advanced-caching 0.1.3

Production-ready composable caching with TTL, SWR, and background refresh patterns for Python.

advanced-caching

Production-ready caching library with decorators for TTL, stale-while-revalidate (SWR), and background refresh. Type-safe, fast, and framework-agnostic.

Quick Links

• Installation – Get started in 30 seconds
• Quick Examples – Copy-paste ready code
• API Reference – Full decorator & backend docs
• Custom Storage – Implement your own backend
• Benchmarks – See the performance gains
• Use Cases – Real-world examples

Features

Feature	Details
TTL Caching	Simple time-based expiration with key patterns
SWR Pattern	Serve stale data instantly, refresh in background
Background Loading	Pre-load expensive data with periodic refresh
Multiple Backends	In-memory, Redis, custom storage, or hybrid
Thread-Safe	Reentrant locks, atomic operations, concurrent-safe
Type-Safe	Full type hints, IDE-friendly, zero runtime overhead
Framework-Agnostic	Works with FastAPI, Flask, Django, async, or sync
No Required Dependencies	Only APScheduler; Redis is optional

Installation

Quick Install

pip install advanced-caching
# or with uv (recommended)
uv pip install advanced-caching
# with Redis support
pip install "advanced-caching[redis]"

Quick Start

1. TTL Cache – Time-Based Expiration

from advanced_caching import TTLCache

@TTLCache.cached("user:{}", ttl=300)  # Cache 5 minutes
def get_user(user_id: int) -> dict:
    return db.fetch(user_id)

user = get_user(42)  # First: executes & caches
user = get_user(42)  # Later: instant from cache ~0.001ms

2. SWR Cache – Serve Stale, Refresh in Background

from advanced_caching import SWRCache

@SWRCache.cached("product:{}", ttl=60, stale_ttl=30)
def get_product(product_id: int) -> dict:
    return api.fetch_product(product_id)

product = get_product(1)  # Returns immediately (fresh or stale)
# Stale data served instantly, refresh happens in background

3. Background Cache – Pre-Loaded Data

from advanced_caching import BGCache

@BGCache.register_loader("inventory", interval_seconds=300)
def load_inventory() -> list[dict]:
    return warehouse_api.get_all_items()

inventory = load_inventory()  # Instant ~0.001ms (pre-loaded)
# Refreshes every 5 minutes automatically

4. Async Support

# All decorators work with async functions
@TTLCache.cached("user:{}", ttl=300)
async def get_user_async(user_id: int) -> dict:
    return await db.fetch_user(user_id)

user = await get_user_async(42)

Benchmarks

Full benchmarks available in tests/benchmark.py.

API Reference

Key templates & custom keys

All caching decorators share the same key concept:

• key: str – String template or literal
• key: Callable[..., str] – Function that returns a string key

Supported patterns:

1. Positional placeholder – first positional argument:

   @TTLCache.cached("user:{}", ttl=60)
   def get_user(user_id: int):
       ...
   
   get_user(42)  # key -> "user:42"
   

2. Named placeholder – keyword arguments by name:

   @TTLCache.cached("user:{user_id}", ttl=60)
   def get_user(*, user_id: int):
       ...
   
   get_user(user_id=42)  # key -> "user:42"
   

3. Named with extra kwargs – only the named part is used for the key:

   @SWRCache.cached("i18n:{lang}", ttl=60, stale_ttl=30)
   def load_i18n(lang: str, region: str | None = None):
       ...
   
   load_i18n(lang="en", region="US")  # key -> "i18n:en"
   

4. Default arguments + robust key lambda – recommended for complex/default cases:

   @SWRCache.cached(
       key=lambda *a, **k: f"i18n:all:{k.get('lang', a[0] if a else 'en')}",
       ttl=60,
       stale_ttl=30,
   )
   def load_all(lang: str = "en") -> dict:
       print(f"Loading i18n for {lang}")
       return {"hello": f"Hello in {lang}"}
   
   load_all()           # key -> "i18n:all:en"
   load_all("en")      # key -> "i18n:all:en"
   load_all(lang="en") # key -> "i18n:all:en"
   # Body runs once, subsequent calls are cached
   

---

TTLCache.cached(key, ttl, cache=None)

Simple time-based cache with configurable TTL.

Signature:

TTLCache.cached(
    key: str | Callable[..., str],
    ttl: int,
    cache: CacheStorage | None = None,
) -> Callable

Parameters:

• key (str | callable): Cache key template or generator function
• ttl (int): Time-to-live in seconds
• cache (CacheStorage): Optional custom backend (defaults to InMemCache)

Examples:

Positional key:

@TTLCache.cached("user:{},", ttl=300)
def get_user(user_id: int):
    return db.fetch(user_id)

get_user(42)  # key -> "user:42"

Named key:

@TTLCache.cached("user:{user_id}", ttl=300)
def get_user(*, user_id: int):
    return db.fetch(user_id)

get_user(user_id=42)  # key -> "user:42"

Custom key function:

@TTLCache.cached(key=lambda *a, **k: f"user:{k.get('user_id', a[0])}", ttl=300)
def get_user(user_id: int = 0):
    return db.fetch(user_id)

---

SWRCache.cached(key, ttl, stale_ttl=0, cache=None, enable_lock=True)

Serve stale data instantly while refreshing in background.

