Struct PersistentResultCacheWriter 

pub struct PersistentResultCacheWriter { /* private fields */ }

The PersistentResultCacheWriter. The query thread calls PersistentResultCacheWriter::enqueue_store / [enqueue_remove] / enqueue_clear; the worker calls [drain_one] in a loop and re-validates the op before publishing.

Implementations

impl PersistentResultCacheWriter

pub fn new(metrics: LookupMetrics, limits: WriterLimits) -> Self

pub fn enqueue_store(&self, entry: PersistableEntry)

Enqueue a Store op. Coalesces with a previous Store for the same key (the new entry supersedes the old one — old bytes are subtracted from the queue’s approx_bytes first). Drops the op and increments the dropped counter when the queue is full.

pub fn enqueue_remove(&self, key: u64)

Enqueue a Remove op. Always supersedes any pending Store for the same key (its bytes are subtracted so the queue can free capacity before the worker actually deletes the file).

pub fn enqueue_clear(&self)

Advance the global clear generation and enqueue a Clear op so the worker performs the actual file deletion. The in-memory pending map is also dropped because every existing op is now stale.

pub fn drain_one(&self) -> Option<DrainedOp>

Pop the next pending op, waiting on the condvar until one is queued or shutdown is requested. Returns None only after shutdown AND the queue is empty — the worker drains remaining ops before exit.

pub fn try_drain_one(&self) -> Option<DrainedOp>

Non-blocking variant: returns Some(op) if any op is queued, else None. Used by flush_persistent_cache(deadline) to drain the queue under a deadline.

pub fn shutdown(&self)

Mark the writer as shutdown. The worker drains remaining ops until the queue is empty or the optional deadline expires; anything still queued at that point is counted as abandoned.

pub fn pending_count(&self) -> u64

Count the ops still queued at the moment of the call. Used to compute the abandoned count on shutdown.

pub fn drain_all_as_abandoned(&self) -> u64

Drain every remaining op synchronously, accumulating their per-op byte estimates into abandoned_bytes and counting each as abandoned. Returns the number of abandoned ops. Used by shutdown_persistent_cache(deadline) to clear the queue on close.

pub fn record_outcome(&self, outcome: DrainOutcome)

pub fn enqueued_total(&self) -> u64

pub fn coalesced_total(&self) -> u64

pub fn dropped_total(&self) -> u64

pub fn remove_total(&self) -> u64

pub fn stale_total(&self) -> u64

pub fn errors_total(&self) -> u64

pub fn abandoned_total(&self) -> u64

pub fn queue_depth(&self) -> usize

pub fn writes_in_flight(&self) -> u64

Number of I/O operations the worker has not yet completed.

pub fn persist_snapshot(&self) -> LookupMetricsSnapshot

Point-in-time copy of the persistent-cache publish counters. Exposed so external integration tests can assert on the writer’s bookkeeping without going through Table::lookup_metrics_snapshot.

pub fn for_test(limits: WriterLimits) -> Self

Construct a writer with a fresh LookupMetrics (the canonical metrics type is pub(crate) and not constructible from external integration tests).

pub fn bump_persist_generation(&self, key: u64) -> u64

Bump the writer’s per-key generation for key and return the new generation. Used by the cache when it allocates a fresh entry generation just before enqueueing, so a subsequent invalidation (Remove / Clear) is observed as newer.