diff --git a/.gitignore b/.gitignore
index df5ca018c1..a4cd169ec1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -30,8 +30,14 @@
 # Unignore vendored gems
 !**/vendor/bundle-standalone/ruby/*/gems/*/lib
 
-# Ignore backports gem (we don't need all files)
+# Ignore partially included gems where we don't need all files
+**/vendor/bundle-standalone/ruby/*/gems/activesupport-*/lib
+**/vendor/bundle-standalone/ruby/*/gems/concurrent-ruby-*/lib
 **/vendor/bundle-standalone/ruby/*/gems/backports-*/lib
+**/vendor/bundle-standalone/ruby/*/gems/i18n-*/lib
+**/vendor/bundle-standalone/ruby/*/gems/minitest-*/lib
+**/vendor/bundle-standalone/ruby/*/gems/thread_safe-*/lib
+**/vendor/bundle-standalone/ruby/*/gems/tzinfo-*/lib
 
 # Ignore `bin` contents (again).
 /bin
diff --git a/Library/Homebrew/cask/cmd/doctor.rb b/Library/Homebrew/cask/cmd/doctor.rb
index 459da9fcf5..2fd07ee071 100644
--- a/Library/Homebrew/cask/cmd/doctor.rb
+++ b/Library/Homebrew/cask/cmd/doctor.rb
@@ -75,7 +75,7 @@ module Cask
 
         ohai "Homebrew Cask Taps:"
         [default_tap, *alt_taps].each do |tap|
-          if tap.path.nil? || tap.path.to_s.empty?
+          if tap.path.blank?
             puts none_string
           else
             puts "#{tap.path} (#{cask_count_for_tap(tap)})"
diff --git a/Library/Homebrew/dev-cmd/audit.rb b/Library/Homebrew/dev-cmd/audit.rb
index 8b13751fae..0fda62b902 100644
--- a/Library/Homebrew/dev-cmd/audit.rb
+++ b/Library/Homebrew/dev-cmd/audit.rb
@@ -961,7 +961,7 @@ module Homebrew
     def audit_version
       if version.nil?
         problem "missing version"
-      elsif version.to_s.empty?
+      elsif version.blank?
         problem "version is set to an empty string"
       elsif !version.detected_from_url?
         version_text = version
diff --git a/Library/Homebrew/dev-cmd/bottle.rb b/Library/Homebrew/dev-cmd/bottle.rb
index 724491e01b..07cc31eb1d 100644
--- a/Library/Homebrew/dev-cmd/bottle.rb
+++ b/Library/Homebrew/dev-cmd/bottle.rb
@@ -453,7 +453,7 @@ module Homebrew
                 tag = tag.to_s.delete ":"
 
                 unless tag.empty?
-                  if !bottle_hash["bottle"]["tags"][tag].to_s.empty?
+                  if bottle_hash["bottle"]["tags"][tag].present?
                     mismatches << "#{key} => #{tag}"
                   else
                     bottle.send(key, old_value => tag.to_sym)
diff --git a/Library/Homebrew/download_strategy.rb b/Library/Homebrew/download_strategy.rb
index 2bb9c488fe..7439bf20fe 100644
--- a/Library/Homebrew/download_strategy.rb
+++ b/Library/Homebrew/download_strategy.rb
@@ -1109,7 +1109,7 @@ class BazaarDownloadStrategy < VCSDownloadStrategy
   def source_modified_time
     out, = system_command("bzr", args: ["log", "-l", "1", "--timezone=utc", cached_location])
     timestamp = out.chomp
-    raise "Could not get any timestamps from bzr!" if timestamp.to_s.empty?
+    raise "Could not get any timestamps from bzr!" if timestamp.blank?
     Time.parse(timestamp)
   end
 
diff --git a/Library/Homebrew/extend/os/linux/diagnostic.rb b/Library/Homebrew/extend/os/linux/diagnostic.rb
index ea3e1ab8ad..f4bff47a84 100644
--- a/Library/Homebrew/extend/os/linux/diagnostic.rb
+++ b/Library/Homebrew/extend/os/linux/diagnostic.rb
@@ -35,7 +35,7 @@ module Homebrew
       end
 
       def check_xdg_data_dirs
-        return if ENV["XDG_DATA_DIRS"].to_s.empty?
+        return if ENV["XDG_DATA_DIRS"].blank?
         return if ENV["XDG_DATA_DIRS"].split("/").include?(HOMEBREW_PREFIX/"share")
         <<~EOS
           Homebrew's share was not found in your XDG_DATA_DIRS but you have
diff --git a/Library/Homebrew/global.rb b/Library/Homebrew/global.rb
index 6a09581da0..94b3ede042 100644
--- a/Library/Homebrew/global.rb
+++ b/Library/Homebrew/global.rb
@@ -130,6 +130,7 @@ require "extend/pathname"
 require "extend/module"
 require "extend/predicable"
 require "extend/string"
+require "active_support/core_ext/object/blank"
 
 require "constants"
 require "exceptions"
diff --git a/Library/Homebrew/missing_formula.rb b/Library/Homebrew/missing_formula.rb
index 616efd4a8b..5d0e58b3f2 100644
--- a/Library/Homebrew/missing_formula.rb
+++ b/Library/Homebrew/missing_formula.rb
@@ -142,8 +142,7 @@ module Homebrew
           hash, short_hash, *commit_message, relative_path =
             Utils.popen_read(log_command).gsub("\\n", "\n").lines.map(&:chomp)
 
-          if hash.to_s.empty? || short_hash.to_s.empty? ||
-             relative_path.to_s.empty?
+          if hash.blank? || short_hash.blank? || relative_path.blank?
