Easy way to return the first matching value and stop all tasks? #292
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I'm writing a password bruteforcer using the async gems, and I want to try all combinations of usernames and passwords. I'm using |
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Replies: 1 comment 12 replies
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Following code comes from: Can't you just use waiter = Async::Waiter.new(parent: barrier)
Async do
jobs.each do |job|
waiter.async do
# ... process job ...
end
end
# Wait for the first two jobs to complete:
done = waiter.wait(2)
# You may use the barrier to stop the remaining jobs
barrier.stop
end |
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Here's a working version #!/usr/bin/env ruby
require 'bundler/setup'
require 'async'
require 'async/queue'
require 'async/barrier'
require 'async/waiter'
require 'async/variable'
WORKERS = 10
queue = Queue.new
barrier = Async::Barrier.new
waiter = Async::Waiter.new(parent: barrier)
variable = Async::Variable.new
values = (1..100).to_a
Sync do |task|
task.async do
values.each do |value|
queue.push(value)
end
WORKERS.times do
queue.push(nil)
end
end
WORKERS.times do
waiter.async do
while (value = queue.pop)
sleep 1
puts "Testing value #{value} ..."
if value == 42
puts "Discovered the matching value! #{value}"
variable.resolve(value)
break
end
end
end
end
waiter.wait(1)
barrier.stop
if variable.resolved?
puts "Got the matching value: #{variable.value}"
end
end
puts "Done!"Using Async's LimitedQueue, it works partially. Something keeps the reactor alive and the program doesn't terminate |
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@j-manu I kind of need to use |
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You can use Async instead of Sync here. In the context of this script, Sync made more sense. |
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I think I know why the LimitedQueue is not working. Since the tasks have stopped, the queue fills up and the enqueueing blocks. You will have to stop those Async tasks also. I'm traveling right now. So can't test the assumption. |
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ooooh! Changing the producer task to be #!/usr/bin/env ruby
require 'bundler/setup'
require 'async'
require 'async/queue'
require 'async/barrier'
require 'async/waiter'
require 'async/variable'
WORKERS = 10
queue = Async::LimitedQueue.new(WORKERS)
barrier = Async::Barrier.new
waiter = Async::Waiter.new(parent: barrier)
variable = Async::Variable.new
values = (1..100).to_a
Async do |task|
barrier.async do
values.each do |value|
queue.enqueue(value)
end
WORKERS.times do
queue.enqueue(nil)
end
end
WORKERS.times do
waiter.async do
while (value = queue.dequeue)
puts "Testing value #{value} ..."
if value == 42
puts "Discovered the matching value! #{value}"
variable.resolve(value)
barrier.stop
break
end
end
end
end
waiter.wait
task.stop
end
if variable.resolved?
puts "Got the matching value: #{variable.value}"
end |
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You can just stop that specific producer task. I don't think stopping the main task from inside it is idiomatic. #!/usr/bin/env ruby
require 'bundler/setup'
require 'async'
require 'async/queue'
require 'async/barrier'
require 'async/waiter'
require 'async/variable'
WORKERS = 10
queue = Async::LimitedQueue.new(WORKERS)
barrier = Async::Barrier.new
waiter = Async::Waiter.new(parent: barrier)
variable = Async::Variable.new
values = (1..100).to_a
Async do |task|
producer_task = task.async do
values.each do |value|
queue.enqueue(value)
end
WORKERS.times do
queue.enqueue(nil)
end
end
WORKERS.times do
waiter.async do
while (value = queue.dequeue)
puts "Testing value #{value} ..."
if value == 42
puts "Discovered the matching value! #{value}"
variable.resolve(value)
break
end
end
end
end
waiter.wait(1)
producer_task.stop
barrier.stop
if variable.resolved?
puts "Got the matching value: #{variable.value}"
end
end |
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Hmm now I'm dealing with race conditions if I make my worker pool size very large (100), because some of the workers complete while values are still being tested, which triggers |
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Ah ha! Calling |
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I think I know why the LimitedQueue is not working. Since the tasks have stopped, the queue fills up and the enqueueing blocks. You will have to stop those Async tasks also.
I'm traveling right now. So can't test the assumption.