Introduction to DiskCache

DiskCache is a powerful and efficient caching library for Python applications. It leverages the file system for temporary storage, making it both fast and reliable. Whether you’re optimizing a web application, enhancing a script, or building a data processing pipeline, DiskCache can significantly improve performance.

Getting Started with DiskCache

First, you need to install the DiskCache library:

pip install diskcache

Basic Cache Usage

Here’s a simple example of using DiskCache:

import diskcache as dc

cache = dc.Cache('/tmp/mycache')
cache.set('key', 'value')
assert cache.get('key') == 'value'

API Examples

Setting a Value with Expiration

cache.set('key_with_expiration', 'value', expire=60)  # Expires in 60 seconds

Retrieving a Value with Default

value = cache.get('missing_key', default='default_value')

Checking if a Key Exists

is_key_in_cache = 'key' in cache

Deleting a Key

del cache['key']

Iterating Over Keys

for key in cache:
   print(key)

Clearing the Cache

cache.clear()

Using Context Manager

with dc.Cache('/tmp/mycache') as cache:
    cache.set('key', 'value')

Transactional Mode

with cache.transact():
    cache.set('key1', 'value1')
    cache.set('key2', 'value2')

Advanced Features

Cache Statistics

stats = cache.stats(enable=True)
print(stats)

Eviction Policies

cache.evict()  # Manually evict items based on the default policy

Backends and Caches

disk = dc.Caches()
with disk() as invalids:
    cache = dc.Cache('/tmp/myafscache')
    cache.set('key_a', 'val_a')

Application Example Using DiskCache

Let’s look at a more complete example, demonstrating how DiskCache can be used in a simple web application:

from flask import Flask, request
import diskcache as dc

app = Flask(__name__)
cache = dc.Cache('/tmp/webapp_cache')

@app.route('/set')
def set_value():
    key = request.args.get('key')
    value = request.args.get('value')
    cache.set(key, value)
    return f'Key {key} set to {value}'

@app.route('/get')
def get_value():
    key = request.args.get('key')
    value = cache.get(key, default='Not Found')
    return f'Value for {key} is {value}'

if __name__ == '__main__':
    app.run(debug=True)

This simple Flask application sets and retrieves values from the cache, demonstrating the integration of DiskCache with a web framework.

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