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| Current File : //usr/share/rubygems/rubygems/dependency_resolver.rb |
require 'rubygems'
require 'rubygems/dependency'
require 'rubygems/exceptions'
require 'uri'
require 'net/http'
module Gem
# Raised when a DependencyConflict reaches the toplevel.
# Indicates which dependencies were incompatible.
#
class DependencyResolutionError < Gem::Exception
def initialize(conflict)
@conflict = conflict
a, b = conflicting_dependencies
super "unable to resolve conflicting dependencies '#{a}' and '#{b}'"
end
attr_reader :conflict
def conflicting_dependencies
@conflict.conflicting_dependencies
end
end
# Raised when a dependency requests a gem for which there is
# no spec.
#
class UnsatisfiableDepedencyError < Gem::Exception
def initialize(dep)
super "unable to find any gem matching dependency '#{dep}'"
@dependency = dep
end
attr_reader :dependency
end
# Raised when dependencies conflict and create the inability to
# find a valid possible spec for a request.
#
class ImpossibleDependenciesError < Gem::Exception
def initialize(request, conflicts)
s = conflicts.size == 1 ? "" : "s"
super "detected #{conflicts.size} conflict#{s} with dependency '#{request.dependency}'"
@request = request
@conflicts = conflicts
end
def dependency
@request.dependency
end
attr_reader :conflicts
end
# Given a set of Gem::Dependency objects as +needed+ and a way
# to query the set of available specs via +set+, calculates
# a set of ActivationRequest objects which indicate all the specs
# that should be activated to meet the all the requirements.
#
class DependencyResolver
# Represents a specification retrieved via the rubygems.org
# API. This is used to avoid having to load the full
# Specification object when all we need is the name, version,
# and dependencies.
#
class APISpecification
attr_reader :set # :nodoc:
def initialize(set, api_data)
@set = set
@name = api_data[:name]
@version = Gem::Version.new api_data[:number]
@dependencies = api_data[:dependencies].map do |name, ver|
Gem::Dependency.new name, ver.split(/\s*,\s*/)
end
end
attr_reader :name, :version, :dependencies
def == other # :nodoc:
self.class === other and
@set == other.set and
@name == other.name and
@version == other.version and
@dependencies == other.dependencies
end
def full_name
"#{@name}-#{@version}"
end
end
# The global rubygems pool, available via the rubygems.org API.
# Returns instances of APISpecification.
#
class APISet
def initialize
@data = Hash.new { |h,k| h[k] = [] }
@dep_uri = URI 'https://rubygems.org/api/v1/dependencies'
end
# Return data for all versions of the gem +name+.
#
def versions(name)
if @data.key?(name)
return @data[name]
end
uri = @dep_uri + "?gems=#{name}"
str = Gem::RemoteFetcher.fetcher.fetch_path uri
Marshal.load(str).each do |ver|
@data[ver[:name]] << ver
end
@data[name]
end
# Return an array of APISpecification objects matching
# DependencyRequest +req+.
#
def find_all(req)
res = []
versions(req.name).each do |ver|
if req.dependency.match? req.name, ver[:number]
res << APISpecification.new(self, ver)
end
end
res
end
# A hint run by the resolver to allow the Set to fetch
# data for DependencyRequests +reqs+.
#
def prefetch(reqs)
names = reqs.map { |r| r.dependency.name }
needed = names.find_all { |d| !@data.key?(d) }
return if needed.empty?
