Using /dev/shm as Storage

dev_shm.py

""" Saving Value in to /dev/shm
See: https://gerardnico.com/os/linux/shared_memory

Usage:
myapp.py
-----------------------------------------
ds = DevShm('myapp')
idx = int(ds.get('index', 0))
print('My App index:', idx)
idx += 1
ds.set('index', idx)
-----------------------------------------

$ python3 myapp.py

My App index: 0

$ python3 myapp.py

My App index: 1

$ python3 myapp.py

My App index: 2

...

"""

class DevShm:
    """ Manager /dev/shm """
    __namespace = None
    __filepath = None

    def __init__(self, namespace=__file__):
        self.__set_namespace(str(namespace))
    
    def __set_namespace(self, namespace):
        self.__namespace = namespace.replace('.', '-').replace('/', '-').replace(' ', '_').replace('\\', '-')
        self.__set_filepath()
        return self.__namespace

    def get_namespace(self):
        return self.__namespace

    def __set_filepath(self):
        self.__filepath = '/dev/shm/%s' % str(self.__namespace)
        return self.__filepath

    def get_filepath(self):
        return self.__filepath

    def set(self, name, value=None):
        """ Set Value """
        with open(self.__filepath+'-'+name, 'w+') as f:
            f.write(str(value))
        return value
    
    def get(self, name, default=None):
        """ Get Value """
        value = default
        try:
            with open(self.__filepath+'-'+name, 'r') as f:
                value = f.read()
        except FileNotFoundError as e:
            self.set(name, value)
        return value