1 files changed, 96 insertions, 0 deletions
diff --git a/app/workers/scheduler/accounts_statuses_cleanup_scheduler.rb b/app/workers/scheduler/accounts_statuses_cleanup_scheduler.rb
new file mode 100644
index 000000000..f42d4bca6
--- /dev/null
+++ b/app/workers/scheduler/accounts_statuses_cleanup_scheduler.rb
@@ -0,0 +1,96 @@
+# frozen_string_literal: true
+
+class Scheduler::AccountsStatusesCleanupScheduler
+  include Sidekiq::Worker
+
+  # This limit is mostly to be nice to the fediverse at large and not
+  # generate too much traffic.
+  # This also helps limiting the running time of the scheduler itself.
+  MAX_BUDGET         = 50
+
+  # This is an attempt to spread the load across instances, as various
+  # accounts are likely to have various followers.
+  PER_ACCOUNT_BUDGET = 5
+
+  # This is an attempt to limit the workload generated by status removal
+  # jobs to something the particular instance can handle.
+  PER_THREAD_BUDGET  = 5
+
+  # Those avoid loading an instance that is already under load
+  MAX_DEFAULT_SIZE    = 2
+  MAX_DEFAULT_LATENCY = 5
+  MAX_PUSH_SIZE       = 5
+  MAX_PUSH_LATENCY    = 10
+  # 'pull' queue has lower priority jobs, and it's unlikely that pushing
+  # deletes would cause much issues with this queue if it didn't cause issues
+  # with default and push. Yet, do not enqueue deletes if the instance is
+  # lagging behind too much.
+  MAX_PULL_SIZE       = 500
+  MAX_PULL_LATENCY    = 300
+
+  # This is less of an issue in general, but deleting old statuses is likely
+  # to cause delivery errors, and thus increase the number of jobs to be retried.
+  # This doesn't directly translate to load, but connection errors and a high
+  # number of dead instances may lead to this spiraling out of control if
+  # unchecked.
+  MAX_RETRY_SIZE = 50_000
+
+  sidekiq_options retry: 0, lock: :until_executed
+
+  def perform
+    return if under_load?
+
+    budget = compute_budget
+    first_policy_id = last_processed_id
+
+    loop do
+      num_processed_accounts = 0
+
+      scope = AccountStatusesCleanupPolicy.where(enabled: true)
+      scope.where(Account.arel_table[:id].gt(first_policy_id)) if first_policy_id.present?
+      scope.find_each(order: :asc) do |policy|
+        num_deleted = AccountStatusesCleanupService.new.call(policy, [budget, PER_ACCOUNT_BUDGET].min)
+        num_processed_accounts += 1 unless num_deleted.zero?
+        budget -= num_deleted
+        if budget.zero?
+          save_last_processed_id(policy.id)
+          break
+        end
+      end
+
+      # The idea here is to loop through all policies at least once until the budget is exhausted
+      # and start back after the last processed account otherwise
+      break if budget.zero? || (num_processed_accounts.zero? && first_policy_id.nil?)
+      first_policy_id = nil
+    end
+  end
+
+  def compute_budget
+    threads = Sidekiq::ProcessSet.new.filter { |x| x['queues'].include?('push') }.map { |x| x['concurrency'] }.sum
+    [PER_THREAD_BUDGET * threads, MAX_BUDGET].min
+  end
+
+  def under_load?
+    return true if Sidekiq::Stats.new.retry_size > MAX_RETRY_SIZE
+    queue_under_load?('default', MAX_DEFAULT_SIZE, MAX_DEFAULT_LATENCY) || queue_under_load?('push', MAX_PUSH_SIZE, MAX_PUSH_LATENCY) || queue_under_load?('pull', MAX_PULL_SIZE, MAX_PULL_LATENCY)
+  end
+
+  private
+
+  def queue_under_load?(name, max_size, max_latency)
+    queue = Sidekiq::Queue.new(name)
+    queue.size > max_size || queue.latency > max_latency
+  end
+
+  def last_processed_id
+    Redis.current.get('account_statuses_cleanup_scheduler:last_account_id')
+  end
+
+  def save_last_processed_id(id)
+    if id.nil?
+      Redis.current.del('account_statuses_cleanup_scheduler:last_account_id')
+    else
+      Redis.current.set('account_statuses_cleanup_scheduler:last_account_id', id, ex: 1.hour.seconds)
+    end
+  end
+end