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Class: RuboCop::Cop::Lint::IncompatibleIoSelectWithFiberScheduler

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/incompatible_io_select_with_fiber_scheduler.rb

Overview

Checks for IO.select that is incompatible with Fiber Scheduler since Ruby 3.0.

When an array of IO objects waiting for an exception (the third argument of IO.select) is used as an argument, there is no alternative API, so offenses are not registered.

Note
When the method is successful the return value of IO.select is , and the return value of io.wait_readable and io.wait_writable are self. They are not autocorrected when assigning a return value because these types are different. It’s up to user how to handle the return value.

Examples:

# bad
IO.select([io], [], [], timeout)

# good
io.wait_readable(timeout)

# bad
IO.select([], [io], [], timeout)

# good
io.wait_writable(timeout)

Cop Safety Information:

  • This cop’s autocorrection is unsafe because NoMethodError occurs if require 'io/wait' is not called.

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

#io_select(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/incompatible_io_select_with_fiber_scheduler.rb', line 41

def_node_matcher :io_select, <<~PATTERN
  (send
    (const {nil? cbase} :IO) :select $...)
PATTERN

#on_send(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/incompatible_io_select_with_fiber_scheduler.rb', line 46

def on_send(node)
  read, write, excepts, timeout = *io_select(node)
  return if excepts && !excepts.children.empty?
  return unless scheduler_compatible?(read, write) || scheduler_compatible?(write, read)

  preferred = preferred_method(read, write, timeout)
  message = format(MSG, preferred: preferred, current: node.source)

  add_offense(node, message: message) do |corrector|
    next if node.parent&.assignment?

    corrector.replace(node, preferred)
  end
end

#preferred_method(read, write, timeout) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/incompatible_io_select_with_fiber_scheduler.rb', line 69

def preferred_method(read, write, timeout)
  timeout_argument = timeout.nil? ? '' : "(#{timeout.source})"

  if read.array_type? && read.values[0]
    "#{read.values[0].source}.wait_readable#{timeout_argument}"
  else
    "#{write.values[0].source}.wait_writable#{timeout_argument}"
  end
end

#scheduler_compatible?(io1, io2) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/incompatible_io_select_with_fiber_scheduler.rb', line 63

def scheduler_compatible?(io1, io2)
  return false unless io1&.array_type? && io1.values.size == 1

  io2&.array_type? ? io2.values.empty? : (io2.nil? || io2.nil_type?)
end