rails/activejob/test/cases/queuing_test.rb
Daniel Morton ee60ce5606 Communicate enqueue failures to callers of perform_later
There is presently no clean way of telling a caller of `perform_later`
the reason why a job failed to enqueue. When the job is enqueued
successfully, the job object itself is returned, but when the job can
not be enqueued, only `false` is returned. This does not allow callers
to distinguish between classes of failures.

One important class of failures is when the job backend experiences a
network partition when communicating with its underlying datastore. It
is entirely possible for that network partition to recover and as such,
code attempting to enqueue a job may wish to take action to reenqueue
that job after a brief delay. This is distinguished from the class of
failures where due a business rule defined in a callback in the
application, a job fails to enqueue and should not be retried.

This PR changes the following:

- Allows a block to be passed to the `perform_later` method. After the
  `enqueue` method is executed, but before the result is returned, the
  job will be yielded to the block. This allows the code invoking the
  `perform_later` method to inspect the job object, even in failure
  scenarios.

- Adds an exception `EnqueueError` which job adapters can raise if they
  detect a problem specific to their underlying implementation or
  infrastructure during the enqueue process.

- Adds two properties to the job base class: `successfully_enqueued` and
  `enqueue_error`. `enqueue_error` will be populated by the `enqueue`
  method if it rescues an `EnqueueError` raised by the job backend.
  `successfully_enqueued` will be true if the job is not rejected by
  callbacks and does not cause the job backend to raise an
  `EnqueueError` and will be `false` otherwise.

This will allow developers to do something like the following:

    MyJob.perform_later do |job|
      unless job.successfully_enqueued?
        if job.enqueue_error&.message == "Redis was unavailable"
          # invoke some code that will retry the job after a delay
        end
      end
    end
2021-02-05 16:32:43 -05:00

58 lines
1.6 KiB
Ruby

# frozen_string_literal: true
require "helper"
require "jobs/hello_job"
require "jobs/enqueue_error_job"
require "active_support/core_ext/numeric/time"
class QueuingTest < ActiveSupport::TestCase
setup do
JobBuffer.clear
end
test "run queued job" do
HelloJob.perform_later
assert_equal "David says hello", JobBuffer.last_value
end
test "run queued job with arguments" do
HelloJob.perform_later "Jamie"
assert_equal "Jamie says hello", JobBuffer.last_value
end
test "run queued job later" do
result = HelloJob.set(wait_until: 1.second.ago).perform_later "Jamie"
assert result
rescue NotImplementedError
skip
end
test "job returned by enqueue has the arguments available" do
job = HelloJob.perform_later "Jamie"
assert_equal [ "Jamie" ], job.arguments
end
test "job returned by perform_at has the timestamp available" do
job = HelloJob.set(wait_until: Time.utc(2014, 1, 1)).perform_later
assert_equal Time.utc(2014, 1, 1).to_f, job.scheduled_at
rescue NotImplementedError
skip
end
test "job is yielded to block after enqueue with successfully_enqueued property set" do
HelloJob.perform_later "John" do |job|
assert_equal "John says hello", JobBuffer.last_value
assert_equal [ "John" ], job.arguments
assert_equal true, job.successfully_enqueued?
assert_nil job.enqueue_error
end
end
test "when enqueuing raises an EnqueueError job is yielded to block with error set on job" do
EnqueueErrorJob.perform_later do |job|
assert_equal false, job.successfully_enqueued?
assert_equal ActiveJob::EnqueueError, job.enqueue_error.class
end
end
end