import logging

import os

import sys

import sqlite3

import threading

import time

from utils import AUTHORS_BOOKS

logging.basicConfig(level=logging.DEBUG,

format='%(asctime)s (%(threadName)-10s) %(message)s',

)

DB_FILENAME = 'books.db'

DB_IS_NEW = not os.path.exists(DB_FILENAME)

author_insert = "INSERT INTO author (name) VALUES(?);"

author_query = "SELECT * FROM author;"

book_query = "SELECT * FROM book;"

book_insert = """

INSERT INTO book (title, author) VALUES(?, (

SELECT authorid FROM author WHERE name=? ));

"""

def show_query_results(conn, query):

cur = conn.cursor()

logging.debug("beginning read")

cur.execute(query)

logging.debug("selects issued")

had_rows = False

for row in cur.fetchall():

print row

had_rows = True

logging.debug("results fetched")

if not had_rows:

print "no rows returned"

def show_authors(conn):

query = author_query

show_query_results(conn, query)

def show_books(conn):

query = book_query

show_query_results(conn, query)

def populate_db(conn):

authors = ([author] for author in AUTHORS_BOOKS.keys())

cur = conn.cursor()

logging.debug("connected")

cur.executemany(author_insert, authors)

for author in AUTHORS_BOOKS.keys():

params = ([book, author] for book in AUTHORS_BOOKS[author])

cur.executemany(book_insert, params)

logging.debug("changes made")

def writer():

logging.debug("connecting")

with sqlite3.connect(DB_FILENAME, isolation_level="EXCLUSIVE") as conn:

populate_db(conn)

logging.debug("waiting to sync")

ready.wait()

logging.debug("PAUSING")

time.sleep(3)

conn.commit()

logging.debug("CHANGES COMMITTED")

return

def reader():

with sqlite3.connect(DB_FILENAME, isolation_level="EXCLUSIVE") as conn:

logging.debug("waiting to sync")

ready.wait()

logging.debug("beginning read")

show_authors(conn)

show_books(conn)

return

if __name__ == '__main__':

if DB_IS_NEW:

print "Database does not yet exist, please run `createdb` first"

sys.exit(1)

ready = threading.Event()

threads = [

threading.Thread(name="Reader", target=reader),

threading.Thread(name="Writer", target=writer),

]

[t.start() for t in threads]

time.sleep(2)

logging.debug('sending sync event')

ready.set()

[t.join() for t in threads]