Detailed Explanation of Cached Data by Python Annotation

The directory background is used to simplify the code summary through the decorator class

Background

Load should be reloaded every time the data is loaded. I want to develop the cache mechanism by adding annotations, so I don't need to write code every time I cache it

Disadvantages: At present, only one return value is supported. Although it can be used as a dictionary, it has already met personal needs and has no motivation to change (dog head).

Bring it and use it

New File Cache.py

class Cache:
    def __init__(self, cache_path='.', nocache=False):
        self.cache_path = cache_path
        self.cache = not nocache
    def __call__(self, func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            s = f'{func.__code__.co_filename}.{func.__name__}'
            s += ','.join(list(args[1:]) + [f'{k}={v}' for k, v in kwargs.items()])
            md5 = hashlib.md5()
            md5.update(s.encode('utf-8'))
            cache_file = f'{self.cache_path}/{md5.hexdigest()}'
            if self.cache and os.path.exists(cache_file):
                print('Loading from cache')
                return pickle.load(open(cache_file, 'rb'))
            else:
                if not os.path.exists(self.cache_path):
                    os.makedirs(self.cache_path)
                data = func(*args, **kwargs)
                pickle.dump(data, file=open(cache_file, 'wb'))
                print(f'Dump finished {cache_file}')
            return data
        return wrapper

from .Cache import Cache
@Cache(root_path, nocache=True)
def load_data(self, inpath):
    return 'Wula~a~a~!'

Practice process

For the first time, let's simply inherit the parent class

class Cache(object):
    def __init__(self, cache_path=None):
        self.cache_path = cache_path if cache_path else '.'
        self.cache_path = f'{self.cache_path}/cache'
        self.data = self.load_cache()
    def load_cache(self):
        if os.path.exists(self.cache_path):
            print('Loading from cache')
            return pickle.load(open(self.cache_path, 'rb'))
        else:
            return None
    def save_cache(self):
        pickle.dump(self.data, file=open(self.cache_path, 'wb'))
        print(f'Dump finished {self.cache_path}')
class Filter4Analyzer(Cache):
    def __init__(self, rootpath, datapath):
        super().__init__(rootpath)
        self.root_path = rootpath
        if self.data is None:
            self.data = self.load_data(datapath)
            self.save_cache()

As long as the inheritance Cache class is OK, but there are many limitations, for example, you can only specify a parameter to be cache, for example, you have to write saved code in Filter4Analyzer.

In the next step, python nests decorators to improve this problem

from functools import wraps
import hashlib
def cached(cache_path):
    def wrapperper(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            s = f'{func.__code__.co_filename}.{func.__name__}' + ','.join(args[1:])
            s += ','.join(list(args[1:]) + [f'{k}={v}' for k, v in kwargs.items()])
            md5 = hashlib.md5()
            md5.update(s.encode('utf-8'))
            cache_file = f'{cache_path}/{md5.hexdigest()}' if cache_path else './cache'
            if os.path.exists(cache_file):
                print('Loading from cache')
                return pickle.load(open(cache_file, 'rb'))
            else:
                if not os.path.exists(cache_path):
                    os.makedirs(cache_path)
                data = func(*args, **kwargs)
                pickle.dump(data, file=open(cache_file, 'wb'))
                print(f'Dump finished {cache_file}')
            return data
        return wrapper
    return wrapperper
class Tester:
    @cached(cache_path='./workpath_test')
    def test(self, data_path):
        return ['hiahia']

Simplify code through decorator classes

class Cache:
    def __init__(self, cache_path='.', nocache=False):
        self.cache_path = cache_path
        self.cache = not nocache
    def __call__(self, func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            s = f'{func.__code__.co_filename}.{func.__name__}'
            s += ','.join(list(args[1:]) + [f'{k}={v}' for k, v in kwargs.items()])
            md5 = hashlib.md5()
            md5.update(s.encode('utf-8'))
            cache_file = f'{self.cache_path}/{md5.hexdigest()}'
            if self.cache and os.path.exists(cache_file):
                print('Loading from cache')
                return pickle.load(open(cache_file, 'rb'))
            else:
                if not os.path.exists(self.cache_path):
                    os.makedirs(self.cache_path)
                data = func(*args, **kwargs)
                pickle.dump(data, file=open(cache_file, 'wb'))
                print(f'Dump finished {cache_file}')
            return data
        return wrapper

Reference:

Python Function Decorator

Python Function Properties and PyCodeObject

Summarize

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