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require 'thread' | |
require 'timeout' | |
class Scatter | |
include Enumerable | |
def initialize(*callables) | |
@threads = [] | |
@callables = callables | |
@queue = Queue.new | |
@timeout = 60 | |
end | |
def each(&block) | |
prepare | |
enumerate(&block) | |
ensure | |
cleanup | |
end | |
def first_successful | |
detect { |entry| !entry.is_a?(Exception) } | |
end | |
private | |
attr_reader :callables, :timeout, :queue | |
attr_accessor :threads | |
def cleanup | |
@threads.map(&:kill) | |
end | |
def enumerate | |
Timeout::timeout(timeout) do | |
callables.length.times do | |
yield queue.deq | |
end | |
end | |
end | |
def prepare | |
threads = callables.map do |callable| | |
Thread.new do | |
begin | |
message = callable.call | |
rescue Exception => error | |
ensure | |
queue.enq(error or message) | |
end | |
end | |
end | |
end | |
end | |
beta = proc { sleep 3; :beta } | |
gamma = proc { sleep 30; :gamma } | |
alpha = proc { raise :alpha } | |
theta = proc { sleep 1; :theta } | |
# returns once the first successful block completes. | |
# Great for working with unreliable IO | |
Scatter.new(alpha, beta, gamma, theta).first_successful | |
# you can also get direct access to the enumerator | |
enum = Scatter.new(alpha, beta, gamma, theta).to_enum | |
enum.next | |
> #<TypeError: exception class/object expected> | |
enum.next | |
> :theta | |
enum.next | |
> :beta | |
enum.next | |
> :gamma | |
enum.rewind | |
enum.next | |
> #<TypeError: exception class/object expected> | |
enum.next | |
> :theta | |
enum.next | |
> :gamma | |
enum.rewind | |
enum.take(4) | |
> [#<TypeError: exception class/object expected>, :theta, :beta, :gamma] |
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