#!/usr/bin/env python
     # encoding: utf-8
     #
     # Copyright (c) 2010 Doug Hellmann.  All rights reserved.
     #
     """Illustrate the effect of autocommit mode.
     """
     #end_pymotw_header
     
     import logging
     import sqlite3
     import sys
     import threading
     import time
     
     logging.basicConfig(level=logging.DEBUG,
                         format='%(asctime)s (%(threadName)-10s) %(message)s',
                         )
     
     db_filename = 'todo.db'
     isolation_level = None # autocommit mode
     
     def writer():
         my_name = threading.currentThread().name
         logging.debug('connecting')
         with sqlite3.connect(db_filename, isolation_level=isolation_level) as conn:
             cursor = conn.cursor()
             logging.debug('connected')
             cursor.execute('update task set priority = priority + 1')
             logging.debug('changes made')
             logging.debug('waiting to synchronize')
             ready.wait() # synchronize
             logging.debug('PAUSING')
             time.sleep(1)
         return
     
     def reader():
         my_name = threading.currentThread().name
         with sqlite3.connect(db_filename, isolation_level=isolation_level) as conn:
             cursor = conn.cursor()
             logging.debug('waiting to synchronize')
             ready.wait() # synchronize
             logging.debug('wait over')
             cursor.execute('select * from task')
             logging.debug('SELECT EXECUTED')
             results = cursor.fetchall()
             logging.debug('results fetched')
         return
     
     if __name__ == '__main__':
         ready = threading.Event()
     
         threads = [
             threading.Thread(name='Reader 1', target=reader),
             threading.Thread(name='Reader 2', target=reader),
             threading.Thread(name='Writer 1', target=writer),
             threading.Thread(name='Writer 2', target=writer),
             ]
         
         [ t.start() for t in threads ]
         
         time.sleep(1)
         logging.debug('setting ready')
         ready.set()
     
         [ t.join() for t in threads ]