Signature:

SWRCache.cached(
    key: str | Callable[..., str],
    ttl: int,
    stale_ttl: int = 0,
    cache: CacheStorage | None = None,
    enable_lock: bool = True,
) -> Callable

Parameters:

• key (str | callable): Cache key (same patterns as TTLCache)
• ttl (int): Fresh data TTL in seconds
• stale_ttl (int): Grace period to serve stale data while refreshing
• cache (CacheStorage): Optional custom backend
• enable_lock (bool): Prevent thundering herd (default: True)

Examples:

Basic SWR with positional key:

@SWRCache.cached("product:{}", ttl=60, stale_ttl=30)
def get_product(product_id: int):
    return api.fetch_product(product_id)

get_product(1)  # key -> "product:1"

Named key with kwargs:

@SWRCache.cached("i18n:{lang}", ttl=60, stale_ttl=30)
def load_i18n(*, lang: str = "en") -> dict:
    return {"hello": f"Hello in {lang}"}

load_i18n(lang="en")  # key -> "i18n:en"

Default arg + key lambda (robust):

@SWRCache.cached(
    key=lambda *a, **k: f"i18n:all:{k.get('lang', a[0] if a else 'en')}",
    ttl=60,
    stale_ttl=30,
)
def load_all(lang: str = "en") -> dict:
    return {"hello": f"Hello in {lang}"}

---

BGCache.register_loader(key, interval_seconds, ttl=None, run_immediately=True, on_error=None, cache=None)

Pre-load expensive data with periodic refresh.

Signature:

BGCache.register_loader(
    key: str,
    interval_seconds: int,
    ttl: int | None = None,
    run_immediately: bool = True,
    on_error: Callable[[Exception], None] | None = None,
    cache: CacheStorage | None = None,
) -> Callable

Parameters:

• key (str): Unique cache key (no formatting, fixed string)
• interval_seconds (int): Refresh interval in seconds
• ttl (int | None): Cache TTL (defaults to 2 × interval_seconds when None)
• run_immediately (bool): Load once at registration (default: True)
• on_error (callable): Error handler function (Exception) -> None
• cache (CacheStorage): Optional custom backend

Examples:

Sync loader:

from advanced_caching import BGCache

@BGCache.register_loader(key="inventory", interval_seconds=300, ttl=900)
def load_inventory() -> list[dict]:
    return warehouse_api.get_all_items()

# Later
items = load_inventory()  # instant access to cached data

Async loader:

@BGCache.register_loader(key="products", interval_seconds=300, ttl=900)
async def load_products() -> list[dict]:
    return await api.fetch_products()

products = await load_products()  # returns cached list

With error handling:

errors: list[Exception] = []

def on_error(exc: Exception) -> None:
    errors.append(exc)

@BGCache.register_loader(
    key="unstable",
    interval_seconds=60,
    run_immediately=True,
    on_error=on_error,
)
def maybe_fails() -> dict:
    raise RuntimeError("boom")

# errors list will contain the exception from background job

Shutdown scheduler when done:

BGCache.shutdown(wait=True)

---

Storage Backends

InMemCache()

Thread-safe in-memory cache with TTL.

from advanced_caching import InMemCache

cache = InMemCache()
cache.set("key", value, ttl=60)
value = cache.get("key")  # None if expired
cache.delete("key")
cache.exists("key")  # bool
cache.set_if_not_exists("key", value, ttl)  # bool
cache.cleanup_expired()  # int count

RedisCache(redis_client, prefix="")

Redis-backed distributed cache.

import redis
from advanced_caching import RedisCache

client = redis.Redis(host="localhost", port=6379)
cache = RedisCache(client, prefix="app:")
# Same methods as InMemCache

HybridCache(l1_cache=None, l2_cache=None, l1_ttl=60)

Two-level cache: L1 (fast in-memory) + L2 (persistent Redis).

cache = HybridCache(
    l1_cache=None,  # Defaults to InMemCache
    l2_cache=RedisCache(client),
    l1_ttl=60
)
# Hits from L1 (fast), misses fetch from L2 (distributed)

validate_cache_storage(cache) -> bool

Check if object implements CacheStorage protocol.

from advanced_caching import validate_cache_storage

assert validate_cache_storage(my_cache)  # True if valid

CacheEntry

Access cache metadata (advanced use).

entry = cache.get_entry("key")
if entry and entry.is_fresh():
    print(f"Age: {entry.age():.1f}s")

Custom Storage

Implement the CacheStorage protocol for custom backends (DynamoDB, file-based, encrypted storage, etc.).

