Struct FoyerCacheConfig 

pub struct FoyerCacheConfig {
    pub ram_bytes: u64,
    pub ssd_dir: PathBuf,
    pub ssd_bytes: u64,
    pub block_size: usize,
    pub buffer_pool_size: usize,
    pub iouring: bool,
}

Tuning knobs for the hybrid cache.

Fields

ram_bytes: u64

Memory-tier budget in bytes.

ssd_dir: PathBuf

On-disk tier directory. Created if missing.

ssd_bytes: u64

On-disk tier budget in bytes.

block_size: usize

Block size for the on-disk engine. Should be at least as large as the largest blob the caller will store.

buffer_pool_size: usize

Per-flusher I/O buffer pool size in bytes.

Foyer’s BlockEngine writes via N flushers, each owning an in-RAM staging buffer of buffer_pool_size / flushers bytes (foyer 0.22 default: 16 MiB / 1 flusher = 16 MiB per flusher). An entry whose serialized size exceeds the per-flusher buffer is silently dropped at Buffer::push with storage_queue_buffer_overflow and never reaches SSD, the failure mode that broke the WombatKV “foyer SSD as a hot tier across restarts” claim for our 28-42 MB ds4 KV blobs.

This must be larger than the biggest blob put through put_kv. We default to 256 MiB so single 30-60 MB ds4 / vLLM KV payloads land on SSD without the caller having to think about it. Bump via WMBT_KV_PUFFER_BUFFER_POOL_BYTES for larger blobs.

iouring: bool

Use io_uring on Linux when true. Falls back to psync otherwise.

Trait Implementations

impl Clone for FoyerCacheConfig

fn clone(&self) -> FoyerCacheConfig

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FoyerCacheConfig

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

Formats the value using the given formatter.

impl Default for FoyerCacheConfig

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for FoyerCacheConfig

fn eq(&self, other: &FoyerCacheConfig) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for FoyerCacheConfig

impl StructuralPartialEq for FoyerCacheConfig