Google Cookbook - Google App Engine

m = Mutex("Some Key", 2)
try:
  m.lock();
  # Do stuff here....
except:
  # Handle errors here....
  pass
finally:
  m.unlock()

from google.appengine.api.memcache import Client as mcClient
import time
import random
class Mutex:
    
    def __init__(self, key, maxTimeOut=1.5):
        self.key = key
        self.maxTimeOut = maxTimeOut
        self.locked = False
        
    def lock(self):
        if self.locked == True:
            return
        import datetime as dt
        mc = mcClient()
        mc.add(key=self.key + "@lockedAt", value=dt.datetime.now(), namespace="Mutex")
        v = mc.incr(self.key, namespace="Mutex", initial_value=1)
        while v != 1:
            mc.decr(self.key, namespace="Mutex")
            lastLockedAt = mc.get(self.key + "@lockedAt", namespace="Mutex")
            if lastLockedAt is None or \
                (dt.datetime.now() - lastLockedAt > dt.timedelta(seconds=self.maxTimeOut*4)):
                mc.set(key=self.key, value=0, namespace="Mutex")
            else:
                random.seed(time.time())
                time.sleep(random.random() * self.maxTimeOut)
            v = mc.incr(self.key, namespace="Mutex", initial_value=1)
        mc.set(key=self.key + "@lockedAt", value=dt.datetime.now(), namespace="Mutex")
        self.locked = True
    def unlock(self):
        if self.locked == True:
            mc = mcClient()
            mc.decr(self.key, namespace="Mutex")
            self.locked = False
    def __del__(self):
        if self.locked == True:
            self.unlock()
    

from google.appengine.tools import appengine_rpchost = 'appengine.google.com'def auth_function():    return ('yourusername','yourpassword')source = 'yourapplication.appspot.com'rpc_server = appengine_rpc.HttpRpcServer(host, auth_function, 'Python 2.6', source)#Authenticaterpc_server._Authenticate();if rpc_server.authenticated == True:    print 'Authentication Successful.'    for cookie in rpc_server.cookie_jar:        if cookie.name and cookie.name == 'ACSID':            print 'Authentication Token Obtained (%s =

>

 %s)' % (cookie.name, cookie.value)      '''index_payload is description of your indexes in YAML - This can be generated in various different ways. '''index_payload = 'indexes:\n- kind: Comment\n  properties:\n  - name: name\n    direction: asc\n  - name: comment\n    direction: asc'#Uploading Indexprint rpc_server.Send(request_path='/api/datastore/index/add', payload= index_payload, app_id='

<

yourApplicationId

>

', version='

<

yourVersionString

>

')print 'Uploading Index Successful'

#! /usr/bin/python --
"""
reg.cgi by Michael Thornburgh.
This file is in the public domain.
IMPORTANT: This script is for illustrative purposes only. It does
not have user authentication or other access control measures that
a real production service would have.
This script should be placed in the cgi-bin location according to
your web server installation. The database is an SQLite3 database.
Edit the location of the database in variable "dbFile".
Create it with the following schema:
.schema
CREATE TABLE registrations (
    m_username VARCHAR COLLATE NOCASE,
    m_identity VARCHAR,
    m_updatetime DATETIME,
    
    PRIMARY KEY (m_username)
);
CREATE INDEX registrations_updatetime ON registrations (m_updatetime ASC);
"""
# CHANGE THIS
dbFile = '.../registrations.db'
import cgi
import sqlite3
import xml.sax.saxutils

query = cgi.parse()
db = sqlite3.connect(dbFile)
user = query.get('username', [None])[0]
identity = query.get('identity', [None])[0]
friends = query.get('friends', [])

print 'Content-type: text/plain\n\n\n'
if user:
	try:
		c = db.cursor()
		c.execute("insert or replace into registrations values (?, ?, datetime('now'))", (user, identity))
		print '\ttrue'
	except:
		print '\tfalse'
for f in friends:
	print "\t\n\t\t%s" % (xml.sax.saxutils.escape(f), )
	c = db.cursor()
	c.execute("select m_username, m_identity from registrations where m_username = ? and m_updatetime > datetime('now', '-1 hour')", (f, ))
	for result in c.fetchall():
		eachIdent = result[1]
		if not eachIdent:
			eachIdent = ""
		print "\t\t%s" % (xml.sax.saxutils.escape(eachIdent), )
		if f != result[0]:
			print "\t\t%s" % (xml.sax.saxutils.escape(result[0]), )
	print "\t"
db.commit()
print ""

q = model.Message.all()
q.filter("status =", "visible")
if sex != "":
        q.filter("sex =", sex)
if sexual_orientation != "":
        q.filter("sexual_orientation =", sexual_orientation)
if age != "":
        birth_year = now.year - int(age)
        q.filter("birth_year =", birth_year)
if residency != "":
        q.filter("residency =", residency)
if birth_country != "":
        q.filter("birth_country =", birth_country)
q.order("-last_update")

NeedIndexError: no matching index found.
This query needs this index:
- kind: Message
  properties:
  - name: sex
  - name: status
  - name: last_update
    direction: desc 

INDEX = '''\
- kind: Message
  properties:
%s  - name: status
  - name: last_update
    direction: desc
	
'''
INDEX_NAME = '''\
  - name: %s
'''
def bin(n, p):
	pad = "%%0%is" % p
	s = ''
	while n != 0:
		if n % 2 == 0:
			bit = '0'
		else:
			bit = '1'
		s = bit + s
		n >>= 1
	s = pad % s
	s = s.replace(" ", "0")
	return s
	
def names(l, bin):
	bin = bin[::-1]
	
	text = ""
	count = 0
	for b in bin:
		if b == "1":
			text += INDEX_NAME % l[count]
		count += 1
		
	return text

def main():
	filters = ["sex", "sexual_orientation", "birth_year", "residency", "birth_country"]
	filters_size = len(filters)
	combinations = 2**filters_size
	
	text = ""
	for i in range(combinations):
		text += INDEX % names(filters, bin(i, filters_size))
		
	print text
main()

with open("app.yaml") as f:
  import yaml
  data=yaml.load(f, Loader=yaml.Loader)
os.system("git tag -f -a 'v%s' -m 'automatically set by deployment script'" % data['version'])

import cProfile, pstats, StringIO
class ProfileWSGIMiddleware(object):
    def __init__(self, app):
        self.app = app
    def __call__(self, environ, start_response):
        # This is the main function for profiling
        # We've renamed our original main() above to real_main()
        prof = cProfile.Profile()
        prof = prof.runctx("self.app(environ, start_response)", globals(), locals())
        stream = StringIO.StringIO()
        stats = pstats.Stats(prof, stream=stream)
        stats.sort_stats("time")  # Or cumulative
        stats.print_stats(80)  # 80 = how many to print
        # The rest is optional.
        # stats.print_callees()
        # stats.print_callers()
        logging.info("Profile data:\n%s", stream.getvalue())

application = ProfileWSGIMiddleware(application)

SELECT * FROM Model WHERE user='me@gmail.com'

SELECT * FROM Model WHERE user='me'

SELECT * FROM Model WHERE user=User('me@gmail.com')

SELECT * FROM Model WHERE user='me@gmail.com'

SELECT * FROM Model WHERE user='me'

SELECT * FROM Model WHERE user=User('me@gmail.com')