Struct StatementCache 

#[non_exhaustive]
pub struct StatementCache { /* private fields */ }

A least-recently-used (LRU) cache for prepared statements.

The cache is keyed by SQL text. When a statement is looked up that is not in the cache, it is prepared on the server and stored. If the cache is at capacity, the least-recently-used statement is evicted (closed on the server) before the new one is inserted.

Implementations

impl StatementCache

pub fn new(capacity: usize) -> Self

Create a new cache with the given capacity.

pub fn len(&self) -> usize

Returns the number of statements currently cached.

pub fn is_empty(&self) -> bool

Returns true if the cache contains no statements.

pub fn get(&mut self, sql: &str) -> Option<&PreparedStatement>

Look up a prepared statement by SQL text.

Returns Some if the statement is cached. The statement is moved to the front of the LRU order.

pub fn insert(&mut self, stmt: PreparedStatement) -> Option<PreparedStatement>

Insert a prepared statement into the cache.

If the cache is at capacity, the LRU entry is removed from the map (but not closed on the server — the caller must do that if needed). Returns the evicted statement, if any.

pub fn remove(&mut self, sql: &str) -> Option<PreparedStatement>

Remove a statement from the cache by SQL text.

Returns the removed statement, if any.

pub fn clear(&mut self) -> Vec<PreparedStatement>

Clear all entries from the cache.

Returns the evicted statements. The caller is responsible for closing them on the server if needed.

Trait Implementations

impl Clone for StatementCache

fn clone(&self) -> StatementCache

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for StatementCache

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.