Class: Bundler::Resolver

Inherits:
Object
  • Object
show all
Defined in:
lib/bowline/bundler/resolver.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(sources, source_requirements) ⇒ Resolver

Returns a new instance of Resolver.



77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
# File 'lib/bowline/bundler/resolver.rb', line 77

def initialize(sources, source_requirements)
  @errors = {}
  @stack  = []
  @specs  = Hash.new { |h,k| h[k] = [] }
  @by_gem = source_requirements
  @cache  = {}
  @index  = {}

  sources.each do |source|
    source.gems.each do |name, specs|
      # Hack to work with a regular Gem::SourceIndex
      specs = [specs] unless specs.is_a?(Array)
      specs.compact.each do |spec|
        next if @specs[spec.name].any? { |s| s.version == spec.version && s.platform == spec.platform }
        @specs[spec.name] << spec
      end
    end
  end
end

Instance Attribute Details

#errorsObject (readonly)

Returns the value of attribute errors.



27
28
29
# File 'lib/bowline/bundler/resolver.rb', line 27

def errors
  @errors
end

Class Method Details

.resolve(requirements, sources) ⇒ Object

Figures out the best possible configuration of gems that satisfies the list of passed dependencies and any child dependencies without causing any gem activation errors.

Parameters

*dependencies<Gem::Dependency>

The list of dependencies to resolve

Returns

<GemBundle>,nil

If the list of dependencies can be resolved, a

collection of gemspecs is returned. Otherwise, nil is returned.


39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
# File 'lib/bowline/bundler/resolver.rb', line 39

def self.resolve(requirements, sources)
  source_requirements = {}

  requirements.each do |r|
    next unless r.source
    source_requirements[r.name] = r.source
  end

  resolver = new(sources, source_requirements)
  result = catch(:success) do
    resolver.resolve(requirements, {})
    output = resolver.errors.inject("") do |o, (conflict, (origin, requirement))|
      o << "  Conflict on: #{conflict.inspect}:\n"
      o << "    * #{conflict} (#{origin.version}) activated by #{origin.required_by.first}\n"
      o << "    * #{requirement} required by #{requirement.required_by.first}\n"
      o << "    All possible versions of origin requirements conflict."
    end
    raise VersionConflict, "No compatible versions could be found for required dependencies:\n  #{output}"
    nil
  end
  if result
    # Order gems in order of dependencies. Every gem's dependency is at
    # a smaller index in the array.
    ordered = []
    result.values.each do |spec1|
      spec1.no_bundle = true if source_requirements[spec1.name] == SystemGemSource.instance
      index = nil
      place = ordered.detect do |spec2|
        spec1.dependencies.any? { |d| d.name == spec2.name }
      end
      place ?
        ordered.insert(ordered.index(place), spec1) :
        ordered << spec1
    end
    ordered.reverse
  end
end

Instance Method Details

#debugObject



97
98
99
# File 'lib/bowline/bundler/resolver.rb', line 97

def debug
  puts yield if defined?($debug) && $debug
end

#resolve(reqs, activated) ⇒ Object



101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
# File 'lib/bowline/bundler/resolver.rb', line 101

def resolve(reqs, activated)
  # If the requirements are empty, then we are in a success state. Aka, all
  # gem dependencies have been resolved.
  throw :success, activated if reqs.empty?

  debug { STDIN.gets ; print "\e[2J\e[f" ; "==== Iterating ====\n\n" }

  # Sort dependencies so that the ones that are easiest to resolve are first.
  # Easiest to resolve is defined by:
  #   1) Is this gem already activated?
  #   2) Do the version requirements include prereleased gems?
  #   3) Sort by number of gems available in the source.
  reqs = reqs.sort_by do |a|
    [ activated[a.name] ? 0 : 1,
      a.version_requirements.prerelease? ? 0 : 1,
      @errors[a.name]   ? 0 : 1,
      activated[a.name] ? 0 : search(a).size ]
  end

  debug { "Activated:\n" + activated.values.map { |a| "  #{a.name} (#{a.version})" }.join("\n") }
  debug { "Requirements:\n" + reqs.map { |r| "  #{r.name} (#{r.version_requirements})"}.join("\n") }

  activated = activated.dup
  # Pull off the first requirement so that we can resolve it
  current   = reqs.shift

