Is `dripper/perform.rb` locating wrong `campaign` when database is MySQL?

[erwin]

I've been struggling with this one non-stop since Saturday. Please pardon me if I have missed something. It was a lot of work to slice this out of my app and find the breaking point. It's very subtle.

I've done my best to create a minimal reproducible test. I'm not sure if it impacts production or only the test harness.

The issue I'm seeing is that when using MySQL, the first call to perform! works fine.

caffeinate/lib/caffeinate/dripper/perform.rb

Line 17 in 0356067

def perform!

But in subsequent calls, the value of campaign is set incorrectly (I think to the value from the previous call)

caffeinate/lib/caffeinate/dripper/perform.rb

Line 40 in 0356067

.merge(Caffeinate::CampaignSubscription.active.where(caffeinate_campaign: campaign))

The result is upcoming_mailings returns an empty set on subsequent calls to perform, and thus the campaign is only run the first time.

Debugging the `Caffeinate::CampaignSubscription` result set inside of `Perform!`

I modified perform to dump the Caffeinate::CampaignSubscription set as it's filtered so I can see what was happening:

caffeinate/lib/caffeinate/dripper/perform.rb

Line 19 in 0356067

self.class.upcoming_mailings

Print the Caffeinate::CampaignSubscription inside of perform!:

        puts "Caffeinate::CampaignSubscription.active, `campaign.id` == #{campaign.id}"
        tp(Caffeinate::CampaignSubscription.active, :id, :caffeinate_campaign_id, :subscriber_type, :subscriber_id, :user_type, :user_id, :ended_at, :unsubscribed_at)

        puts "Caffeinate::CampaignSubscription.active.where(caffeinate_campaign == #{campaign.id})"
        tp(Caffeinate::CampaignSubscription.active.where(caffeinate_campaign: campaign), :id, :caffeinate_campaign_id, :subscriber_type, :subscriber_id, :user_type, :user_id, :ended_at, :unsubscribed_at)

I created an empty rails 7 project that uses sqlite3 and the following works as expected:

• Creates a campaign
• Subscribes to a campaign
• And then twice calls .perform! on the campaign, to execute both of the drippers connected to the campaign.
• Then repeat the same in a second test

However, when I do the same thing on a blank rails 7 project that uses MySQL, when perform! is called in the 2nd test, the Caffeinate::CampaignSubscription result set is blank (because campaign is pointing to an invalid record, and thus no drips are sent the second time around.

From inside of calls to perform!, if we print all of the active campaigns with: Caffeinate::CampaignSubscription.active it contains:

Caffeinate::CampaignSubscription.active, `campaign.id` ==  44
                                                          ^^^^
ID | CAFFEINATE_CAMPAIGN_ID | SUBSCRIBER_TYPE | SUBSCRIBER_ID | USER_TYPE | USER_ID   | ENDED_AT | UNSUBSCRIBED_AT
---|------------------------|-----------------|---------------|-----------|-----------|----------|----------------
27 | 45                     | Subscriber      | 980190993     | User      | 980191007 |          |                
    ^^^^

You see how campaign.id does not match CAFFEINATE_CAMPAIGN_ID... So when we print the active campaigns where the campaign id matches, we get an empty set:

Caffeinate::CampaignSubscription.active.where(caffeinate_campaign == 44)
No data.

---

Reproducing...