             ofail "No previously deleted formula found." unless silent
             return
           end
diff --git a/Library/Homebrew/vendor/Gemfile b/Library/Homebrew/vendor/Gemfile
index 70cbcaa226..0ea1675a5a 100644
--- a/Library/Homebrew/vendor/Gemfile
+++ b/Library/Homebrew/vendor/Gemfile
@@ -1,5 +1,7 @@
 source "https://rubygems.org"
 
+gem "activesupport"
+gem "concurrent-ruby"
 gem "backports"
 gem "plist"
 gem "ruby-macho"
diff --git a/Library/Homebrew/vendor/Gemfile.lock b/Library/Homebrew/vendor/Gemfile.lock
index 8507595bb5..e4bdddf994 100644
--- a/Library/Homebrew/vendor/Gemfile.lock
+++ b/Library/Homebrew/vendor/Gemfile.lock
@@ -1,15 +1,29 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    activesupport (5.2.1)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      i18n (>= 0.7, < 2)
+      minitest (~> 5.1)
+      tzinfo (~> 1.1)
     backports (3.11.4)
+    concurrent-ruby (1.0.5)
+    i18n (1.1.0)
+      concurrent-ruby (~> 1.0)
+    minitest (5.11.3)
     plist (3.4.0)
     ruby-macho (2.0.0)
+    thread_safe (0.3.6)
+    tzinfo (1.2.5)
+      thread_safe (~> 0.1)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
+  activesupport
   backports
+  concurrent-ruby
   plist
   ruby-macho
 
diff --git a/Library/Homebrew/vendor/bundle-standalone/bundler/setup.rb b/Library/Homebrew/vendor/bundle-standalone/bundler/setup.rb
index 6de844fd2b..fe61467fb5 100644
--- a/Library/Homebrew/vendor/bundle-standalone/bundler/setup.rb
+++ b/Library/Homebrew/vendor/bundle-standalone/bundler/setup.rb
@@ -3,6 +3,12 @@ require 'rbconfig'
 ruby_engine = defined?(RUBY_ENGINE) ? RUBY_ENGINE : 'ruby'
 ruby_version = RbConfig::CONFIG["ruby_version"]
 path = File.expand_path('..', __FILE__)
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/concurrent-ruby-1.0.5/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/i18n-1.1.0/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/minitest-5.11.3/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/thread_safe-0.3.6/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/tzinfo-1.2.5/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/activesupport-5.2.1/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/backports-3.11.4/lib"
 $:.unshift "#{path}/"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/plist-3.4.0/lib"
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/activesupport-5.2.1/lib/active_support/core_ext/object/blank.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/activesupport-5.2.1/lib/active_support/core_ext/object/blank.rb
new file mode 100644
index 0000000000..2ca431ab10
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/activesupport-5.2.1/lib/active_support/core_ext/object/blank.rb
@@ -0,0 +1,156 @@
+# frozen_string_literal: true
+
+require "active_support/core_ext/regexp"
+require "concurrent/map"
+
+class Object
+  # An object is blank if it's false, empty, or a whitespace string.
+  # For example, +false+, '', '   ', +nil+, [], and {} are all blank.
+  #
+  # This simplifies
+  #
+  #   !address || address.empty?
+  #
+  # to
+  #
+  #   address.blank?
+  #
+  # @return [true, false]
+  def blank?
+    respond_to?(:empty?) ? !!empty? : !self
+  end
+
+  # An object is present if it's not blank.
+  #
+  # @return [true, false]
+  def present?
+    !blank?
+  end
+
+  # Returns the receiver if it's present otherwise returns +nil+.
+  # <tt>object.presence</tt> is equivalent to
+  #
+  #    object.present? ? object : nil
+  #
+  # For example, something like
+  #
+  #   state   = params[:state]   if params[:state].present?
+  #   country = params[:country] if params[:country].present?
+  #   region  = state || country || 'US'
+  #
+  # becomes
+  #
+  #   region = params[:state].presence || params[:country].presence || 'US'
+  #
+  # @return [Object]
+  def presence
+    self if present?
+  end
+end
+
+class NilClass
+  # +nil+ is blank:
+  #
+  #   nil.blank? # => true
+  #
+  # @return [true]
+  def blank?
+    true
+  end
+end
+
+class FalseClass
+  # +false+ is blank:
+  #
+  #   false.blank? # => true
+  #
+  # @return [true]
+  def blank?
+    true
+  end
+end
+
+class TrueClass
+  # +true+ is not blank:
+  #
+  #   true.blank? # => false
+  #
+  # @return [false]
+  def blank?
+    false
+  end
+end
+
+class Array
+  # An array is blank if it's empty:
+  #
+  #   [].blank?      # => true
+  #   [1,2,3].blank? # => false
+  #
+  # @return [true, false]
+  alias_method :blank?, :empty?
+end
+
+class Hash
+  # A hash is blank if it's empty:
+  #
+  #   {}.blank?                # => true
+  #   { key: 'value' }.blank?  # => false
+  #
+  # @return [true, false]
+  alias_method :blank?, :empty?
+end
+
+class String
+  BLANK_RE = /\A[[:space:]]*\z/
+  ENCODED_BLANKS = Concurrent::Map.new do |h, enc|
+    h[enc] = Regexp.new(BLANK_RE.source.encode(enc), BLANK_RE.options | Regexp::FIXEDENCODING)
+  end
+
+  # A string is blank if it's empty or contains whitespaces only:
+  #
+  #   ''.blank?       # => true
+  #   '   '.blank?    # => true
+  #   "\t\n\r".blank? # => true
+  #   ' blah '.blank? # => false
+  #
+  # Unicode whitespace is supported:
+  #
+  #   "\u00a0".blank? # => true
+  #
+  # @return [true, false]
+  def blank?
+    # The regexp that matches blank strings is expensive. For the case of empty
+    # strings we can speed up this method (~3.5x) with an empty? call. The
+    # penalty for the rest of strings is marginal.
+    empty? ||
+      begin
+        BLANK_RE.match?(self)
+      rescue Encoding::CompatibilityError
+        ENCODED_BLANKS[self.encoding].match?(self)
+      end
+  end
+end
+
+class Numeric #:nodoc:
+  # No number is blank:
+  #
+  #   1.blank? # => false
+  #   0.blank? # => false
+  #
+  # @return [false]
+  def blank?
+    false
+  end
+end
+
+class Time #:nodoc:
+  # No Time is blank:
+  #
+  #   Time.now.blank? # => false
+  #
+  # @return [false]
+  def blank?
+    false
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/activesupport-5.2.1/lib/active_support/core_ext/regexp.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/activesupport-5.2.1/lib/active_support/core_ext/regexp.rb
new file mode 100644
index 0000000000..efbd708aee
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/activesupport-5.2.1/lib/active_support/core_ext/regexp.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class Regexp #:nodoc:
+  def multiline?
+    options & MULTILINE == MULTILINE
+  end
+
+  def match?(string, pos = 0)
+    !!match(string, pos)
+  end unless //.respond_to?(:match?)
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/collection/map/mri_map_backend.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/collection/map/mri_map_backend.rb
new file mode 100644
index 0000000000..d5d809dfc1
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/collection/map/mri_map_backend.rb
@@ -0,0 +1,66 @@
+require 'thread'
+require 'concurrent/collection/map/non_concurrent_map_backend'
+
+module Concurrent
+
+  # @!visibility private
+  module Collection
+
+    # @!visibility private
+    class MriMapBackend < NonConcurrentMapBackend
+
+      def initialize(options = nil)
+        super(options)
+        @write_lock = Mutex.new
+      end
+
+      def []=(key, value)
+        @write_lock.synchronize { super }
+      end
+
+      def compute_if_absent(key)
+        if stored_value = _get(key) # fast non-blocking path for the most likely case
+          stored_value
+        else
+          @write_lock.synchronize { super }
+        end
+      end
+
+      def compute_if_present(key)
+        @write_lock.synchronize { super }
+      end
+
+      def compute(key)
+        @write_lock.synchronize { super }
+      end
+
+      def merge_pair(key, value)
+        @write_lock.synchronize { super }
+      end
+
+      def replace_pair(key, old_value, new_value)
+        @write_lock.synchronize { super }
+      end
+
+      def replace_if_exists(key, new_value)
+        @write_lock.synchronize { super }
+      end
+
+      def get_and_set(key, value)
+        @write_lock.synchronize { super }
+      end
+
+      def delete(key)
+        @write_lock.synchronize { super }
+      end
+
+      def delete_pair(key, value)
+        @write_lock.synchronize { super }
+      end
+
+      def clear
+        @write_lock.synchronize { super }
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/collection/map/non_concurrent_map_backend.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/collection/map/non_concurrent_map_backend.rb
new file mode 100644
index 0000000000..ba86d7c0fb
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/collection/map/non_concurrent_map_backend.rb
@@ -0,0 +1,141 @@
+require 'concurrent/constants'
+
+module Concurrent
+
+  # @!visibility private
+  module Collection
+
+    # @!visibility private
+    class NonConcurrentMapBackend
+
+      # WARNING: all public methods of the class must operate on the @backend
+      # directly without calling each other. This is important because of the
+      # SynchronizedMapBackend which uses a non-reentrant mutex for perfomance
+      # reasons.
