# frozen_string_literal: true module Gem::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_set the set of specs that was unable to be # activated due to a conflict. # @attr [Object] locked_requirement the relevant locking requirement. # @attr [Array>] requirement_trees the different requirement # trees that led to every requirement for the conflicting name. # @attr [{String=>Object}] activated_by_name the already-activated specs. # @attr [Object] underlying_error an error that has occurred during resolution, and # will be raised at the end of it if no resolution is found. Conflict = Struct.new( :requirement, :requirements, :existing, :possibility_set, :locked_requirement, :requirement_trees, :activated_by_name, :underlying_error ) class Conflict # @return [Object] a spec that was unable to be activated due to a conflict def possibility possibility_set && possibility_set.latest_version end end # A collection of possibility states that share the same dependencies # @attr [Array] dependencies the dependencies for this set of possibilities # @attr [Array] possibilities the possibilities PossibilitySet = Struct.new(:dependencies, :possibilities) class PossibilitySet # String representation of the possibility set, for debugging def to_s "[#{possibilities.join(', ')}]" end # @return [Object] most up-to-date dependency in the possibility set def latest_version possibilities.last end end # Details of the state to unwind to when a conflict occurs, and the cause of the unwind # @attr [Integer] state_index the index of the state to unwind to # @attr [Object] state_requirement the requirement of the state we're unwinding to # @attr [Array] requirement_tree for the requirement we're relaxing # @attr [Array] conflicting_requirements the requirements that combined to cause the conflict # @attr [Array] requirement_trees for the conflict # @attr [Array] requirements_unwound_to_instead array of unwind requirements that were chosen over this unwind UnwindDetails = Struct.new( :state_index, :state_requirement, :requirement_tree, :conflicting_requirements, :requirement_trees, :requirements_unwound_to_instead ) class UnwindDetails include Comparable # We compare UnwindDetails when choosing which state to unwind to. If # two options have the same state_index we prefer the one most # removed from a requirement that caused the conflict. Both options # would unwind to the same state, but a `grandparent` option will # filter out fewer of its possibilities after doing so - where a state # is both a `parent` and a `grandparent` to requirements that have # caused a conflict this is the correct behaviour. # @param [UnwindDetail] other UnwindDetail to be compared # @return [Integer] integer specifying ordering def <=>(other) if state_index > other.state_index 1 elsif state_index == other.state_index reversed_requirement_tree_index <=> other.reversed_requirement_tree_index else -1 end end # @return [Integer] index of state requirement in reversed requirement tree # (the conflicting requirement itself will be at position 0) def reversed_requirement_tree_index @reversed_requirement_tree_index ||= if state_requirement requirement_tree.reverse.index(state_requirement) else 999_999 end end # @return [Boolean] where the requirement of the state we're unwinding # to directly caused the conflict. Note: in this case, it is # impossible for the state we're unwinding to be a parent of # any of the other conflicting requirements (or we would have # circularity) def unwinding_to_primary_requirement? requirement_tree.last == state_requirement end # @return [Array] array of sub-dependencies to avoid when choosing a # new possibility for the state we've unwound to. Only relevant for # non-primary unwinds def sub_dependencies_to_avoid @requirements_to_avoid ||= requirement_trees.map do |tree| index = tree.index(state_requirement) tree[index + 1] if index end.compact end # @return [Array] array of all the requirements that led to the need for # this unwind def all_requirements @all_requirements ||= requirement_trees.flatten(1) end end # @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 # Initializes a new resolution. # @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 @parents_of = Hash.new { |h, k| h[k] = [] } 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 if !state.requirement && state.requirements.empty? 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 do |s| if s states.push(s) activated.tag(s) end end end process_topmost_state end resolve_activated_specs 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] 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 push_initial_state debug { "Starting resolution (#{@started_at})\nUser-requested dependencies: #{original_requested}" } resolver_ui.before_resolution end def resolve_activated_specs activated.vertices.each do |_, vertex| next unless vertex.payload latest_version = vertex.payload.possibilities.reverse_each.find do |possibility| vertex.requirements.all? { |req| requirement_satisfied_by?