Module: Querrel::MapReduce

Included in:
Querreller
Defined in:
lib/querrel/map_reduce.rb

Instance Method Summary collapse

Instance Method Details

#map(scope, options = {}, &blk) ⇒ Object



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# File 'lib/querrel/map_reduce.rb', line 8

def map(scope, options = {}, &blk)
  options = @options.merge(options)
  if options.key?(:on)
    resolver = ConnectionResolver.new(options[:on], !!options[:db_names])
    dbs = resolver.configurations.keys
  else
    resolver = @connection_resolver
    dbs = @connection_resolver.configurations.keys
  end

  query_model = scope.model
  results = {}
  results_semaphore = Mutex.new

  pool = StaticPool.new(options[:threads] || 20)
  dbs.each do |db|
    pool.enqueue do
      Thread.current[:querrel_connected_models] = []
      con_spec = retrieve_connection_spec(db, resolver)
      Thread.current[:querrel_con_spec] = con_spec
      dynamic_class = ConnectedModelFactory[query_model, con_spec]

      begin
        local_scope = dynamic_class.all.merge(scope)
        local_results = if block_given?
          res = yield(local_scope, ConnectedModelFactory)
          res.to_a.each(&:readonly!) if res.is_a?(ActiveRecord::Relation)
          res
        else
          local_scope.to_a.map do |r|
            query_model.instantiate(r.attributes, {}).tap(&:readonly!)
          end
        end

        results_semaphore.synchronize { results[db] = local_results }
      ensure
        Thread.current[:querrel_connected_models].each do |m|
          m.connection_pool.release_connection
        end
        Thread.current[:querrel_connected_models] = nil
      end
    end
  end
  pool.do_your_thang!

  results
end

#query(scope, options = {}, &blk) ⇒ Object



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# File 'lib/querrel/map_reduce.rb', line 3

def query(scope, options = {}, &blk)
  buckets = map(scope, options, &blk)
  reduce(buckets)
end

#reduce(buckets) ⇒ Object



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# File 'lib/querrel/map_reduce.rb', line 56

def reduce(buckets)
  buckets.flat_map{ |db, results| results }
end