+      def initialize(options = nil)
+        @backend = {}
+      end
+
+      def [](key)
+        @backend[key]
+      end
+
+      def []=(key, value)
+        @backend[key] = value
+      end
+
+      def compute_if_absent(key)
+        if NULL != (stored_value = @backend.fetch(key, NULL))
+          stored_value
+        else
+          @backend[key] = yield
+        end
+      end
+
+      def replace_pair(key, old_value, new_value)
+        if pair?(key, old_value)
+          @backend[key] = new_value
+          true
+        else
+          false
+        end
+      end
+
+      def replace_if_exists(key, new_value)
+        if NULL != (stored_value = @backend.fetch(key, NULL))
+          @backend[key] = new_value
+          stored_value
+        end
+      end
+
+      def compute_if_present(key)
+        if NULL != (stored_value = @backend.fetch(key, NULL))
+          store_computed_value(key, yield(stored_value))
+        end
+      end
+
+      def compute(key)
+        store_computed_value(key, yield(@backend[key]))
+      end
+
+      def merge_pair(key, value)
+        if NULL == (stored_value = @backend.fetch(key, NULL))
+          @backend[key] = value
+        else
+          store_computed_value(key, yield(stored_value))
+        end
+      end
+
+      def get_and_set(key, value)
+        stored_value = @backend[key]
+        @backend[key] = value
+        stored_value
+      end
+
+      def key?(key)
+        @backend.key?(key)
+      end
+
+      def delete(key)
+        @backend.delete(key)
+      end
+
+      def delete_pair(key, value)
+        if pair?(key, value)
+          @backend.delete(key)
+          true
+        else
+          false
+        end
+      end
+
+      def clear
+        @backend.clear
+        self
+      end
+
+      def each_pair
+        return enum_for :each_pair unless block_given?
+        dupped_backend.each_pair do |k, v|
+          yield k, v
+        end
+        self
+      end
+
+      def size
+        @backend.size
+      end
+
+      def get_or_default(key, default_value)
+        @backend.fetch(key, default_value)
+      end
+
+      alias_method :_get, :[]
+      alias_method :_set, :[]=
+      private :_get, :_set
+      private
+      def initialize_copy(other)
+        super
+        @backend = {}
+        self
+      end
+
+      def dupped_backend
+        @backend.dup
+      end
+
+      def pair?(key, expected_value)
+        NULL != (stored_value = @backend.fetch(key, NULL)) && expected_value.equal?(stored_value)
+      end
+
+      def store_computed_value(key, new_value)
+        if new_value.nil?
+          @backend.delete(key)
+          nil
+        else
+          @backend[key] = new_value
+        end
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/constants.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/constants.rb
new file mode 100644
index 0000000000..4f9bedf245
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/constants.rb
@@ -0,0 +1,8 @@
+module Concurrent
+
+  # Various classes within allows for +nil+ values to be stored,
+  # so a special +NULL+ token is required to indicate the "nil-ness".
+  # @!visibility private
+  NULL = Object.new
+
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/map.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/map.rb
new file mode 100644
index 0000000000..814deb0085
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/map.rb
@@ -0,0 +1,240 @@
+require 'thread'
+require 'concurrent/constants'
+require 'concurrent/synchronization'
+
+module Concurrent
+  # @!visibility private
+  module Collection
+
+    # @!visibility private
+    MapImplementation = if Concurrent.java_extensions_loaded?
+                          # noinspection RubyResolve
+                          JRubyMapBackend
+                        elsif defined?(RUBY_ENGINE)
+                          case RUBY_ENGINE
+                          when 'ruby'
+                            require 'concurrent/collection/map/mri_map_backend'
+                            MriMapBackend
+                          when 'rbx'
+                            require 'concurrent/collection/map/atomic_reference_map_backend'
+                            AtomicReferenceMapBackend
+                          when 'jruby+truffle'
+                            require 'concurrent/collection/map/atomic_reference_map_backend'
+                            AtomicReferenceMapBackend
+                          else
+                            warn 'Concurrent::Map: unsupported Ruby engine, using a fully synchronized Concurrent::Map implementation' if $VERBOSE
+                            require 'concurrent/collection/map/synchronized_map_backend'
+                            SynchronizedMapBackend
+                          end
+                        else
+                          MriMapBackend
+                        end
+  end
+
+  # `Concurrent::Map` is a hash-like object and should have much better performance
+  # characteristics, especially under high concurrency, than `Concurrent::Hash`.
+  # However, `Concurrent::Map `is not strictly semantically equivalent to a ruby `Hash`
+  # -- for instance, it does not necessarily retain ordering by insertion time as `Hash`
+  # does. For most uses it should do fine though, and we recommend you consider
+  # `Concurrent::Map` instead of `Concurrent::Hash` for your concurrency-safe hash needs.
+  #
+  # > require 'concurrent'
+  # >
+  # > map = Concurrent::Map.new
+  class Map < Collection::MapImplementation
+
+    # @!macro [new] map_method_is_atomic
+    #   This method is atomic. Atomic methods of `Map` which accept a block
+    #   do not allow the `self` instance to be used within the block. Doing
+    #   so will cause a deadlock.
