diff options
Diffstat (limited to 'lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb')
| -rw-r--r-- | lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb | 430 |
1 files changed, 430 insertions, 0 deletions
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb new file mode 100644 index 0000000000..712864495f --- /dev/null +++ b/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb @@ -0,0 +1,430 @@ +module Gem::Resolver::Molinillo + class Resolver + # A specific resolution from a given {Resolver} + class Resolution + # A conflict that the resolution process encountered + # @attr [Object] requirement the requirement that immediately led to the conflict + # @attr [{String,Nil=>[Object]}] requirements the requirements that caused the conflict + # @attr [Object, nil] existing the existing spec that was in conflict with + # the {#possibility} + # @attr [Object] possibility the spec that was unable to be activated due + # to a conflict + # @attr [Object] locked_requirement the relevant locking requirement. + # @attr [Array<Array<Object>>] requirement_trees the different requirement + # trees that led to every requirement for the conflicting name. + Conflict = Struct.new( + :requirement, + :requirements, + :existing, + :possibility, + :locked_requirement, + :requirement_trees + ) + + # @return [SpecificationProvider] the provider that knows about + # dependencies, requirements, specifications, versions, etc. + attr_reader :specification_provider + + # @return [UI] the UI that knows how to communicate feedback about the + # resolution process back to the user + attr_reader :resolver_ui + + # @return [DependencyGraph] the base dependency graph to which + # dependencies should be 'locked' + attr_reader :base + + # @return [Array] the dependencies that were explicitly required + attr_reader :original_requested + + # @param [SpecificationProvider] specification_provider + # see {#specification_provider} + # @param [UI] resolver_ui see {#resolver_ui} + # @param [Array] requested see {#original_requested} + # @param [DependencyGraph] base see {#base} + def initialize(specification_provider, resolver_ui, requested, base) + @specification_provider = specification_provider + @resolver_ui = resolver_ui + @original_requested = requested + @base = base + @states = [] + @iteration_counter = 0 + end + + # Resolves the {#original_requested} dependencies into a full dependency + # graph + # @raise [ResolverError] if successful resolution is impossible + # @return [DependencyGraph] the dependency graph of successfully resolved + # dependencies + def resolve + start_resolution + + while state + break unless state.requirements.any? || state.requirement + indicate_progress + if state.respond_to?(:pop_possibility_state) # DependencyState + debug(depth) { "Creating possibility state for #{requirement} (#{possibilities.count} remaining)" } + state.pop_possibility_state.tap { |s| states.push(s) if s } + end + process_topmost_state + end + + activated.freeze + ensure + end_resolution + end + + # @return [Integer] the number of resolver iterations in between calls to + # {#resolver_ui}'s {UI#indicate_progress} method + attr_accessor :iteration_rate + private :iteration_rate + + # @return [Time] the time at which resolution began + attr_accessor :started_at + private :started_at + + # @return [Array<ResolutionState>] the stack of states for the resolution + attr_accessor :states + private :states + + private + + # Sets up the resolution process + # @return [void] + def start_resolution + @started_at = Time.now + + handle_missing_or_push_dependency_state(initial_state) + + debug { "Starting resolution (#{@started_at})" } + resolver_ui.before_resolution + end + + # Ends the resolution process + # @return [void] + def end_resolution + resolver_ui.after_resolution + debug do + "Finished resolution (#{@iteration_counter} steps) " \ + "(Took #{(ended_at = Time.now) - @started_at} seconds) (#{ended_at})" + end + debug { 'Unactivated: ' + Hash[activated.vertices.reject { |_n, v| v.payload }].keys.join(', ') } if state + debug { 'Activated: ' + Hash[activated.vertices.select { |_n, v| v.payload }].keys.join(', ') } if state + end + + require 'rubygems/resolver/molinillo/lib/molinillo/state' + require 'rubygems/resolver/molinillo/lib/molinillo/modules/specification_provider' + + ResolutionState.new.members.each do |member| + define_method member do |*args, &block| + current_state = state || ResolutionState.empty + current_state.send(member, *args, &block) + end + end + + SpecificationProvider.instance_methods(false).each do |instance_method| + define_method instance_method do |*args, &block| + begin + specification_provider.send(instance_method, *args, &block) + rescue NoSuchDependencyError => error + if state + vertex = activated.vertex_named(name_for error.dependency) + error.required_by += vertex.incoming_edges.map { |e| e.origin.name } + error.required_by << name_for_explicit_dependency_source unless vertex.explicit_requirements.empty? + end + raise + end + end + end + + # Processes the topmost available {RequirementState} on the stack + # @return [void] + def process_topmost_state + if possibility + attempt_to_activate + else + create_conflict if state.is_a? PossibilityState + unwind_for_conflict until possibility && state.is_a?