aboutsummaryrefslogtreecommitdiffstats
path: root/activesupport/lib/active_support/dependencies.rb
blob: eaba46dd9ccc13dc399356a0715b0ee1b1974da7 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
require 'set'
require 'active_support/core_ext/module/attribute_accessors'
require 'active_support/core_ext/load_error'
require 'active_support/core_ext/kernel'

module Dependencies #:nodoc:
  extend self

  # Should we turn on Ruby warnings on the first load of dependent files?
  mattr_accessor :warnings_on_first_load
  self.warnings_on_first_load = false

  # All files ever loaded.
  mattr_accessor :history
  self.history = Set.new

  # All files currently loaded.
  mattr_accessor :loaded
  self.loaded = Set.new

  # Should we load files or require them?
  mattr_accessor :mechanism
  self.mechanism = :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 load_once_paths.
  mattr_accessor :load_paths
  self.load_paths = []

  # The set of directories from which automatically loaded constants are loaded
  # only once. All directories in this set must also be present in +load_paths+.
  mattr_accessor :load_once_paths
  self.load_once_paths = []

  # 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
  self.autoloaded_constants = []

  # 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
  self.explicitly_unloadable_constants = []

  # Set to true to enable logging of const_missing and file loads
  mattr_accessor :log_activity
  self.log_activity = false

  # An internal stack used to record which constants are loaded by any block.
  mattr_accessor :constant_watch_stack
  self.constant_watch_stack = []

  def load?
    mechanism == :load
  end

  def depend_on(file_name, swallow_load_errors = false)
    path = search_for_file(file_name)
    require_or_load(path || file_name)
  rescue LoadError
    raise unless swallow_load_errors
  end

  def associate_with(file_name)
    depend_on(file_name, true)
  end

  def clear
    log_call
    loaded.clear
    remove_unloadable_constants!
  end

  def require_or_load(file_name, const_path = nil)
    log_call file_name, const_path
    file_name = $1 if file_name =~ /^(.*)\.rb$/
    expanded = File.expand_path(file_name)
    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

    if load?
      log "loading #{file_name}"
      begin
        # Enable warnings iff 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 or history.include?(expanded)
          result = load_file(*load_args)
        else
          enable_warnings { result = load_file(*load_args) }
        end
      rescue Exception
        loaded.delete expanded
        raise
      end
    else
      log "requiring #{file_name}"
      result = require file_name
    end

    # Record history *after* loading so first load gets warnings.
    history << expanded
    return result
  end

  # Is the provided constant path defined?
  def qualified_const_defined?(path)
    raise NameError, "#{path.inspect} is not a valid constant name!" unless
      /^(::)?([A-Z]\w*)(::[A-Z]\w*)*$/ =~ path

    names = path.to_s.split('::')
    names.shift if names.first.empty?

    # We can't use defined? because it will invoke const_missing for the parent
    # of the name we are checking.
    names.inject(Object) do |mod, name|
      return false unless uninherited_const_defined?(mod, name)
      mod.const_get name
    end
    return true
  end

  if Module.method(:const_defined?).arity == 1
    # Does this module define this constant?
    # Wrapper to accomodate changing Module#const_defined? in Ruby 1.9
    def uninherited_const_defined?(mod, const)
      mod.const_defined?(const)
    end
  else
    def uninherited_const_defined?(mod, const) #:nodoc:
      mod.const_defined?(const, false)
    end
  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 = load_paths)
    path = $1 if path =~ /\A(.*)\.rb\Z/
    expanded_path = File.expand_path(path)

    bases.collect do |root|
      expanded_root = File.expand_path(root)
      next unless %r{\A#{Regexp.escape(expanded_root)}(/|\\)} =~ expanded_path

      nesting = expanded_path[(expanded_root.size)..-1]
      nesting = nesting[1..-1] if nesting && nesting[0] == ?/
      next if nesting.blank?

