14878: Add comment.

[arvados.git] / services / api / lib / update_priority.rb

diff --git a/services/api/lib/update_priority.rb b/services/api/lib/update_priority.rb
index 21cd74bae67d3cbf94257284aedf05ab20aaad57..c688ac008b44b21944e86b36cdb3abbb15273e12 100644 (file)
--- a/services/api/lib/update_priority.rb
+++ b/services/api/lib/update_priority.rb
@@ -12,14 +12,19 @@ module UpdatePriority
   #
   # If container priority=0 but there are committed container requests
   # for it with priority>0, update priority.
-  def self.update_priority
+  #
+  # Normally, update_priority is a no-op if another thread/process is
+  # already updating. Test cases that need to check priorities after
+  # updating can force a (possibly overlapping) update in the current
+  # thread/transaction by setting the "nolock" flag. See #14878.
+  def self.update_priority(nolock: false)
     if !File.owned?(Rails.root.join('tmp'))
       Rails.logger.warn("UpdatePriority: not owner of #{Rails.root}/tmp, skipping")
       return
     end
     lockfile = Rails.root.join('tmp', 'update_priority.lock')
     File.open(lockfile, File::RDWR|File::CREAT, 0600) do |f|
-      return unless f.flock(File::LOCK_NB|File::LOCK_EX)
+      return unless nolock || f.flock(File::LOCK_NB|File::LOCK_EX)
 
       # priority>0 but should be 0:
       ActiveRecord::Base.connection.