uri = @dep_uri + "?gems=#{needed.sort.join ','}"
str = Gem::RemoteFetcher.fetcher.fetch_path uri
Marshal.load(str).each do |ver|
@data[ver[:name]] << ver
end
end
end
# Represents a possible Specification object returned
# from IndexSet. Used to delay needed to download full
# Specification objects when only the +name+ and +version+
# are needed.
#
class IndexSpecification
def initialize(set, name, version, source, plat)
@set = set
@name = name
@version = version
@source = source
@platform = plat
@spec = nil
end
attr_reader :name, :version, :source
def full_name
"#{@name}-#{@version}"
end
def spec
@spec ||= @set.load_spec(@name, @version, @source)
end
def dependencies
spec.dependencies
end
end
# The global rubygems pool represented via the traditional
# source index.
#
class IndexSet
def initialize
@f = Gem::SpecFetcher.fetcher
@all = Hash.new { |h,k| h[k] = [] }
list, _ = @f.available_specs(:released)
list.each do |uri, specs|
specs.each do |n|
@all[n.name] << [uri, n]
end
end
@specs = {}
end
# Return an array of IndexSpecification objects matching
# DependencyRequest +req+.
#
def find_all(req)
res = []
name = req.dependency.name
@all[name].each do |uri, n|
if req.dependency.match? n
res << IndexSpecification.new(self, n.name, n.version,
uri, n.platform)
end
end
res
end
# No prefetching needed since we load the whole index in
# initially.
#
def prefetch(gems)
end
# Called from IndexSpecification to get a true Specification
# object.
#
def load_spec(name, ver, source)
key = "#{name}-#{ver}"
@specs[key] ||= source.fetch_spec(Gem::NameTuple.new(name, ver))
end
end
# A set which represents the installed gems. Respects
# all the normal settings that control where to look
# for installed gems.
#
class CurrentSet
def find_all(req)
req.dependency.matching_specs
end
def prefetch(gems)
end
end
# Create DependencyResolver object which will resolve
# the tree starting with +needed+ Depedency objects.
#
# +set+ is an object that provides where to look for
# specifications to satisify the Dependencies. This
# defaults to IndexSet, which will query rubygems.org.
#
def initialize(needed, set=IndexSet.new)
@set = set || IndexSet.new # Allow nil to mean IndexSet
@needed = needed
@conflicts = nil
end
# Provide a DependencyResolver that queries only against
# the already installed gems.
#
def self.for_current_gems(needed)
new needed, CurrentSet.new
end
# Contains all the conflicts encountered while doing resolution
#
attr_reader :conflicts
# Proceed with resolution! Returns an array of ActivationRequest
# objects.
#
def resolve
@conflicts = []
needed = @needed.map { |n| DependencyRequest.new(n, nil) }
res = resolve_for needed, []
if res.kind_of? DependencyConflict
raise DependencyResolutionError.new(res)
end
res
end
# Used internally to indicate that a dependency conflicted
# with a spec that would be activated.
#
class DependencyConflict
def initialize(dependency, activated, failed_dep=dependency)
@dependency = dependency
@activated = activated
@failed_dep = failed_dep
end
attr_reader :dependency, :activated
# Return the Specification that listed the dependency
#
def requester
@failed_dep.requester
end
def for_spec?(spec)
@dependency.name == spec.name
end
# Return the 2 dependency objects that conflicted
#
def conflicting_dependencies
[@failed_dep.dependency, @activated.request.dependency]
end
end
# Used Internally. Wraps a Depedency object to also track
# which spec contained the Dependency.
#
class DependencyRequest
def initialize(dep, act)
@dependency = dep
@requester = act
end
attr_reader :dependency, :requester
def name
@dependency.name
end
def matches_spec?(spec)
@dependency.matches_spec? spec
end
def to_s
@dependency.to_s
end
def ==(other)
case other
when Dependency
@dependency == other
when DependencyRequest
@dependency == other.dependency && @requester == other.requester
else
false
end
end
end
# Specifies a Specification object that should be activated.
# Also contains a dependency that was used to introduce this
# activation.
#
class ActivationRequest
def initialize(spec, req, others_possible=true)
@spec = spec
@request = req
@others_possible = others_possible
end
attr_reader :spec, :request
# Indicate if this activation is one of a set of possible
# requests for the same Dependency request.
#
def others_possible?
