# frozen_string_literal: true
require "thread"
module Bundler
class Worker
POISON = Object.new
class WrappedException < StandardError
attr_reader :exception
def initialize(exn)
@exception = exn
end
end
# @return [String] the name of the worker
attr_reader :name
# Creates a worker pool of specified size
#
# @param size [Integer] Size of pool
# @param name [String] name the name of the worker
# @param func [Proc] job to run in inside the worker pool
def initialize(size, name, func)
@name = name
@request_queue = Queue.new
@response_queue = Queue.new
@func = func
@size = size
@threads = nil
SharedHelpers.trap("INT") { abort_threads }
end
# Enqueue a request to be executed in the worker pool
#
# @param obj [String] mostly it is name of spec that should be downloaded
def enq(obj)
create_threads unless @threads
@request_queue.enq obj
end
# Retrieves results of job function being executed in worker pool
def deq
result = @response_queue.deq
raise result.exception if result.is_a?(WrappedException)
result
end
def stop
stop_threads
end
private
def process_queue(i)
loop do
obj = @request_queue.deq
break if obj.equal? POISON
@response_queue.enq apply_func(obj, i)
end
end
def apply_func(obj, i)
@func.call(obj, i)
rescue Exception => e
WrappedException.new(e)
end
# Stop the worker threads by sending a poison object down the request queue
# so as worker threads after retrieving it, shut themselves down
def stop_threads
return unless @threads
@threads.each { @request_queue.enq POISON }
@threads.each(&:join)
@threads = nil
end
def abort_threads
return unless @threads
Bundler.ui.debug("\n#{caller.join("\n")}")
@threads.each(&:exit)
exit 1
end
def create_threads
creation_errors = []
@threads = Array.new(@size) do |i|
begin
Thread.start { process_queue(i) }.tap do |thread|
thread.name = "#{name} Worker ##{i}" if thread.respond_to?(:name=)
end
rescue ThreadError => e
creation_errors << e
nil
end
end.compact
return if creation_errors.empty?
message = "Failed to create threads for the #{name} worker: #{creation_errors.map(&:to_s).uniq.join(", ")}"
raise ThreadCreationError, message if @threads.empty?
Bundler.ui.info message
end
end
end
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