require "set" require "thread" require "concurrent/map" require "pathname" require "active_support/core_ext/module/aliasing" require "active_support/core_ext/module/attribute_accessors" require "active_support/core_ext/module/introspection" require "active_support/core_ext/module/anonymous" require "active_support/core_ext/object/blank" require "active_support/core_ext/kernel/reporting" require "active_support/core_ext/load_error" require "active_support/core_ext/name_error" require "active_support/core_ext/string/starts_ends_with" require "active_support/dependencies/interlock" require "active_support/inflector" module ActiveSupport #:nodoc: module Dependencies #:nodoc: extend self mattr_accessor :interlock, default: Interlock.new # :doc: # Execute the supplied block without interference from any # concurrent loads. def self.run_interlock Dependencies.interlock.running { yield } end # Execute the supplied block while holding an exclusive lock, # preventing any other thread from being inside a #run_interlock # block at the same time. def self.load_interlock Dependencies.interlock.loading { yield } end # Execute the supplied block while holding an exclusive lock, # preventing any other thread from being inside a #run_interlock # block at the same time. def self.unload_interlock Dependencies.interlock.unloading { yield } end # :nodoc: # Should we turn on Ruby warnings on the first load of dependent files? mattr_accessor :warnings_on_first_load, default: false # All files ever loaded. mattr_accessor :history, default: Set.new # All files currently loaded. mattr_accessor :loaded, default: Set.new # Stack of files being loaded. mattr_accessor :loading, default: [] # Should we load files or require them? mattr_accessor :mechanism, default: ENV["NO_RELOAD"] ? :require : :load # The set of directories from which we may automatically load files. Files # under these directories will be reloaded on each request in development mode, # unless the directory also appears in autoload_once_paths. mattr_accessor :autoload_paths, default: [] # The set of directories from which automatically loaded constants are loaded # only once. All directories in this set must also be present in +autoload_paths+. mattr_accessor :autoload_once_paths, default: [] # An array of qualified constant names that have been loaded. Adding a name # to this array will cause it to be unloaded the next time Dependencies are # cleared. mattr_accessor :autoloaded_constants, default: [] # An array of constant names that need to be unloaded on every request. Used # to allow arbitrary constants to be marked for unloading. mattr_accessor :explicitly_unloadable_constants, default: [] # The WatchStack keeps a stack of the modules being watched as files are # loaded. If a file in the process of being loaded (parent.rb) triggers the # load of another file (child.rb) the stack will ensure that child.rb # handles the new constants. # # If child.rb is being autoloaded, its constants will be added to # autoloaded_constants. If it was being `require`d, they will be discarded. # # This is handled by walking back up the watch stack and adding the constants # found by child.rb to the list of original constants in parent.rb. class WatchStack include Enumerable # @watching is a stack of lists of constants being watched. For instance, # if parent.rb is autoloaded, the stack will look like [[Object]]. If # parent.rb then requires namespace/child.rb, the stack will look like # [[Object], [Namespace]]. def initialize @watching = [] @stack = Hash.new { |h, k| h[k] = [] } end def each(&block) @stack.each(&block) end def watching? !@watching.empty? end # Returns a list of new constants found since the last call to # watch_namespaces. def new_constants constants = [] # Grab the list of namespaces that we're looking for new constants under @watching.last.each do |namespace| # Retrieve the constants that were present under the namespace when watch_namespaces # was originally called original_constants = @stack[namespace].last mod = Inflector.constantize(namespace) if Dependencies.qualified_const_defined?(namespace) next unless mod.is_a?