Struct SpaceSaving 

pub struct SpaceSaving<K>
where
    K: Hash + Eq + Clone,
{ /* private fields */ }

Streaming top-K tracker with O(K) memory.

Examples

use anomstream_core::SpaceSaving;

let mut ss: SpaceSaving<u32> = SpaceSaving::with_default_capacity().unwrap();
// 1 000 observations of "10" versus 5 of "99".
for _ in 0..1_000 {
    ss.observe(10_u32);
}
for _ in 0..5 {
    ss.observe(99_u32);
}
let top = ss.top_k(1);
assert_eq!(top[0].key, 10);
assert_eq!(top[0].estimate, 1_000);

Implementations

impl<K> SpaceSaving<K>

where K: Hash + Eq + Clone,

pub fn new(capacity: usize) -> RcfResult<Self>

Build a tracker with caller-chosen capacity.

Errors

Returns RcfError::InvalidConfig on capacity == 0.

pub fn with_default_capacity() -> RcfResult<Self>

Default tracker — capacity = 128.

Errors

Never in practice — DEFAULT_CAPACITY is a positive compile-time constant.

pub fn capacity(&self) -> usize

Configured capacity (max tracked keys).

pub fn len(&self) -> usize

Current number of tracked keys (≤ capacity).

pub fn is_empty(&self) -> bool

true when the table holds no keys.

pub fn total(&self) -> u64

Total observations — sum of every Self::observe weight.

pub fn error_bound(&self) -> u64

Worst-case per-estimate error bound (N/K). Keys whose true frequency exceeds this are guaranteed to be tracked.

pub fn observe(&mut self, key: K)

Ingest one occurrence of key with unit weight.

pub fn observe_weighted(&mut self, key: K, weight: u64)

Ingest key with caller-supplied weight — byte-count heavy hitters in NDR workloads (per-packet bytes, not just packet counts).

pub fn estimate(&self, key: &K) -> Option<HeavyHitterEntry>

Frequency estimate for key. Returns None when the key is not tracked (its true count may still be up to Self::error_bound).

pub fn top_k(&self, n: usize) -> Vec<HeavyHitter<K>>

Ranked top-n snapshot — sorted by descending estimate. n is clamped to Self::len.

pub fn iter(&self) -> impl Iterator<Item = (&K, &HeavyHitterEntry)>

Iterate every tracked (&K, HeavyHitterEntry) in insertion order (not ranked). Useful for ad-hoc scans / serialisation sinks.

pub fn reset(&mut self)

Drop every tracked key. Allocation is preserved.

Trait Implementations

impl<K> Clone for SpaceSaving<K>

where K: Hash + Eq + Clone + Clone,

fn clone(&self) -> SpaceSaving<K>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<K> Debug for SpaceSaving<K>

where K: Hash + Eq + Clone + Debug,

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

Formats the value using the given formatter.

impl<'de, K> Deserialize<'de> for SpaceSaving<K>

where K: Hash + Eq + Clone + Deserialize<'de>,

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<K> Serialize for SpaceSaving<K>

where K: Hash + Eq + Clone + Serialize,

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.