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Contents
module Internals
module Query
# Combinations are a number of Combination-s.
#
# They are the core of an allocation.
# An allocation consists of a number of combinations.
#
module Combinations # :nodoc:all
# Memory Combinations contain specific methods for
# calculating score and ids in memory.
#
class Memory < Base
# Returns the result ids for the allocation.
#
# Sorts the ids by size and & through them in the following order (sizes):
# 0. [100_000, 400, 30, 2]
# 1. [2, 30, 400, 100_000]
# 2. (100_000 & (400 & (30 & 2))) # => result
#
# Note: Uses a C-optimized intersection routine for speed and memory efficiency.
#
# Note: In the memory based version we ignore the (amount) needed hint.
# TODO Not ignore it?
#
def ids _, _
return [] if @combinations.empty?
# Get the ids for each combination.
#
# TODO For combinations with Redis
#
id_arrays = @combinations.inject([]) do |total, combination|
total << combination.ids
end
# Order by smallest size first such that the intersect can be performed faster.
#
# TODO Move into the memory_efficient_intersect such that
# this precondition for a fast algorithm is always given.
#
id_arrays.sort! { |this_array, that_array| this_array.size <=> that_array.size }
# Call the optimized C algorithm.
#
Performant::Array.memory_efficient_intersect id_arrays
end
end
end
end
end
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11 entries across 11 versions & 1 rubygems