Unlock the Power of DiskCache: Enhance Python App Performance

DiskCache is a robust and efficient disk and file cache system for Python applications, designed to provide a persistent, durable cache. Below, we explore dozens of useful APIs provided by DiskCache with practical examples.

Introduction to DiskCache

DiskCache stores data on the filesystem, ensuring that your cache survives application restarts and provides a fallback when memory is exhausted. It supports multi-threading, multi-processing, and has a zero-copy design that minimizes serialization overhead.

Installation

pip install diskcache

Basic Usage

The basic usage of DiskCache starts with importing the Cache class and creating a cache instance:

 from diskcache import Cache cache = Cache('/tmp/my_cache') 

Here’s how you can perform basic CRUD operations with DiskCache:

• Setting a value:

cache['key'] = 'value'

• Getting a value:

value = cache['key']

• Deleting a value:

del cache['key']

• Checking if a key exists:

'key' in cache

Advanced Features

Timeouts and Expirations

You can set a timeout for cache entries, allowing them to expire after a specified duration:

cache.set('key', 'value', expire=10)  # expires after 10 seconds

Cache Eviction Policies

DiskCache supports several cache eviction policies, including Least Recently Used (LRU), Least Frequently Used (LFU), and random eviction:

 from diskcache import Cache
cache = Cache('/tmp/my_cache', eviction_policy='LFU') 

Transactional Support

DiskCache offers transactional support for critical sections:

 with cache.transact():
    cache['key1'] = 'value1'
    cache['key2'] = 'value2'

Compression Support

To save space, DiskCache supports automatic compression of values:

 from diskcache import FanoutCache
cache = FanoutCache('/tmp/my_cache', compress_level=1) 

Fanout Cache

For multi-threaded environments, using FanoutCache can significantly improve performance:

 from diskcache import FanoutCache
cache = FanoutCache('/tmp/my_cache', shards=8) 

Example App Using DiskCache APIs

Let’s create a simple Python application that caches a list of users with DiskCache:

 import time from diskcache import Cache
cache = Cache('/tmp/users_cache')
def fetch_users():
    # Simulate a delay
    time.sleep(2)
    return ['Alice', 'Bob', 'Charlie']

def get_users():
    if 'users' in cache:
        print('Cache hit!')
        return cache['users']
    else:
        print('Cache miss!')
        users = fetch_users()
        cache.set('users', users, expire=60)
        return users

if __name__ == '__main__':
    users = get_users()
    print(users)

This app first checks if the user data is present in the cache. If not, it fetches the data, stores it in the cache with an expiry time, and then returns the user list. On subsequent runs within the expiry time, the data will be retrieved from the cache, enhancing performance significantly.

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