feat: remove stale ONLINE_PRESENCE contact keys in redis (#9558)

50% of Redis memory size comes from ONLINE_PRESENCE keys. This PR adds a
periodic job to remove stale keys from all accounts.

app/jobs/internal/process_stale_redis_keys_job.rb

@@ -0,0 +1,11 @@
+# housekeeping
+# remove contact inboxes that does not have any conversations
+# and are older than 3 months
+
+class Internal::ProcessStaleRedisKeysJob < ApplicationJob
+  queue_as :low
+
+  def perform(account)
+    Internal::RemoveStaleRedisKeysService.new(account_id: account.id).perform
+  end
+end

app/jobs/internal/remove_stale_redis_keys_job.rb

@@ -0,0 +1,14 @@
+# housekeeping
+# ensure stale ONLINE PRESENCE KEYS for contacts are removed periodically
+# should result in 50% redis mem size reduction
+
+class Internal::RemoveStaleRedisKeysJob < ApplicationJob
+  queue_as :scheduled_jobs
+
+  def perform
+    Account.find_each do |account|
+      Rails.logger.info "Enqueuing ProcessStaleRedisKeysJob for account #{account.id}"
+      Internal::ProcessStaleRedisKeysJob.perform_later(account)
+    end
+  end
+end

app/services/internal/remove_stale_redis_keys_service.rb

@@ -0,0 +1,10 @@
+class Internal::RemoveStaleRedisKeysService
+  pattr_initialize [:account_id!]
+
+  def perform(account_id)
+    range_start = (Time.zone.now - PRESENCE_DURATION).to_i
+    # exclusive minimum score is specified by prefixing (
+    # we are clearing old records because this could clogg up the sorted set
+    ::Redis::Alfred.zremrangebyscore(presence_key(account_id, 'Contact'), '-inf', "(#{range_start}")
+  end
+end

config/schedule.yml

@@ -26,3 +26,10 @@ remove_stale_contact_inboxes_job.rb:
   cron: '30 22 * * *'
   class: 'Internal::RemoveStaleContactInboxesJob'
   queue: scheduled_jobs
+
+# executed daily at 2230 UTC
+# which is our lowest traffic time
+remove_stale_redis_keys_job.rb:
+  cron: '30 22 * * *'
+  class: 'Internal::RemoveStaleRedisKeysJob'
+  queue: scheduled_jobs