""" AUTHOR: Khushal P Soonderji DATE: Thursday, 11th April, 2024 OBJECTIVE: To provide an easy way to work with '.json' files in an async manner. REFERENCES: 1) https://www.w3schools.com/python/python_json.asp DOWNLOADS: N/A """ # ***************************************************************************************************************** # ***** **** # *** IMPORT *** # ***** **** # ***************************************************************************************************************** # To use redis: import redis.asyncio as redis # Other utils: from utils_v2.string import json # For debugging: from icecream import IceCreamDebugger # To make a decorator: from functools import wraps # For hashing and shortening the hash: import hashlib import base64 # ***************************************************************************************************************** # ***** **** # *** MACROS / ONE-TIME INIT *** # ***** **** # ***************************************************************************************************************** # --- Nothing Yet # ***************************************************************************************************************** # ***** **** # *** VARIABLES *** # ***** **** # ***************************************************************************************************************** # --- Nothing Yet # ***************************************************************************************************************** # ***** **** # *** FUNCTIONS *** # ***** **** # ***************************************************************************************************************** # --- Nothing Yet # ***************************************************************************************************************** # ***** **** # *** WRAPPERS *** # ***** **** # ***************************************************************************************************************** def cache_it(cache = None, expiry = 120): """ This decorator factory takes an instance of the async caching class 'AsyncRedisCache' and holds your data there. If a subsequent call is made to the same decorated function with the same inputs, the result is fetched from the cache instead of going through the whole function again. :param cache: The instance of 'AsyncRedisCache'. :param expiry: The time in seconds after which the cached data must be cleared. :return: The decorator that automatically caches your data. """ def decorator(func): @wraps(func) async def wrapper(*args, **kwargs): # We first use the name of the function and the inputs given to it to generate a key for Redis with the # simple hashing and shortening by way of base64 strings: inputs_given = func.__name__ + str([_ for _ in args]) + str(kwargs) sha256_hash = hashlib.sha256() sha256_hash.update(inputs_given.encode("utf-8")) hashed_key = sha256_hash.digest() base64_key = base64.b64encode(hashed_key).decode("utf-8") # Now we check if we have the value in cache: try: response = await cache.get(base64_key, raise_exception = True) # If the key doesn't exist, we pass through the function and store the results. except: response = await func(*args, **kwargs) await cache.set(key = base64_key, value = response, expiry = expiry) # Return the response from the wrapped function. return response return wrapper return decorator # ***************************************************************************************************************** # ***** **** # *** CLASSES *** # ***** **** # ***************************************************************************************************************** class AsyncRedisCache: # Handle datatypes when setting values to cache: __set_converters = { "set": lambda x: list(x), "tuple": lambda x: list(x), "complex": lambda x: {"r": x.real, "i": x.imag} } # Handle datatypes when getting from cache: __get_converters = { "set": lambda x: set(x), "tuple": lambda x: tuple(x), "complex": lambda x: complex(x["r"], x["i"]) } def __init__( self, connection_string, ping_counter = 1_000, debug = False, debug_prefix = "R-Cache | " ): """ Implements a simple cache in Redis which holds and returns all native datatypes like ints, floats, bools, strings, dicts, lists, sets, and tuples :) :param connection_string: The connection URL for connecting to Redis. :param ping_counter: The number of requests to Redis after which you want to ping to ensure connection. :param debug: Whether, or not, you want to show debugging messages from the start. :param debug_prefix: The prefix text to show with the debugging messages. """ # Note down the configuration: self.__client = None self.__ping_counter = ping_counter self.__requests_since_last_ping = 0 self.__connection_string = connection_string # For debugging: self.__printer = IceCreamDebugger(prefix = debug_prefix, includeContext = True) if not debug: self.__printer.disable() def enable_debug(self): self.__printer.enable() def disable_debug(self): self.__printer.disable() @staticmethod def make_key(*args, **kwargs): """ Generates a key by hashing the args and kwargs sent to it. Can be useful to generate a predictable key. If the inputs stay the same, the output stays the same. :param args: Any number of args that you would like to use to generate the key. :param kwargs: Any number of kwargs that you would like to use to generate the key. :return: A string that can be used as a key to store values on Redis. """ # Take everything into one plain text string: plain_text = "".join(str(a) for a in args) plain_text += json.to_string(kwargs, no_space = True) # Hash the plain text value, and create a key from it: sha256_hash = hashlib.sha256() sha256_hash.update(plain_text.encode("utf-8")) hashed_key = sha256_hash.digest() base64_key = base64.b64encode(hashed_key).decode("utf-8") # Done here: return base64_key def add_converter( self, type_name, set_converter_func, get_converter_func, ): """ To add custom data converters to handle new values. RULE: Each of the converter functions must take in exactly on argument. :param type_name: The name of the type of the object to handle. HINT: type(obj).__name__. :param set_converter_func: A converter function that converts from the custom datatype to a datatype that Redis can work with. Try converting to an bool, int, float, str, list or dict. :param get_converter_func: The inverse of the set converter. This function will be used to convert from a datatype that Redis can work with to the custom datatype. :return: None. """ self.