Quick tip: simple unique jobs on Solid Queue

I recently migrated from Sidekiq to Solid Queue on a personal project, and generally found the transition to be quite painless. However, at the time of writing, Solid Queue doesn’t support unique jobs, either natively or through a 3rd party gem. (Sidekiq has both, through the popular sidekiq-unique-jobs or via its Enterprise offering.)

The good news is that native support seems to be in progress, but in the meantime, it’s quite easy to roll your own unique job class using the around_enqueue callback and a simple query against Solid Queue’s Job table.

class UniqueJob < ApplicationJob
  around_enqueue do |job, block|
    # `.scheduled` scope == all unfinished jobs
    if SolidQueue::Job.scheduled.where(class_name: job.class.name).none?
      block.call # enqueue the job
    else
      Rails.logger.info("Skipping #{job.class.name} because it is already present")
      # If we don't invoke `block.call`, the job won't be enqueued
    end
  end

  def perform(...)
    # UniqueJob is an abstract class, we shouldn't enqueue it directly
    raise NotImplementedError
  end
end

Now any job that inherits from UniqueJob can only be enqueued if a job of that class is not already enqueued, running or scheduled:

class ExampleJob < UniqueJob
  def perform
    sleep 20
  end
end

If I try to enqueue the job twice, the second call will be skipped¹ with a log message:

> ExampleJob.perform_later
[ActiveJob]   SolidQueue::Job Exists? (2.3ms)  SELECT 1 AS one FROM "solid_queue_jobs" WHERE "solid_queue_jobs"."finished_at" IS NULL AND "solid_queue_jobs"."class_name" = $1 LIMIT $2  [["class_name", "ExampleJob"], ["LIMIT", 1]]
[ActiveJob]   TRANSACTION (0.2ms)  BEGIN
[ActiveJob]   SolidQueue::Job Create (1.7ms)  INSERT INTO "solid_queue_jobs" ("queue_name", "class_name", "arguments", "priority", "active_job_id", "scheduled_at", "finished_at", "concurrency_key", "created_at", "updated_at") VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10) RETURNING "id"  [["queue_name", "default"], ["class_name", "ExampleJob"], ["arguments", "{\"job_class\":\"ExampleJob\",\"job_id\":\"a0f861a9-43c2-4879-a7f2-71a51aa946c1\",\"provider_job_id\":null,\"queue_name\":\"default\",\"priority\":500,\"arguments\":[],\"executions\":0,\"exception_executions\":{},\"locale\":\"en\",\"timezone\":\"UTC\",\"enqueued_at\":\"2025-03-23T12:39:54.064482095Z\",\"scheduled_at\":\"2025-03-23T12:39:54.064000220Z\"}"], ["priority", 500], ["active_job_id", "a0f861a9-43c2-4879-a7f2-71a51aa946c1"], ["scheduled_at", "2025-03-23 12:39:54.064000"], ["finished_at", nil], ["concurrency_key", nil], ["created_at", "2025-03-23 12:39:54.068897"], ["updated_at", "2025-03-23 12:39:54.068897"]]
[ActiveJob]   TRANSACTION (0.1ms)  SAVEPOINT active_record_1
[ActiveJob]   SolidQueue::Job Load (1.1ms)  SELECT "solid_queue_jobs".* FROM "solid_queue_jobs" WHERE "solid_queue_jobs"."id" = $1 LIMIT $2  [["id", 234], ["LIMIT", 1]]
[ActiveJob]   SolidQueue::ReadyExecution Create (1.5ms)  INSERT INTO "solid_queue_ready_executions" ("job_id", "queue_name", "priority", "created_at") VALUES ($1, $2, $3, $4) RETURNING "id"  [["job_id", 234], ["queue_name", "default"], ["priority", 500], ["created_at", "2025-03-23 12:39:54.086915"]]
[ActiveJob]   TRANSACTION (0.1ms)  RELEASE SAVEPOINT active_record_1
[ActiveJob]   TRANSACTION (0.5ms)  COMMIT
[ActiveJob] Enqueued ExampleJob (Job ID: a0f861a9-43c2-4879-a7f2-71a51aa946c1) to SolidQueue(default)

> ExampleJob.perform_later
[ActiveJob]   SolidQueue::Job Exists? (0.3ms)  SELECT 1 AS one FROM "solid_queue_jobs" WHERE "solid_queue_jobs"."finished_at" IS NULL AND "solid_queue_jobs"."class_name" = $1 LIMIT $2  [["class_name", "ExampleJob"], ["LIMIT", 1]]
[ActiveJob] Skipping ExampleJob because it is already present
[ActiveJob] Enqueued ExampleJob (Job ID: 41e8ff4c-ec58-4821-a686-ca58740af2ca) to SolidQueue(default)
[ActiveJob] ↳ (apmovies):9:in `<main>'

This setup is basically equivalent to the sidekiq-unique-jobs configured with sidekiq_options lock: :until_executed, on_conflict: :log.