data synchronization

[o-jill]

you may have to lock DB when you want to update it like

db = DB.new
db.lock
db.read
db.change_something
db.write
db.unlock

now locking files are used but it's not enough.

[o-jill]

db = DB.new
db.change_something

class DB
 def change_something
 File.open(path, "r+") do |file|
  file.flock(File::LOCK_EX)
  data = file.read
  edit_something(data)
  file.write(data)
 end
end

[o-jill]

now, data shown below should be considered.

• mandatory
  • user info file
  • taikyoku-chu file
  • taikyoku file
• maybe not mandatory because of adding only.
  • chat file
  • taikyoku file
• don't have to
  • admin config file
  • match info file
  • jkf file
  • sfen log

[o-jill]

adding a user become thread-safer. c91c5c6fa. adding a game become thread-safer. c3b4eb43.

[o-jill]

situations:

• update a user's stats.
• update a game's last move.
• remove a game from taikyoku-chu.

[o-jill]

begin
  db = DB.new
  db.lock
  db.read
  db.change_something
  db.write
rescure StandardError => e
 puts "error:#{e}"
ensure
  db.unlock
end

def lock
  if !Dir.mkdir('lock.dir', 0o755)
    // locked
  else
    // lock failed or some already locked.
  end
end

def unlock
  Dir.rmdir('lock.dir')
end

[o-jill]

require 'timeout'

class AccessDenied < StandardError; end

def lock(&block)
  # 10秒以内に終わらない場合はAccessDenied例外が発生
  Timeout::timeout(10) do
    open(File.join(Dir.tmpdir, 'my-application.lock'), 'w') do |f|
      begin
        f.flock(File::LOCK_EX)
        block.call
      ensure
        f.flock(File::LOCK_UN)
      end
    end
  end
rescue Exception => ex
  raise AccessDenied.new('timeout')
end

lock do
  # 排他処理
end

refer:http://qiita.com/yuku_t/items/5aeff2a617576b9bc6d2

[o-jill]

locking was implemented for UserInfoFile class in 25ff05cb51.

[o-jill]

locking for Taikyoku/Taikyokuchu class was implemented but still only for append().

[o-jill]

lock for Taikyoku/Taikyokuchu class was fully imlemented in 4afd8f8.

[o-jill]

you have to use DB Server to avoid this issue!

[o-jill]

now, data shown below should be considered.

• mandatory
  • user info file
  • taikyoku-chu file
  • taikyoku file
  • match info file <-- moved here
  • jkf file <-- moved here
• maybe not mandatory because of adding only.
  • chat file
  • taikyoku file
• don't have to
  • admin config file
  • match info file
  • jkf file
  • sfen log

[o-jill]

match info file and jkf file are moved to mandatory because players and byouyomichan will update them asynchronously.