Malet

class DoubleUserBalance < ActiveRecord::Migration
  def up
    # Double user's balance
    prepared = ActiveRecord::Base.connection.raw_connection.prepare("
      UPDATE users
      SET balance = balance * ?
    ")
    prepared.execute(2)
    prepared.close
  end

Malet

class Hash
  def stringify_keys
    result = {}
    each_key do |key|
      result[key.to_s] = if self[key].class == Hash
          self[key].stringify_keys
        else
          self[key]
        end
    end

Malet

def tputs(*params)
  $io_lock ||= Mutex.new
  $io_lock.synchronize{ puts(*params) }
end

Malet

class String
  REPLACE_INVALID_WITH = '�'

  def to_utf8
    self.encode('utf-8', invalid: :replace, undef: :replace, replace: REPLACE_INVALID_WITH).
      chars.map{ |i| i.valid_encoding? ? i : REPLACE_INVALID_WITH }.join
  end
end

Malet

class ThreadPool
  def initialize(input_array:, callback:, threads: 128)
    @callback, @input_array, @threads = callback, input_array, threads
  end

  def run
    results = []
    input_queue, results_queue = Queue.new, Queue.new

    @input_array.each{ |item| input_queue << item }