Class: ActiveRecord::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/rails_atomic_increment.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.optimize_table ⇒ Object

this is for database table maintenance - May only work on MySQL? Vacuum for Postgres



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# File 'lib/rails_atomic_increment.rb', line 40

def self.optimize_table
  connection.execute("OPTIMIZE TABLE #{quoted_table_name}")
end

Instance Method Details

#atomic_decrement!(attribute, by = 1, reload = false) ⇒ Object 



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# File 'lib/rails_atomic_increment.rb', line 9

def atomic_decrement!(attribute, by = 1, reload = false)
  by = -by #invert the sign so we're subtracting the passed in value from the current value
  self.update_counters!({attribute => by}, reload)
end

#atomic_increment!(attribute, by = 1, reload = false) ⇒ Object

These methods are to update counters atomically so we don’t have any issues with counters being off because of concurrent increment or decriment requests



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# File 'lib/rails_atomic_increment.rb', line 5

def atomic_increment!(attribute, by = 1, reload = false)
  self.update_counters!({attribute => by}, reload)
end

#decrement_counters!(counters, reload = false) ⇒ Object

this expects an array of counter attributes to update and turns it into a hash to pass to update_counters



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# File 'lib/rails_atomic_increment.rb', line 20

def decrement_counters!(counters, reload = false)
  self.update_counters!(counters.inject({}) {|h,c| h.merge(c => -1)}, reload)
end

#increment_counters!(counters, reload = false) ⇒ Object

this expects an array of counter attributes to update and turns it into a hash to pass to update_counters



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# File 'lib/rails_atomic_increment.rb', line 15

def increment_counters!(counters, reload = false)
  self.update_counters!(counters.inject({}) {|h,c| h.merge(c => 1)}, reload)
end

#update_counters!(counters, reload = false) ⇒ Object 



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# File 'lib/rails_atomic_increment.rb', line 24

def update_counters!(counters, reload = false)
  counters.each do |attribute, value|
    raise "attribute '#{attribute}' can NOT be incremented because it was already changed and that change will be lost." if !new_record? && changed_attributes[attribute.to_s]
    self[attribute] ||= 0
    self[attribute] += value
    @changed_attributes.delete(attribute.to_s) unless new_record? # mark this column as unchanged so it won't get updated in the DB if a save is performed on the object!
  end
  if new_record?
    self.save
  else
    self.class.update_counters(self.id, counters)
  end
  self.reload if reload # if we care about the new numbers in the db after the update
end