  debug { "Attempting:\n  #{current.name} (#{current.version_requirements})"}

  # Check if the gem has already been activated, if it has, we will make sure
  # that the currently activated gem satisfies the requirement.
  if existing = activated[current.name]
    if current.version_requirements.satisfied_by?(existing.version)
      debug { "    * [SUCCESS] Already activated" }
      @errors.delete(existing.name)
      # Since the current requirement is satisfied, we can continue resolving
      # the remaining requirements.
      resolve(reqs, activated)
    else
      debug { "    * [FAIL] Already activated" }
      @errors[existing.name] = [existing, current]
      debug { current.required_by.map {|d| "      * #{d.name} (#{d.version_requirements})" }.join("\n") }
      # debug { "    * All current conflicts:\n" + @errors.keys.map { |c| "      - #{c}" }.join("\n") }
      # Since the current requirement conflicts with an activated gem, we need
      # to backtrack to the current requirement's parent and try another version
      # of it (maybe the current requirement won't be present anymore). If the
      # current requirement is a root level requirement, we need to jump back to
      # where the conflicting gem was activated.
      parent = current.required_by.last || existing.required_by.last
      # We track the spot where the current gem was activated because we need
      # to keep a list of every spot a failure happened.
      debug { "    -> Jumping to: #{parent.name}" }
      throw parent.name, existing.required_by.last.name
    end
  else
    # There are no activated gems for the current requirement, so we are going
    # to find all gems that match the current requirement and try them in decending
    # order. We also need to keep a set of all conflicts that happen while trying
    # this gem. This is so that if no versions work, we can figure out the best
    # place to backtrack to.
    conflicts = Set.new

    # Fetch all gem versions matching the requirement
    #
    # TODO: Warn / error when no matching versions are found.
    matching_versions = search(current)

    if matching_versions.empty?
      if current.required_by.empty?
        location = @by_gem[current.name] ? @by_gem[current.name] : "any of the sources"
        raise GemNotFound, "Could not find gem '#{current}' in #{location}"
      end
      Bundler.logger.warn "Could not find gem '#{current}' (required by '#{current.required_by.last}') in any of the sources"
    end

    matching_versions.reverse_each do |spec|
      conflict = resolve_requirement(spec, current, reqs.dup, activated.dup)
      conflicts << conflict if conflict
    end
    # If the current requirement is a root level gem and we have conflicts, we
    # can figure out the best spot to backtrack to.
    if current.required_by.empty? && !conflicts.empty?
      # Check the current "catch" stack for the first one that is included in the
      # conflicts set. That is where the parent of the conflicting gem was required.
      # By jumping back to this spot, we can try other version of the parent of
      # the conflicting gem, hopefully finding a combination that activates correctly.
      @stack.reverse_each do |savepoint|
        if conflicts.include?(savepoint)
          debug { "    -> Jumping to: #{savepoint}" }
          throw savepoint
        end
      end
    end
  end
end

#resolve_requirement(spec, requirement, reqs, activated) ⇒ Object



196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
# File 'lib/bowline/bundler/resolver.rb', line 196

def resolve_requirement(spec, requirement, reqs, activated)
  # We are going to try activating the spec. We need to keep track of stack of
  # requirements that got us to the point of activating this gem.
  spec.required_by.replace requirement.required_by
  spec.required_by << requirement

  activated[spec.name] = spec
  debug { "  Activating: #{spec.name} (#{spec.version})" }
  debug { spec.required_by.map { |d| "    * #{d.name} (#{d.version_requirements})" }.join("\n") }

  # Now, we have to loop through all child dependencies and add them to our
  # array of requirements.
  debug { "    Dependencies"}
  spec.dependencies.each do |dep|
    next if dep.type == :development
    debug { "    * #{dep.name} (#{dep.version_requirements})" }
    dep.required_by.replace(requirement.required_by)
    dep.required_by << requirement
    reqs << dep
  end

  # We create a savepoint and mark it by the name of the requirement that caused
  # the gem to be activated. If the activated gem ever conflicts, we are able to
  # jump back to this point and try another version of the gem.
  length = @stack.length
  @stack << requirement.name
  retval = catch(requirement.name) do
    resolve(reqs, activated)
  end
  # Since we're doing a lot of throw / catches. A push does not necessarily match
  # up to a pop. So, we simply slice the stack back to what it was before the catch
  # block.
  @stack.slice!(length..-1)
  retval
end

#search(dependency) ⇒ Object



232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
# File 'lib/bowline/bundler/resolver.rb', line 232

def search(dependency)
  @cache[dependency.hash] ||= begin
    pinned = @by_gem[dependency.name].gems if @by_gem[dependency.name]
    specs  = (pinned || @specs)[dependency.name]

    wants_prerelease = dependency.version_requirements.prerelease?
    only_prerelease  = specs.all? {|spec| spec.version.prerelease? }

    found = specs.select { |spec| dependency =~ spec }

    unless wants_prerelease || (pinned && only_prerelease)
      found.reject! { |spec| spec.version.prerelease? }
    end

    found.sort_by {|s| [s.version, s.platform.to_s == 'ruby' ? "\0" : s.platform.to_s] }
  end
end