(Module) # Get a list of the constants that were added new_constants = mod.constants(false) - original_constants # @stack[namespace] returns an Array of the constants that are being evaluated # for that namespace. For instance, if parent.rb requires child.rb, the first # element of @stack[Object] will be an Array of the constants that were present # before parent.rb was required. The second element will be an Array of the # constants that were present before child.rb was required. @stack[namespace].each do |namespace_constants| namespace_constants.concat(new_constants) end # Normalize the list of new constants, and add them to the list we will return new_constants.each do |suffix| constants << ([namespace, suffix] - ["Object"]).join("::".freeze) end end constants ensure # A call to new_constants is always called after a call to watch_namespaces pop_modules(@watching.pop) end # Add a set of modules to the watch stack, remembering the initial # constants. def watch_namespaces(namespaces) @watching << namespaces.map do |namespace| module_name = Dependencies.to_constant_name(namespace) original_constants = Dependencies.qualified_const_defined?(module_name) ? Inflector.constantize(module_name).constants(false) : [] @stack[module_name] << original_constants module_name end end private def pop_modules(modules) modules.each { |mod| @stack[mod].pop } end end # An internal stack used to record which constants are loaded by any block. mattr_accessor :constant_watch_stack, default: WatchStack.new # Module includes this module. module ModuleConstMissing #:nodoc: def self.append_features(base) base.class_eval do # Emulate #exclude via an ivar return if defined?(@_const_missing) && @_const_missing @_const_missing = instance_method(:const_missing) remove_method(:const_missing) end super end def self.exclude_from(base) base.class_eval do define_method :const_missing, @_const_missing @_const_missing = nil end end def const_missing(const_name) from_mod = anonymous? ? guess_for_anonymous(const_name) : self Dependencies.load_missing_constant(from_mod, const_name) end # We assume that the name of the module reflects the nesting # (unless it can be proven that is not the case) and the path to the file # that defines the constant. Anonymous modules cannot follow these # conventions and therefore we assume that the user wants to refer to a # top-level constant. def guess_for_anonymous(const_name) if Object.const_defined?(const_name) raise NameError.new "#{const_name} cannot be autoloaded from an anonymous class or module", const_name else Object end end def unloadable(const_desc = self) super(const_desc) end end # Object includes this module. module Loadable #:nodoc: def self.exclude_from(base) base.class_eval do define_method(:load, Kernel.instance_method(:load)) private :load end end def require_or_load(file_name) Dependencies.require_or_load(file_name) end # Interprets a file using mechanism and marks its defined # constants as autoloaded. file_name can be either a string or # respond to to_path. # # Use this method in code that absolutely needs a certain constant to be # defined at that point. A typical use case is to make constant name # resolution deterministic for constants with the same relative name in # different namespaces whose evaluation would depend on load order # otherwise. def require_dependency(file_name, message = "No such file to load -- %s.rb") file_name = file_name.to_path if file_name.respond_to?(:to_path) unless file_name.is_a?(String) raise ArgumentError, "the file name must either be a String or implement #to_path -- you passed #{file_name.inspect}" end Dependencies.depend_on(file_name, message) end def load_dependency(file) if Dependencies.load? && Dependencies.constant_watch_stack.watching? Dependencies.new_constants_in(Object) { yield } else yield end rescue Exception => exception # errors from loading file exception.blame_file! file if exception.respond_to? :blame_file! raise end # Mark the given constant as unloadable. Unloadable constants are removed # each time dependencies are cleared. # # Note that marking a constant for unloading need only be done once. Setup # or init scripts may list each unloadable constant that may need unloading; # each constant will be removed for every subsequent clear, as opposed to # for the first clear. # # The provided constant descriptor may be a (non-anonymous) module or class, # or a qualified constant name as a string or symbol. # # Returns +true+ if the constant was not previously marked for unloading, # +false+ otherwise. def unloadable(const_desc) Dependencies.mark_for_unload const_desc end private def load(file, wrap = false) result = false load_dependency(file) { result = super } result end def require(file) result = false load_dependency(file) { result = super } result end end # Exception file-blaming. module Blamable #:nodoc: def blame_file!