Handle GCM reflections in batches.

[balbesina]

Since we push messages to GCM in a batch and the response comes with each registration_id delivery status, there is no need to reflect each device separately. This feature allows to receive all successful and failed statues per single reflection.

# example usage
Rpush.configure do |config|
  config.gcm_batch_reflections = true
end
Rpush.reflect do |on|
  on.gcm_delivered_to_recipients do |notification, successes_map|
    success_values = successes_map.keys.map { |token| [notification.id, token] }
    DeviceDeliveryStatus.import %i[notification_id device_token], success_values
  end
end

[aried3r]

Hey! Thanks for your PR, I think it makes a lot of sense :)

Could you please add tests for it? There's quite a lot going on, new conditionals and changes in behavior. I think it'd be best some tests would document this.

[balbesina]

I'll find some time on the upcoming weekend for that.

[balbesina]

Added same option for notifications: :notification_batch_reflections
Added spec coverage.

[balbesina]

Please provide acceptable resolution for rubocop's "block too long" of delivery_spec:

1. add disable comment for block length in file
2. extend block length for spec folder in .rubocop.yml
3. extract new examples to separate delivery2_spec

[aried3r]

Hey! Sorry I've neglected this PR for a while. @rpush/maintainers, kindly asking for a second pair of eyes for review.

[AlexTatarnikov]

It looks like potential memory issue here and for failures_map in handle_errors as well.

successes can hold thousands of objects and map will create a new array in memory, the same to_h does.

You can use something like inject or each_with_object in order to reduce the number of iterations and objects but still not sure if it is good idea "double" the memory consumption.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. If this is still an issue, please leave another comment. This issue will be closed if no further activity occurs.
Thank you for all your contributions!