[3], vec![30]).unwrap();
t.insert(&[4], vec![40]).unwrap();
t.insert(&[5], vec![50]).unwrap();

assert_eq!(&t.pop_min().unwrap().unwrap().0, &[0]);
assert_eq!(&t.pop_min().unwrap().unwrap().0, &[1]);
assert_eq!(&t.pop_min().unwrap().unwrap().0, &[2]);
assert_eq!(&t.pop_min().unwrap().unwrap().0, &[3]);
assert_eq!(&t.pop_min().unwrap().unwrap().0, &[4]);
assert_eq!(&t.pop_min().unwrap().unwrap().0, &[5]);
assert_eq!(t.pop_min().unwrap(), None);

pub fn len(&self) -> usize[src]

Returns the number of elements in this tree.

Beware: performs a full O(n) scan under the hood.

Examples

let config = sled::Config::new().temporary(true);
let t = config.open().unwrap();
t.insert(b"a", vec![0]);
t.insert(b"b", vec![1]);
assert_eq!(t.len(), 2);

pub fn is_empty(&self) -> bool[src]

Returns true if the Tree contains no elements.

pub fn clear(&self) -> Result<()>[src]

Clears the Tree, removing all values.

Note that this is not atomic.

pub fn name(&self) -> Vec<u8>[src]

Returns the name of the tree.

pub fn checksum(&self) -> Result<u32>[src]

Returns the CRC32 of all keys and values in this Tree.

This is O(N) and locks the underlying tree for the duration of the entire scan.

Trait Implementations

impl<'_, E> Transactional<E> for &'_ Tree[src]

type View = TransactionalTree

An internal reference to an internal proxy type that mediates transactional reads and writes. Read more

impl<E> Transactional<E> for Tree[src]

type View = TransactionalTree

An internal reference to an internal proxy type that mediates transactional reads and writes. Read more

impl Send for Tree[src]

impl Sync for Tree[src]

impl<'_> IntoIterator for &'_ Tree[src]

type Item = Result<(IVec, IVec)>

The type of the elements being iterated over.

type IntoIter = Iter

Which kind of iterator are we turning this into?

impl Clone for Tree[src]

impl Debug for Tree[src]

impl Deref for Tree[src]

type Target = TreeInner

The resulting type after dereferencing.

Auto Trait Implementations

impl Unpin for Tree

impl !UnwindSafe for Tree

impl !RefUnwindSafe for Tree

Blanket Implementations

impl<T, U> Into<U> for T where
    U: From<T>, 
[src]

impl<T> From<T> for T[src]

impl<T> ToOwned for T where
    T: Clone
[src]

type Owned = T

The resulting type after obtaining ownership.

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
[src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

impl<T> Borrow<T> for T where
    T: ?Sized
[src]

impl<T> BorrowMut<T> for T where
    T: ?Sized
[src]

impl<T> Any for T where
    T: 'static + ?Sized
[src]