Versions:

ubuntu-22-04% ruby -v
ruby 3.0.2p107 (2021-07-07 revision 0db68f0233) [x86_64-linux-gnu]
ubuntu-22-04% rails -v
Rails 7.0.6
ubuntu-22-04% cat /etc/debian_version
bookworm/sid

Create a new rails7 project to reproduce the bug:

rails new --minimal repro -d mysql
cd repro
bin/bundle add caffeinate awesome_print table_print
rails g caffeinate:install
rails g model User name email before_drip_run_counter:integer
rails g model Subscriber name email
sudo mysql -e "CREATE DATABASE repro_development"
sudo mysql -e "CREATE DATABASE repro_test"
sudo mysql mysql -e "ALTER USER 'root'@'localhost' IDENTIFIED BY '';"
rails db:migrate

application_dripper.rb

app/drippers/application_dripper.rb

# frozen_string_literal: true

class ApplicationDripper < ::Caffeinate::Dripper::Base
  def self.process_unsubscribes(_drip,mailing)
    puts "Calling process_unsubscribes..."
    user = mailing.user
    
    user.before_drip_run_counter = user.before_drip_run_counter.to_i + 1
    user.save
  end
end

test_dripper.rb

app/drippers/test_dripper.rb

class TestDripper < ApplicationDripper
  self.campaign = :test

  before_drip do |_drip, mailing|
    process_unsubscribes(_drip, mailing)
  end

  drip :first_reminder,   action_class: 'TestAction', delay: 0.seconds
  drip :second_reminder,  action_class: 'TestAction', delay: 1.seconds
end

test_action.rb

app/actions/test_action.rb

class TestAction < Caffeinate::ActionProxy
  def first_reminder(mailing)
    puts("Running first_reminder")
  end

  def second_reminder(mailing)
    puts("Running second_reminder")
  end
end

caffeinate_test.rb

test/integration/caffeinate_test.rb

require "test_helper"

class CaffeinateTest < ActionDispatch::IntegrationTest
  test "foo" do
    campaign = Caffeinate::Campaign.find_or_create_by!(name: "Test", slug: "test")
    user = User.create!(name: "foo", email: "foo@foo")
    subscriber = Subscriber.create!(name: "bar", email: "bar@bar")
    assert Caffeinate::CampaignSubscription.count == 0

    campaign.subscribe(subscriber, user: user)
    assert user.before_drip_run_counter.to_i == 0
    TestDripper.perform!
    user.reload
    assert user.before_drip_run_counter == 1

    sleep 1.seconds
    TestDripper.perform!
    user.reload
    assert user.before_drip_run_counter == 2
  end

  test "foo-bar" do
    campaign = Caffeinate::Campaign.find_or_create_by!(name: "Test", slug: "test")
    user = User.create!(name: "bar", email: "bar@bar")
    subscriber = Subscriber.create!(name: "foo", email: "foo@foo")
    campaign.subscribe(subscriber, user: user)
    assert user.before_drip_run_counter.to_i == 0
    TestDripper.perform!
    user.reload
    assert user.before_drip_run_counter == 1

    sleep 1.seconds
    TestDripper.perform!
    user.reload
    assert user.before_drip_run_counter == 2
  end
end

If you run the above, but do not specify -d mysql (using the default sqlite3), then it will work fine.

But if you run it with mysql, it will fail.

test foo and test foo-bar should be equivalent, producing equivalent output, but running: bin/rails test you will get:

test output for mysql version

ubuntu-22-04% bin/rails test
Running 2 tests in a single process (parallelization threshold is 50)
Run options: --seed 48614

# Running:

Calling process_unsubscribes...
Running first_reminder
Calling process_unsubscribes...
Running second_reminder
.F

Failure:
CaffeinateTest#test_foo [repro/test/integration/caffeinate_test.rb:14]:
Expected false to be truthy.


rails test test/integration/caffeinate_test.rb:4

When you run the same thing under sqlite3 though, the test passes as you would expect.

create the sqlite3 version of the same app

rails new --minimal repro2
cd repro2
bin/bundle add caffeinate awesome_print table_print
rails g caffeinate:install
rails g model User name email before_drip_run_counter:integer
rails g model Subscriber name email
rails db:migrate

test output for sqlite3 version

ubuntu-22-04% bin/rails test
Running 2 tests in a single process (parallelization threshold is 50)
Run options: --seed 50242

# Running:

Calling process_unsubscribes...
Running first_reminder
Calling process_unsubscribes...
Running second_reminder
.Calling process_unsubscribes...
Running first_reminder
Calling process_unsubscribes...
Running second_reminder
.