+
+    # @!method put_if_absent
+    #   @!macro map_method_is_atomic
+
+    # @!method compute_if_absent
+    #   @!macro map_method_is_atomic
+
+    # @!method compute_if_present
+    #   @!macro map_method_is_atomic
+
+    # @!method compute
+    #   @!macro map_method_is_atomic
+
+    # @!method merge_pair
+    #   @!macro map_method_is_atomic
+
+    # @!method replace_pair
+    #   @!macro map_method_is_atomic
+
+    # @!method replace_if_exists
+    #   @!macro map_method_is_atomic
+
+    # @!method get_and_set
+    #   @!macro map_method_is_atomic
+
+    # @!method delete
+    #   @!macro map_method_is_atomic
+
+    # @!method delete_pair
+    #   @!macro map_method_is_atomic
+
+    def initialize(options = nil, &block)
+      if options.kind_of?(::Hash)
+        validate_options_hash!(options)
+      else
+        options = nil
+      end
+
+      super(options)
+      @default_proc = block
+    end
+
+    def [](key)
+      if value = super # non-falsy value is an existing mapping, return it right away
+        value
+        # re-check is done with get_or_default(key, NULL) instead of a simple !key?(key) in order to avoid a race condition, whereby by the time the current thread gets to the key?(key) call
+        # a key => value mapping might have already been created by a different thread (key?(key) would then return true, this elsif branch wouldn't be taken and an incorrent +nil+ value
+        # would be returned)
+        # note: nil == value check is not technically necessary
+      elsif @default_proc && nil == value && NULL == (value = get_or_default(key, NULL))
+        @default_proc.call(self, key)
+      else
+        value
+      end
+    end
+
+    alias_method :get, :[]
+    alias_method :put, :[]=
+
+    # @!macro [attach] map_method_not_atomic
+    #   The "fetch-then-act" methods of `Map` are not atomic. `Map` is intended
+    #   to be use as a concurrency primitive with strong happens-before
+    #   guarantees. It is not intended to be used as a high-level abstraction
+    #   supporting complex operations. All read and write operations are
+    #   thread safe, but no guarantees are made regarding race conditions
+    #   between the fetch operation and yielding to the block. Additionally,
+    #   this method does not support recursion. This is due to internal
+    #   constraints that are very unlikely to change in the near future.
+    def fetch(key, default_value = NULL)
+      if NULL != (value = get_or_default(key, NULL))
+        value
+      elsif block_given?
+        yield key
+      elsif NULL != default_value
+        default_value
+      else
+        raise_fetch_no_key
+      end
+    end
+
+    # @!macro map_method_not_atomic
+    def fetch_or_store(key, default_value = NULL)
+      fetch(key) do
+        put(key, block_given? ? yield(key) : (NULL == default_value ? raise_fetch_no_key : default_value))
+      end
+    end
+
+    # @!macro map_method_is_atomic
+    def put_if_absent(key, value)
+      computed = false
+      result = compute_if_absent(key) do
+        computed = true
+        value
+      end
+      computed ? nil : result
+    end unless method_defined?(:put_if_absent)
+
+    def value?(value)
+      each_value do |v|
+        return true if value.equal?(v)
+      end
+      false
+    end
+
+    def keys
+      arr = []
+      each_pair {|k, v| arr << k}
+      arr
+    end unless method_defined?(:keys)
+
+    def values
+      arr = []
+      each_pair {|k, v| arr << v}
+      arr
+    end unless method_defined?(:values)
+
+    def each_key
+      each_pair {|k, v| yield k}
+    end unless method_defined?(:each_key)
+
+    def each_value
+      each_pair {|k, v| yield v}
+    end unless method_defined?(:each_value)
+
+    alias_method :each, :each_pair unless method_defined?(:each)
+
+    def key(value)
+      each_pair {|k, v| return k if v == value}
+      nil
+    end unless method_defined?(:key)
+    alias_method :index, :key if RUBY_VERSION < '1.9'
+
+    def empty?
+      each_pair {|k, v| return false}
+      true
+    end unless method_defined?(:empty?)
+
+    def size
+      count = 0
+      each_pair {|k, v| count += 1}
+      count
+    end unless method_defined?(:size)
+
+    def marshal_dump
+      raise TypeError, "can't dump hash with default proc" if @default_proc
+      h = {}
+      each_pair {|k, v| h[k] = v}
+      h
+    end
+
+    def marshal_load(hash)
+      initialize
+      populate_from(hash)
+    end
+
+    undef :freeze
+
+    # @!visibility private
+    DEFAULT_OBJ_ID_STR_WIDTH = 0.size == 4 ? 7 : 14 # we want to look "native", 7 for 32-bit, 14 for 64-bit
+    # override default #inspect() method: firstly, we don't want to be spilling our guts (i-vars), secondly, MRI backend's
+    # #inspect() call on its @backend i-var will bump @backend's iter level while possibly yielding GVL
+    def inspect
+      id_str = (object_id << 1).to_s(16).rjust(DEFAULT_OBJ_ID_STR_WIDTH, '0')
+      "#<#{self.class.name}:0x#{id_str} entries=#{size} default_proc=#{@default_proc.inspect}>"
+    end
+
+    private
+    def raise_fetch_no_key
+      raise KeyError, 'key not found'
+    end
+
+    def initialize_copy(other)
+      super
+      populate_from(other)
+    end
+
+    def populate_from(hash)
+      hash.each_pair {|k, v| self[k] = v}
+      self
+    end
+
+    def validate_options_hash!(options)
+      if (initial_capacity = options[:initial_capacity]) && (!initial_capacity.kind_of?(Integer) || initial_capacity < 0)
+        raise ArgumentError, ":initial_capacity must be a positive Integer"
+      end
+      if (load_factor = options[:load_factor]) && (!load_factor.kind_of?(Numeric) || load_factor <= 0 || load_factor > 1)
+        raise ArgumentError, ":load_factor must be a number between 0 and 1"
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization.rb
new file mode 100644
index 0000000000..62575baa55
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization.rb
@@ -0,0 +1,31 @@
+require 'concurrent/utility/engine'
+
+require 'concurrent/synchronization/abstract_object'
+require 'concurrent/utility/native_extension_loader' # load native parts first
+Concurrent.load_native_extensions
+
+require 'concurrent/synchronization/mri_object'
+require 'concurrent/synchronization/jruby_object'
+require 'concurrent/synchronization/rbx_object'
+require 'concurrent/synchronization/truffle_object'
+require 'concurrent/synchronization/object'
+require 'concurrent/synchronization/volatile'
+
+require 'concurrent/synchronization/abstract_lockable_object'
+require 'concurrent/synchronization/mri_lockable_object'
+require 'concurrent/synchronization/jruby_lockable_object'
+require 'concurrent/synchronization/rbx_lockable_object'
+require 'concurrent/synchronization/truffle_lockable_object'
+
+require 'concurrent/synchronization/lockable_object'
+
+require 'concurrent/synchronization/condition'
+require 'concurrent/synchronization/lock'
+
+module Concurrent
+  # {include:file:doc/synchronization.md}
+  # {include:file:doc/synchronization-notes.md}
+  module Synchronization
+  end
+end
+
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/abstract_lockable_object.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/abstract_lockable_object.rb
new file mode 100644
index 0000000000..be7befc8fa
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/abstract_lockable_object.rb
@@ -0,0 +1,98 @@
+module Concurrent
+  module Synchronization
+
+    # @!visibility private
+    class AbstractLockableObject < Synchronization::Object
+
+      protected
+
+      # @!macro [attach] synchronization_object_method_synchronize
+      #
+      #   @yield runs the block synchronized against this object,
+      #     equivalent of java's `synchronize(this) {}`
+      #   @note can by made public in descendants if required by `public :synchronize`
+      def synchronize
+        raise NotImplementedError
+      end
+
+      # @!macro [attach] synchronization_object_method_ns_wait_until
+      #
+      #   Wait until condition is met or timeout passes,
+      #   protects against spurious wake-ups.
