Struct rocksdb::Cache

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

Implementations§

source§

impl Cache

source

pub fn new_lru_cache(capacity: size_t) -> Cache

Creates an LRU cache with capacity in bytes.

source

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.

source

pub fn get_usage(&self) -> usize

Returns the cache memory usage in bytes.

source

pub fn get_pinned_usage(&self) -> usize

Returns the pinned memory usage in bytes.

source

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

Sets cache capacity in bytes.

Trait Implementations§

source§

impl Clone for Cache

source§

fn clone(&self) -> Cache

Returns a copy of the value. Read more
1.0.0 · source§

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

Performs copy-assignment from source. Read more

Auto Trait Implementations§

§

impl Freeze for Cache

§

impl RefUnwindSafe for Cache

§

impl Send for Cache

§

impl Sync for Cache

§

impl Unpin for Cache

§

impl UnwindSafe for Cache

Blanket Implementations§

source§

impl<T> Any for T
where T: 'static + ?Sized,

source§

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
source§

impl<T> Borrow<T> for T
where T: ?Sized,

source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
source§

impl<T> BorrowMut<T> for T
where T: ?Sized,

source§

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
source§

impl<T> CloneToUninit for T
where T: Clone,

source§

default unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
source§

impl<T> From<T> for T

source§

fn from(t: T) -> T

Returns the argument unchanged.

source§

impl<T, U> Into<U> for T
where U: From<T>,

source§

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

source§

impl<T> ToOwned for T
where T: Clone,

§

type Owned = T

The resulting type after obtaining ownership.
source§

fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
source§

fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
source§

impl<T, U> TryFrom<U> for T
where U: Into<T>,

§

type Error = Infallible

The type returned in the event of a conversion error.
source§

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
source§

impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

§

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

The type returned in the event of a conversion error.
source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.