(req, activated, possibility) } end activated.set_payload(vertex.name, latest_version) end activated.freeze 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_relative 'state' require_relative 'modules/specification_provider' require_relative 'delegates/resolution_state' require_relative 'delegates/specification_provider' include Gem::Molinillo::Delegates::ResolutionState include Gem::Molinillo::Delegates::SpecificationProvider # Processes the topmost available {RequirementState} on the stack # @return [void] def process_topmost_state if possibility attempt_to_activate else create_conflict unwind_for_conflict end rescue CircularDependencyError => underlying_error create_conflict(underlying_error) unwind_for_conflict 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 and pushes the initial state for the resolution, based upon the # {#requested} dependencies # @return [void] def push_initial_state graph = DependencyGraph.new.tap do |dg| original_requested.each do |requested| vertex = dg.add_vertex(name_for(requested), nil, true) vertex.explicit_requirements << requested end dg.tag(:initial_state) end push_state_for_requirements(original_requested, true, graph) end # Unwinds the states stack because a conflict has been encountered # @return [void] def unwind_for_conflict details_for_unwind = build_details_for_unwind unwind_options = unused_unwind_options debug(depth) { "Unwinding for conflict: #{requirement} to #{details_for_unwind.state_index / 2}" } conflicts.tap do |c| sliced_states = states.slice!((details_for_unwind.state_index + 1)..-1) raise_error_unless_state(c) activated.rewind_to(sliced_states.first || :initial_state) if sliced_states state.conflicts = c state.unused_unwind_options = unwind_options filter_possibilities_after_unwind(details_for_unwind) index = states.size - 1 @parents_of.each { |_, a| a.reject! { |i| i >= index } } state.unused_unwind_options.reject! { |uw| uw.state_index >= index } end end # Raises a VersionConflict error, or any underlying error, if there is no # current state # @return [void] def raise_error_unless_state(conflicts) return if state error = conflicts.values.map(&:underlying_error).compact.first raise error || VersionConflict.new(conflicts, specification_provider) end # @return [UnwindDetails] Details of the nearest index to which we could unwind def build_details_for_unwind # Get the possible unwinds for the current conflict current_conflict = conflicts[name] binding_requirements = binding_requirements_for_conflict(current_conflict) unwind_details = unwind_options_for_requirements(binding_requirements) last_detail_for_current_unwind = unwind_details.sort.last current_detail = last_detail_for_current_unwind # Look for past conflicts that could be unwound to affect the # requirement tree for the current conflict all_reqs = last_detail_for_current_unwind.all_requirements all_reqs_size = all_reqs.size relevant_unused_unwinds = unused_unwind_options.select do |alternative| diff_reqs = all_reqs - alternative.requirements_unwound_to_instead next if diff_reqs.size == all_reqs_size # Find the highest index unwind whilst looping through current_detail = alternative if alternative > current_detail alternative end # Add the current unwind options to the `unused_unwind_options` array. # The "used" option will be filtered out during `unwind_for_conflict`. state.unused_unwind_options += unwind_details.reject { |detail| detail.state_index == -1 } # Update the requirements_unwound_to_instead on any relevant unused unwinds relevant_unused_unwinds.each do |d| (d.requirements_unwound_to_instead << current_detail.state_requirement).uniq! end unwind_details.each do |d| (d.requirements_unwound_to_instead << current_detail.state_requirement).uniq! end current_detail end # @param [Array] binding_requirements array of requirements that combine to create a conflict # @return [Array] array of UnwindDetails that have a chance # of resolving the passed requirements def unwind_options_for_requirements(binding_requirements) unwind_details = [] trees = [] binding_requirements.reverse_each do |r| partial_tree = [r] trees << partial_tree unwind_details << UnwindDetails.new(-1, nil, partial_tree, binding_requirements, trees, []) # If this requirement has alternative possibilities, check if any would # satisfy the other requirements that created this conflict requirement_state = find_state_for(r) if conflict_fixing_possibilities?