Demonstrating the Queue API

The Queue API provides a traditional FIFO (first-in-first-out) queue, but also provides the concepts of:

  • "Creating" a queued item, which means inserting it into a queue.
  • "Claiming" a queued item, which essentially means requesting the next item from the queue and holding a lock on that item for a specified period of time.
  • "Releasing" an item, which means giving up a claim but leaving the item in the queue.
  • "Deleting" an item, which means finally removing it from the queue.

This example demonstrates only basic queue functionality, and will use the default queue implementation, which is SystemQueue, managed using persistent database storage.

Further resources include the limited Queue operations documentation. More:

Batch vs Queue Presentation slides by John VanDyk

See also

Parent topics


modules/examples/queue_example/queue_example.module, line 7
Examples demonstrating the Backdrop Queue API.


Name Locationsort descending Description
queue_example_menu modules/examples/queue_example/queue_example.module Implements hook_menu().
queue_example_add_remove_form modules/examples/queue_example/queue_example.module Form generator for managing the queue.
queue_example_add_remove_form_insert modules/examples/queue_example/queue_example.module Submit function for the insert-into-queue button.
queue_example_show_queue modules/examples/queue_example/queue_example.module Submit function for the show-queue button.
queue_example_add_remove_form_claim modules/examples/queue_example/queue_example.module Submit function for the "claim" button.
queue_example_add_remove_form_delete modules/examples/queue_example/queue_example.module Submit function for "Claim and delete" button.
queue_example_add_remove_form_run_cron modules/examples/queue_example/queue_example.module Submit function for "run cron" button.
queue_example_add_remove_form_clear_queue modules/examples/queue_example/queue_example.module Submit handler for clearing/deleting the queue.
queue_example_retrieve_queue modules/examples/queue_example/queue_example.module Retrieves the queue from the database for display purposes only.
theme_queue_items modules/examples/queue_example/queue_example.module Themes the queue display.
queue_example_theme modules/examples/queue_example/queue_example.module Implements hook_theme().


Name Locationsort descending Description
QueueExampleTestCase modules/examples/queue_example/tests/queue_example.test Functional tests for the Queue Example module.