２倍になる数のソースコード

      #!/usr/bin/python
      #coding: utf-8
      
      import fcntl, os, sys, time
      
      COUNTER = os.path.join(os.path.dirname(os.path.abspath(__file__)), "counter.txt")
      
      def counter():
      lock_ex = False
      fd_open = False
      try:
      fd = os.open(COUNTER, os.O_CREAT|os.O_RDWR, 0755)
      fd_open = True
      for i in range(100):
      try:
      fcntl.flock(fd, fcntl.LOCK_EX|fcntl.LOCK_NB)
      lock_ex = True
      except IOError:
      # IOError: ロックを取得できなかった
      time.sleep(0.1)
      continue
      else:
      break
      if not lock_ex:
      sys.stderr.write("access_counter.cgi: File lock timeout.")
      return "File lock timeout."
      eof = os.lseek(fd, 0, os.SEEK_END)
      os.lseek(fd, 0, os.SEEK_SET)
      count = os.read(fd, eof)
      try:
      count = str(int(count)*2)
      except ValueError:
      count = "1"
      os.lseek(fd, 0, os.SEEK_SET)
      os.ftruncate(fd, len(count))
      os.write(fd, count)
      os.fsync(fd)
      except AttributeError:
      # AttributeError: OSの制約で利用できない関数や定数があった
      return "Your environment not supported."
    finally:
    if lock_ex:
    fcntl.flock(fd, fcntl.LOCK_UN)
    if fd_open:
    os.close(fd)
    return count
    
    if __name__ == "__main__":
    sys.stdout.write("Content-Type: text/html\n\n%s\n" % counter())