Module growth_policy 

Growth policies that map a hash to a bucket and decide the next table size.

A policy owns the current bucket count and translates a hash into a bucket index. Three strategies are provided:

• PowerOfTwo keeps the bucket count a power of two and maps with a mask. Fast, and the default.
• Mod grows by a rational factor and maps with a modulo. Useful for slower growth.
• Prime uses a fixed table of primes. It spreads values better when the hash function is poor, such as an identity hash of pointers.

Each policy is constructed from a minimum bucket count. The policy may round that value up and reports the value it settled on. A request above the policy maximum returns LengthError.

Structs

LengthError

The requested bucket count exceeds what a growth policy can represent.

Mod

Grow by the rational factor NUM / DEN and map with a modulo.

PowerOfTwo

Grow by a power-of-two factor and map with a mask.

Prime

Grow by stepping through a fixed table of primes and map with a modulo.

Constants

PRIMES_TABLE

The prime table used by Prime. Ascending, 40 entries.

Traits

GrowthPolicy

Strategy for sizing the bucket array and mapping a hash to a bucket.