Test the optimistic locking with Sequel

optlock_test.rb

require 'rubygems'
require 'sequel'
require 'sqlite3'
require 'logger'

DB = Sequel.sqlite '', :loggers => [Logger.new($stdout)]

Sequel::Model.plugin :instance_filters
Sequel::Model.plugin :optimistic_locking

DB.create_table! :entries do
  primary_key :id
  String :title
  String :description
  String :notes
  Integer :lock_version, :default => 0
end

class Entry < Sequel::Model
    many_to_one :office
end

def create_entry()
  entry = Entry.new
  entry.title = "This is a title"
  entry.description = "This is a description"
  entry.notes = "This is a note"
  entry.save
end

def concurrency_test(i)
  e1 = Entry[1]
  e2 = Entry[1]

  puts "Before updates:"
  puts "Lock_version of e1 is #{e1.lock_version}"
  puts "Lock_version of e2 is #{e2.lock_version}"

  e1.update(:title=>"This is an updated title #{i}")

  puts "After update to e1:"
  puts "Lock_version of e1 is #{e1.lock_version}"
  puts "Lock_version of e2 is #{e2.lock_version}"

  e2.update(:title=>"This should not work")

  puts "After update to e2:"
  puts "Lock_version of e1 is #{e1.lock_version}"
  puts "Lock_version of e2 is #{e2.lock_version}"
end

create_entry

10.times.each do |i|
  begin
    puts "\n**Run Tests**"
    concurrency_test(i)
  rescue Sequel::NoExistingObject
    puts " Caught the lock error!"
  ensure
    sleep 5
  end
end