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Class: RuboCop::Cop::Lint::NonAtomicFileOperation

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::AutoCorrector, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/lint/non_atomic_file_operation.rb

Overview

Checks for non-atomic file operation. And then replace it with a nearly equivalent and atomic method.

These can cause problems that are difficult to reproduce, especially in cases of frequent file operations in parallel, such as test runs with parallel_rspec.

For examples: creating a directory if there is none, has the following problems

An exception occurs when the directory didn’t exist at the time of exist?, but someone else created it before mkdir was executed.

Subsequent processes are executed without the directory that should be there when the directory existed at the time of exist?, but someone else deleted it shortly afterwards.

Examples:

# bad - race condition with another process may result in an error in `mkdir`
unless Dir.exist?(path)
  FileUtils.mkdir(path)
end

# good - atomic and idempotent creation
FileUtils.mkdir_p(path)

# bad - race condition with another process may result in an error in `remove`
if File.exist?(path)
  FileUtils.remove(path)
end

# good - atomic and idempotent removal
FileUtils.rm_f(path)

Cop Safety Information:

  • This cop is unsafe, because autocorrection change to atomic processing. The atomic processing of the replacement destination is not guaranteed to be strictly equivalent to that before the replacement.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,
.support_autocorrect?

Returns if class supports autocorrect.

.support_multiple_source?

Override if your cop should be called repeatedly for multiple investigations Between calls to on_new_investigation and on_investigation_end, the result of processed_source will remain constant.

Class Method Summary

::RuboCop::Cop::Base - Inherited

.autocorrect_incompatible_with

List of cops that should not try to autocorrect at the same time as this cop.

.badge

Naming.

.callbacks_needed, .cop_name, .department,
.documentation_url

Returns an url to view this cops documentation online.

.exclude_from_registry

Call for abstract Cop classes.

.inherited,
.joining_forces

Override and return the Force class(es) you need to join.

.match?

Returns true if the cop name or the cop namespace matches any of the given names.

.new,
.requires_gem

Register a version requirement for the given gem name.

.restrict_on_send

::RuboCop::ExcludeLimit - Extended

exclude_limit

Sets up a configuration option to have an exclude limit tracked.

transform

Instance Attribute Summary

Instance Method Summary

::RuboCop::Cop::Base - Inherited

#add_global_offense

Adds an offense that has no particular location.

#add_offense

Adds an offense on the specified range (or node with an expression) Unless that offense is disabled for this range, a corrector will be yielded to provide the cop the opportunity to autocorrect the offense.

#begin_investigation

Called before any investigation.

#callbacks_needed,
#cop_config

Configuration Helpers.

#cop_name, #excluded_file?,
#external_dependency_checksum

This method should be overridden when a cop’s behavior depends on state that lives outside of these locations:

#inspect
#message

Gets called if no message is specified when calling add_offense or add_global_offense Cops are discouraged to override this; instead pass your message directly.

#name

Alias for Base#cop_name.

#offenses,
#on_investigation_end

Called after all on_…​

#on_new_investigation

Called before all on_…​

#on_other_file

Called instead of all on_…​

#parse

There should be very limited reasons for a Cop to do it’s own parsing.

#parser_engine,
#ready

Called between investigations.

#relevant_file?, #target_rails_version, #target_ruby_version, #annotate, #apply_correction, #attempt_correction,
#callback_argument

Reserved for Cop::Cop.

#complete_investigation

Called to complete an investigation.

#correct, #current_corrector,
#current_offense_locations

Reserved for Commissioner:

#current_offenses, #currently_disabled_lines, #custom_severity, #default_severity, #disable_uncorrectable, #enabled_line?, #file_name_matches_any?, #find_message, #find_severity, #range_for_original, #range_from_node_or_range,
#reset_investigation

Actually private methods.

#use_corrector

::RuboCop::Cop::AutocorrectLogic - Included

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

This class inherits a constructor from RuboCop::Cop::Base

Instance Method Details

#allowable_use_with_if?(if_node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 97

def allowable_use_with_if?(if_node)
  if_node.condition.and_type? || if_node.condition.or_type? || if_node.else_branch
end

#autocorrect(corrector, node, range) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 121

def autocorrect(corrector, node, range)
  corrector.remove(range)
  autocorrect_replace_method(corrector, node)

  if node.parent.modifier_form?
    corrector.remove(node.source_range.end.join(node.parent.loc.keyword.begin))
  else
    corrector.remove(node.parent.loc.end)
  end
end

#autocorrect_replace_method(corrector, node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 132

def autocorrect_replace_method(corrector, node)
  return if force_method?(node)

  corrector.replace(node.child_nodes.first.loc.name, 'FileUtils')
  corrector.replace(node.loc.selector, replacement_method(node))
end

#explicit_not_force?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 76

def_node_search :explicit_not_force?, <<~PATTERN
  (pair (sym :force) (:false))
PATTERN

#force?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 71

def_node_search :force?, <<~PATTERN
  (pair (sym :force) (:true))
PATTERN

#force_method?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 151

def force_method?(node)
  force_method_name?(node) || force_option?(node)
end

#force_method_name?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 159

def force_method_name?(node)
  (MAKE_FORCE_METHODS + REMOVE_FORCE_METHODS).include?(node.method_name)
end

#force_option?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 155

def force_option?(node)
  node.arguments.any? { |arg| force?(arg) }
end

#if_node_child?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 91

def if_node_child?(node)
  return false unless (parent = node.parent)

  parent.if_type? && !allowable_use_with_if?(parent)
end

#message_change_force_method(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 112

def message_change_force_method(node)
  format(MSG_CHANGE_FORCE_METHOD, method_name: replacement_method(node))
end

#message_remove_file_exist_check(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 116

def message_remove_file_exist_check(node)
  receiver, method_name = receiver_and_method_name(node)
  format(MSG_REMOVE_FILE_EXIST_CHECK, receiver: receiver, method_name: method_name)
end

#on_send(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 80

def on_send(node)
  return unless if_node_child?(node)
  return if explicit_not_force?(node)
  return unless (exist_node = send_exist_node(node.parent).first)
  return unless exist_node.first_argument == node.first_argument

  register_offense(node, exist_node)
end

#receiver_and_method_name(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 66

def_node_matcher :receiver_and_method_name, <<~PATTERN
  (send (const nil? $_) $_ ...)
PATTERN

#register_offense(node, exist_node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 101

def register_offense(node, exist_node)
  add_offense(node, message: message_change_force_method(node)) unless force_method?(node)

  parent = node.parent
  range = parent.loc.keyword.begin.join(parent.condition.source_range.end)

  add_offense(range, message: message_remove_file_exist_check(exist_node)) do |corrector|
    autocorrect(corrector, node, range) unless parent.elsif?
  end
end

#replacement_method(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 139

def replacement_method(node)
  if MAKE_METHODS.include?(node.method_name)
    'mkdir_p'
  elsif REMOVE_METHODS.include?(node.method_name)
    'rm_f'
  elsif RECURSIVE_REMOVE_METHODS.include?(node.method_name)
    'rm_rf'
  else
    node.method_name
  end
end

#send_exist_node(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/non_atomic_file_operation.rb', line 61

def_node_search :send_exist_node, <<~PATTERN
  $(send (const nil? {:FileTest :File :Dir :Shell}) {:exist? :exists?} ...)
PATTERN