ruby 43 lines · 7 steps

Debouncing search reindex jobs in Rails

A cache-backed lock collapses rapid record changes into a single delayed reindex job.

Explained by highlit
Rails Advanced debouncing background-jobs caching idempotency atomic-locks
1class SearchIndexReconciler
2 DEBOUNCE_WINDOW = 5.seconds
3 
4 def self.schedule(record)
5 new(record).schedule
6 end
7 
8 def initialize(record)
9 @record = record
10 @key = "reconcile:#{record.class.name.underscore}:#{record.id}"
11 end
12 
13 def schedule
14 return if debounced?
15 
16 ReconcileSearchIndexJob
17 .set(wait: DEBOUNCE_WINDOW)
18 .perform_later(@record.class.name, @record.id)
19 
20 mark_scheduled
21 end
22 
23 private
24 
25 def debounced?
26 !Rails.cache.write(@key, true, unless_exist: true, expires_in: DEBOUNCE_WINDOW)
27 end
28 
29 def mark_scheduled
30 Rails.logger.info("[#{self.class}] enqueued reconciliation for #{@key}")
31 end
32end
33 
34class ReconcileSearchIndexJob < ApplicationJob
35 queue_as :indexing
36 discard_on ActiveRecord::RecordNotFound
37 
38 def perform(class_name, id)
39 record = class_name.constantize.find(id)
40 Rails.cache.delete("reconcile:#{class_name.underscore}:#{id}")
41 Search::Indexer.new(record).reindex!
42 end
43end
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1An atomic cache write with unless_exist gives you a distributed debounce lock for free.
  2. 2Deferring the job with a wait window lets bursts of changes settle into one reindex.
  3. 3Deleting the debounce key inside the job reopens the window so future edits get scheduled.

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