@others_possible
end
# Return the ActivationRequest that contained the dependency
# that we were activated for.
#
def parent
@request.requester
end
def name
@spec.name
end
def full_name
@spec.full_name
end
def version
@spec.version
end
def full_spec
Gem::Specification === @spec ? @spec : @spec.spec
end
def download(path)
if @spec.respond_to? :source
source = @spec.source
else
source = Gem.sources.first
end
Gem.ensure_gem_subdirectories path
source.download full_spec, path
end
def ==(other)
case other
when Gem::Specification
@spec == other
when ActivationRequest
@spec == other.spec && @request == other.request
else
false
end
end
##
# Indicates if the requested gem has already been installed.
def installed?
this_spec = full_spec
Gem::Specification.any? do |s|
s == this_spec
end
end
end
def requests(s, act)
reqs = []
s.dependencies.each do |d|
next unless d.type == :runtime
reqs << DependencyRequest.new(d, act)
end
@set.prefetch(reqs)
reqs
end
# The meat of the algorithm. Given +needed+ DependencyRequest objects
# and +specs+ being a list to ActivationRequest, calculate a new list
# of ActivationRequest objects.
#
def resolve_for(needed, specs)
until needed.empty?
dep = needed.shift
# If there is already a spec activated for the requested name...
if existing = specs.find { |s| dep.name == s.name }
# then we're done since this new dep matches the
# existing spec.
next if dep.matches_spec? existing
# There is a conflict! We return the conflict
# object which will be seen by the caller and be
# handled at the right level.
# If the existing activation indicates that there
# are other possibles for it, then issue the conflict
# on the dep for the activation itself. Otherwise, issue
# it on the requester's request itself.
#
if existing.others_possible?
conflict = DependencyConflict.new(dep, existing)
else
depreq = existing.request.requester.request
conflict = DependencyConflict.new(depreq, existing, dep)
end
@conflicts << conflict
return conflict
end
# Get a list of all specs that satisfy dep
possible = @set.find_all(dep)
case possible.size
when 0
# If there are none, then our work here is done.
raise UnsatisfiableDepedencyError.new(dep)
when 1
# If there is one, then we just add it to specs
# and process the specs dependencies by adding
# them to needed.
spec = possible.first
act = ActivationRequest.new(spec, dep, false)
specs << act
# Put the deps for at the beginning of needed
# rather than the end to match the depth first
# searching done by the multiple case code below.
#
# This keeps the error messages consistent.
needed = requests(spec, act) + needed
else
# There are multiple specs for this dep. This is
# the case that this class is built to handle.
# Sort them so that we try the highest versions
# first.
possible = possible.sort_by { |s| s.version }
# We track the conflicts seen so that we can report them
# to help the user figure out how to fix the situation.
conflicts = []
# To figure out which to pick, we keep resolving
# given each one being activated and if there isn't
# a conflict, we know we've found a full set.
#
# We use an until loop rather than #reverse_each
# to keep the stack short since we're using a recursive
# algorithm.
#
until possible.empty?
s = possible.pop
# Recursively call #resolve_for with this spec
# and add it's dependencies into the picture...
act = ActivationRequest.new(s, dep)
try = requests(s, act) + needed
res = resolve_for(try, specs + [act])
# While trying to resolve these dependencies, there may
# be a conflict!
if res.kind_of? DependencyConflict
# The conflict might be created not by this invocation
# but rather one up the stack, so if we can't attempt
# to resolve this conflict (conflict isn't with the spec +s+)
# then just return it so the caller can try to sort it out.
return res unless res.for_spec? s
# Otherwise, this is a conflict that we can attempt to fix
conflicts << [s, res]
# Optimization:
#
# Because the conflict indicates the dependency that trigger
# it, we can prune possible based on this new information.
#
# This cuts down on the number of iterations needed.
possible.delete_if { |x| !res.dependency.matches_spec? x }
else
# No conflict, return the specs
return res
end
end
# We tried all possibles and nothing worked, so we let the user
# know and include as much information about the problem since
# the user is going to have to take action to fix this.
raise ImpossibleDependenciesError.new(dep, conflicts)
end
end
specs
end
end
end