Class: Delayed::Job

Inherits:
ActiveRecord::Base show all
Includes:
Backend::Base
Defined in:
app/models/delayed/job.rb

Constant Summary collapse

REENQUEUE_BUFFER = 
30.seconds

Constants included from Backend::Base

Backend::Base::ParseObjectFromYaml

Instance Attribute Summary

Attributes included from Backend::Base

#error

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Backend::Base

#destroy_failed_jobs?, #fail!, #failed?, #hook, included, #invoke_job, #max_attempts, #max_run_time, #name, #payload_object, #payload_object=, #priority, #priority=, #reschedule_at, #unlock

Methods inherited from ActiveRecord::Base

#to_yaml_properties, yaml_new

Class Method Details

.claimable_clause(as_of = db_time_now) ⇒ Object 



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# File 'app/models/delayed/job.rb', line 55

def self.claimable_clause(as_of = db_time_now)
  arel_table[:locked_at].eq(nil).or arel_table[:locked_at].lt(as_of - lock_timeout)
end

.claimed_clause(as_of = db_time_now) ⇒ Object 



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# File 'app/models/delayed/job.rb', line 51

def self.claimed_clause(as_of = db_time_now)
  arel_table[:locked_at].gteq(as_of - lock_timeout)
end

.clear_locks!(worker) ⇒ Object

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



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# File 'app/models/delayed/job.rb', line 75

def self.clear_locks!(worker)
  claimed_by(worker).update_all(locked_by: nil, locked_at: nil)
end

.connection_config ⇒ Object 



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# File 'app/models/delayed/job.rb', line 231

def self.connection_config
  connection_db_config.configuration_hash
end

.database_adapter_name ⇒ Object 



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# File 'app/models/delayed/job.rb', line 226

def self.database_adapter_name
  connection_config[:adapter]
end

.database_name ⇒ Object 



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# File 'app/models/delayed/job.rb', line 222

def self.database_name
  connection_config[:database]
end

.db_time_now ⇒ Object

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.



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# File 'app/models/delayed/job.rb', line 192

def self.db_time_now
  if Time.zone
    Time.zone.now
  elsif default_timezone == :utc
    Time.now.utc
  else
    Time.current
  end
end

.default_timezone ⇒ Object 



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# File 'app/models/delayed/job.rb', line 203

def self.default_timezone
  ActiveRecord.default_timezone
end

.erroring_clause ⇒ Object 



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# File 'app/models/delayed/job.rb', line 39

def self.erroring_clause
  arel_table[:attempts].gt(0)
end

.future_clause(as_of = db_time_now) ⇒ Object 



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# File 'app/models/delayed/job.rb', line 43

def self.future_clause(as_of = db_time_now)
  arel_table[:run_at].gt(as_of)
end

.lock_timeout ⇒ Object 



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# File 'app/models/delayed/job.rb', line 70

def self.lock_timeout
  Worker.max_run_time + REENQUEUE_BUFFER
end

.pending_clause(as_of = db_time_now) ⇒ Object 



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# File 'app/models/delayed/job.rb', line 47

def self.pending_clause(as_of = db_time_now)
  arel_table[:run_at].lteq(as_of)
end

.reserve(worker, as_of = db_time_now) ⇒ Object 



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# File 'app/models/delayed/job.rb', line 79

def self.reserve(worker, as_of = db_time_now)
  ActiveSupport::Notifications.instrument('delayed.worker.reserve_jobs', worker_tags(worker)) do
    reserve_with_scope(claimable_by(worker, as_of), worker, as_of)
  end
end

.reserve_with_scope(ready_scope, worker, now) ⇒ Object 



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# File 'app/models/delayed/job.rb', line 85

def self.reserve_with_scope(ready_scope, worker, now)
  case connection.adapter_name
    when "PostgreSQL", "PostGIS"
      reserve_with_scope_using_optimized_postgres(ready_scope, worker, now)
    when "MySQL", "Mysql2"
      reserve_with_scope_using_optimized_mysql(ready_scope, worker, now)
    when "MSSQL", "Teradata"
      reserve_with_scope_using_optimized_mssql(ready_scope, worker, now)
    # Fallback for unknown / other DBMS
    else
      reserve_with_scope_using_default_sql(ready_scope, worker, now)
  end
end

.reserve_with_scope_using_default_sql(ready_scope, worker, now) ⇒ Object 



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# File 'app/models/delayed/job.rb', line 99

def self.reserve_with_scope_using_default_sql(ready_scope, worker, now)
  # This is our old fashion, tried and true, but possibly slower lookup
  # Instead of reading the entire job record for our detect loop, we select only the id,
  # and only read the full job record after we've successfully locked the job.
  # This can have a noticable impact on large read_ahead configurations and large payload jobs.
  attrs = { locked_at: now, locked_by: worker.name }

  jobs = []
  ready_scope.limit(worker.read_ahead).select(:id).each do |job|
    break if jobs.count >= worker.max_claims
    next unless ready_scope.where(id: job.id).update_all(attrs) == 1

    jobs << job.reload
  end

  jobs
end

.reserve_with_scope_using_optimized_mssql(ready_scope, worker, now) ⇒ Object 



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# File 'app/models/delayed/job.rb', line 174

def self.reserve_with_scope_using_optimized_mssql(ready_scope, worker, now)
  # 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 = connection.quote_table_name(table_name)
  sql = "UPDATE #{quoted_table_name} SET locked_at = ?, locked_by = ? WHERE id IN (#{subquery_sql})"
  count = connection.execute(sanitize_sql([sql, now, worker.name]))
  return [] if count.zero?

