Struct Spill 

struct Spill {
    queue: Mutex<VecDeque<Arc<ChunkMeta>>>,
    cv: Condvar,
    enabled: AtomicBool,
    eager: AtomicBool,
    threads: AtomicU64,
    in_flight: AtomicU64,
}

Available on Unix and crate feature pool only.

Hand-off point between budget enforcement and spill threads. Eviction I/O (compression and the synchronous-reclaim pageout) runs on spill threads when enabled, keeping multi-millisecond work off the threads that trip the budget; with no spill threads, eviction runs inline on the caller.

Fields

queue: Mutex<VecDeque<Arc<ChunkMeta>>>

Chunks in WriteInFlight, awaiting a spill thread.

cv: Condvar

Parks idle spill threads. Notified when work lands in queue, when eager backing turns on, and at shutdown; threads additionally wake on a timeout so eager backing scans for write-behind work without a dedicated wakeup per candidate.

enabled: AtomicBool

Whether evictions are handed to spill threads. Set when threads are first spawned; cleared to fall back to inline eviction.

eager: AtomicBool

Whether idle spill threads eagerly compress unbacked chunks to BackedResident (write-behind): the chunk stays readable in its slot while a compressed extent accumulates on the swap device, so a later budget-driven eviction is a pure page release instead of a compression. Costs CPU on chunks that die before eviction would have reached them; pays at every pressure event.

threads: AtomicU64

Number of spill threads spawned (spawn-once; later config changes only toggle enabled).

in_flight: AtomicU64

Queued plus currently-processing entries; quiesce waits on zero.

Trait Implementations

impl Debug for Spill

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

Formats the value using the given formatter.

impl Default for Spill

fn default() -> Spill

Returns the “default value” for a type.