Struct CachedQueryRunner 

pub struct CachedQueryRunner<F, E>
where
    F: FnMut(&str) -> Result<RowSet, E>,
{ /* private fields */ }

A read-through adapter that wraps a synchronous query executor with a SqlQueryCache.

The executor F is a FnMut(&str) -> Result<RowSet, E> — a closure or function pointer that actually runs the SQL against a database backend.

On a cache hit the executor is never called. On a miss the executor is called, the result stored in the cache, and returned to the caller.

Example

use oxisql_core::{Row, RowSet, Value};
use oxisql_cache::CachedQueryRunner;

let mut runner = CachedQueryRunner::new(
    32,
    |sql: &str| -> Result<RowSet, String> {
        // Simulated DB hit.
        Ok(RowSet::from_rows(vec![Row::new(
            vec!["n".into()],
            vec![Value::I64(1)],
        )]))
    },
);

let r1 = runner.run("SELECT 1").unwrap();
let r2 = runner.run("SELECT 1").unwrap();
assert_eq!(r1.len(), r2.len());
assert_eq!(runner.hits(), 1);
assert_eq!(runner.misses(), 1);

Implementations

impl<F, E> CachedQueryRunner<F, E>

where F: FnMut(&str) -> Result<RowSet, E>,

pub fn new(capacity: usize, executor: F) -> Self

Create a new runner with the given cache capacity and executor.

pub fn run(&mut self, sql: &str) -> Result<RowSet, E>

Run sql against the cache/executor.

Returns a cached RowSet clone on a hit. On a miss, calls the executor, caches the result (without TTL), and returns it.

Errors

Propagates any error returned by the executor.

pub fn run_with_ttl(&mut self, sql: &str, ttl: Duration) -> Result<RowSet, E>

Run sql with a TTL on the cached result.

Cached results expire after ttl; the next call after expiry will re-execute the query.

Errors

Propagates any error returned by the executor.

pub fn invalidate(&mut self, sql: &str)

Invalidate a specific cached result.

pub fn clear(&mut self)

Remove all cached results.

pub fn hits(&self) -> u64

Return the number of cache hits since creation.

pub fn misses(&self) -> u64

Return the number of cache misses since creation.

pub fn stats(&self) -> QueryCacheStats

Return a stats snapshot.