  # MSSQL JDBC doesn't support OUTPUT INSERTED.* for returning a result set, so query locked row
  where(locked_at: now, locked_by: worker.name, failed_at: nil)
end

.reserve_with_scope_using_optimized_mysql(ready_scope, worker, now) ⇒ Object 



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# File 'app/models/delayed/job.rb', line 138

def self.reserve_with_scope_using_optimized_mysql(ready_scope, worker, now)
  # Removing the millisecond precision from now(time object)
  # MySQL 5.6.4 onwards millisecond precision exists, but the
  # datetime object created doesn't have precision, so discarded
  # while updating. But during the where clause, for mysql(>=5.6.4),
  # it queries with precision as well. So removing the precision
  now = now.change(usec: 0)
  # Despite MySQL's support of UPDATE...LIMIT, it has an optimizer bug
  # that results in filesorts rather than index scans, which is very
  # expensive with a large number of jobs in the table:
  # http://bugs.mysql.com/bug.php?id=74049
  # The PostgreSQL and MSSQL reserve strategies, while valid syntax in
  # MySQL, result in deadlocks so we use a SELECT then UPDATE strategy
  # that is more likely to false-negative when attempting to reserve
  # jobs in parallel but doesn't rely on subselects or transactions.

  # Also, we are fetching multiple candidate_jobs at a time to try to
  # avoid the situation where multiple workers try to grab the same
  # job at the same time. That previously had caused poor performance
  # since ready_scope.where(id: job.id) would return nothing even
  # though there was a large number of jobs on the queue.
  attrs = { locked_at: now, locked_by: worker.name }

  jobs = []
  ready_scope.limit(worker.read_ahead).each do |job|
    break if jobs.count >= worker.max_claims
    next unless ready_scope.where(id: job.id).update_all(attrs) == 1

    job.assign_attributes(attrs)
    job.send(:changes_applied)
    jobs << job
  end

  jobs
end

.reserve_with_scope_using_optimized_postgres(ready_scope, worker, now) ⇒ Object

rubocop:disable Metrics/AbcSize



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# File 'app/models/delayed/job.rb', line 117

def self.reserve_with_scope_using_optimized_postgres(ready_scope, worker, now) # rubocop:disable Metrics/AbcSize
  # 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
  table = connection.quote_table_name(table_name)

  # Rather than relying on a primary key, we use "WHERE ctid =", resulting in a fast 'Tid Scan'.
  if worker.max_claims > 1
    subquery = ready_scope.limit(worker.max_claims).lock("FOR UPDATE SKIP LOCKED").select("ctid").to_sql
    sql = "UPDATE #{table} SET locked_at = ?, locked_by = ? WHERE ctid = ANY (ARRAY (#{subquery})) RETURNING *"
  else
    subquery = ready_scope.limit(1).lock("FOR UPDATE SKIP LOCKED").select("ctid").to_sql
    sql = "UPDATE #{table} SET locked_at = ?, locked_by = ? WHERE ctid = (#{subquery}) RETURNING *"
  end

  find_by_sql([sql, now, worker.name]).sort_by(&:priority)
end

.set_delayed_job_table_name ⇒ Object 



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# File 'app/models/delayed/job.rb', line 63

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

.worker_tags(worker) ⇒ Object 



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# File 'app/models/delayed/job.rb', line 208

def self.worker_tags(worker)
  {
    min_priority: worker.min_priority,
    max_priority: worker.max_priority,
    max_claims: worker.max_claims,
    read_ahead: worker.read_ahead,
    queues: worker.queues,
    table: table_name,
    database: database_name,
    database_adapter: database_adapter_name,
    worker: worker,
  }
end

Instance Method Details

#age ⇒ Object 



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# File 'app/models/delayed/job.rb', line 265

def age
  [(locked_at || self.class.db_time_now) - run_at, 0].max
end

#age_alert? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'app/models/delayed/job.rb', line 273

def age_alert?
  alert_age&.<= age
end

#alert_age ⇒ Object 



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# File 'app/models/delayed/job.rb', line 241

def alert_age
  if payload_object.respond_to?(:alert_age)
    payload_object.alert_age
  else
    priority.alert_age
  end
end

#alert_attempts ⇒ Object 



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# File 'app/models/delayed/job.rb', line 257

def alert_attempts
  if payload_object.respond_to?(:alert_attempts)
    payload_object.alert_attempts
  else
    priority.alert_attempts
  end
end

#alert_run_time ⇒ Object 



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# File 'app/models/delayed/job.rb', line 249

def alert_run_time
  if payload_object.respond_to?(:alert_run_time)
    payload_object.alert_run_time
  else
    priority.alert_run_time
  end
end

#attempts_alert? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'app/models/delayed/job.rb', line 281

def attempts_alert?
  alert_attempts&.<= attempts
end

#reload(*args) ⇒ Object 



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# File 'app/models/delayed/job.rb', line 236

def reload(*args)
  reset
  super
end

#run_time ⇒ Object 



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# File 'app/models/delayed/job.rb', line 269

def run_time
  self.class.db_time_now - locked_at if locked_at
end

#run_time_alert? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'app/models/delayed/job.rb', line 277

def run_time_alert?
  alert_run_time&.<= run_time if run_time # locked_at may be `nil` if `delay_jobs` is false
end