(requirement_state, binding_requirements) unwind_details << UnwindDetails.new( states.index(requirement_state), r, partial_tree, binding_requirements, trees, [] ) end # Next, look at the parent of this requirement, and check if the requirement # could have been avoided if an alternative PossibilitySet had been chosen parent_r = parent_of(r) next if parent_r.nil? partial_tree.unshift(parent_r) requirement_state = find_state_for(parent_r) if requirement_state.possibilities.any? { |set| !set.dependencies.include?(r) } unwind_details << UnwindDetails.new( states.index(requirement_state), parent_r, partial_tree, binding_requirements, trees, [] ) end # Finally, look at the grandparent and up of this requirement, looking # for any possibilities that wouldn't create their parent requirement grandparent_r = parent_of(parent_r) until grandparent_r.nil? partial_tree.unshift(grandparent_r) requirement_state = find_state_for(grandparent_r) if requirement_state.possibilities.any? { |set| !set.dependencies.include?(parent_r) } unwind_details << UnwindDetails.new( states.index(requirement_state), grandparent_r, partial_tree, binding_requirements, trees, [] ) end parent_r = grandparent_r grandparent_r = parent_of(parent_r) end end unwind_details end # @param [DependencyState] state # @param [Array] binding_requirements array of requirements # @return [Boolean] whether or not the given state has any possibilities # that could satisfy the given requirements def conflict_fixing_possibilities?(state, binding_requirements) return false unless state state.possibilities.any? do |possibility_set| possibility_set.possibilities.any? do |poss| possibility_satisfies_requirements?(poss, binding_requirements) end end end # Filter's a state's possibilities to remove any that would not fix the # conflict we've just rewound from # @param [UnwindDetails] unwind_details details of the conflict just # unwound from # @return [void] def filter_possibilities_after_unwind(unwind_details) return unless state && !state.possibilities.empty? if unwind_details.unwinding_to_primary_requirement? filter_possibilities_for_primary_unwind(unwind_details) else filter_possibilities_for_parent_unwind(unwind_details) end end # Filter's a state's possibilities to remove any that would not satisfy # the requirements in the conflict we've just rewound from # @param [UnwindDetails] unwind_details details of the conflict just unwound from # @return [void] def filter_possibilities_for_primary_unwind(unwind_details) unwinds_to_state = unused_unwind_options.select { |uw| uw.state_index == unwind_details.state_index } unwinds_to_state << unwind_details unwind_requirement_sets = unwinds_to_state.map(&:conflicting_requirements) state.possibilities.reject! do |possibility_set| possibility_set.possibilities.none? do |poss| unwind_requirement_sets.any? do |requirements| possibility_satisfies_requirements?(poss, requirements) end end end end # @param [Object] possibility a single possibility # @param [Array] requirements an array of requirements # @return [Boolean] whether the possibility satisfies all of the # given requirements def possibility_satisfies_requirements?(possibility, requirements) name = name_for(possibility) activated.tag(:swap) activated.set_payload(name, possibility) if activated.vertex_named(name) satisfied = requirements.all? { |r| requirement_satisfied_by?(r, activated, possibility) } activated.rewind_to(:swap) satisfied end # Filter's a state's possibilities to remove any that would (eventually) # create a requirement in the conflict we've just rewound from # @param [UnwindDetails] unwind_details details of the conflict just unwound from # @return [void] def filter_possibilities_for_parent_unwind(unwind_details) unwinds_to_state = unused_unwind_options.select { |uw| uw.state_index == unwind_details.state_index } unwinds_to_state << unwind_details primary_unwinds = unwinds_to_state.select(&:unwinding_to_primary_requirement?).uniq parent_unwinds = unwinds_to_state.uniq - primary_unwinds allowed_possibility_sets = primary_unwinds.flat_map do |unwind| states[unwind.state_index].possibilities.select do |possibility_set| possibility_set.possibilities.any? do |poss| possibility_satisfies_requirements?(poss, unwind.conflicting_requirements) end end end requirements_to_avoid = parent_unwinds.flat_map(&:sub_dependencies_to_avoid) state.possibilities.reject! do |possibility_set| !allowed_possibility_sets.include?