Finished in 2.118785s, 0.9439 runs/s, 3.3038 assertions/s.
2 runs, 7 assertions, 0 failures, 0 errors, 0 skips

---

One other issue that I also see when using MySQL but not when using sqlite3...

If we call subscribe as:

    TestDripper.subscribe(subscriber, user: user)

Instead of:

    campaign.subscribe(subscriber, user: user)

In the second test that calls TestDripper.subscribe it will return with:

Error:
CaffeinateTest#test_foo-bar:
NoMethodError: undefined method `to_dripper' for nil:NilClass
    test/integration/caffeinate_test.rb:31:in `block in <class:CaffeinateTest>'

When I run the same using sqlite3 it works fine...

Reproducing second issue...

Use the same content for application_dripper.rb, test_dripper.rb and test_action.rb.

Alternate version of caffeinate_test.rb

require "test_helper"

class CaffeinateTest < ActionDispatch::IntegrationTest
  test "foo" do
    campaign = Caffeinate::Campaign.find_or_create_by!(name: "Test", slug: "test")
    user = User.create!(name: "foo", email: "foo@foo")
    subscriber = Subscriber.create!(name: "bar", email: "bar@bar")
    assert Caffeinate::CampaignSubscription.count == 0

    campaign.subscribe(subscriber, user: user)
    assert user.before_drip_run_counter.to_i == 0
    TestDripper.perform!
    user.reload
    assert user.before_drip_run_counter == 1

    sleep 1.seconds
    TestDripper.perform!
    user.reload
    assert user.before_drip_run_counter == 2
  end

  test "foo-bar" do
    campaign = Caffeinate::Campaign.find_or_create_by!(name: "Test", slug: "test")
    user = User.create!(name: "bar", email: "bar@bar")
    subscriber = Subscriber.create!(name: "foo", email: "foo@foo")

    ########################################################
    # Here we're calling it as TestDripper.subscribe
    # rather than campaign.subscribe
    TestDripper.subscribe(subscriber, user: user)
    ########################################################
    assert user.before_drip_run_counter.to_i == 0
    TestDripper.perform!
    user.reload
    assert user.before_drip_run_counter == 1

    sleep 1.seconds
    TestDripper.perform!
    user.reload
    assert user.before_drip_run_counter == 2
  end
end

output when running under sqlite3

ubuntu-22-04% bin/rails test
Running 2 tests in a single process (parallelization threshold is 50)
Run options: --seed 64571

# Running:

Calling process_unsubscribes...
Running first_reminder
Calling process_unsubscribes...
Running second_reminder
.Calling process_unsubscribes...
Running first_reminder
Calling process_unsubscribes...
Running second_reminder
.

Finished in 2.134845s, 0.9368 runs/s, 3.2789 assertions/s.
2 runs, 7 assertions, 0 failures, 0 errors, 0 skips

test output when running under mysql

ubuntu-22-04% bin/rails test
Running 2 tests in a single process (parallelization threshold is 50)
Run options: --seed 58143

# Running:

Calling process_unsubscribes...
Running first_reminder
Calling process_unsubscribes...
Running second_reminder
.F

Failure:
CaffeinateTest#test_foo [/home/erwin/Dev/os.cash/repro/test/integration/caffeinate_test.rb:14]:
Expected false to be truthy.


rails test test/integration/caffeinate_test.rb:4



Finished in 1.112693s, 1.7974 runs/s, 5.3923 assertions/s.
2 runs, 6 assertions, 1 failures, 0 errors, 0 skips

Hopefully you made it this far... That's an awful lot to digest. It's been quite a challenge trying to trace exactly what is happening. Hopefully you've got some ideas on how we can patch caffeinate to get these test to pass, or if I'm just misunderstanding something basic and using caffeinate incorrectly.

