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Diffstat (limited to 'lib/gitlab/usage/metrics/aggregates/sources/calculations/intersection.rb')
-rw-r--r-- | lib/gitlab/usage/metrics/aggregates/sources/calculations/intersection.rb | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/lib/gitlab/usage/metrics/aggregates/sources/calculations/intersection.rb b/lib/gitlab/usage/metrics/aggregates/sources/calculations/intersection.rb new file mode 100644 index 00000000000..dabf757c8a7 --- /dev/null +++ b/lib/gitlab/usage/metrics/aggregates/sources/calculations/intersection.rb @@ -0,0 +1,76 @@ +# frozen_string_literal: true + +module Gitlab + module Usage + module Metrics + module Aggregates + module Sources + module Calculations + module Intersection + def calculate_metrics_intersections(metric_names:, start_date:, end_date:, recorded_at:, subset_powers_cache: Hash.new({})) + # calculate power of intersection of all given metrics from inclusion exclusion principle + # |A + B + C| = (|A| + |B| + |C|) - (|A & B| + |A & C| + .. + |C & D|) + (|A & B & C|) => + # |A & B & C| = - (|A| + |B| + |C|) + (|A & B| + |A & C| + .. + |C & D|) + |A + B + C| + # |A + B + C + D| = (|A| + |B| + |C| + |D|) - (|A & B| + |A & C| + .. + |C & D|) + (|A & B & C| + |B & C & D|) - |A & B & C & D| => + # |A & B & C & D| = (|A| + |B| + |C| + |D|) - (|A & B| + |A & C| + .. + |C & D|) + (|A & B & C| + |B & C & D|) - |A + B + C + D| + + # calculate each components of equation except for the last one |A & B & C & D| = (|A| + |B| + |C| + |D|) - (|A & B| + |A & C| + .. + |C & D|) + (|A & B & C| + |B & C & D|) - ... + subset_powers_data = subsets_intersection_powers(metric_names, start_date, end_date, recorded_at, subset_powers_cache) + + # calculate last component of the equation |A & B & C & D| = .... - |A + B + C + D| + power_of_union_of_all_metrics = begin + subset_powers_cache[metric_names.size][metric_names.join('_+_')] ||= \ + calculate_metrics_union(metric_names: metric_names, start_date: start_date, end_date: end_date, recorded_at: recorded_at) + end + + # in order to determine if part of equation (|A & B & C|, |A & B & C & D|), that represents the intersection that we need to calculate, + # is positive or negative in particular equation we need to determine if number of subsets is even or odd. Please take a look at two examples below + # |A + B + C| = (|A| + |B| + |C|) - (|A & B| + |A & C| + .. + |C & D|) + |A & B & C| => + # |A & B & C| = - (|A| + |B| + |C|) + (|A & B| + |A & C| + .. + |C & D|) + |A + B + C| + # |A + B + C + D| = (|A| + |B| + |C| + |D|) - (|A & B| + |A & C| + .. + |C & D|) + (|A & B & C| + |B & C & D|) - |A & B & C & D| => + # |A & B & C & D| = (|A| + |B| + |C| + |D|) - (|A & B| + |A & C| + .. + |C & D|) + (|A & B & C| + |B & C & D|) - |A + B + C + D| + subset_powers_size_even = subset_powers_data.size.even? + + # sum all components of equation except for the last one |A & B & C & D| = (|A| + |B| + |C| + |D|) - (|A & B| + |A & C| + .. + |C & D|) + (|A & B & C| + |B & C & D|) - ... => + sum_of_all_subset_powers = sum_subset_powers(subset_powers_data, subset_powers_size_even) + + # add last component of the equation |A & B & C & D| = sum_of_all_subset_powers - |A + B + C + D| + sum_of_all_subset_powers + (subset_powers_size_even ? power_of_union_of_all_metrics : -power_of_union_of_all_metrics) + end + + private + + def subsets_intersection_powers(metric_names, start_date, end_date, recorded_at, subset_powers_cache) + subset_sizes = (1...metric_names.size) + + subset_sizes.map do |subset_size| + if subset_size > 1 + # calculate sum of powers of intersection between each subset (with given size) of metrics: #|A + B + C + D| = ... - (|A & B| + |A & C| + .. + |C & D|) + metric_names.combination(subset_size).sum do |metrics_subset| + subset_powers_cache[subset_size][metrics_subset.join('_&_')] ||= + calculate_metrics_intersections(metric_names: metrics_subset, start_date: start_date, end_date: end_date, recorded_at: recorded_at, subset_powers_cache: subset_powers_cache) + end + else + # calculate sum of powers of each set (metric) alone #|A + B + C + D| = (|A| + |B| + |C| + |D|) - ... + metric_names.sum do |metric| + subset_powers_cache[subset_size][metric] ||= \ + calculate_metrics_union(metric_names: metric, start_date: start_date, end_date: end_date, recorded_at: recorded_at) + end + end + end + end + + def sum_subset_powers(subset_powers_data, subset_powers_size_even) + sum_without_sign = subset_powers_data.to_enum.with_index.sum do |value, index| + (index + 1).odd? ? value : -value + end + + (subset_powers_size_even ? -1 : 1) * sum_without_sign + end + end + end + end + end + end + end +end |