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require "active_support/execution_wrapper"
module ActiveSupport
#--
# This class defines several callbacks:
#
# to_prepare -- Run once at application startup, and also from
# +to_run+.
#
# to_run -- Run before a work run that is reloading. If
# +reload_classes_only_on_change+ is true (the default), the class
# unload will have already occurred.
#
# to_complete -- Run after a work run that has reloaded. If
# +reload_classes_only_on_change+ is false, the class unload will
# have occurred after the work run, but before this callback.
#
# before_class_unload -- Run immediately before the classes are
# unloaded.
#
# after_class_unload -- Run immediately after the classes are
# unloaded.
#
class Reloader < ExecutionWrapper
define_callbacks :prepare
define_callbacks :class_unload
def self.to_prepare(*args, &block)
set_callback(:prepare, *args, &block)
end
def self.before_class_unload(*args, &block)
set_callback(:class_unload, *args, &block)
end
def self.after_class_unload(*args, &block)
set_callback(:class_unload, :after, *args, &block)
end
to_run(:after) { self.class.prepare! }
# Initiate a manual reload
def self.reload!
executor.wrap do
new.tap do |instance|
begin
instance.run!
ensure
instance.complete!
end
end
end
prepare!
end
def self.run! # :nodoc:
if check!
super
else
Null
end
end
# Run the supplied block as a work unit, reloading code as needed
def self.wrap
executor.wrap do
super
end
end
class_attribute :executor
class_attribute :check
self.executor = Executor
self.check = lambda { false }
def self.check! # :nodoc:
@should_reload ||= check.call
end
def self.reloaded! # :nodoc:
@should_reload = false
end
def self.prepare! # :nodoc:
new.run_callbacks(:prepare)
end
def initialize
super
@locked = false
end
# Acquire the ActiveSupport::Dependencies::Interlock unload lock,
# ensuring it will be released automatically
def require_unload_lock!
unless @locked
ActiveSupport::Dependencies.interlock.start_unloading
@locked = true
end
end
# Release the unload lock if it has been previously obtained
def release_unload_lock!
if @locked
@locked = false
ActiveSupport::Dependencies.interlock.done_unloading
end
end
def run! # :nodoc:
super
release_unload_lock!
end
def class_unload!(&block) # :nodoc:
require_unload_lock!
run_callbacks(:class_unload, &block)
end
def complete! # :nodoc:
super
self.class.reloaded!
ensure
release_unload_lock!
end
end
end