(file) (@blamed_files ||= []).unshift file end def blamed_files @blamed_files ||= [] end def describe_blame return nil if blamed_files.empty? "This error occurred while loading the following files:\n #{blamed_files.join "\n "}" end def copy_blame!(exc) @blamed_files = exc.blamed_files.clone self end end def hook! Object.class_eval { include Loadable } Module.class_eval { include ModuleConstMissing } Exception.class_eval { include Blamable } end def unhook! ModuleConstMissing.exclude_from(Module) Loadable.exclude_from(Object) end def load? mechanism == :load end def depend_on(file_name, message = "No such file to load -- %s.rb") path = search_for_file(file_name) require_or_load(path || file_name) rescue LoadError => load_error if file_name = load_error.message[/ -- (.*?)(\.rb)?$/, 1] load_error.message.replace(message % file_name) load_error.copy_blame!(load_error) end raise end def clear Dependencies.unload_interlock do loaded.clear loading.clear remove_unloadable_constants! end end def require_or_load(file_name, const_path = nil) file_name = $` if file_name =~ /\.rb\z/ expanded = File.expand_path(file_name) return if loaded.include?(expanded) Dependencies.load_interlock do # Maybe it got loaded while we were waiting for our lock: return if loaded.include?(expanded) # Record that we've seen this file *before* loading it to avoid an # infinite loop with mutual dependencies. loaded << expanded loading << expanded begin if load? # Enable warnings if this file has not been loaded before and # warnings_on_first_load is set. load_args = ["#{file_name}.rb"] load_args << const_path unless const_path.nil? if !warnings_on_first_load || history.include?(expanded) result = load_file(*load_args) else enable_warnings { result = load_file(*load_args) } end else result = require file_name end rescue Exception loaded.delete expanded raise ensure loading.pop end # Record history *after* loading so first load gets warnings. history << expanded result end end # Is the provided constant path defined? def qualified_const_defined?(path) Object.const_defined?(path, false) end # Given +path+, a filesystem path to a ruby file, return an array of # constant paths which would cause Dependencies to attempt to load this # file. def loadable_constants_for_path(path, bases = autoload_paths) path = $` if path =~ /\.rb\z/ expanded_path = File.expand_path(path) paths = [] bases.each do |root| expanded_root = File.expand_path(root) next unless expanded_path.start_with?(expanded_root) root_size = expanded_root.size next if expanded_path[root_size] != ?/.freeze nesting = expanded_path[(root_size + 1)..-1] paths << nesting.camelize unless nesting.blank? end paths.uniq! paths end # Search for a file in autoload_paths matching the provided suffix. def search_for_file(path_suffix) path_suffix = path_suffix.sub(/(\.rb)?$/, ".rb".freeze) autoload_paths.each do |root| path = File.join(root, path_suffix) return path if File.file? path end nil # Gee, I sure wish we had first_match ;-) end # Does the provided path_suffix correspond to an autoloadable module? # Instead of returning a boolean, the autoload base for this module is # returned. def autoloadable_module?(path_suffix) autoload_paths.each do |load_path| return load_path if File.directory? File.join(load_path, path_suffix) end nil end def load_once_path?(path) # to_s works around a ruby issue where String#starts_with?(Pathname) # will raise a TypeError: no implicit conversion of Pathname into String autoload_once_paths.any? { |base| path.starts_with? base.to_s } end # Attempt to autoload the provided module name by searching for a directory # matching the expected path suffix. If found, the module is created and # assigned to +into+'s constants with the name +const_name+. Provided that # the directory was loaded from a reloadable base path, it is added to the # set of constants that are to be unloaded. def autoload_module!(into, const_name, qualified_name, path_suffix) return nil unless base_path = autoloadable_module?(path_suffix) mod = Module.new into.const_set const_name, mod autoloaded_constants << qualified_name unless autoload_once_paths.include?