class Delayed::Backend::ActiveRecord::Job

A job object that is persisted to the database. Contains the work object as a YAML field.

Public Class Methods

after_fork() click to toggle source
# File lib/delayed/backend/active_record.rb, line 34
def self.after_fork
  ::ActiveRecord::Base.establish_connection
end
before_fork() click to toggle source
# File lib/delayed/backend/active_record.rb, line 30
def self.before_fork
  ::ActiveRecord::Base.clear_all_connections!
end
clear_locks!(worker_name) click to toggle source

When a worker is exiting, make sure we don't have any locked jobs.

# File lib/delayed/backend/active_record.rb, line 39
def self.clear_locks!(worker_name)
  where(:locked_by => worker_name).update_all(:locked_by => nil, :locked_at => nil)
end
db_time_now() click to toggle source

Get the current time (GMT or local depending on DB) Note: This does not ping the DB to get the time, so all your clients must have syncronized clocks.

# File lib/delayed/backend/active_record.rb, line 94
def self.db_time_now
  if Time.zone
    Time.zone.now
  elsif ::ActiveRecord::Base.default_timezone == :utc
    Time.now.utc
  else
    Time.now
  end
end
ready_to_run(worker_name, max_run_time) click to toggle source
# File lib/delayed/backend/active_record.rb, line 26
def self.ready_to_run(worker_name, max_run_time)
  where('(run_at <= ? AND (locked_at IS NULL OR locked_at < ?) OR locked_by = ?) AND failed_at IS NULL', db_time_now, db_time_now - max_run_time, worker_name)
end
reserve(worker, max_run_time = Worker.max_run_time) click to toggle source
# File lib/delayed/backend/active_record.rb, line 43
def self.reserve(worker, max_run_time = Worker.max_run_time)
  # scope to filter to records that are "ready to run"
  ready_scope = self.ready_to_run(worker.name, max_run_time)

  # scope to filter to the single next eligible job
  ready_scope = ready_scope.where('priority >= ?', Worker.min_priority) if Worker.min_priority
  ready_scope = ready_scope.where('priority <= ?', Worker.max_priority) if Worker.max_priority
  ready_scope = ready_scope.where(:queue => Worker.queues) if Worker.queues.any?
  ready_scope = ready_scope.by_priority

  now = self.db_time_now

  # Optimizations for faster lookups on some common databases
  case self.connection.adapter_name
  when "PostgreSQL"
    # Custom SQL required for PostgreSQL because postgres does not support UPDATE...LIMIT
    # This locks the single record 'FOR UPDATE' in the subquery (http://www.postgresql.org/docs/9.0/static/sql-select.html#SQL-FOR-UPDATE-SHARE)
    # Note: active_record would attempt to generate UPDATE...LIMIT like sql for postgres if we use a .limit() filter, but it would not use
    # 'FOR UPDATE' and we would have many locking conflicts
    quoted_table_name = self.connection.quote_table_name(self.table_name)
    subquery_sql      = ready_scope.limit(1).lock(true).select('id').to_sql
    reserved          = self.find_by_sql(["UPDATE #{quoted_table_name} SET locked_at = ?, locked_by = ? WHERE id IN (#{subquery_sql}) RETURNING *", now, worker.name])
    reserved[0]
  when "MySQL", "Mysql2"
    # This works on MySQL and possibly some other DBs that support UPDATE...LIMIT. It uses separate queries to lock and return the job
    count = ready_scope.limit(1).update_all(:locked_at => now, :locked_by => worker.name)
    return nil if count == 0
    self.where(:locked_at => now, :locked_by => worker.name, :failed_at => nil).first
  when "MSSQL", "Teradata"
    # The MSSQL driver doesn't generate a limit clause when update_all is called directly
    subsubquery_sql = ready_scope.limit(1).to_sql
    # select("id") doesn't generate a subquery, so force a subquery
    subquery_sql = "SELECT id FROM (#{subsubquery_sql}) AS x"
    quoted_table_name = self.connection.quote_table_name(self.table_name)
    sql = ["UPDATE #{quoted_table_name} SET locked_at = ?, locked_by = ? WHERE id IN (#{subquery_sql})", now, worker.name]
    count = self.connection.execute(sanitize_sql(sql))
    return nil if count == 0
    # MSSQL JDBC doesn't support OUTPUT INSERTED.* for returning a result set, so query locked row
    self.where(:locked_at => now, :locked_by => worker.name, :failed_at => nil).first
  else
    # This is our old fashion, tried and true, but slower lookup
    ready_scope.limit(worker.read_ahead).detect do |job|
      count = ready_scope.where(:id => job.id).update_all(:locked_at => now, :locked_by => worker.name)
      count == 1 && job.reload
    end
  end
end
set_delayed_job_table_name() click to toggle source
# File lib/delayed/backend/active_record.rb, line 19
def self.set_delayed_job_table_name
  delayed_job_table_name = "#{::ActiveRecord::Base.table_name_prefix}delayed_jobs"
  self.table_name = delayed_job_table_name
end

Public Instance Methods

reload(*args) click to toggle source
Calls superclass method
# File lib/delayed/backend/active_record.rb, line 104
def reload(*args)
  reset
  super
end