Class: MOSAIK::Extractors::Evolution

Inherits:
MOSAIK::Extractor show all
Defined in:
lib/mosaik/extractors/evolution.rb

Overview

Evolutionary (logical and contributor) coupling extraction

Instance Attribute Summary

Attributes inherited from MOSAIK::Extractor

#graph, #options

Instance Method Summary collapse

Methods inherited from MOSAIK::Extractor

#initialize

Constructor Details

This class inherits a constructor from MOSAIK::Extractor

Instance Method Details

#call ⇒ Object 



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# File 'lib/mosaik/extractors/evolution.rb', line 15

def call
  # Open the git repository
  git = Git.open(options[:directory], log: ::Logger.new(File::NULL))

  # Fetch commits, limited to the last N commits
  commits = git.log(options[:limit])

  # Limit commits to the load paths
  commits = commits.path(MOSAIK.configuration.load_paths)

  # Limit commits to a specific date
  commits = commits.since(options[:since]) if options[:since]

  info "Analyzing #{commits.size} commits"

  # Create a co-change matrix for each pair of constants (logical coupling)
  co_changes = Hash.new { |h, k| h[k] = Hash.new(0) }

  # Create a contributor matrix for each constant (contributor coupling)
  contributors = Hash.new { |h, k| h[k] = Set.new }

  # Iterate over each commit
  commits.each do |commit|
    # Get the files for the commit
    files = commit.diff_parent.stats[:files]

    # Select only included files
    files = files
      .map { |file, _| File.join(options[:directory], file) }
      .select { |file| file.in? MOSAIK.configuration.files }

    # Resolve file paths to class name
    constants = files.map { |file| resolver.resolve_file!(file) }

    debug "Commit #{commit.sha} (#{constants.size} constants: #{constants.join(', ')})"

    # Increment the co-change number between each pair of constants (logical coupling)
    constants
      .permutation(2)
      .each { |(a, b)| co_changes[a][b] += 1 }

    # Add the commit author to the contributors for each constant (contributor coupling)
    constants.each { |constant| contributors[constant] << commit.author.email }
  end

  if options[:couplings].include?(:logical)
    info "Constructing logical coupling graph..."

    # For each non-zero pair of constants in the co-change matrix (logical coupling)
    co_changes.each do |a, row|
      row.each do |b, co_change|
        # Skip if there are no co-changes
        next if co_change.zero?

        graph.find_or_add_vertex(a)
        graph.find_or_add_vertex(b)

        # Add an edge from the constant to the receiver
        edge = graph.find_or_add_edge(a, b, type: "logical")

        # Set or increment weight on edge
        edge.attributes[:weight] = edge.attributes.fetch(:weight, 0) + co_change
      end
    end
  end

  return unless options[:couplings].include?(:contributor)

  info "Constructing contributor coupling graph..."

  # For each non-empty pair of constants in the contributor matrix (contributor coupling)
  contributors.keys.permutation(2).each do |(a, b)|
    next if contributors[a].empty? || contributors[b].empty?

    # Calculate coupling (cardinality of the intersection of sets of developers)
    coupling = (contributors[a] & contributors[b]).size

    # Skip if the coupling is one (no shared contributors)
    next if coupling == 1

    graph.find_or_add_vertex(a)
    graph.find_or_add_vertex(b)

    # Add an edge from the constant to the receiver
    edge = graph.find_or_add_edge(a, b, type: "contributor")

    # Set weight on edge
    edge.attributes[:weight] = edge.attributes.fetch(:weight, 0) + coupling
  end
end

#validate ⇒ Object

Raises:



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# File 'lib/mosaik/extractors/evolution.rb', line 11

def validate
  raise OptionError, "directory is not a git repository" unless File.directory?(File.join(options[:directory], ".git"))
end