Implement job batches

README.md

@@ -324,6 +324,52 @@ class MyJob < ActiveJob::Base
 end
 ```
 
+### Grouping jobs into batches
+
+```ruby
+job       = MyJob.perform_later
+other_job = OtherJob.perform_later 
+
+batch = ActiveJob::Status::Batch.new([job, other_job])
+batch.status
+# "queued"
+```
+
+The batch status can be `queued`, `failed`, `completed` or `working`.
+
+1. The batch is considered `queued` if **all** of the jobs are `queued`
+2. The batch is considered `failed` if **one** of the jobs is `failed`
+3. The batch is considered `completed` if **all** of the jobs are `completed`
+4. The batch is considered `working` in all other circumstances
+
+### Callbacks
+
+You can implement callbacks, by listening to the completion of a batch with a
+simple ActiveJob job.
+
+```ruby
+# frozen_string_literal: true
+
+require 'activejob-status'
+
+class CallbacksJob < ApplicationJob
+  queue_as :real_time
+
+  def perform(*job_ids)
+    batch = ActiveJob::Status::Batch.new(job_ids)
+
+    case batch.status
+    when :queued, :working
+      MonitorAnalysisBatchJob.set(wait: 5.seconds).perform_later(*job_ids)
+    when :completed
+      # Completed callback
+    when :failed
+      # Failed callback
+    end
+  end
+end
+```
+
 ## ActiveJob::Status and exceptions
 
 Internally, ActiveJob::Status uses `ActiveSupport#rescue_from` to catch every `Exception` to apply the `failed` status

lib/activejob-status.rb

@@ -8,6 +8,7 @@
 require "activejob-status/status"
 require "activejob-status/progress"
 require "activejob-status/throttle"
+require "activejob-status/batch"
 
 module ActiveJob
   module Status

lib/activejob-status/batch.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module ActiveJob
+  module Status
+    class Batch
+      def initialize(jobs)
+        @jobs = jobs
+        @storage = ActiveJob::Status::Storage.new
+      end
+
+      def status
+        statuses = read.values.pluck(:status)
+
+        if statuses.include?(:failed)
+          :failed
+        elsif statuses.all?(:queued)
+          :queued
+        elsif statuses.all?(:completed)
+          :completed
+        else
+          :working
+        end
+      end
+
+      def read
+        @storage.read_multi(@jobs)
+      end
+      alias_method :to_h, :read
+    end
+  end
+end

lib/activejob-status/storage.rb

@@ -26,6 +26,12 @@ def read(job)
         store.read(key(job)) || {}
       end
 
+      def read_multi(jobs)
+        keys = jobs.map { |job| key(job) }
+        data = store.read_multi(*keys)
+        keys.index_with { |k| data.fetch(k, {}) }
+      end
+
       def write(job, message, force: false)
         @throttle.wrap(force: force) do
           store.write(key(job), message, expires_in: @expires_in)

spec/specs/active_job/status/batch_spec.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+require_relative "../../../spec_helper"
+require_relative "../../../jobs/test_jobs"
+
+RSpec.describe ActiveJob::Status::Batch do
+  describe "#status" do
+    it "returns queued when all jobs are queued" do
+      first_job = BaseJob.perform_later
+      second_job = BaseJob.perform_later
+      batch = described_class.new([first_job, second_job])
+
+      ActiveJob::Status.get(first_job).update(status: :queued)
+      ActiveJob::Status.get(second_job).update(status: :queued)
+
+      expect(batch.status).to eq(:queued)
+    end
+
+    it "returns failed when one job is failed" do
+      first_job = BaseJob.perform_later
+      second_job = BaseJob.perform_later
+      batch = described_class.new([first_job, second_job])
+
+      ActiveJob::Status.get(first_job).update(status: :failed)
+      ActiveJob::Status.get(second_job).update(status: :completed)
+
+      expect(batch.status).to eq(:failed)
+    end
+
+    it "returns completed when all jobs are completed" do
+      first_job = BaseJob.perform_later
+      second_job = BaseJob.perform_later
+      batch = described_class.new([first_job, second_job])
+
+      ActiveJob::Status.get(first_job).update(status: :completed)
+      ActiveJob::Status.get(second_job).update(status: :completed)
+
+      expect(batch.status).to eq(:completed)
+    end
+
+    it "returns working in other cases" do
+      first_job = BaseJob.perform_later
+      second_job = BaseJob.perform_later
+      batch = described_class.new([first_job, second_job])
+
+      ActiveJob::Status.get(first_job).update(status: :queued)
+      ActiveJob::Status.get(second_job).update(status: :working)
+
+      expect(batch.status).to eq(:working)
+    end
+  end
+end