在GAE上使用Python 2.7的注意事项

try:
	import json
except ImportError:
	import simplejson as json

if os.environ['APPENGINE_RUNTIME'] == 'python27':
	import json
else:
	import simplejson as json

1. 解析os.environ，用print或sys.out.write输出响应（包括HTML头）。
   
2. 生成一个WSGI应用，在main()函数里传递给google.appengine.ext.webapp.util.run_wsgi_app()来执行。
   

request_arrive_time = 0
db_count = 0
db_time = 0
db_start_time = 0

def before_db(service, call, request, response):
	global db_count, db_start_time
	db_count += 1
	db_start_time = time()

def after_db(service, call, request, response):
	global db_time
	dt = time() - db_start_time
	db_time += dt

apiproxy_stub_map.apiproxy.GetPreCallHooks().Append('before_db', before_db, 'datastore_v3')
apiproxy_stub_map.apiproxy.GetPostCallHooks().Push('after_db', after_db, 'datastore_v3')

def main():
	hook.db_count = 0
	hook.db_time = 0
	hook.db_start_time = 0
	hook.request_arrive_time = time()
	util.run_wsgi_app(application)

if __name__ == '__main__':
	main()

class WsgiApplication(yui.WsgiApplication):
	def __call__(self, environ, start_response):
		local.request_arrive_time = time()
		local.db_count = 0
		local.db_time = 0
		local.db_start_time = 0
		return super(WsgiApplication, self).__call__(environ, start_response)


local = threading.local()
local.request_arrive_time = 0
local.db_count = 0
local.db_time = 0
local.db_start_time = 0

def before_db(service, call, request, response):
	if hasattr(local, 'db_count'):
		local.db_count += 1
	else:
		local.db_count = 1
	local.db_start_time = time()

def after_db(service, call, request, response):
	if hasattr(local, 'db_start_time') and hasattr(local, 'db_time'):
		dt = time() - local.db_start_time
		local.db_time += dt

def hook_app(app):
	def wrap(environ, start_response):
		local.request_arrive_time = time()
		local.db_count = 0
		local.db_time = 0
		local.db_start_time = 0
		return app(environ, start_response)
	return wrap

application = hook.hook_app(application)