(base_path) mod end # Load the file at the provided path. +const_paths+ is a set of qualified # constant names. When loading the file, Dependencies will watch for the # addition of these constants. Each that is defined will be marked as # autoloaded, and will be removed when Dependencies.clear is next called. # # If the second parameter is left off, then Dependencies will construct a # set of names that the file at +path+ may define. See # +loadable_constants_for_path+ for more details. def load_file(path, const_paths = loadable_constants_for_path(path)) const_paths = [const_paths].compact unless const_paths.is_a? Array parent_paths = const_paths.collect { |const_path| const_path[/.*(?=::)/] || ::Object } result = nil newly_defined_paths = new_constants_in(*parent_paths) do result = Kernel.load path end autoloaded_constants.concat newly_defined_paths unless load_once_path?(path) autoloaded_constants.uniq! result end # Returns the constant path for the provided parent and constant name. def qualified_name_for(mod, name) mod_name = to_constant_name mod mod_name == "Object" ? name.to_s : "#{mod_name}::#{name}" end # Load the constant named +const_name+ which is missing from +from_mod+. If # it is not possible to load the constant into from_mod, try its parent # module using +const_missing+. def load_missing_constant(from_mod, const_name) unless qualified_const_defined?(from_mod.name) && Inflector.constantize(from_mod.name).equal?(from_mod) raise ArgumentError, "A copy of #{from_mod} has been removed from the module tree but is still active!" end qualified_name = qualified_name_for from_mod, const_name path_suffix = qualified_name.underscore file_path = search_for_file(path_suffix) if file_path expanded = File.expand_path(file_path) expanded.sub!(/\.rb\z/, "".freeze) if loading.include?(expanded) raise "Circular dependency detected while autoloading constant #{qualified_name}" else require_or_load(expanded, qualified_name) raise LoadError, "Unable to autoload constant #{qualified_name}, expected #{file_path} to define it" unless from_mod.const_defined?(const_name, false) return from_mod.const_get(const_name) end elsif mod = autoload_module!(from_mod, const_name, qualified_name, path_suffix) return mod elsif (parent = from_mod.parent) && parent != from_mod && ! from_mod.parents.any? { |p| p.const_defined?(const_name, false) } # If our parents do not have a constant named +const_name+ then we are free # to attempt to load upwards. If they do have such a constant, then this # const_missing must be due to from_mod::const_name, which should not # return constants from from_mod's parents. begin # Since Ruby does not pass the nesting at the point the unknown # constant triggered the callback we cannot fully emulate constant # name lookup and need to make a trade-off: we are going to assume # that the nesting in the body of Foo::Bar is [Foo::Bar, Foo] even # though it might not be. Counterexamples are # # class Foo::Bar # Module.nesting # => [Foo::Bar] # end # # or # # module M::N # module S::T # Module.nesting # => [S::T, M::N] # end # end # # for example. return parent.const_missing(const_name) rescue NameError => e raise unless e.missing_name? qualified_name_for(parent, const_name) end end name_error = NameError.new("uninitialized constant #{qualified_name}", const_name) name_error.set_backtrace(caller.reject { |l| l.starts_with? __FILE__ }) raise name_error end # Remove the constants that have been autoloaded, and those that have been # marked for unloading. Before each constant is removed a callback is sent # to its class/module if it implements +before_remove_const+. # # The callback implementation should be restricted to cleaning up caches, etc. # as the environment will be in an inconsistent state, e.g. other constants # may have already been unloaded and not accessible. def remove_unloadable_constants! autoloaded_constants.each { |const| remove_constant const } autoloaded_constants.clear Reference.clear! explicitly_unloadable_constants.each { |const| remove_constant const } end class ClassCache def initialize @store = Concurrent::Map.new end def empty? @store.empty? end def key?(key) @store.key?(key) end def get(key) key = key.name if key.respond_to?(:name) @store[key] ||= Inflector.constantize(key) end alias :[] :get def safe_get(key) key = key.name if key.respond_to?(:name) @store[key] ||= Inflector.safe_constantize(key) end def store(klass) return self unless klass.respond_to?