(possibility_set) && (requirements_to_avoid - possibility_set.dependencies).empty? end end # @param [Conflict] conflict # @return [Array] minimal array of requirements that would cause the passed # conflict to occur. def binding_requirements_for_conflict(conflict) return [conflict.requirement] if conflict.possibility.nil? possible_binding_requirements = conflict.requirements.values.flatten(1).uniq # When there's a `CircularDependency` error the conflicting requirement # (the one causing the circular) won't be `conflict.requirement` # (which won't be for the right state, because we won't have created it, # because it's circular). # We need to make sure we have that requirement in the conflict's list, # otherwise we won't be able to unwind properly, so we just return all # the requirements for the conflict. return possible_binding_requirements if conflict.underlying_error possibilities = search_for(conflict.requirement) # If all the requirements together don't filter out all possibilities, # then the only two requirements we need to consider are the initial one # (where the dependency's version was first chosen) and the last if binding_requirement_in_set?(nil, possible_binding_requirements, possibilities) return [conflict.requirement, requirement_for_existing_name(name_for(conflict.requirement))].compact end # Loop through the possible binding requirements, removing each one # that doesn't bind. Use a `reverse_each` as we want the earliest set of # binding requirements, and don't use `reject!` as we wish to refine the # array *on each iteration*. binding_requirements = possible_binding_requirements.dup possible_binding_requirements.reverse_each do |req| next if req == conflict.requirement unless binding_requirement_in_set?(req, binding_requirements, possibilities) binding_requirements -= [req] end end binding_requirements end # @param [Object] requirement we wish to check # @param [Array] possible_binding_requirements array of requirements # @param [Array] possibilities array of possibilities the requirements will be used to filter # @return [Boolean] whether or not the given requirement is required to filter # out all elements of the array of possibilities. def binding_requirement_in_set?(requirement, possible_binding_requirements, possibilities) possibilities.any? do |poss| possibility_satisfies_requirements?(poss, possible_binding_requirements - [requirement]) end end # @param [Object] requirement # @return [Object] the requirement that led to `requirement` being added # to the list of requirements. def parent_of(requirement) return unless requirement return unless index = @parents_of[requirement].last return unless parent_state = @states[index] parent_state.requirement end # @param [String] name # @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 vertex = activated.vertex_named(name) return nil unless vertex.payload states.find { |s| s.name == name }.requirement end # @param [Object] requirement # @return [ResolutionState] the state whose `requirement` is the given # `requirement`. def find_state_for(requirement) return nil unless requirement states.find { |i| requirement == i.requirement } end # @param [Object] underlying_error # @return [Conflict] a {Conflict} that reflects the failure to activate # the {#possibility} in conjunction with the current {#state} def create_conflict(underlying_error = nil) vertex = activated.vertex_named(name) locked_requirement = locked_requirement_named(name) requirements = {} unless vertex.explicit_requirements.empty? requirements[name_for_explicit_dependency_source] = vertex.explicit_requirements end requirements[name_for_locking_dependency_source] = [locked_requirement] if locked_requirement vertex.incoming_edges.each do |edge| (requirements[edge.origin.payload.latest_version] ||= []).unshift(edge.requirement) end activated_by_name = {} activated.each { |v| activated_by_name[v.name] = v.payload.latest_version if v.payload } conflicts[name] = Conflict.new( requirement, requirements, vertex.payload && vertex.payload.latest_version, possibility, locked_requirement, requirement_trees, activated_by_name, underlying_error ) end # @return [Array>] The different requirement # trees that led to every requirement for the current spec. def requirement_trees vertex = activated.vertex_named(name) vertex.requirements.map { |r| requirement_tree_for(r) } end # @param [Object] requirement # @return [Array] 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_vertex = activated.vertex_named(name) if existing_vertex.payload debug(depth) { "Found existing spec (#{existing_vertex.payload})" } attempt_to_filter_existing_spec(existing_vertex) else latest = possibility.latest_version possibility.possibilities.select! do |possibility| requirement_satisfied_by?