+      #   @param [Numeric, nil] timeout in seconds, `nil` means no timeout
+      #   @yield condition to be met
+      #   @yieldreturn [true, false]
+      #   @return [true, false] if condition met
+      #   @note only to be used inside synchronized block
+      #   @note to provide direct access to this method in a descendant add method
+      #     ```
+      #     def wait_until(timeout = nil, &condition)
+      #       synchronize { ns_wait_until(timeout, &condition) }
+      #     end
+      #     ```
+      def ns_wait_until(timeout = nil, &condition)
+        if timeout
+          wait_until = Concurrent.monotonic_time + timeout
+          loop do
+            now              = Concurrent.monotonic_time
+            condition_result = condition.call
+            return condition_result if now >= wait_until || condition_result
+            ns_wait wait_until - now
+          end
+        else
+          ns_wait timeout until condition.call
+          true
+        end
+      end
+
+      # @!macro [attach] synchronization_object_method_ns_wait
+      #
+      #   Wait until another thread calls #signal or #broadcast,
+      #   spurious wake-ups can happen.
+      #
+      #   @param [Numeric, nil] timeout in seconds, `nil` means no timeout
+      #   @return [self]
+      #   @note only to be used inside synchronized block
+      #   @note to provide direct access to this method in a descendant add method
+      #     ```
+      #     def wait(timeout = nil)
+      #       synchronize { ns_wait(timeout) }
+      #     end
+      #     ```
+      def ns_wait(timeout = nil)
+        raise NotImplementedError
+      end
+
+      # @!macro [attach] synchronization_object_method_ns_signal
+      #
+      #   Signal one waiting thread.
+      #   @return [self]
+      #   @note only to be used inside synchronized block
+      #   @note to provide direct access to this method in a descendant add method
+      #     ```
+      #     def signal
+      #       synchronize { ns_signal }
+      #     end
+      #     ```
+      def ns_signal
+        raise NotImplementedError
+      end
+
+      # @!macro [attach] synchronization_object_method_ns_broadcast
+      #
+      #   Broadcast to all waiting threads.
+      #   @return [self]
+      #   @note only to be used inside synchronized block
+      #   @note to provide direct access to this method in a descendant add method
+      #     ```
+      #     def broadcast
+      #       synchronize { ns_broadcast }
+      #     end
+      #     ```
+      def ns_broadcast
+        raise NotImplementedError
+      end
+
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/abstract_object.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/abstract_object.rb
new file mode 100644
index 0000000000..532388b2b8
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/abstract_object.rb
@@ -0,0 +1,24 @@
+module Concurrent
+  module Synchronization
+
+    # @!visibility private
+    # @!macro internal_implementation_note
+    class AbstractObject
+
+      # @abstract has to be implemented based on Ruby runtime
+      def initialize
+        raise NotImplementedError
+      end
+
+      # @!visibility private
+      # @abstract
+      def full_memory_barrier
+        raise NotImplementedError
+      end
+
+      def self.attr_volatile(*names)
+        raise NotImplementedError
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/condition.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/condition.rb
new file mode 100644
index 0000000000..ac528bc256
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/condition.rb
@@ -0,0 +1,58 @@
+module Concurrent
+  module Synchronization
+    # TODO (pitr-ch 04-Dec-2016): should be in edge
+    class Condition < LockableObject
+      safe_initialization!
+
+      # TODO (pitr 12-Sep-2015): locks two objects, improve
+      # TODO (pitr 26-Sep-2015): study
+      # http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/8-b132/java/util/concurrent/locks/AbstractQueuedSynchronizer.java#AbstractQueuedSynchronizer.Node
+
+      singleton_class.send :alias_method, :private_new, :new
+      private_class_method :new
+
+      def initialize(lock)
+        super()
+        @Lock = lock
+      end
+
+      def wait(timeout = nil)
+        @Lock.synchronize { ns_wait(timeout) }
+      end
+
+      def ns_wait(timeout = nil)
+        synchronize { super(timeout) }
+      end
+
+      def wait_until(timeout = nil, &condition)
+        @Lock.synchronize { ns_wait_until(timeout, &condition) }
+      end
+
+      def ns_wait_until(timeout = nil, &condition)
+        synchronize { super(timeout, &condition) }
+      end
+
+      def signal
+        @Lock.synchronize { ns_signal }
+      end
+
+      def ns_signal
+        synchronize { super }
+      end
+
+      def broadcast
+        @Lock.synchronize { ns_broadcast }
+      end
+
+      def ns_broadcast
+        synchronize { super }
+      end
+    end
+
+    class LockableObject < LockableObjectImplementation
+      def new_condition
+        Condition.private_new(self)
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/jruby_lockable_object.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/jruby_lockable_object.rb
new file mode 100644
index 0000000000..359a032b7b
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/jruby_lockable_object.rb
@@ -0,0 +1,13 @@
+module Concurrent
+  module Synchronization
+
+    if Concurrent.on_jruby? && Concurrent.java_extensions_loaded?
+
+      # @!visibility private
+      # @!macro internal_implementation_note
+      class JRubyLockableObject < AbstractLockableObject
+
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/jruby_object.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/jruby_object.rb
new file mode 100644
index 0000000000..b04382f1ca
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/jruby_object.rb
@@ -0,0 +1,44 @@
+module Concurrent
+  module Synchronization
+
+    if Concurrent.on_jruby? && Concurrent.java_extensions_loaded?
+
+      module JRubyAttrVolatile
+        def self.included(base)
+          base.extend(ClassMethods)
+        end
+
+        module ClassMethods
+          def attr_volatile(*names)
+            names.each do |name|
+
+              ivar = :"@volatile_#{name}"
+
+              class_eval <<-RUBY, __FILE__, __LINE__ + 1
+                def #{name}
+                  instance_variable_get_volatile(:#{ivar})
+                end
+
+                def #{name}=(value)
+                  instance_variable_set_volatile(:#{ivar}, value)
+                end
+              RUBY
+
+            end
+            names.map { |n| [n, :"#{n}="] }.flatten
+          end
+        end
+      end
+
+      # @!visibility private
+      # @!macro internal_implementation_note
+      class JRubyObject < AbstractObject
+        include JRubyAttrVolatile
+
+        def initialize
+          # nothing to do
+        end
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/lock.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/lock.rb
new file mode 100644
index 0000000000..ed865b38b4
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/lock.rb
@@ -0,0 +1,34 @@
+module Concurrent
+  module Synchronization
+    # TODO (pitr-ch 04-Dec-2016): should be in edge
+    class Lock < LockableObject
+      # TODO use JavaReentrantLock on JRuby
+
+      public :synchronize
+
+      def wait(timeout = nil)
+        synchronize { ns_wait(timeout) }
+      end
+
+      public :ns_wait
+
+      def wait_until(timeout = nil, &condition)
+        synchronize { ns_wait_until(timeout, &condition) }
+      end
+
+      public :ns_wait_until
+
+      def signal
+        synchronize { ns_signal }
+      end
+
+      public :ns_signal
+
+      def broadcast
+        synchronize { ns_broadcast }
+      end
+
+      public :ns_broadcast
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/lockable_object.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/lockable_object.rb
new file mode 100644
index 0000000000..a28d5af004
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/lockable_object.rb
@@ -0,0 +1,74 @@
+module Concurrent
+  module Synchronization
+
+    # @!visibility private
+    # @!macro internal_implementation_note
+    LockableObjectImplementation = case
+                                   when Concurrent.on_cruby? && Concurrent.ruby_version(:<=, 1, 9, 3)
+                                     MriMonitorLockableObject
+                                   when Concurrent.on_cruby? && Concurrent.ruby_version(:>, 1, 9, 3)
+                                     MriMutexLockableObject
+                                   when Concurrent.on_jruby?