__set_converters[type_name] = lambda x: set_converter_func(x) self.__get_converters[type_name] = lambda x: get_converter_func(x) async def connect(self): """ To make an asynchronous connection request to the Redis server to establish a connection. :return: True if connected, else False. """ try: self.__client = redis.from_url( self.__connection_string ) return True except Exception as exception: self.__printer(exception) return False async def disconnect(self): """ Close the connection to the Redis server. :return: True if successful, else False. """ if self.__client is not None: try: await self.__client.close() except Exception as exception: self.__printer(exception) return False return True return True async def ensure_connection(self): """ To ensure that we are connected. We keep pinging the Redis server every once in a while even when connected. :return: True if connected, else False. """ # If we are not connected, we try to establish a connection: if self.__client is None: return await self.connect() # Else we check if we are connected. If not, we try to connect. # But we check only once in a while. In the meantime, we assume that we are connected. elif self.__requests_since_last_ping > self.__ping_counter: try: await self.__client.ping() self.__requests_since_last_ping = 0 return True except Exception as exception: self.__printer(exception) return await self.connect() else: self.__requests_since_last_ping += 1 return True async def set(self, key, value, expiry: float = 120, raise_exception = False): """ Saves some value to the cache. :param key: The key with which the data will be stored and retrieved. :param value: The value to store. :param expiry: The time in seconds after which the data will expire. Must be a positive number. :param raise_exception: If you want to raise an exception if the process fails. :return: True if cached, else False. """ await self.ensure_connection() try: # We handle conversion for unsupported Pythonic datatypes: original_type = type(value).__name__ converter = self.__set_converters.get(original_type) if converter is not None: value = converter(value) # Here we actually try to store the data: response = await self.__client.setex( key, int(expiry), json.to_string({ "value": value, "type": original_type }, indent = 0, no_space = False) ) return response except Exception as exception: self.__printer(exception) if raise_exception: raise else: return False async def get(self, key, raise_exception = False, on_fail = None): """ Retrieve the cached value. :param key: The key with which the data was saved. :param raise_exception: If you want to raise an exception if the process fails. :param on_fail: What to return if the process fails due to an exception. :return: The retrieved data or null if not found. """ await self.ensure_connection() try: data = await self.__client.get(key) data = data.decode("utf-8") data = json.from_string(data) converter = self.__get_converters.get(data["type"]) if converter is not None: return converter(data["value"]) return data["value"] except Exception as exception: self.__printer(exception) if raise_exception: raise else: return on_fail async def delete(self, key, raise_exception = False): """ Prematurely delete the value from the cache before it expires. :param key: The key with which the data was saved. :param raise_exception: If you want to raise an exception if the process fails. :return: True if deleted, else False. """ await self.ensure_connection() try: response = await self.__client.delete(key) return True if response else False except Exception as exception: self.__printer(exception) if raise_exception: raise else: return False async def count(self, key, value: int = 1, expiry: float = None, raise_exception = False): """ To use simple counters. If the counter (identified by the 'key') exists, it will be incremented, else the counter will be created and the value will be incremented from 0. :param key: The name of the counter. :param value: The amount to increment the value by. Send negative values to count backwards. :param expiry: The time (in seconds) in which the counter expires. Starts from the time the counter is created. This value has to be an integer. If a float is passed, the value will be rounded off. :param raise_exception: If you want to raise an exception if the process fails. :return: The latest value of the counter. Will be null if something went wrong and the exception was suppressed. """ await self.ensure_connection() try: already_existed = await self.__client.exists(key) new_value = await self.__client.incrby(key, value) if expiry and not already_existed: await self.__client.expire(key, int(expiry)) return new_value except Exception as exception: self.__printer(exception) if raise_exception: raise else: return None # ***************************************************************************************************************** # ***** **** # *** MAIN PROGRAM *** # ***** **** # ***************************************************************************************************************** if __name__ == "__main__": import asyncio def set_complex(x): return {"r": x.real, "i": x.imag} def get_complex(x): return complex(x["r"], x["i"]) async def main(): my_cache = AsyncRedisCache( connection_string = r"redis://:dc4da94197c843ab6a730113c2b801d9@redis.ditscentre.in/0", ping_counter = 100, debug = False ) my_cache.add_converter( type_name = type(2j).__name__, set_converter_func = set_complex, get_converter_func = get_complex ) value = await my_cache.get(key = "6b61afd0-b066-4611-9791-411a30d34624") print("GET:", value) print("TYP:", type(value), end = "\n\n") # success = await my_cache.set( # key = "name", # value = {"first": "John", "last": "Doe"}, # expiry = 10 # ) # print("SET:", success, end = "\n\n") # # value = await my_cache.get(key = "name") # print("GET:", value) # print("TYP:", type(value), end = "\n\n") # # success = await my_cache.delete(key = "name") # print("DEL:", success, end = "\n\n") # # value = await my_cache.get(key = "cnt") # print("GET:", value) # print("TYP:", type(value), end = "\n\n") # # await my_cache.delete(key = "cnt") # for _ in range(50): # await asyncio.sleep(1.0) # counter = await my_cache.count(key = "cnt", value = 1, expiry = 10) # print("COUNTER:", counter) asyncio.run(main())