      [
        nesting.camelize,
        # Special case: application.rb might define ApplicationControlller.
        ('ApplicationController' if nesting == 'application')
      ]
    end.flatten.compact.uniq
  end

  # Search for a file in load_paths matching the provided suffix.
  def search_for_file(path_suffix)
    path_suffix = path_suffix + '.rb' unless path_suffix.ends_with? '.rb'
    load_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)
    load_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)
    load_once_paths.any? { |base| path.starts_with? base }
  end

  # Attempt to autoload the provided module name by searching for a directory
  # matching the expect 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 load_once_paths.include?(base_path)
    return 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))
    log_call path, const_paths
    const_paths = [const_paths].compact unless const_paths.is_a? Array
    parent_paths = const_paths.collect { |const_path| /(.*)::[^:]+\Z/ =~ const_path ? $1 : :Object }

    result = nil
    newly_defined_paths = new_constants_in(*parent_paths) do
      result = load_without_new_constant_marking path
    end

    autoloaded_constants.concat newly_defined_paths unless load_once_path?(path)
    autoloaded_constants.uniq!
    log "loading #{path} defined #{newly_defined_paths * ', '}" unless newly_defined_paths.empty?
    return result
  end

  # Return the constant path for the provided parent and constant name.
  def qualified_name_for(mod, name)
    mod_name = to_constant_name mod
    (%w(Object Kernel).include? mod_name) ? 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)
    log_call from_mod, const_name
    if from_mod == Kernel
      if ::Object.const_defined?(const_name)
        log "Returning Object::#{const_name} for Kernel::#{const_name}"
        return ::Object.const_get(const_name)
      else
        log "Substituting Object for Kernel"
        from_mod = Object
      end
    end

    # If we have an anonymous module, all we can do is attempt to load from Object.
    from_mod = Object if from_mod.name.blank?

    unless qualified_const_defined?(from_mod.name) && from_mod.name.constantize.object_id == from_mod.object_id
      raise ArgumentError, "A copy of #{from_mod} has been removed from the module tree but is still active!"
    end

    raise ArgumentError, "#{from_mod} is not missing constant #{const_name}!" if uninherited_const_defined?(from_mod, const_name)

    qualified_name = qualified_name_for from_mod, const_name
    path_suffix = qualified_name.underscore
    name_error = NameError.new("uninitialized constant #{qualified_name}")

    file_path = search_for_file(path_suffix)
    if file_path && ! loaded.include?(File.expand_path(file_path)) # We found a matching file to load
      require_or_load file_path
      raise LoadError, "Expected #{file_path} to define #{qualified_name}" unless uninherited_const_defined?(from_mod, const_name)
      return from_mod.const_get(const_name)
    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| uninherited_const_defined?(p, const_name) }
      # 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
        return parent.const_missing(const_name)
      rescue NameError => e
        raise unless e.missing_name? qualified_name_for(parent, const_name)
        raise name_error
      end
    else
      raise name_error
    end
  end

  # Remove the constants that have been autoloaded, and those that have been
  # marked for unloading.
  def remove_unloadable_constants!
    autoloaded_constants.each { |const| remove_constant const }
    autoloaded_constants.clear
    explicitly_unloadable_constants.each { |const| remove_constant const }
  end

  # Determine if the given constant has been automatically loaded.
  def autoloaded?(desc)
    # No name => anonymous module.
    return false if desc.is_a?(Module) && desc.name.blank?
    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?(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
      return false
    else
      explicitly_unloadable_constants << name
      return 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)
    log_call(*descs)

    # Build the watch frames. Each frame is a tuple of
    #   [module_name_as_string, constants_defined_elsewhere]
    watch_frames = descs.collect do |desc|
      if desc.is_a? Module
        mod_name = desc.name
        initial_constants = desc.local_constant_names
      elsif desc.is_a?(String) || desc.is_a?(Symbol)
        mod_name = desc.to_s

        # Handle the case where the module has yet to be defined.
        initial_constants = if qualified_const_defined?(mod_name)
          mod_name.constantize.local_constant_names
        else
         []
        end
      else
        raise Argument, "#{desc.inspect} does not describe a module!"
      end

      [mod_name, initial_constants]
    end

    constant_watch_stack.concat watch_frames

    aborting = true
    begin
      yield # Now yield to the code that is to define new constants.
      aborting = false
    ensure
      # Find the new constants.
      new_constants = watch_frames.collect do |mod_name, prior_constants|
        # Module still doesn't exist? Treat it as if it has no constants.
        next [] unless qualified_const_defined?(mod_name)

        mod = mod_name.constantize
        next [] unless mod.is_a? Module
        new_constants = mod.local_constant_names - prior_constants