+                                     JRubyLockableObject
+                                   when Concurrent.on_rbx?
+                                     RbxLockableObject
+                                   when Concurrent.on_truffle?
+                                     MriMutexLockableObject
+                                   else
+                                     warn 'Possibly unsupported Ruby implementation'
+                                     MriMonitorLockableObject
+                                   end
+    private_constant :LockableObjectImplementation
+
+    #   Safe synchronization under any Ruby implementation.
+    #   It provides methods like {#synchronize}, {#wait}, {#signal} and {#broadcast}.
+    #   Provides a single layer which can improve its implementation over time without changes needed to
+    #   the classes using it. Use {Synchronization::Object} not this abstract class.
+    #
+    #   @note this object does not support usage together with
+    #     [`Thread#wakeup`](http://ruby-doc.org/core-2.2.0/Thread.html#method-i-wakeup)
+    #     and [`Thread#raise`](http://ruby-doc.org/core-2.2.0/Thread.html#method-i-raise).
+    #     `Thread#sleep` and `Thread#wakeup` will work as expected but mixing `Synchronization::Object#wait` and
+    #     `Thread#wakeup` will not work on all platforms.
+    #
+    #   @see {Event} implementation as an example of this class use
+    #
+    #   @example simple
+    #     class AnClass < Synchronization::Object
+    #       def initialize
+    #         super
+    #         synchronize { @value = 'asd' }
+    #       end
+    #
+    #       def value
+    #         synchronize { @value }
+    #       end
+    #     end
+    #
+    # @!visibility private
+    class LockableObject < LockableObjectImplementation
+
+      # TODO (pitr 12-Sep-2015): make private for c-r, prohibit subclassing
+      # TODO (pitr 12-Sep-2015): we inherit too much ourselves :/
+
+      # @!method initialize(*args, &block)
+      #   @!macro synchronization_object_method_initialize
+
+      # @!method synchronize
+      #   @!macro synchronization_object_method_synchronize
+
+      # @!method wait_until(timeout = nil, &condition)
+      #   @!macro synchronization_object_method_ns_wait_until
+
+      # @!method wait(timeout = nil)
+      #   @!macro synchronization_object_method_ns_wait
+
+      # @!method signal
+      #   @!macro synchronization_object_method_ns_signal
+
+      # @!method broadcast
+      #   @!macro synchronization_object_method_ns_broadcast
+
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/mri_lockable_object.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/mri_lockable_object.rb
new file mode 100644
index 0000000000..22120280b9
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/mri_lockable_object.rb
@@ -0,0 +1,71 @@
+module Concurrent
+  module Synchronization
+
+    # @!visibility private
+    # @!macro internal_implementation_note
+    class MriLockableObject < AbstractLockableObject
+      protected
+
+      def ns_signal
+        @__condition__.signal
+        self
+      end
+
+      def ns_broadcast
+        @__condition__.broadcast
+        self
+      end
+    end
+
+
+    # @!visibility private
+    # @!macro internal_implementation_note
+    class MriMutexLockableObject < MriLockableObject
+      safe_initialization!
+
+      def initialize(*defaults)
+        super(*defaults)
+        @__lock__      = ::Mutex.new
+        @__condition__ = ::ConditionVariable.new
+      end
+
+      protected
+
+      def synchronize
+        if @__lock__.owned?
+          yield
+        else
+          @__lock__.synchronize { yield }
+        end
+      end
+
+      def ns_wait(timeout = nil)
+        @__condition__.wait @__lock__, timeout
+        self
+      end
+    end
+
+    # @!visibility private
+    # @!macro internal_implementation_note
+    class MriMonitorLockableObject < MriLockableObject
+      safe_initialization!
+
+      def initialize(*defaults)
+        super(*defaults)
+        @__lock__      = ::Monitor.new
+        @__condition__ = @__lock__.new_cond
+      end
+
+      protected
+
+      def synchronize # TODO may be a problem with lock.synchronize { lock.wait }
+        @__lock__.synchronize { yield }
+      end
+
+      def ns_wait(timeout = nil)
+        @__condition__.wait timeout
+        self
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/mri_object.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/mri_object.rb
new file mode 100644
index 0000000000..74202f53e7
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/mri_object.rb
@@ -0,0 +1,43 @@
+module Concurrent
+  module Synchronization
+
+    module MriAttrVolatile
+      def self.included(base)
+        base.extend(ClassMethods)
+      end
+
+      module ClassMethods
+        def attr_volatile(*names)
+          names.each do |name|
+            ivar = :"@volatile_#{name}"
+            class_eval <<-RUBY, __FILE__, __LINE__ + 1
+              def #{name}
+                #{ivar}
+              end
+
+              def #{name}=(value)
+                #{ivar} = value
+              end
+            RUBY
+          end
+          names.map { |n| [n, :"#{n}="] }.flatten
+        end
+      end
+
+      def full_memory_barrier
+        # relying on undocumented behavior of CRuby, GVL acquire has lock which ensures visibility of ivars
+        # https://github.com/ruby/ruby/blob/ruby_2_2/thread_pthread.c#L204-L211
+      end
+    end
+
+    # @!visibility private
+    # @!macro internal_implementation_note
+    class MriObject < AbstractObject
+      include MriAttrVolatile
+
+      def initialize
+        # nothing to do
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/object.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/object.rb
new file mode 100644
index 0000000000..21b5695df2
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/object.rb
@@ -0,0 +1,153 @@
+module Concurrent
+  module Synchronization
+
+    # @!visibility private
+    # @!macro internal_implementation_note
+    ObjectImplementation = case
+                           when Concurrent.on_cruby?
+                             MriObject
+                           when Concurrent.on_jruby?
+                             JRubyObject
+                           when Concurrent.on_rbx?
+                             RbxObject
+                           when Concurrent.on_truffle?
