Struct StatsTable 

pub struct StatsTable { /* private fields */ }

The table. Feed it samples; read it per key or in aggregate.

Bounded. A CLI runs for --for seconds and exits, so an unbounded map was fine; a GUI left open overnight on a bus carrying content-addressed or per-request keys would grow one entry per key forever. The table therefore keeps at most DEFAULT_MAX_KEYS entries, evicting the least-recently-seen first — the keys that stopped publishing are the ones a live view has least use for — and counts every eviction, so a shrinking key set is never mistaken for a quiet bus (RFC 09 §5.1).

The keys are Arc<str> rather than String so that rows — the copy the ingest lock is held for (#330) — is a refcount bump per key and not a per-key allocation. Lookups still borrow: Arc<str>: Borrow<str>, so get(&str) allocates nothing on the hot hit path.

Implementations

impl StatsTable

pub fn new() -> Self

pub fn with_capacity(max_keys: usize) -> Self

A table bounded at max_keys entries.

pub fn evicted(&self) -> u64

Keys dropped to stay within the bound.

Non-zero means the view is partial: some keys that carried traffic are no longer represented in len, totals or any tree built from this table.

pub fn max_keys(&self) -> usize

The bound in force.

pub fn unwatched(&self) -> u64

Keys retired because no active watch covers them any more (retire_unwatched).

The third O6 category, deliberately distinct from evicted (“chose to forget under the bound”) and the broadcast’s dropped (“could not keep up”): this one is “stopped looking, by request” — and a key set that shrinks because the user unwatched a subtree must say so, or it reads as a quieting bus.

pub fn retire_unwatched(&mut self, gone: &str, kept: &[String]) -> usize

Retire every key that gone covers and no selector in kept still covers, counting them under unwatched. Returns how many were retired. Selectors that fail to parse as key expressions cover nothing (gone) / keep nothing (kept).

pub fn record( &mut self, key: &str, payload_len: usize, sn: Option<u32>, now: Instant, latency: Option<(i64, StampClass)>, stamper: Option<TimestampId>, )

Record one sample. now is injected for deterministic tests; latency is the pre-computed skewed latency (#119) with the class of clock that produced it (#213) — None for an unstamped sample, which is counted, not defaulted. stamper names a third-party stamping node when there was one.

pub fn get(&self, key: &str) -> Option<&KeyStats>

pub fn iter(&self) -> impl Iterator<Item = (&str, &KeyStats)>

pub fn rows(&self) -> TreeRows

The compact rows a KeyTreeSnapshot is folded from, plus the table’s own O6 counters (#330).

This is the whole of what the tree needs, and it is deliberately a copy: MonitorCore::tick holds the ingest mutex for exactly this call and folds afterwards, so the network callback thread waits on an O(keys) walk of Copy fields and one refcount bump per key — never on the O(keys × chunks) BTreeMap descent with a String allocation per new node that the fold is. Before the split, four ticks a second each held the lock for the whole rebuild, and Monitor::watch’s promise that a slow UI cannot push back into the network layer was false for as long as each one took.

pub fn len(&self) -> usize

pub fn is_empty(&self) -> bool

pub fn totals(&self) -> (u64, u64, f64)

Aggregate totals: (samples, bytes, summed EWMA rate).

Trait Implementations

impl Debug for StatsTable

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

Formats the value using the given formatter.

impl Default for StatsTable

fn default() -> Self

Returns the “default value” for a type.