Class: ActiveRecord::Turntable::Mixer

Inherits:
Object
  • Object
show all
Extended by:
ActiveSupport::Autoload
Defined in:
lib/active_record/turntable/mixer.rb,
lib/active_record/turntable/mixer/fader.rb,
lib/active_record/turntable/mixer/fader/specified_shard.rb,
lib/active_record/turntable/mixer/fader/insert_shards_merge_result.rb,
lib/active_record/turntable/mixer/fader/select_shards_merge_result.rb,
lib/active_record/turntable/mixer/fader/update_shards_merge_result.rb,
lib/active_record/turntable/mixer/fader/calculate_shards_sum_result.rb

Defined Under Namespace

Classes: Fader

Constant Summary collapse

NOT_USED_FOR_SHARDING_OPERATORS_REGEXP = 
/\A(NOT IN|IS|IS NOT|BETWEEN|LIKE|\!\=|<<|>>|<>|>\=|<=|[\*\+\-\/\%\|\&><])\z/

Instance Method Summary collapse

Constructor Details

#initialize(proxy) ⇒ Mixer

Returns a new instance of Mixer.



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# File 'lib/active_record/turntable/mixer.rb', line 16

def initialize(proxy)
  @proxy = proxy
end

Instance Method Details

#build_fader(method_name, query, *args, &block) ⇒ Object 



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# File 'lib/active_record/turntable/mixer.rb', line 20

def build_fader(method_name, query, *args, &block)
  method = method_name.to_s
  if @proxy.shard_fixed?
    return SpecifiedShard.new(@proxy,
                              { @proxy.fixed_shard => query },
                              method, query, *args, &block)
  end
  binds = (method == 'insert') ? args[4] : args[1]
  binded_query = bind_sql(query, binds)

  begin
    tree = SQLTree[binded_query]
  rescue Exception => err
    logger.warn { "[ActiveRecord::Turntable] Error on Parsing SQL: #{binded_query}, on_method: #{method_name}" }
    raise err
  end

  case tree
  when SQLTree::Node::SelectQuery
    build_select_fader(tree, method, query, *args, &block)
  when SQLTree::Node::UpdateQuery, SQLTree::Node::DeleteQuery
    build_update_fader(tree, method, query, *args, &block)
  when SQLTree::Node::InsertQuery
    build_insert_fader(tree, method, query, *args, &block)
  else
    # send to master shard
    Fader::SpecifiedShard.new(@proxy,
                       { @proxy.master => query },
                       method, query, *args, &block)
  end
rescue Exception => err
  logger.warn { "[ActiveRecord::Turntable] Error on Building Fader: #{binded_query}, on_method: #{method_name}, err: #{err}" }
  raise err
end

#find_shard_keys(tree, table_name, shard_key) ⇒ Object 



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# File 'lib/active_record/turntable/mixer.rb', line 55

def find_shard_keys(tree, table_name, shard_key)
  return [] unless tree.respond_to?(:operator)

  case tree.operator
  when "OR"
    lkeys = find_shard_keys(tree.lhs, table_name, shard_key)
    rkeys = find_shard_keys(tree.rhs, table_name, shard_key)
    if lkeys.present? and rkeys.present?
      lkeys + rkeys
    else
      []
    end
  when "AND"
    lkeys = find_shard_keys(tree.lhs, table_name, shard_key)
    rkeys = find_shard_keys(tree.rhs, table_name, shard_key)
    if lkeys.present? or rkeys.present?
      lkeys + rkeys
    else
      []
    end
  when "IN", "=", "=="
    field = tree.lhs.respond_to?(:table) ? tree.lhs : nil
    if tree.rhs.is_a?(SQLTree::Node::SubQuery)
      if field.try(:table) == table_name and field.name == shard_key
        find_shard_keys(tree.rhs.where, table_name, shard_key)
      else
        []
      end
    else
      values = Array(tree.rhs)
      if field.try(:table) == table_name and field.name == shard_key and
          !tree.rhs.is_a?(SQLTree::Node::SubQuery)
        values.map(&:value).compact
      else
        []
      end
    end
  when NOT_USED_FOR_SHARDING_OPERATORS_REGEXP
    []
  else
    raise ActiveRecord::Turntable::UnknownOperatorError,
      "[ActiveRecord::Turntable] Found Unknown SQL Operator:'#{tree.operator if tree.respond_to?(:operaor)}', Please report this bug."
  end
end