Struct Tree

Source

pub struct Tree<V, E, F> { /* private fields */ }

Expand description

A flash-sympathetic persistent lock-free B+ tree

This tree keeps track of insert and update times if requested

Implementations§

Source §

impl<V, E, F> ExpiringTree<V, E, F>
where E: Encoding<HashSet<IVec>> + Encoding<DateTime<Utc>> + 'static, F: Encoding<V> + 'static,

Source

pub fn cloned(&self) -> Self

Clone for structures where V, E, and F aren’t Clone

Source

pub fn transaction<G, R>(&self, g: G) -> TransactionResult<Result<R>>
where G: Fn(ExpiringTransactionalTree<'_, V, E, F>) -> ConflictableTransactionResult<Result<R>>,

Perform a multi-key serializable transaction.

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.

Source

pub fn apply_batch(&self, batch: ExpiringBatch<V, F>) -> Result<()>

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.

Source

pub fn compare_and_swap<K>( &self, key: K, old: Option<V>, new: Option<V>, ) -> Result<Result<(), CompareAndSwapError<V>>>
where K: AsRef<[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.

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.

Source

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

Retrieve a value from the Tree if it exists.

Source

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

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

Source

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

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

Source

pub fn update_and_fetch<K>( &self, key: K, f: impl Fn(Option<V>) -> Option<V>, ) -> Result<Option<V>>
where K: AsRef<[u8]>,

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.

Source

pub fn fetch_and_update<K>( &self, key: K, f: impl Fn(Option<V>) -> Option<V>, ) -> Result<Option<V>>
where K: AsRef<[u8]>,

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.

Source

pub fn flush(&self) -> Result<()>

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.

Source