File-Based Cache Example

import json
import time
from pathlib import Path
from advanced_caching import CacheStorage, TTLCache, validate_cache_storage


class FileCache(CacheStorage):
    """File-based cache storage."""

    def __init__(self, directory: str = "/tmp/cache"):
        self.directory = Path(directory)
        self.directory.mkdir(parents=True, exist_ok=True)

    def _get_path(self, key: str) -> Path:
        safe_key = key.replace("/", "_").replace(":", "_")
        return self.directory / f"{safe_key}.json"

    def get(self, key: str):
        path = self._get_path(key)
        if not path.exists():
            return None
        try:
            with open(path) as f:
                data = json.load(f)
            if data["fresh_until"] < time.time():
                path.unlink()
                return None
            return data["value"]
        except (json.JSONDecodeError, KeyError, OSError):
            return None

    def set(self, key: str, value, ttl: int = 0) -> None:
        now = time.time()
        fresh_until = now + ttl if ttl > 0 else float("inf")
        data = {"value": value, "fresh_until": fresh_until, "created_at": now}
        with open(self._get_path(key), "w") as f:
            json.dump(data, f)

    def delete(self, key: str) -> None:
        self._get_path(key).unlink(missing_ok=True)

    def exists(self, key: str) -> bool:
        return self.get(key) is not None

    def set_if_not_exists(self, key: str, value, ttl: int) -> bool:
        if self.exists(key):
            return False
        self.set(key, value, ttl)
        return True


# Use it
cache = FileCache("/tmp/app_cache")
assert validate_cache_storage(cache)

@TTLCache.cached("user:{}", ttl=300, cache=cache)
def get_user(user_id: int):
    return {"id": user_id, "name": f"User {user_id}"}

user = get_user(42)  # Stores in /tmp/app_cache/user_42.json

Best Practices

1. TTL Handling – Implement expiration check in get()
2. Thread Safety – Use locks for multi-threaded access
3. Error Handling – Handle I/O errors gracefully
4. Cleanup – Remove expired entries periodically
5. Validation – Use validate_cache_storage() to verify

Testing

Run Tests

pytest tests/test_correctness.py -v

Run Benchmarks

python tests/benchmark.py

---

Use Cases

Web API Caching

from fastapi import FastAPI
from advanced_caching import TTLCache

app = FastAPI()

@app.get("/users/{user_id}")
@TTLCache.cached("user:{}", ttl=300)
async def get_user(user_id: int):
    return await db.fetch_user(user_id)

Database Query Caching

from advanced_caching import SWRCache

@SWRCache.cached("posts:{}", ttl=60, stale_ttl=30)
def get_posts(user_id: int):
    # Serves stale posts while fetching fresh ones
    return db.query("SELECT * FROM posts WHERE user_id = ?", user_id)

Configuration/Settings

from advanced_caching import BGCache

@BGCache.register_loader("config", interval_seconds=300, run_immediately=True)
def load_config():
    # Pre-loaded in background, always fresh
    return settings.load_from_file()

# In app startup
app.config = load_config()

Distributed Caching

import redis
from advanced_caching import HybridCache, RedisCache, TTLCache

client = redis.Redis(host="redis-server")
cache = HybridCache(
    l1_cache=None,
    l2_cache=RedisCache(client),
    l1_ttl=60
)

@TTLCache.cached("data:{}", ttl=300, cache=cache)
def get_data(data_id):
    return expensive_operation(data_id)

---

Comparison with Alternatives

Feature	advanced-caching	functools.lru_cache	cachetools	Redis	Memcached
TTL Support	✅	❌	✅	✅	✅
SWR Pattern	✅	❌	❌	Manual	Manual
Background Refresh	✅	❌	❌	Manual	Manual
Custom Backends	✅	❌	❌	N/A	N/A
Distributed	✅ (Redis)	❌	❌	✅	✅
Async Support	✅	❌	❌	✅	✅
Type Safe	✅	✅	✅	❌	❌
Zero Dependencies	❌ (APScheduler)	✅	✅	❌	❌

---

Development

Setup

git clone https://github.com/agkloop/advanced_caching.git
cd advanced_caching
uv sync
uv run pytest tests/ -v

---

Contributing

Contributions welcome! Please:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/my-feature)
3. Add tests for new functionality
4. Ensure all tests pass (pytest)
5. Submit a pull request

---

License

MIT License – See LICENSE for details.

---

Changelog

0.1.0 (Initial Release)

• ✅ TTL Cache decorator
• ✅ SWR Cache decorator
• ✅ Background Cache with APScheduler
• ✅ InMemCache, RedisCache, HybridCache storage backends
• ✅ Full async/sync support
• ✅ Custom storage protocol
• ✅ Comprehensive test suite
• ✅ Benchmark suite

---

Roadmap

• Distributed tracing/observability
• Metrics export (Prometheus)
• Cache warming strategies
• Serialization plugins (msgpack, protobuf)
• Redis cluster support
• DynamoDB backend example

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