Class: Zeitwerk::Loader

Inherits:
Object
  • Object
show all
Includes:
Callbacks
Defined in:
lib/zeitwerk/loader.rb

Defined Under Namespace

Modules: Callbacks

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Callbacks

#on_dir_autoloaded, #on_file_autoloaded, #on_namespace_loaded

Constructor Details

#initialize ⇒ Loader

Returns a new instance of Loader.



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# File 'lib/zeitwerk/loader.rb', line 120

def initialize
  @initialized_at = Time.now

  @tag       = SecureRandom.hex(3)
  @inflector = Inflector.new
  @logger    = self.class.default_logger

  @root_dirs             = {}
  @preloads              = []
  @ignored               = Set.new
  @ignored_paths         = Set.new
  @autoloads             = {}
  @loaded_cpaths         = Set.new
  @lazy_subdirs          = {}
  @shadowed_files        = {}
  @eager_load_exclusions = Set.new

  # TODO: find a better name for these mutexes.
  @mutex        = Mutex.new
  @mutex2       = Mutex.new
  @setup        = false
  @eager_loaded = false

  Registry.register_loader(self)
end

Class Attribute Details

.default_logger ⇒ #call, ...

Returns:

  • (#call, #debug, nil) 


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# File 'lib/zeitwerk/loader.rb', line 329

def default_logger
  @default_logger
end

.mutex ⇒ Mutex

Returns:

  • (Mutex) 


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# File 'lib/zeitwerk/loader.rb', line 333

def mutex
  @mutex
end

Instance Attribute Details

#autoloads ⇒ {String => (Module, String)} (readonly)

Maps real absolute paths for which an autoload has been set to their corresponding parent class or module and constant name.

"/Users/fxn/blog/app/models/user.rb"          => [Object, "User"],
"/Users/fxn/blog/app/models/hotel/pricing.rb" => [Hotel, "Pricing"]
...

Returns:

  • ({String => (Module, String)}) 


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# File 'lib/zeitwerk/loader.rb', line 80

def autoloads
  @autoloads
end

#eager_load_exclusions ⇒ Set<String> (readonly)

Absolute paths of files or directories not to be eager loaded.

Returns:

  • (Set<String>) 


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# File 'lib/zeitwerk/loader.rb', line 110

def eager_load_exclusions
  @eager_load_exclusions
end

#ignored ⇒ Set<String> (readonly)

Absolute paths of files, directories, of glob patterns to be totally ignored.

Returns:

  • (Set<String>) 


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# File 'lib/zeitwerk/loader.rb', line 46

def ignored
  @ignored
end

#ignored_paths ⇒ Set<String> (readonly)

The actual collection of absolute file and directory names at the time the ignored glob patterns were expanded. Computed on setup, and recomputed on reload.

Returns:

  • (Set<String>) 


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# File 'lib/zeitwerk/loader.rb', line 54

def ignored_paths
  @ignored_paths
end

#inflector ⇒ #camelize

Returns:

  • (#camelize) 


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# File 'lib/zeitwerk/loader.rb', line 15

def inflector
  @inflector
end

#lazy_subdirs ⇒ {String => <String>} (readonly)

Maps constant paths of namespaces to arrays of corresponding directories.

For example, given this mapping:

"Admin" => [
  "/Users/fxn/blog/app/controllers/admin",
  "/Users/fxn/blog/app/models/admin",
  ...
]

when ‘Admin` gets defined we know that it plays the role of a namespace and that its children are spread over those directories. We’ll visit them to set up the corresponding autoloads.

Returns:

  • ({String => <String>}) 


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# File 'lib/zeitwerk/loader.rb', line 104

def lazy_subdirs
  @lazy_subdirs
end

#loaded_cpaths ⇒ Set<String> (readonly)

Constant paths loaded so far.

Returns:

  • (Set<String>) 


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# File 'lib/zeitwerk/loader.rb', line 86

def loaded_cpaths
  @loaded_cpaths
end

#logger ⇒ #call, ...

Returns:

  • (#call, #debug, nil) 


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# File 'lib/zeitwerk/loader.rb', line 18

def logger
  @logger
end

#mutex ⇒ Mutex (readonly)

Returns:

  • (Mutex) 


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# File 'lib/zeitwerk/loader.rb', line 114

def mutex
  @mutex
end

#mutex2 ⇒ Mutex (readonly)

Returns:

  • (Mutex) 


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# File 'lib/zeitwerk/loader.rb', line 118

def mutex2
  @mutex2
end

#preloads ⇒ <String> (readonly)

Absolute paths of files or directories that have to be preloaded.

