Struct LSMTree

pub struct LSMTree<K, V> { /* private fields */ }

LSMTree manages a tree of layers to provide a key/value store. Each layer contains deltas on the preceding layer. The top layer is an in-memory mutable layer. Layers can be compacted to form a new combined layer.

Implementations

impl<'tree, K: MergeableKey, V: Value> LSMTree<K, V>

pub fn new(merge_fn: MergeFn<K, V>, cache: Box<dyn ObjectCache<K, V>>) -> Self

Creates a new empty tree.

pub async fn open( merge_fn: MergeFn<K, V>, handles: impl IntoIterator<Item = impl ReadObjectHandle + 'static>, cache: Box<dyn ObjectCache<K, V>>, ) -> Result<Self, Error>

Opens an existing tree from the provided handles to the layer objects.

pub fn set_layers(&self, layers: Vec<Arc<dyn Layer<K, V>>>)

Replaces the immutable layers.

pub async fn append_layers( &self, handles: impl IntoIterator<Item = impl ReadObjectHandle + 'static>, ) -> Result<(), Error>

Appends to the given layers at the end i.e. they should be base layers. This is supposed to be used after replay when we are opening a tree and we have discovered the base layers.

pub fn reset_immutable_layers(&self)

Resets the immutable layers.

pub fn seal(&self)

Seals the current mutable layer and creates a new one.

pub fn reset(&self)

Resets the tree to an empty state.

pub async fn compact_with_iterator<W: WriteBytes + Send>( &self, iterator: impl LayerIterator<K, V>, num_items: usize, writer: W, block_size: u64, ) -> Result<(), Error>

Writes the items yielded by the iterator into the supplied object.

pub fn empty_layer_set(&self) -> LayerSet<K, V>

Returns an empty layer-set for this tree.

pub fn add_all_layers_to_layer_set(&self, layer_set: &mut LayerSet<K, V>)

Adds all the layers (including the mutable layer) to layer_set.

pub fn layer_set(&self) -> LayerSet<K, V>

Returns a clone of the current set of layers (including the mutable layer), after which one can get an iterator.

pub fn immutable_layer_set(&self) -> LayerSet<K, V>

Returns the current set of immutable layers after which one can get an iterator (for e.g. compacting). Since these layers are immutable, getting an iterator should not block anything else.

pub fn insert(&self, item: Item<K, V>) -> Result<(), Error>

Inserts an item into the mutable layer. Returns error if item already exists.

pub fn replace_or_insert(&self, item: Item<K, V>)

Replaces or inserts an item into the mutable layer.

pub fn merge_into(&self, item: Item<K, V>, lower_bound: &K)

Merges the given item into the mutable layer.

pub async fn find(&self, search_key: &K) -> Result<Option<Item<K, V>>, Error>

where K: Eq,

Searches for an exact match for the given key. If the value is equal to Value::DELETED_MARKER the item is considered missing and will not be returned.

pub fn mutable_layer(&self) -> Arc<SkipListLayer<K, V>>

pub fn set_mutation_callback(&self, mutation_callback: MutationCallback<K, V>)

Sets a mutation callback which is a callback that is triggered whenever any mutations are applied to the tree. This might be useful for tests that want to record the precise sequence of mutations that are applied to the tree.

pub fn get_earliest_version(&self) -> Version

Returns the earliest version used by a layer in the tree.

pub fn new_mutable_layer() -> Arc<SkipListLayer<K, V>>

Returns a new mutable layer.

pub fn set_mutable_layer(&self, layer: Arc<SkipListLayer<K, V>>)

Replaces the mutable layer.

pub fn record_inspect_data(&self, root: &Node)

Records inspect data for the LSM tree into node. Called lazily when inspect is queried.