Module: EmptyEye::ShardWrangler::ClassMethods

Defined in:
lib/empty_eye/shard_wrangler.rb

Instance Method Summary collapse

Instance Method Details

#cascade_delete_all(conditions) ⇒ Object

batch deletion when there are conditions kill indiscriminately otherwise



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# File 'lib/empty_eye/shard_wrangler.rb', line 173

def cascade_delete_all(conditions)
  mti_clear_identity_map
  affected = 0
  ids = []
  ids = conditions ? select(arel_table[primary_key.to_sym]).where(conditions).collect(&:id) : []
  transaction do
    begin
      batch = ids.pop(10000)
      shards.each do |shard|
        result = if conditions.nil?
          shard.klass.delete_all
        elsif shard.polymorphic_type
          shard.klass.delete_all(shard.foreign_key => batch, shard.polymorphic_type => shard.type_value)
        else
          shard.klass.delete_all(shard.foreign_key => batch)
        end
        affected = [affected, result].max
      end 
    end until ids.to_a.empty?
  end
  affected
end

#cascade_update_all(updates, conditions, options) ⇒ Object 



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# File 'lib/empty_eye/shard_wrangler.rb', line 196

def cascade_update_all(updates, conditions, options)
  mti_clear_identity_map
  affected = 0
  stringified_updates = updates.stringify_keys
  ids = conditions ? select(arel_table[primary_key.to_sym]).where(conditions).apply_finder_options(options.slice(:limit, :order)).collect(&:id) : []
  transaction do
    begin
      batch = ids.pop(10000)
      shards.each do |shard|
        cols = shards.delegate_map(shard.name, stringified_updates)
        next if cols.empty?
        result = if conditions.nil?
          shard.klass.update_all(cols)
        elsif shard.polymorphic_type
          shard.klass.update_all(cols, shard.foreign_key => batch, shard.polymorphic_type => shard.type_value)
        else
          shard.klass.update_all(cols, shard.foreign_key => batch)
        end
        affected = [affected, result].max
      end
    end until ids.to_a.empty?
  end
  affected
end

#compute_view_name ⇒ Object

we need a name for the view need to have a way to set this



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# File 'lib/empty_eye/shard_wrangler.rb', line 227

def compute_view_name
  if master_class.descends_from_active_record?
    master_class.send(:compute_table_name)
  else
    master_class.name.underscore.pluralize
  end
end

#create_reflection(macro, name, options, active_record) ⇒ Object

the wrangler uses special reflection; overriden here

Raises:



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# File 'lib/empty_eye/shard_wrangler.rb', line 110

def create_reflection(macro, name, options, active_record)
  raise(EmptyEye::NotYetSupported, "through associations are not yet spported") if options[:through]
  klass = options[:through] ? ShardThroughReflection : ShardAssociationReflection
  reflection = klass.new(macro, name, options, active_record)

  self.reflections = self.reflections.merge(name => reflection)
  reflection
end

#find_by_id(val) ⇒ Object

overriding find_by_id this is used to retrieve the wrangler instance for the master instance the type column is removed



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# File 'lib/empty_eye/shard_wrangler.rb', line 129

def find_by_id(val)
  query = columns_except_type
  query = query.where(arel_table[:id].eq(val))
  find_by_sql(query.to_sql).first
end

#has_one(name, options = {}) ⇒ Object

the wrangler uses a special association builder



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# File 'lib/empty_eye/shard_wrangler.rb', line 136

def has_one(name, options = {})
  Associations::Builder::ShardHasOne.build(self, name, options)
end

#master_class ⇒ Object

reflection on master class; this should never change



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# File 'lib/empty_eye/shard_wrangler.rb', line 141

def master_class
  @master_class
end

#master_class=(klass) ⇒ Object

the master_class value is set with this setter; should happen only once



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# File 'lib/empty_eye/shard_wrangler.rb', line 146

def master_class=(klass)
  @master_class = klass
end

#primary_shard ⇒ Object

the primary shard



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# File 'lib/empty_eye/shard_wrangler.rb', line 157

def primary_shard
  shards.primary
end

#reset_column_information ⇒ Object

overriding to reset the special instance variable



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# File 'lib/empty_eye/shard_wrangler.rb', line 151

def reset_column_information
  @columns_except_type = nil
  super
end

#shards ⇒ Object 



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# File 'lib/empty_eye/shard_wrangler.rb', line 221

def shards
  @shards ||= EmptyEye::ShardCollection.new(self)
end

#type_condition(table = arel_table) ⇒ Object

finder methods should use the master class’s type not the wrangler’s



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# File 'lib/empty_eye/shard_wrangler.rb', line 120

def type_condition(table = arel_table)
  sti_column = table[inheritance_column.to_sym]

  sti_column.eq(master_class.name)
end

#wrangle_shards(mti_ancestors) ⇒ Object

we know the associations and we know what they can do we will make a mti class accordingly here



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# File 'lib/empty_eye/shard_wrangler.rb', line 163

def wrangle_shards(mti_ancestors)
  mti_ancestors.each do |assoc|
    shards.create_with(assoc)
  end
  create_view
  master_class.reset_column_information
end