+                             TruffleObject
+                           else
+                             MriObject
+                           end
+    private_constant :ObjectImplementation
+
+    # Abstract object providing final, volatile, ans CAS extensions to build other concurrent abstractions.
+    # - final instance variables see {Object.safe_initialization!}
+    # - volatile instance variables see {Object.attr_volatile}
+    # - volatile instance variables see {Object.attr_atomic}
+    class Object < ObjectImplementation
+      # TODO make it a module if possible
+
+      # @!method self.attr_volatile(*names)
+      #   Creates methods for reading and writing (as `attr_accessor` does) to a instance variable with
+      #   volatile (Java) semantic. The instance variable should be accessed oly through generated methods.
+      #
+      #   @param [Array<Symbol>] names of the instance variables to be volatile
+      #   @return [Array<Symbol>] names of defined method names
+
+      # Has to be called by children.
+      def initialize
+        super
+        initialize_volatile_with_cas
+      end
+
+      # By calling this method on a class, it and all its children are marked to be constructed safely. Meaning that
+      # all writes (ivar initializations) are made visible to all readers of newly constructed object. It ensures
+      # same behaviour as Java's final fields.
+      # @example
+      #   class AClass < Concurrent::Synchronization::Object
+      #     safe_initialization!
+      #
+      #     def initialize
+      #       @AFinalValue = 'value' # published safely, does not have to be synchronized
+      #     end
+      #   end
+      def self.safe_initialization!
+        # define only once, and not again in children
+        return if safe_initialization?
+
+        def self.new(*args, &block)
+          object = super(*args, &block)
+        ensure
+          object.full_memory_barrier if object
+        end
+
+        @safe_initialization = true
+      end
+
+      # @return [true, false] if this class is safely initialized.
+      def self.safe_initialization?
+        @safe_initialization = false unless defined? @safe_initialization
+        @safe_initialization || (superclass.respond_to?(:safe_initialization?) && superclass.safe_initialization?)
+      end
+
+      # For testing purposes, quite slow. Injects assert code to new method which will raise if class instance contains
+      # any instance variables with CamelCase names and isn't {.safe_initialization?}.
+      def self.ensure_safe_initialization_when_final_fields_are_present
+        Object.class_eval do
+          def self.new(*args, &block)
+            object = super(*args, &block)
+          ensure
+            has_final_field = object.instance_variables.any? { |v| v.to_s =~ /^@[A-Z]/ }
+            if has_final_field && !safe_initialization?
+              raise "there was an instance of #{object.class} with final field but not marked with safe_initialization!"
+            end
+          end
+        end
+      end
+
+      # Creates methods for reading and writing to a instance variable with
+      # volatile (Java) semantic as {.attr_volatile} does.
+      # The instance variable should be accessed oly through generated methods.
+      # This method generates following methods: `value`, `value=(new_value) #=> new_value`,
+      # `swap_value(new_value) #=> old_value`,
+      # `compare_and_set_value(expected, value) #=> true || false`, `update_value(&block)`.
+      # @param [Array<Symbol>] names of the instance variables to be volatile with CAS.
+      # @return [Array<Symbol>] names of defined method names.
+      def self.attr_atomic(*names)
+        @volatile_cas_fields ||= []
+        @volatile_cas_fields += names
+        safe_initialization!
+        define_initialize_volatile_with_cas
+
+        names.each do |name|
+          ivar = :"@Atomic#{name.to_s.gsub(/(?:^|_)(.)/) { $1.upcase }}"
+          class_eval <<-RUBY, __FILE__, __LINE__ + 1
+            def #{name}
+              #{ivar}.get
+            end
+
+            def #{name}=(value)
+              #{ivar}.set value
+            end
+
+            def swap_#{name}(value)
+              #{ivar}.swap value
+            end
+
+            def compare_and_set_#{name}(expected, value)
+              #{ivar}.compare_and_set expected, value
+            end
+
+            def update_#{name}(&block)
+              #{ivar}.update(&block)
+            end
+          RUBY
+        end
+        names.flat_map { |n| [n, :"#{n}=", :"swap_#{n}", :"compare_and_set_#{n}", :"update_#{n}"] }
+      end
+
+      # @param [true,false] inherited should inherited volatile with CAS fields be returned?
+      # @return [Array<Symbol>] Returns defined volatile with CAS fields on this class.
+      def self.volatile_cas_fields(inherited = true)
+        @volatile_cas_fields ||= []
+        ((superclass.volatile_cas_fields if superclass.respond_to?(:volatile_cas_fields) && inherited) || []) +
+            @volatile_cas_fields
+      end
+
+      private
+
+      def self.define_initialize_volatile_with_cas
+        assignments = @volatile_cas_fields.map { |name| "@Atomic#{name.to_s.gsub(/(?:^|_)(.)/) { $1.upcase }} = AtomicReference.new(nil)" }.join("\n")
+        class_eval <<-RUBY
+          def initialize_volatile_with_cas
+            super
+            #{assignments}
+          end
+        RUBY
+      end
+
+      private_class_method :define_initialize_volatile_with_cas
+
+      def initialize_volatile_with_cas
+      end
+
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/rbx_lockable_object.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/rbx_lockable_object.rb
new file mode 100644
index 0000000000..8dbd3c3453
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/rbx_lockable_object.rb
@@ -0,0 +1,65 @@
+module Concurrent
+  module Synchronization
+
+    # @!visibility private
+    # @!macro internal_implementation_note
+    class RbxLockableObject < AbstractLockableObject
+      safe_initialization!
+
+      def initialize(*defaults)
+        super(*defaults)
+        @__Waiters__ = []
+        @__owner__   = nil
+      end
+
+      protected
+
+      def synchronize(&block)
+        if @__owner__ == Thread.current
+          yield
+        else
+          result = nil
+          Rubinius.synchronize(self) do
+            begin
+              @__owner__ = Thread.current
+              result     = yield
+            ensure
+              @__owner__ = nil
+            end
+          end
+          result
+        end
+      end
+
+      def ns_wait(timeout = nil)
+        wchan = Rubinius::Channel.new
+
+        begin
+          @__Waiters__.push wchan
+          Rubinius.unlock(self)
+          signaled = wchan.receive_timeout timeout
+        ensure
+          Rubinius.lock(self)
+
+          if !signaled && !@__Waiters__.delete(wchan)
+            # we timed out, but got signaled afterwards,
+            # so pass that signal on to the next waiter
+            @__Waiters__.shift << true unless @__Waiters__.empty?
+          end
+        end
+
+        self
+      end
+
+      def ns_signal
+        @__Waiters__.shift << true unless @__Waiters__.empty?
+        self
+      end
+
+      def ns_broadcast
+        @__Waiters__.shift << true until @__Waiters__.empty?