Returns:

  • (<String>) 


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# File 'lib/zeitwerk/loader.rb', line 39

def preloads
  @preloads
end

#root_dirs ⇒ {String => true} (readonly)

Absolute paths of the root directories. Stored in a hash to preserve order, easily handle duplicates, and also be able to have a fast lookup, needed for detecting nested paths.

"/Users/fxn/blog/app/assets"   => true,
"/Users/fxn/blog/app/channels" => true,
...

This is a private collection maintained by the loader. The public interface for it is ‘push_dir` and `dirs`.

Returns:

  • ({String => true}) 


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# File 'lib/zeitwerk/loader.rb', line 33

def root_dirs
  @root_dirs
end

#shadowed_files ⇒ {String => String} (readonly)

Keeps track of shadowed files.

A shadowed file is a file managed by this autoloader that is skipped because its matching constant path has already been seen. Think $LOAD_PATH and require, only the first occurrence of a given relative name is loaded.

If the existing occurrence is an autoload, we map the file name to the shadowing autoload path. If the existing occurrence is an already defined constant, the file name is mapped to the constant path, meaning it was loaded elsewhere.

Returns:

  • ({String => String}) 


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# File 'lib/zeitwerk/loader.rb', line 69

def shadowed_files
  @shadowed_files
end

#tag ⇒ String

Returns:

  • (String) 


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# File 'lib/zeitwerk/loader.rb', line 12

def tag
  @tag
end

Class Method Details

.all_dirs ⇒ <String>

Returns an array with the absolute paths of the root directories of all registered loaders. This is a read-only collection.

Returns:

  • (<String>) 


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# File 'lib/zeitwerk/loader.rb', line 363

def all_dirs
  Registry.loaders.flat_map(&:dirs).freeze
end

.eager_load_all ⇒ void

This method returns an undefined value.

Broadcasts ‘eager_load` to all loaders.



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# File 'lib/zeitwerk/loader.rb', line 355

def eager_load_all
  Registry.loaders.each(&:eager_load)
end

.for_gem ⇒ Zeitwerk::Loader

This is a shortcut for

require "zeitwerk"
loader = Zeitwerk::Loader.new
loader.tag = File.basename(__FILE__, ".rb")
loader.inflector = Zeitwerk::GemInflector.new
loader.push_dir(__dir__)

except that this method returns the same object in subsequent calls from the same file, in the unlikely case the gem wants to be able to reload.

Returns:



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# File 'lib/zeitwerk/loader.rb', line 347

def for_gem
  called_from = caller[0].split(':')[0]
  Registry.loader_for_gem(called_from)
end

Instance Method Details

#dirs ⇒ <String>

Absolute paths of the root directories. This is a read-only collection, please push here via ‘push_dir`.

Returns:

  • (<String>) 


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# File 'lib/zeitwerk/loader.rb', line 157

def dirs
  root_dirs.keys.freeze
end

#do_not_eager_load(*paths) ⇒ void

This method returns an undefined value.

Let eager load ignore the given files or directories. The constants defined in those files are still autoloadable.

Parameters:

  • paths (<String, Pathname, <String, Pathname>>) 


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# File 'lib/zeitwerk/loader.rb', line 313

def do_not_eager_load(*paths)
  mutex.synchronize { eager_load_exclusions.merge(expand_paths(paths)) }
end

#eager_load ⇒ void

This method returns an undefined value.

Eager loads all files in the root directories, recursively. Files do not need to be in ‘$LOAD_PATH`, absolute file names are used. Ignored files are not eager loaded. You can opt-out specifically in specific files and directories with `do_not_eager_load`.



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# File 'lib/zeitwerk/loader.rb', line 287

def eager_load
  mutex.synchronize do
    break if @eager_loaded

    queue = non_ignored_root_dirs.reject { |dir| eager_load_exclusions.member?(dir) }
    while dir = queue.shift
      each_abspath(dir) do |abspath|
        next if eager_load_exclusions.member?(abspath)

        if ruby?(abspath)
          require abspath unless shadowed_files.key?(abspath)
        elsif dir?(abspath)
          queue << abspath
        end
      end
    end

    @eager_loaded = true
  end
end

#expand_ignored_glob_patterns ⇒ void

This method returns an undefined value.



