Struct LmdbReadPool 

pub struct LmdbReadPool { /* private fields */ }

LMDB Read Transaction Pool

Manages a pool of read-only transaction slots using a semaphore. This limits concurrent read transactions and provides timeout support.

Example

let pool = LmdbReadPool::new(env.clone(), state_db, ReadPoolConfig::enabled(4));

// Acquire a pooled read transaction
let txn = pool.acquire().await?;
let value = txn.get_state(b"key")?;
// Transaction and permit are released when `txn` is dropped

Implementations

impl LmdbReadPool

pub fn new( env: Arc<Environment>, state_db: Database, config: ReadPoolConfig, ) -> Self

Create a new read pool with the given configuration

pub async fn acquire(&self) -> Result<PooledLmdbReadTxn<'_>>

Acquire a pooled read-only transaction

Waits up to the configured timeout for a slot to become available. Returns an error if the timeout is exceeded.

pub fn try_acquire(&self) -> Result<Option<PooledLmdbReadTxn<'_>>>

Try to acquire a pooled read-only transaction without waiting

Returns None if no slot is immediately available.

pub fn acquire_blocking(&self) -> Result<PooledLmdbReadTxn<'_>>

Acquire a pooled read-only transaction (blocking)

This is a synchronous version that blocks the current thread using exponential backoff (1ms, 2ms, 4ms, … capped at 32ms) up to the configured acquire_timeout.

Prefer acquire() in async contexts.

pub fn available_permits(&self) -> usize

Get the number of available slots in the pool

pub fn is_enabled(&self) -> bool

Check if pooling is enabled