Thank you.

[jon-sully]

Wow, you've put a ton of work into this issue before posting, and we super appreciate that. Than you for all the info!

You've actually stumbled upon something I patched in my company's app before I became a contributor to this project directly and I forgot to ever bring up. That's a bummer 🙁. While my usage of Caffeinate on the 'application' side of our application is fine (we only ever call perform! in background jobs in a way that causes no problems), I discovered this issue in the testing side of our app. The campaign value itself is memoized. This does cause issues in line with what you've described, I think. Here's what I did to patch our testing suite:

  config.before(:each) do
    # NOTE: Caffeinate maintains a couple of class-variables under the hood
    # that don't get reset between specs (while the db records they cache do
    # get truncated). This resets the appropriate class-variables between specs

    # NOTE: Caffeinate.dripper_collection gives us all the drippers in the project
    Caffeinate.dripper_collection.instance_variable_get(:@registry).values.each do |drppr|
      drppr.safe_constantize.class_eval { @caffeinate_campaign = nil }
    end
  end

🤔

[erwin]

Thank you!

That fixed it.

  setup do
    Caffeinate.dripper_collection.instance_variable_get(:@registry).values.each do |drppr|
      drppr.safe_constantize.class_eval { @caffeinate_campaign = nil }
    end
  end

Updated working source of caffeinate_test.rb

require "test_helper"

class CaffeinateTest < ActionDispatch::IntegrationTest
  # See:  https://github.com/joshmn/caffeinate/issues/39
  # NOTE: Caffeinate maintains a couple of class-variables under the hood
  # that don't get reset between specs (while the db records they cache do
  # get truncated). This resets the appropriate class-variables between specs

  # NOTE: Caffeinate.dripper_collection gives us all the drippers in the project
  setup do
    Caffeinate.dripper_collection.instance_variable_get(:@registry).values.each do |drppr|
      drppr.safe_constantize.class_eval { @caffeinate_campaign = nil }
    end
  end

  test "foo" do
    campaign = Caffeinate::Campaign.find_or_create_by!(name: "Test", slug: "test")
    user = User.create!(name: "foo", email: "foo@foo")
    subscriber = Subscriber.create!(name: "bar", email: "bar@bar")
    assert Caffeinate::CampaignSubscription.count == 0

    campaign.subscribe(subscriber, user: user)
    assert user.before_drip_run_counter.to_i == 0
    TestDripper.perform!
    user.reload
    assert user.before_drip_run_counter == 1

    sleep 1.seconds
    TestDripper.perform!
    user.reload
    assert user.before_drip_run_counter == 2
  end

  test "foo-bar" do
    campaign = Caffeinate::Campaign.find_or_create_by!(name: "Test", slug: "test")
    user = User.create!(name: "bar", email: "bar@bar")
    subscriber = Subscriber.create!(name: "foo", email: "foo@foo")

    ########################################################
    # Here we're calling it as TestDripper.subscribe
    # rather than campaign.subscribe
    TestDripper.subscribe(subscriber, user: user)
    ########################################################
    assert user.before_drip_run_counter.to_i == 0
    TestDripper.perform!
    user.reload
    assert user.before_drip_run_counter == 1

    sleep 1.seconds
    TestDripper.perform!
    user.reload
    assert user.before_drip_run_counter == 2
  end
end

[joshmn]

@jon-sully thank you!

@erwin the campaigns are indeed memoized. I have actually shot myself in the foot with this before too 😬

@jon-sully what do you think about Caffeinate.test_mode! or something? I'll make a push to readme at some point with this as a disclaimer because it is, in fact, annoying and surprising (in test).

[jon-sully]

Yeah I think having a small macro like that and an explanation in the readme is a good way to go. That's pretty close to how Sidekiq does it, which I think is good

[joshmn]

Added a convenience method called Caffeinate.dripper_collection.clear_cache! in 2.5 that handles this. Closing, and thank you again!