        # Make sure no other frames takes credit for these constants.
        constant_watch_stack.each do |frame_name, constants|
          constants.concat new_constants if frame_name == mod_name
        end

        new_constants.collect do |suffix|
          mod_name == "Object" ? suffix : "#{mod_name}::#{suffix}"
        end
      end.flatten

      log "New constants: #{new_constants * ', '}"

      if aborting
        log "Error during loading, removing partially loaded constants "
        new_constants.each { |name| remove_constant name }
        new_constants.clear
      end
    end

    return new_constants
  ensure
    # Remove the stack frames that we added.
    if defined?(watch_frames) && ! watch_frames.empty?
      frame_ids = watch_frames.collect(&:object_id)
      constant_watch_stack.delete_if do |watch_frame|
        frame_ids.include? watch_frame.object_id
      end
    end
  end

  class LoadingModule #:nodoc:
    # Old style environment.rb referenced this method directly.  Please note, it doesn't
    # actually *do* anything any more.
    def self.root(*args)
      if defined?(RAILS_DEFAULT_LOGGER)
        RAILS_DEFAULT_LOGGER.warn "Your environment.rb uses the old syntax, it may not continue to work in future releases."
        RAILS_DEFAULT_LOGGER.warn "For upgrade instructions please see: http://manuals.rubyonrails.com/read/book/19"
      end
    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:
    name = case desc
      when String then desc.starts_with?('::') ? desc[2..-1] : desc
      when Symbol then desc.to_s
      when Module
        raise ArgumentError, "Anonymous modules have no name to be referenced by" if desc.name.blank?
        desc.name
      else raise TypeError, "Not a valid constant descriptor: #{desc.inspect}"
    end
  end

  def remove_constant(const) #:nodoc:
    return false unless qualified_const_defined? const

    const = $1 if /\A::(.*)\Z/ =~ const.to_s
    names = const.to_s.split('::')
    if names.size == 1 # It's under Object
      parent = Object
    else
      parent = (names[0..-2] * '::').constantize
    end

    log "removing constant #{const}"
    parent.instance_eval { remove_const names.last }
    return true
  end

protected
  def log_call(*args)
    if defined?(RAILS_DEFAULT_LOGGER) && RAILS_DEFAULT_LOGGER && log_activity
      arg_str = args.collect(&:inspect) * ', '
      /in `([a-z_\?\!]+)'/ =~ caller(1).first
      selector = $1 || '<unknown>'
      log "called #{selector}(#{arg_str})"
    end
  end

  def log(msg)
    if defined?(RAILS_DEFAULT_LOGGER) && RAILS_DEFAULT_LOGGER && log_activity
      RAILS_DEFAULT_LOGGER.debug "Dependencies: #{msg}"
    end
  end

end

Object.instance_eval do
  define_method(:require_or_load)     { |file_name| Dependencies.require_or_load(file_name) } unless Object.respond_to?(:require_or_load)
  define_method(:require_dependency)  { |file_name| Dependencies.depend_on(file_name) }       unless Object.respond_to?(:require_dependency)
  define_method(:require_association) { |file_name| Dependencies.associate_with(file_name) }  unless Object.respond_to?(:require_association)
end

class Module #:nodoc:
  # Rename the original handler so we can chain it to the new one
  alias :rails_original_const_missing :const_missing

  # Use const_missing to autoload associations so we don't have to
  # require_association when using single-table inheritance.
  def const_missing(class_id)
    Dependencies.load_missing_constant self, class_id
  end

  def unloadable(const_desc = self)
    super(const_desc)
  end

end

class Class
  def const_missing(const_name)
    if [Object, Kernel].include?(self) || parent == self
      super
    else
      begin
        begin
          Dependencies.load_missing_constant self, const_name
        rescue NameError
          parent.send :const_missing, const_name
        end
      rescue NameError => e
        # Make sure that the name we are missing is the one that caused the error
        parent_qualified_name = Dependencies.qualified_name_for parent, const_name
        raise unless e.missing_name? parent_qualified_name
        qualified_name = Dependencies.qualified_name_for self, const_name
        raise NameError.new("uninitialized constant #{qualified_name}").copy_blame!(e)
      end
    end
  end
end

class Object
  alias_method :load_without_new_constant_marking, :load

  def load(file, *extras) #:nodoc:
    Dependencies.new_constants_in(Object) { super }
  rescue Exception => exception  # errors from loading file
    exception.blame_file! file
    raise
  end

  def require(file, *extras) #:nodoc:
    Dependencies.new_constants_in(Object) { super }
  rescue Exception => exception  # errors from required file
    exception.blame_file! 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
end

# Add file-blaming to exceptions
class Exception #: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