async2.py

import oursql
import sys

from twisted.enterprise import adbapi
from twisted.internet import defer, reactor
from twisted.python import log

log.startLogging(sys.stderr)

# Use 'test' database with default credentials
dbpool = adbapi.ConnectionPool("oursql", db="test")

def createTable():
    """Re-creates t1 every call"""
    def _create(tx):
        tx.execute("DROP TABLE IF EXISTS t1")
        tx.execute("CREATE TABLE t1 (name VARCHAR(30))")

    return dbpool.runInteraction(_create)

def echo(msg):
    def _echo(_):
        print msg
        return _

    return _echo

def runQueries():
    # schedule many queries in parallel
    queries = []
    for i in xrange(10):
        d1 = dbpool.runOperation("INSERT INTO t1 VALUES (?)", (i, ))
        d1.addCallbacks(echo("record inserted (%d)" % i), printError)
        queries.append(d1)

        d2 = dbpool.runQuery("SELECT * FROM t1")
        d2.addCallbacks(printLength, printError)
        queries.append(d2)

    return defer.DeferredList(queries)

def main():
    create = createTable()
    create.addCallbacks(echo("Table Created"), printError)
    # be sure to run queries after table gets created
    # otherwise we will get OperationalErrors and even segmentation fault (?)
    create.addCallback(lambda _: runQueries())

    return create

def printLength(result):
    if result:
        print "Got %d rows" % len(result)
    else:
        print "Got nothing"

def printError(result):
    print "Error", result

def stop(_):
    print "stopping reactor"
    reactor.stop()

if __name__ == '__main__':
    print "starting program"

    d = main()
    d.addBoth(stop)

    print "starting reactor"
    reactor.run()
    print "reactor stopped"

output

2010-08-29 20:02:17-0400 [-] Log opened.
2010-08-29 20:02:17-0400 [-] starting program
2010-08-29 20:02:17-0400 [-] starting reactor
2010-08-29 20:02:17-0400 [-] Table Created
2010-08-29 20:02:17-0400 [-] record inserted (0)
2010-08-29 20:02:17-0400 [-] Got 1 rows
2010-08-29 20:02:17-0400 [-] record inserted (1)
2010-08-29 20:02:17-0400 [-] record inserted (2)
2010-08-29 20:02:17-0400 [-] Got nothing
2010-08-29 20:02:17-0400 [-] Got 3 rows
2010-08-29 20:02:17-0400 [-] record inserted (3)
2010-08-29 20:02:17-0400 [-] record inserted (5)
2010-08-29 20:02:17-0400 [-] Got 4 rows
2010-08-29 20:02:17-0400 [-] Got 4 rows
2010-08-29 20:02:17-0400 [-] record inserted (6)
2010-08-29 20:02:17-0400 [-] Got 5 rows
2010-08-29 20:02:17-0400 [-] Got 6 rows
2010-08-29 20:02:17-0400 [-] Got 6 rows
2010-08-29 20:02:17-0400 [-] record inserted (8)
2010-08-29 20:02:17-0400 [-] record inserted (4)
2010-08-29 20:02:17-0400 [-] record inserted (7)
2010-08-29 20:02:17-0400 [-] Got 9 rows
2010-08-29 20:02:17-0400 [-] record inserted (9)
2010-08-29 20:02:17-0400 [-] Got 10 rows
2010-08-29 20:02:17-0400 [-] stopping reactor
2010-08-29 20:02:17-0400 [-] Main loop terminated.
2010-08-29 20:02:17-0400 [-] reactor stopped