Refector StatusHistoryRescalerJob transactions to prevent deadlocks

The StatusHistoryRescalerJob was wrapping multiple cleanup calls into a
single large database transaction. This held locks
on the status_histories table for the entire duration of the job.

Author: rubhanazeem

src/api/app/jobs/status_history_rescaler_job.rb

@@ -4,20 +4,21 @@ class StatusHistoryRescalerJob < ApplicationJob
   # this is called from a delayed job triggered by clockwork
   def perform
     maxtime = StatusHistory.maximum(:time)
-    StatusHistory.where(time: ...(maxtime - (365 * 24 * 3600))).delete_all if maxtime
+    StatusHistory.where(time: ...(maxtime - (365 * 24 * 3600))).find_in_batches do |batch|
+      ids = batch.map(&:id)
+      StatusHistory.where(id: ids).delete_all
+    end if maxtime
 
     keys = StatusHistory.distinct.pluck(:key)
     keys.each do |key|
-      StatusHistory.transaction do
-        # first rescale a month old
-        cleanup(key, 3600 * 12, 24 * 3600 * 30)
-        # now a week old
-        cleanup(key, 3600 * 6, 24 * 3600 * 7)
-        # now rescale yesterday
-        cleanup(key, 3600, 24 * 3600)
-        # 2h stuff
-        cleanup(key, 200, 3600 * 2)
-      end
+      # first rescale a month old
+      cleanup(key, 3600 * 12, 24 * 3600 * 30)
+      # now a week old
+      cleanup(key, 3600 * 6, 24 * 3600 * 7)
+      # now rescale yesterday
+      cleanup(key, 3600, 24 * 3600)
+      # 2h stuff
+      cleanup(key, 200, 3600 * 2)
     end
   end