Reference library

Caching & Redis

Cache-aside, TTL, invalidation, hot keys, and in-memory lookup patterns at scale.

4 matches
Caching & Redis medium

How to Implement a Write-Through Cache in Python with a Mock Database

A thread-safe write-through cache that updates both cache and mock database atomically, computing values only after a successful write to the database.

caching write-through threading
Python 
import threading
import time
import random


class WriteThroughCache:
    def __init__(self):
        self.cache = {}
        self.db = {}
        self.lock = threading.Lock()

    def write(self, key, value):
        with self.lock:
            # Simulate slow database write
            time.sleep(random.uniform(0.01…
12 0 Open
Caching & Redis medium

How to Mock zlib Compression for Cache Values in Python

Compress cache values with zlib and mock the compress function in unit tests to simulate cache behavior.

zlib mock caching
Python 
import zlib
from unittest.mock import patch

def compress_value(data: bytes) -> bytes:
    """Compress data using zlib and return the compressed bytes."""
    return zlib.compress(data)

def decompress_value(compressed: bytes) -> bytes:
    """Decompress zlib data and return the original bytes."""
    return zlib.deco…
11 0 Open
Caching & Redis medium

How to Serialize Cache Values with JSON and Pickle in Python

Serialize cache values using JSON for simple types or pickle for arbitrary objects, with robust error handling for unsupported types like mocks.

serialization caching json
Python 
import json
import pickle
from unittest.mock import Mock

def serialize(value, method="json"):
    """Serialize a cache value using JSON or pickle with type checking."""
    if method == "json":
        try:
            return json.dumps(value).encode("utf-8")
        except TypeError as e:
            raise ValueErro…
11 0 Open
Caching & Redis medium

Implement a TTL cache with a mock clock in Python

This code creates a simple TTL cache that stores values with an expiration timestamp and allows injecting a mock time function to test expiry behavior deterministically.

cache ttl mocking
Python 
import time
from functools import wraps

class TTLCache:
    def __init__(self, ttl_seconds):
        self.ttl = ttl_seconds
        self.cache = {}
        self._now = time.time

    def set_mock_time(self, mock_time_fn):
        """Inject a mock time function for testing TTL expiry."""
        self._now = mock_time_…
15 0 Open

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