Fixes #4141 - background_services will stop immediately after starting

app/jobs/application_job.rb

@@ -5,6 +5,8 @@ class ApplicationJob < ActiveJob::Base
   include ApplicationJob::HasQueuingPriority
   include ApplicationJob::HasCustomLogging
 
+  discard_on HasActiveJobLock::LockKeyNotGeneratable
+
   ActiveJob::LogSubscriber.detach_from :active_job
 
   # See config/initializers/delayed_jobs_timeout_per_job.rb for details.

app/jobs/concerns/has_active_job_lock.rb

@@ -1,6 +1,8 @@
 # Copyright (C) 2012-2022 Zammad Foundation, https://zammad-foundation.org/
 
 module HasActiveJobLock
+  class LockKeyNotGeneratable < StandardError; end
+
   extend ActiveSupport::Concern
 
   included do
@@ -9,6 +11,9 @@ module HasActiveJobLock
     end
 
     around_perform do |job, block|
+      # do not perform job if lock key cannot be generated anymore
+      raise LockKeyNotGeneratable if job.safe_lock_key.nil?
+
       job.mark_active_job_lock_as_started
 
       block.call
@@ -40,6 +45,16 @@ module HasActiveJobLock
     self.class.name
   end
 
+  # Caches lock key for the duration of the job'
+  # Silences errors thrown when generating lock key
+  #
+  # return [String]
+  def safe_lock_key
+    @safe_lock_key ||= lock_key
+  rescue
+    nil
+  end
+
   def mark_active_job_lock_as_started
     release_active_job_lock_cache
 
@@ -56,28 +71,33 @@ module HasActiveJobLock
   def ensure_active_job_lock_for_enqueue!
     release_active_job_lock_cache
 
+    throw :abort if safe_lock_key.nil?
+
     in_active_job_lock_transaction do
       return if active_job_lock_for_enqueue!.present?
 
       ActiveJobLock.create!(
-        lock_key:      lock_key,
+        lock_key:      safe_lock_key,
         active_job_id: job_id,
       )
     end
   end
 
   def release_active_job_lock!
+    # nothing to release if lock key cannot be generated anymore
+    return if safe_lock_key.nil?
+
     # only delete lock if the current job is the one holding the lock
     # perform_now jobs or perform_later jobs for which follow-up jobs were enqueued
     # don't need to remove any locks
-    lock = ActiveJobLock.lock.find_by(lock_key: lock_key, active_job_id: job_id)
+    lock = ActiveJobLock.lock.find_by(lock_key: safe_lock_key, active_job_id: job_id)
 
     if !lock
-      logger.debug { "Found no ActiveJobLock for #{self.class.name} (Job ID: #{job_id}) with key '#{lock_key}'." }
+      logger.debug { "Found no ActiveJobLock for #{self.class.name} (Job ID: #{job_id}) with key '#{safe_lock_key}'." }
       return
     end
 
-    logger.debug { "Deleting ActiveJobLock for #{self.class.name} (Job ID: #{job_id}) with key '#{lock_key}'." }
+    logger.debug { "Deleting ActiveJobLock for #{self.class.name} (Job ID: #{job_id}) with key '#{safe_lock_key}'." }
     lock.destroy!
   end
 
@@ -114,7 +134,7 @@ module HasActiveJobLock
   end
 
   def active_job_lock
-    @active_job_lock ||= ActiveJobLock.lock.find_by(lock_key: lock_key)
+    @active_job_lock ||= ActiveJobLock.lock.find_by(lock_key: safe_lock_key)
   end
 
   def release_active_job_lock_cache

spec/jobs/concerns/has_active_job_lock_spec.rb

@@ -165,7 +165,7 @@ RSpec.describe HasActiveJobLock, type: :job do
 
   include_examples 'handle locking of jobs'
 
-  context 'custom lock key' do
+  context 'when has custom lock key' do
 
     let(:job_class) do
       Class.new(super()) do
@@ -178,4 +178,48 @@ RSpec.describe HasActiveJobLock, type: :job do
 
     include_examples 'handle locking of jobs'
   end
+
+  context 'when has invalid custom lock key' do
+
+    let(:job_class) do
+      Class.new(super()) do
+
+        def lock_key
+          raise 'Cannot generate lock key anymore'
+        end
+      end
+    end
+
+    it 'does not allow enqueueing of perform_later jobs' do
+      expect { job_class.perform_later }.not_to have_enqueued_job(job_class)
+    end
+
+    it 'does not allow execution of perform_now jobs' do
+      expect { job_class.perform_now }.not_to change(job_class, :perform_counter)
+    end
+  end
+
+  # https://github.com/zammad/zammad/issues/4141
+  context 'when key becomes invalid after enqueueing' do
+    let(:job_class) do
+      Class.new(super()) do
+        cattr_accessor :allow_lock_key, default: true
+
+        def lock_key
+          raise 'Cannot generate lock key anymore' if !allow_lock_key
+
+          'lock key'
+        end
+      end
+    end
+
+    it 'safely handles error in generating lock key', performs_jobs: true do
+      job_class.perform_later
+
+      job_class.allow_lock_key = false
+
+      expect { perform_enqueued_jobs(only: job_class) }
+        .not_to raise_error
+    end
+  end
 end