(DependencyState) + end + end + + # @return [Object] the current possibility that the resolution is trying + # to activate + def possibility + possibilities.last + end + + # @return [RequirementState] the current state the resolution is + # operating upon + def state + states.last + end + + # Creates the initial state for the resolution, based upon the + # {#requested} dependencies + # @return [DependencyState] the initial state for the resolution + def initial_state + graph = DependencyGraph.new.tap do |dg| + original_requested.each { |r| dg.add_root_vertex(name_for(r), nil).tap { |v| v.explicit_requirements << r } } + end + + requirements = sort_dependencies(original_requested, graph, {}) + initial_requirement = requirements.shift + DependencyState.new( + initial_requirement && name_for(initial_requirement), + requirements, + graph, + initial_requirement, + initial_requirement && search_for(initial_requirement), + 0, + {} + ) + end + + # Unwinds the states stack because a conflict has been encountered + # @return [void] + def unwind_for_conflict + debug(depth) { "Unwinding for conflict: #{requirement}" } + conflicts.tap do |c| + states.slice!((state_index_for_unwind + 1)..-1) + raise VersionConflict.new(c) unless state + state.conflicts = c + end + end + + # @return [Integer] The index to which the resolution should unwind in the + # case of conflict. + def state_index_for_unwind + current_requirement = requirement + existing_requirement = requirement_for_existing_name(name) + until current_requirement.nil? + current_state = find_state_for(current_requirement) + return states.index(current_state) if state_any?(current_state) + current_requirement = parent_of(current_requirement) + end + + until existing_requirement.nil? + existing_state = find_state_for(existing_requirement) + return states.index(existing_state) if state_any?(existing_state) + existing_requirement = parent_of(existing_requirement) + end + -1 + end + + # @return [Object] the requirement that led to `requirement` being added + # to the list of requirements. + def parent_of(requirement) + return nil unless requirement + seen = false + state = states.reverse_each.find do |s| + seen ||= s.requirement == requirement + seen && s.requirement != requirement && !s.requirements.include?(requirement) + end + state && state.requirement + end + + # @return [Object] the requirement that led to a version of a possibility + # with the given name being activated. + def requirement_for_existing_name(name) + return nil unless activated.vertex_named(name).payload + states.reverse_each.find { |s| !s.activated.vertex_named(name).payload }.requirement + end + + # @return [ResolutionState] the state whose `requirement` is the given + # `requirement`. + def find_state_for(requirement) + return nil unless requirement + states.reverse_each.find { |i| requirement == i.requirement && i.is_a?(DependencyState) } + end + + # @return [Boolean] whether or not the given state has any possibilities + # left. + def state_any?(state) + state && state.possibilities.any? + end + + # @return [Conflict] a {Conflict} that reflects the failure to activate + # the {#possibility} in conjunction with the current {#state} + def create_conflict + vertex = activated.vertex_named(name) + requirements = { + name_for_explicit_dependency_source => vertex.explicit_requirements, + name_for_locking_dependency_source => Array(locked_requirement_named(name)), + } + vertex.incoming_edges.each { |edge| (requirements[edge.origin.payload] ||= []).unshift(*edge.requirements) } + conflicts[name] = Conflict.new( + requirement, + Hash[requirements.select { |_, r| !r.empty? }], + vertex.payload, + possibility, + locked_requirement_named(name), + requirement_trees + ) + end + + # @return [Array<Array<Object>>] The different requirement + # trees that led to every requirement for the current spec. + def requirement_trees + activated.vertex_named(name).requirements.map { |r| requirement_tree_for(r) } + end + + # @return [Array<Object>] the list of requirements that led to + # `requirement` being required. + def requirement_tree_for(requirement) + tree = [] + while requirement + tree.unshift(requirement) + requirement = parent_of(requirement) + end + tree + end + + # Indicates progress roughly once every second + # @return [void] + def indicate_progress + @iteration_counter += 1 + @progress_rate ||= resolver_ui.progress_rate + if iteration_rate.nil? + if Time.now - started_at >= @progress_rate + self.iteration_rate = @iteration_counter + end + end + + if iteration_rate && (@iteration_counter % iteration_rate) == 0 + resolver_ui.indicate_progress + end + end + + # Calls the {#resolver_ui}'s {UI#debug} method + # @param [Integer] depth the depth of the {#states} stack + # @param [Proc] block a block that yields a {#to_s} + # @return [void] + def debug(depth = 0, &block) + resolver_ui.debug(depth, &block) + end + + # Attempts to activate the current {#possibility} + # @return [void] + def attempt_to_activate + debug(depth) { 'Attempting to activate ' + possibility.to_s } + existing_node = activated.vertex_named(name) + if existing_node.payload + debug(depth) { "Found existing spec (#{existing_node.payload})" } + attempt_to_activate_existing_spec(existing_node) + else + attempt_to_activate_new_spec + end + end + + # Attempts to activate the current {#possibility} (given that it has + # already been activated) + # @return [void] + def attempt_to_activate_existing_spec(existing_node) + existing_spec = existing_node.payload + if requirement_satisfied_by?(requirement, activated, existing_spec) + new_requirements = requirements.dup + push_state_for_requirements(new_requirements) + else + return if attempt_to_swap_possibility + create_conflict + debug(depth) { "Unsatisfied by existing spec (#{existing_node.payload})" } + unwind_for_conflict + end + end + + # Attempts to swp the current {#possibility} with the already-activated + # spec with the given name + # @return [Boolean] Whether the possibility was swapped into {#activated} + def attempt_to_swap_possibility + swapped = activated.dup + swapped.vertex_named(name).payload = possibility + return unless swapped.vertex_named(name).requirements. + all? { |r| requirement_satisfied_by?(r, swapped, possibility) } + attempt_to_activate_new_spec + end + + # Attempts to activate the current {#possibility} (given that it hasn't + # already been activated) + # @return [void] + def attempt_to_activate_new_spec + satisfied = begin + locked_requirement = locked_requirement_named(name) + requested_spec_satisfied = requirement_satisfied_by?(requirement, activated, possibility) + locked_spec_satisfied = !locked_requirement || + requirement_satisfied_by?(locked_requirement, activated, possibility) + debug(depth) { 'Unsatisfied by requested spec' } unless requested_spec_satisfied + debug(depth) { 'Unsatisfied by locked spec' } unless locked_spec_satisfied + requested_spec_satisfied && locked_spec_satisfied + end + if satisfied + activate_spec + else + create_conflict + unwind_for_conflict + end + end + + # @param [String] requirement_name the spec name to search for + # @return [Object] the locked spec named `requirement_name`, if one + # is found on {#base} + def locked_requirement_named(requirement_name) + vertex = base.vertex_named(requirement_name) + vertex && vertex.payload + end + + # Add the current {#possibility} to the dependency graph of the current + # {#state} + # @return [void] + def activate_spec + conflicts.delete(name) + debug(depth) { 'Activated ' + name + ' at ' + possibility.to_s } + vertex = activated.vertex_named(name) + vertex.payload = possibility + require_nested_dependencies_for(possibility) + end + + # Requires the dependencies that the recently activated spec has + # @param [Object] activated_spec the specification that has just been + # activated + # @return [void] + def require_nested_dependencies_for(activated_spec) + nested_dependencies = dependencies_for(activated_spec) + debug(depth) { "Requiring nested dependencies (#{nested_dependencies.map(&:to_s).join(', ')})" } + nested_dependencies.each { |d| activated.add_child_vertex name_for(d), nil, [name_for(activated_spec)], d } + + push_state_for_requirements(requirements + nested_dependencies) + end + + # Pushes a new {DependencyState} that encapsulates both existing and new + # requirements + # @param [Array] new_requirements + # @return [void] + def push_state_for_requirements(new_requirements, new_activated = activated.dup) + new_requirements = sort_dependencies(new_requirements.uniq, new_activated, conflicts) + new_requirement = new_requirements.shift + new_name = new_requirement ? name_for(new_requirement) : '' + possibilities = new_requirement ? search_for(new_requirement) : [] + handle_missing_or_push_dependency_state DependencyState.new( + new_name, new_requirements, new_activated, + new_requirement, possibilities, depth, conflicts.dup + ) + end + + # Pushes a new {DependencyState}. + # If the {#specification_provider} says to + # {SpecificationProvider#allow_missing?} that particular requirement, and + # there are no possibilities for that requirement, then `state` is not + # pushed, and the node in {#activated} is removed, and we continue + # resolving the remaining requirements. + # @param [DependencyState] state + # @return [void] + def handle_missing_or_push_dependency_state(state) + if state.requirement && state.possibilities.empty? && allow_missing?(state.requirement) + state.activated.detach_vertex_named(state.name) + push_state_for_requirements(state.requirements, state.activated) + else + states.push state + end + end + end + end +end |