(requirement, activated, possibility) end if possibility.latest_version.nil? # ensure there's a possibility for better error messages possibility.possibilities << latest if latest create_conflict unwind_for_conflict else activate_new_spec end end end # Attempts to update the existing vertex's `PossibilitySet` with a filtered version # @return [void] def attempt_to_filter_existing_spec(vertex) filtered_set = filtered_possibility_set(vertex) if !filtered_set.possibilities.empty? activated.set_payload(name, filtered_set) new_requirements = requirements.dup push_state_for_requirements(new_requirements, false) else create_conflict debug(depth) { "Unsatisfied by existing spec (#{vertex.payload})" } unwind_for_conflict end end # Generates a filtered version of the existing vertex's `PossibilitySet` using the # current state's `requirement` # @param [Object] vertex existing vertex # @return [PossibilitySet] filtered possibility set def filtered_possibility_set(vertex) PossibilitySet.new(vertex.payload.dependencies, vertex.payload.possibilities & possibility.possibilities) 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_new_spec conflicts.delete(name) debug(depth) { "Activated #{name} at #{possibility}" } activated.set_payload(name, possibility) require_nested_dependencies_for(possibility) end # Requires the dependencies that the recently activated spec has # @param [Object] possibility_set the PossibilitySet that has just been # activated # @return [void] def require_nested_dependencies_for(possibility_set) nested_dependencies = dependencies_for(possibility_set.latest_version) debug(depth) { "Requiring nested dependencies (#{nested_dependencies.join(', ')})" } nested_dependencies.each do |d| activated.add_child_vertex(name_for(d), nil, [name_for(possibility_set.latest_version)], d) parent_index = states.size - 1 parents = @parents_of[d] parents << parent_index if parents.empty? end push_state_for_requirements(requirements + nested_dependencies, !nested_dependencies.empty?) end # Pushes a new {DependencyState} that encapsulates both existing and new # requirements # @param [Array] new_requirements # @param [Boolean] requires_sort # @param [Object] new_activated # @return [void] def push_state_for_requirements(new_requirements, requires_sort = true, new_activated = activated) new_requirements = sort_dependencies(new_requirements.uniq, new_activated, conflicts) if requires_sort new_requirement = nil loop do new_requirement = new_requirements.shift break if new_requirement.nil? || states.none? { |s| s.requirement == new_requirement } end new_name = new_requirement ? name_for(new_requirement) : ''.freeze possibilities = possibilities_for_requirement(new_requirement) handle_missing_or_push_dependency_state DependencyState.new( new_name, new_requirements, new_activated, new_requirement, possibilities, depth, conflicts.dup, unused_unwind_options.dup ) end # Checks a proposed requirement with any existing locked requirement # before generating an array of possibilities for it. # @param [Object] requirement the proposed requirement # @param [Object] activated # @return [Array] possibilities def possibilities_for_requirement(requirement, activated = self.activated) return [] unless requirement if locked_requirement_named(name_for(requirement)) return locked_requirement_possibility_set(requirement, activated) end group_possibilities(search_for(requirement)) end # @param [Object] requirement the proposed requirement # @param [Object] activated # @return [Array] possibility set containing only the locked requirement, if any def locked_requirement_possibility_set(requirement, activated = self.activated) all_possibilities = search_for(requirement) locked_requirement = locked_requirement_named(name_for(requirement)) # Longwinded way to build a possibilities array with either the locked # requirement or nothing in it. Required, since the API for # locked_requirement isn't guaranteed. locked_possibilities = all_possibilities.select do |possibility| requirement_satisfied_by?(locked_requirement, activated, possibility) end group_possibilities(locked_possibilities) end # Build an array of PossibilitySets, with each element representing a group of # dependency versions that all have the same sub-dependency version constraints # and are contiguous. # @param [Array] possibilities an array of possibilities # @return [Array] an array of possibility sets def group_possibilities(possibilities) possibility_sets = [] current_possibility_set = nil possibilities.reverse_each do |possibility| dependencies = dependencies_for(possibility) if current_possibility_set && dependencies_equal?(current_possibility_set.dependencies, dependencies) current_possibility_set.possibilities.unshift(possibility) else possibility_sets.unshift(PossibilitySet.new(dependencies, [possibility])) current_possibility_set = possibility_sets.first end end possibility_sets 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 vertex 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.dup, false, state.activated) else states.push(state).tap { activated.tag(state) } end end end end end