(:name) raise(ArgumentError, "anonymous classes cannot be cached") if klass.name.empty? @store[klass.name] = klass self end def clear! @store.clear end end Reference = ClassCache.new # Store a reference to a class +klass+. def reference(klass) Reference.store klass end # Get the reference for class named +name+. # Raises an exception if referenced class does not exist. def constantize(name) Reference.get(name) end # Get the reference for class named +name+ if one exists. # Otherwise returns +nil+. def safe_constantize(name) Reference.safe_get(name) end # Determine if the given constant has been automatically loaded. def autoloaded?(desc) return false if desc.is_a?(Module) && desc.anonymous? name = to_constant_name desc return false unless qualified_const_defined?(name) return autoloaded_constants.include?(name) end # Will the provided constant descriptor be unloaded? def will_unload?(const_desc) autoloaded?(const_desc) || explicitly_unloadable_constants.include?(to_constant_name(const_desc)) end # Mark the provided constant name for unloading. This constant will be # unloaded on each request, not just the next one. def mark_for_unload(const_desc) name = to_constant_name const_desc if explicitly_unloadable_constants.include? name false else explicitly_unloadable_constants << name true end end # Run the provided block and detect the new constants that were loaded during # its execution. Constants may only be regarded as 'new' once -- so if the # block calls +new_constants_in+ again, then the constants defined within the # inner call will not be reported in this one. # # If the provided block does not run to completion, and instead raises an # exception, any new constants are regarded as being only partially defined # and will be removed immediately. def new_constants_in(*descs) constant_watch_stack.watch_namespaces(descs) success = false begin yield # Now yield to the code that is to define new constants. success = true ensure new_constants = constant_watch_stack.new_constants return new_constants if success # Remove partially loaded constants. new_constants.each { |c| remove_constant(c) } end end # Convert the provided const desc to a qualified constant name (as a string). # A module, class, symbol, or string may be provided. def to_constant_name(desc) #:nodoc: case desc when String then desc.sub(/^::/, "") when Symbol then desc.to_s when Module desc.name || raise(ArgumentError, "Anonymous modules have no name to be referenced by") else raise TypeError, "Not a valid constant descriptor: #{desc.inspect}" end end def remove_constant(const) #:nodoc: # Normalize ::Foo, ::Object::Foo, Object::Foo, Object::Object::Foo, etc. as Foo. normalized = const.to_s.sub(/\A::/, "") normalized.sub!(/\A(Object::)+/, "") constants = normalized.split("::") to_remove = constants.pop # Remove the file path from the loaded list. file_path = search_for_file(const.underscore) if file_path expanded = File.expand_path(file_path) expanded.sub!(/\.rb\z/, "") loaded.delete(expanded) end if constants.empty? parent = Object else # This method is robust to non-reachable constants. # # Non-reachable constants may be passed if some of the parents were # autoloaded and already removed. It is easier to do a sanity check # here than require the caller to be clever. We check the parent # rather than the very const argument because we do not want to # trigger Kernel#autoloads, see the comment below. parent_name = constants.join("::") return unless qualified_const_defined?(parent_name) parent = constantize(parent_name) end # In an autoloaded user.rb like this # # autoload :Foo, 'foo' # # class User < ActiveRecord::Base # end # # we correctly register "Foo" as being autoloaded. But if the app does # not use the "Foo" constant we need to be careful not to trigger # loading "foo.rb" ourselves. While #const_defined? and #const_get? do # require the file, #autoload? and #remove_const don't. # # We are going to remove the constant nonetheless ---which exists as # far as Ruby is concerned--- because if the user removes the macro # call from a class or module that were not autoloaded, as in the # example above with Object, accessing to that constant must err. unless parent.autoload?(to_remove) begin constantized = parent.const_get(to_remove, false) rescue NameError # The constant is no longer reachable, just skip it. return else constantized.before_remove_const if constantized.respond_to?(:before_remove_const) end end begin parent.instance_eval { remove_const to_remove } rescue NameError # The constant is no longer reachable, just skip it. end end end end ActiveSupport::Dependencies.hook!