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251cac39af
* It only imports users and emails so far * It stores mapped IDs and usernames in a SQLite DB. In the future, we might want to copy those into the Discourse DB at the end of a migration. * The importer is split into steps which can mostly be configured with a simple DSL * Data that needs to be shared between steps can be stored in an instance of the `SharedData` class * Steps are automatically sorted via their defined dependencies before they are executed * Common logic for finding unique names (username, group name) is extracted into a helper class * If possible, steps try to avoid loading already imported data (via `mapping.ids` table) * And steps should select the `discourse_id` instead of the `original_id` of mapped IDs via SQL
50 lines
1.1 KiB
Ruby
Vendored
50 lines
1.1 KiB
Ruby
Vendored
# frozen_string_literal: true
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module Migrations::Importer
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class TopologicalSorter
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def self.sort(classes)
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new(classes).sort
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end
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def initialize(classes)
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@classes = classes
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@dependency_graph = build_dependency_graph
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end
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def sort
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in_degree = Hash.new(0)
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@dependency_graph.each_value { |edges| edges.each { |edge| in_degree[edge] += 1 } }
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queue = @classes.reject { |cls| in_degree[cls] > 0 }
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result = []
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while queue.any?
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node = queue.shift
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result << node
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@dependency_graph[node].each do |child|
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in_degree[child] -= 1
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queue << child if in_degree[child] == 0
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end
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end
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raise "Circular dependency detected" if result.size < @classes.size
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result
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end
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private
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def build_dependency_graph
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graph = Hash.new { |hash, key| hash[key] = [] }
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@classes
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.sort_by(&:to_s)
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.each do |klass|
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dependencies = klass.dependencies || []
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dependencies.each { |dependency| graph[dependency] << klass }
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graph[klass] ||= []
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end
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graph
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end
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end
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end
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