+        self
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/rbx_object.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/rbx_object.rb
new file mode 100644
index 0000000000..b9a0e3f901
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/rbx_object.rb
@@ -0,0 +1,48 @@
+module Concurrent
+  module Synchronization
+
+    module RbxAttrVolatile
+      def self.included(base)
+        base.extend(ClassMethods)
+      end
+
+      module ClassMethods
+
+        def attr_volatile(*names)
+          names.each do |name|
+            ivar = :"@volatile_#{name}"
+            class_eval <<-RUBY, __FILE__, __LINE__ + 1
+              def #{name}
+                Rubinius.memory_barrier
+                #{ivar}
+              end
+
+              def #{name}=(value)
+                #{ivar} = value
+                Rubinius.memory_barrier
+              end
+            RUBY
+          end
+          names.map { |n| [n, :"#{n}="] }.flatten
+        end
+
+      end
+
+      def full_memory_barrier
+        # Rubinius instance variables are not volatile so we need to insert barrier
+        # TODO (pitr 26-Nov-2015): check comments like ^
+        Rubinius.memory_barrier
+      end
+    end
+
+    # @!visibility private
+    # @!macro internal_implementation_note
+    class RbxObject < AbstractObject
+      include RbxAttrVolatile
+
+      def initialize
+        # nothing to do
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/truffle_lockable_object.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/truffle_lockable_object.rb
new file mode 100644
index 0000000000..c9328f21f8
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/truffle_lockable_object.rb
@@ -0,0 +1,9 @@
+module Concurrent
+  module Synchronization
+    class TruffleLockableObject < AbstractLockableObject
+      def new(*)
+        raise NotImplementedError
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/truffle_object.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/truffle_object.rb
new file mode 100644
index 0000000000..9b1c3fc76e
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/truffle_object.rb
@@ -0,0 +1,31 @@
+module Concurrent
+  module Synchronization
+
+    module TruffleAttrVolatile
+      def self.included(base)
+        base.extend(ClassMethods)
+      end
+
+      module ClassMethods
+        def attr_volatile(*names)
+          # TODO may not always be available
+          attr_atomic(*names)
+        end
+      end
+
+      def full_memory_barrier
+        Truffle::System.full_memory_barrier
+      end
+    end
+
+    # @!visibility private
+    # @!macro internal_implementation_note
+    class TruffleObject < AbstractObject
+      include TruffleAttrVolatile
+
+      def initialize
+        # nothing to do
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/volatile.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/volatile.rb
new file mode 100644
index 0000000000..45269dff90
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/synchronization/volatile.rb
@@ -0,0 +1,34 @@
+module Concurrent
+  module Synchronization
+
+    # Volatile adds the attr_volatile class method when included.
+    #
+    # @example
+    #   class Foo
+    #     include Concurrent::Synchronization::Volatile
+    #
+    #     attr_volatile :bar
+    #
+    #     def initialize
+    #       self.bar = 1
+    #     end
+    #   end
+    #
+    #  foo = Foo.new
+    #  foo.bar
+    #  => 1
+    #  foo.bar = 2
+    #  => 2
+
+    Volatile = case
+    when Concurrent.on_cruby?
+      MriAttrVolatile
+    when Concurrent.on_jruby?
+      JRubyAttrVolatile
+    when Concurrent.on_rbx? || Concurrent.on_truffle?
+      RbxAttrVolatile
+    else
+      MriAttrVolatile
+    end
+  end
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/utility/engine.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/utility/engine.rb
new file mode 100644
index 0000000000..a83f9fa087
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/utility/engine.rb
@@ -0,0 +1,56 @@
+module Concurrent
+  module Utility
+
+    # @!visibility private
+    module EngineDetector
+      def on_jruby?
+        ruby_engine == 'jruby'
+      end
+
+      def on_jruby_9000?
+        on_jruby? && ruby_version(:>=, 9, 0, 0, JRUBY_VERSION)
+      end
+
+      def on_cruby?
+        ruby_engine == 'ruby'
+      end
+
+      def on_rbx?
+        ruby_engine == 'rbx'
+      end
+
+      def on_truffle?
+        ruby_engine == 'jruby+truffle'
+      end
+
+      def on_windows?
+        !(RbConfig::CONFIG['host_os'] =~ /mswin|mingw|cygwin/).nil?
+      end
+
+      def on_osx?
+        !(RbConfig::CONFIG['host_os'] =~ /darwin|mac os/).nil?
+      end
+
+      def on_linux?
+        !(RbConfig::CONFIG['host_os'] =~ /linux/).nil?
+      end
+
+      def ruby_engine
+        defined?(RUBY_ENGINE) ? RUBY_ENGINE : 'ruby'
+      end
+
+      def ruby_version(comparison, major, minor, patch, version = RUBY_VERSION)
+        result      = (version.split('.').map(&:to_i) <=> [major, minor, patch])
+        comparisons = { :== => [0],
+                        :>= => [1, 0],
+                        :<= => [-1, 0],
+                        :>  => [1],
+                        :<  => [-1] }
+        comparisons.fetch(comparison).include? result
+      end
+    end
+  end
+
+  # @!visibility private
+  extend Utility::EngineDetector
+end
diff --git a/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/utility/native_extension_loader.rb b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/utility/native_extension_loader.rb
new file mode 100644
index 0000000000..f2fcd8c5a9
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.0.5/lib/concurrent/utility/native_extension_loader.rb
@@ -0,0 +1,73 @@
+require 'concurrent/utility/engine'
+
+module Concurrent
+
+  module Utility
+
+    # @!visibility private
+    module NativeExtensionLoader
+
+      def allow_c_extensions?
+        Concurrent.on_cruby?
+      end
+
+      def c_extensions_loaded?
+        @c_extensions_loaded ||= false
+      end
+
+      def java_extensions_loaded?
+        @java_extensions_loaded ||= false
+      end
+
+      def set_c_extensions_loaded
+        @c_extensions_loaded = true
+      end
+
+      def set_java_extensions_loaded
+        @java_extensions_loaded = true
+      end
+
+      def load_native_extensions
+        unless defined? Synchronization::AbstractObject
+          raise 'native_extension_loader loaded before Synchronization::AbstractObject'
+        end
+
+        if Concurrent.on_cruby? && !c_extensions_loaded?
+          tries = [
+            lambda do
+              require 'concurrent/extension'
+              set_c_extensions_loaded
+            end,
+            lambda do
+              # may be a Windows cross-compiled native gem
+              require "concurrent/#{RUBY_VERSION[0..2]}/extension"
+              set_c_extensions_loaded
+            end]
+
+          tries.each do |try|
+            begin
+              try.call
+              break
+            rescue LoadError
+              next
+            end
+          end
+        end
+
+        if Concurrent.on_jruby? && !java_extensions_loaded?
+          begin
+            require 'concurrent_ruby_ext'
+            set_java_extensions_loaded
+          rescue LoadError
+            # move on with pure-Ruby implementations
+            raise 'On JRuby but Java extensions failed to load.'
+          end
+        end
+      end
+    end
+  end
+
+  # @!visibility private
+  extend Utility::NativeExtensionLoader
+end
+