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# File 'lib/zeitwerk/loader.rb', line 198

def expand_ignored_glob_patterns
  # Note that Dir.glob works with regular file names just fine. That is,
  # glob patterns technically need no wildcards.
  ignored_paths.replace(ignored.flat_map { |path| Dir.glob(path) })
end

#ignore(*paths) ⇒ void

This method returns an undefined value.

Configure files, directories, or glob patterns to be totally ignored.

Parameters:

  • paths (<String, Pathname, <String, Pathname>>) 


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# File 'lib/zeitwerk/loader.rb', line 192

def ignore(*paths)
  mutex.synchronize { ignored.merge(expand_paths(paths)) }
end

#loaded?(cpath) ⇒ Boolean

Says if the given constant path has been loaded.

Parameters:

  • cpath (String)

Returns:

  • (Boolean) 


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# File 'lib/zeitwerk/loader.rb', line 321

def loaded?(cpath)
  loaded_cpaths.member?(cpath)
end

#preload(*paths) ⇒ void

This method returns an undefined value.

Files or directories to be preloaded instead of lazy loaded.

Parameters:

  • paths (<String, Pathname, <String, Pathname>>) 


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# File 'lib/zeitwerk/loader.rb', line 179

def preload(*paths)
  mutex.synchronize do
    expand_paths(paths).each do |abspath|
      preloads << abspath
      do_preload_abspath(abspath) if @setup
    end
  end
end

#push_dir(path) ⇒ void

This method returns an undefined value.

Pushes ‘paths` to the list of root directories.

Parameters:

  • path (<String, Pathname>) 


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# File 'lib/zeitwerk/loader.rb', line 165

def push_dir(path)
  abspath = File.expand_path(path)
  if dir?(abspath)
    raise_if_conflicting_directory(abspath)
    root_dirs[abspath] = true
  else
    raise ArgumentError, "the root directory #{abspath} does not exist"
  end
end

#reload ⇒ void

This method returns an undefined value.

Unloads all loaded code, and calls setup again so that the loader is able to pick any changes in the file system.

This method is not thread-safe, please see how this can be achieved by client code in the README of the project.



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# File 'lib/zeitwerk/loader.rb', line 276

def reload
  unload
  setup
end

#setup ⇒ void

This method returns an undefined value.

Sets autoloads in the root namespace and preloads files, if any.



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# File 'lib/zeitwerk/loader.rb', line 207

def setup
  mutex.synchronize do
    break if @setup

    expand_ignored_glob_patterns
    non_ignored_root_dirs.each { |root_dir| set_autoloads_in_dir(root_dir, Object) }
    do_preload

    @setup = true
  end
end

#unload ⇒ void

This method returns an undefined value.

Removes loaded constants and configured autoloads.

The objects the constants stored are no longer reachable through them. In addition, since said objects are normally not referenced from anywhere else, they are eligible for garbage collection, which would effectively unload them.



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# File 'lib/zeitwerk/loader.rb', line 228

def unload
  mutex.synchronize do
    # We are going to keep track of the files that were required by our
    # autoloads to later remove them from $LOADED_FEATURES, thus making them
    # loadable by Kernel#require again.
    #
    # Directories are not stored in $LOADED_FEATURES, keeping track of files
    # is enough.
    unloaded_files = Set.new

    autoloads.each do |realpath, (parent, cname)|
      if parent.autoload?(cname)
        parent.send(:remove_const, cname)
        log("autoload for #{cpath(parent, cname)} removed") if logger
      else
        if cdef?(parent, cname)
          parent.send(:remove_const, cname)
          log("#{cpath(parent, cname)} unloaded") if logger
        else
          # Already unloaded somehow, that is fine.
        end
        unloaded_files.add(realpath) if ruby?(realpath)
      end
    end

    unless unloaded_files.empty?
      $LOADED_FEATURES.reject! { |file| unloaded_files.member?(file) }
    end

    autoloads.clear
    loaded_cpaths.clear
    lazy_subdirs.clear
    shadowed_files.clear

    Registry.on_unload(self)
    ExplicitNamespace.unregister(self)

    @setup = false
  end
end