nanowsgi/decorators.py

#!/usr/bin/python
# -*- coding: utf-8; tab-width: 4; indent-tabs-mode: nil; -*-

from singleton import Singleton
from template import render
from functools import partial


class WSGITemplate( object ):
    __metaclass__ = Singleton

    def __init__( self, basedir='' ):
        import os
        self.__basedir = os.path.normpath( os.path.join( os.path.split(__file__)[0], basedir ) ) + '/'
        self.__fallback_template = \
            "<h1> NO TEMPLATE DEFINED </h1>\n" \
            "{{ from pprint import pformat }}" \
            "<pre>{{ = pformat( { k:v for k,v in locals().iteritems() if k not in ('NOESCAPE','__builtins__','pformat','response') }, width=132 ) }}</pre>\n\n"


    def template( self, filename=None ):
        def real_decorator( wsgi_application ):
            def wrapper( environ, start_response ):
                if filename:
                    environ[ 'template' ] = partial( render, filename=self.__basedir + filename )
                else:
                    environ[ 'template' ] = partial( render, content=self.__fallback_template )
                return wsgi_application( environ, start_response )

            return wrapper

        return real_decorator


class WSGIMySQL( object ):
    __metaclass__ = Singleton

    def __init__( self, dsn, *args ):
        import MySQLdb

        self.__dsn = dsn
        self.__pool = [ self.__newconn() ]
        self.__dict_cursor = MySQLdb.cursors.DictCursor


    def __newconn( self ):
        import MySQLdb

        return MySQLdb.connect(
            host   = self.__dsn["HOST"],
            user   = self.__dsn["USER"],
            passwd = self.__dsn["PASSWORD"],
            db     = self.__dsn["DB"]
        )

    def db( self, *args ):
        def real_decorator( wsgi_application ):
            def wrapper( environ, start_response ):
                try:
                    conn = self.__pool.pop( 0 )
                except IndexError:
                    conn = self.__newconn()

                cur = conn.cursor( self.__dict_cursor )

                environ['mysql.cur'] = cur

                try:
                    for item in wsgi_application( environ, start_response ):
                        yield item
                finally:
                    conn.commit()
                    self.__pool.append( conn )

            return wrapper

        return real_decorator


    def __del__( self ):
        for conn in self.__pool:
            conn.close()