Class: WithAdvisoryLock::PostgreSQL

Inherits:
Base
  • Object
show all
Defined in:
lib/with_advisory_lock/postgresql.rb

Instance Attribute Summary

Attributes inherited from Base

#connection, #lock_name, #timeout_seconds

Instance Method Summary collapse

Methods inherited from Base

#already_locked?, #initialize, lock_stack, #lock_str, #stable_hashcode, #unique_column_name, #with_advisory_lock_if_needed, #yield_with_lock, #yield_with_lock_and_timeout

Constructor Details

This class inherits a constructor from WithAdvisoryLock::Base

Instance Method Details

#execute_successful?(pg_function) ⇒ Boolean

Returns:

  • (Boolean) 


12
13
14
15
16
17
 
# File 'lib/with_advisory_lock/postgresql.rb', line 12

def execute_successful?(pg_function)
  sql = "SELECT #{pg_function}(#{lock_keys.join(',')}) AS #{unique_column_name}"
  result = connection.select_value(sql)
  # MRI returns 't', jruby returns true. YAY!
  (result == 't' || result == true)
end

#lock_keys ⇒ Object

PostgreSQL wants 2 32bit integers as the lock key.



20
21
22
23
24
25
26
27
 
# File 'lib/with_advisory_lock/postgresql.rb', line 20

def lock_keys
  @lock_keys ||= begin
    [stable_hashcode(lock_name), ENV['WITH_ADVISORY_LOCK_PREFIX']].map do |ea|
      # pg advisory args must be 31 bit ints
      ea.to_i & 0x7fffffff
    end
  end
end

#release_lock ⇒ Object 



8
9
10
 
# File 'lib/with_advisory_lock/postgresql.rb', line 8

def release_lock
  execute_successful?('pg_advisory_unlock')
end

#try_lock ⇒ Object

See www.postgresql.org/docs/9.1/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS



4
5
6
 
# File 'lib/with_advisory_lock/postgresql.rb', line 4

def try_lock
  execute_successful?('pg_try_advisory_lock')
end