HRW.
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A bounded-load variant of HRW. Distributes a known set of keys across nodes
such that no node receives more than ceil(|keys| / |nodes| × (1 + epsilon))
keys.
Pure function of (keys, nodes, opts) — any two callers with the same
inputs produce the same assignment, no coordination required. Use this
when the full key set is known at compute time and you want bounded skew.
Summary
Functions
Returns a map of key => node covering every input key. Returns %{}
when keys is empty.
Functions
Returns a map of key => node covering every input key. Returns %{}
when keys is empty.
Each key is assigned to its highest-scoring node, with overflow falling
through to the next-best when a node hits the cap of
ceil(|keys| / |nodes| × (1 + epsilon)).
Options
:epsilon- load slack factor. Smaller values give tighter balance but more movement on node churn. Defaults to0.25.:hash_fn- a functionterm -> integer. Defaults to&:erlang.phash2/1.
Examples
iex> HRW.Bounded.assignments(["a", "b", "c", "d"], ["x", "y"], epsilon: 0.0)
%{"a" => "x", "b" => "x", "c" => "y", "d" => "y"}