Struct rocksdb::Cache

pub struct Cache(/* private fields */);

Implementations

impl Cache

pub fn new_lru_cache(capacity: size_t) -> Cache

Creates an LRU cache with capacity in bytes.

pub fn new_hyper_clock_cache( capacity: size_t, estimated_entry_charge: size_t ) -> Cache

Creates a HyperClockCache with capacity in bytes.

estimated_entry_charge is an important tuning parameter. The optimal choice at any given time is (cache.get_usage() - 64 * cache.get_table_address_count()) / cache.get_occupancy_count(), or approximately cache.get_usage() / cache.get_occupancy_count().

However, the value cannot be changed dynamically, so as the cache composition changes at runtime, the following tradeoffs apply:

• If the estimate is substantially too high (e.g., 25% higher), the cache may have to evict entries to prevent load factors that would dramatically affect lookup times.
• If the estimate is substantially too low (e.g., less than half), then meta data space overhead is substantially higher.

The latter is generally preferable, and picking the larger of block size and meta data block size is a reasonable choice that errs towards this side.

pub fn get_usage(&self) -> usize

Returns the cache memory usage in bytes.

pub fn get_pinned_usage(&self) -> usize

Returns the pinned memory usage in bytes.

pub fn set_capacity(&mut self, capacity: size_t)

Sets cache capacity in bytes.

Trait Implementations

impl Clone for Cache

fn clone(&self) -> Cache

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.