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mirror of https://github.com/NixOS/mobile-nixos.git synced 2024-12-16 03:32:02 +03:00
mobile-nixos/boot/init/lib/task.rb
2020-02-03 16:19:10 -05:00

97 lines
2.3 KiB
Ruby

# Namespace where tasks can be defined, and hosting methods harmonizing a run.
module Tasks
# Register a singleton task to be instantiated and ran.
# @internal
def self.register_singleton(klass)
$logger.debug("Task #{klass.name} registered...")
@singletons_to_be_instantiated ||= []
@singletons_to_be_instantiated << klass
end
# Register one task to be ran.
def self.register(task)
$logger.debug("Task #{task.name} registered...")
@tasks ||= []
@tasks << task
end
# Tries to run *all* tasks.
def self.go()
# Registers tasks that still needs to be instantiated
@singletons_to_be_instantiated.each do |klass|
register(klass.instance)
end
@singletons_to_be_instantiated = []
until @tasks.all?(&:ran) do
$logger.debug("Tasks resolution loop start")
@tasks
.reject(&:ran)
.each do |task|
task._try_run_task
end
# Don't burn the CPU
sleep(0.1)
end
end
end
# Basic task class.
class Task
attr_reader :ran
def self.new(*args)
$logger.debug("New instance of #{self.name}...")
$logger.debug(" -> #{args.inspect}")
instance = super(*args)
Tasks.register(instance)
instance
end
def name
self.class.name
end
def self.inherited(subclass)
$logger.debug("#{subclass.name} created...")
end
def add_dependency(kind, *args)
raise NameError.new("No dependency named #{kind}") unless Dependencies.constants.include?(kind.to_sym)
dependencies << Dependencies.const_get(kind.to_sym).new(*args)
end
def dependencies_fulfilled?()
dependencies.all?(&:fulfilled?)
end
# Internal actual way to run the task
# This runs the `#run` method.
def _try_run_task()
$logger.debug("Looking to run task #{name}...")
return unless dependencies_fulfilled?
unless @ran
$logger.info("Running #{name}...")
run()
$logger.debug("Finished #{name}...")
@ran = true
end
end
def dependencies()
@dependencies ||= []
@dependencies
end
end
# A task that can only have one instance.
class SingletonTask < Task
include Singleton
def self.inherited(subclass)
super
# Delay initializing, as right now we have an fresh new empty class.
Tasks.register_singleton(subclass)
end
end