Ct Cache Lib

A specialized library developed by Credenti for efficient caching in Flask applications.

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Features

• Decorator-based caching for Flask endpoints and functions
• Configurable Valkey connection pooling
• Supports cache key templating with nested attribute access
• Easy integration with Flask app lifecycle

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Installation

pip install ct-cache-lib

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Configuration

Add the following to your Flask app configuration:

app.config["CACHE"] = True              # Enable or disable caching
app.config["CACHE_EXPIRE_TIME"] = 60    # Default cache expiration time in seconds
app.config["CACHE_HOST"] = "localhost"  # Cache host
app.config["CACHE_PORT"] = 6379         # Cache port
app.config["CACHE_USERNAME"] = "user"   # Cache username (if required)
app.config["CACHE_PASSWORD"] = "pass"   # Cache password (if required)
app.config["CACHE_CLIENT_NAME"] = "my-client" # Cache client name

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Usage

The @ct_cache.cache decorator can be applied to any function to enable caching. It supports both positional and keyword arguments.

You can also set read_only=True to prevent the cache from being updated on a cache miss. This is useful for high-priority reads where you want to avoid writing to the cache.

from flask import Flask
from ct_cache_lib import init_cache
import logging

app = Flask(__name__)
logger = logging.getLogger(__name__)

# Initialize the cache
ct_cache = init_cache(app, logger)

@app.route("/idle_time")
@ct_cache.cache(template_cache_key="idle_time_value:$idle_time", field="$idle_time")
def get_idle_time_value(idle_time: str):
    # Your function logic here
    return {"idle_time": idle_time}

Bypassing the Cache

You can dynamically bypass the cache for any decorated function by passing use_cache=False when you call it. This tells the decorator to ignore the cache and execute the function directly.

# This call will use the cache
get_idle_time_value(idle_time="123")

# This call will bypass the cache and execute the function
get_idle_time_value(idle_time="123", use_cache=False)

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Updating a Cache Entry

Update a cache entry directly:

ct_cache.update(
    cache_key="idle_time_value:123",  # Actual cache key
    field="some_field",
    value={"idle_time": 123},
    is_global=False,                  # or True if the key is global
    expire_time=120                   # optional, in seconds
)

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Deleting a Cache Entry

Delete a cache entry:

ct_cache.delete(
    cache_key="idle_time_value:123",  # Actual cache key, not a template
    field="some_field",
    is_global=False                   # or True if the key is global
)

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Deleting Cache Entries by Patterns

Delete cache entries that match one or more patterns. This is useful for bulk invalidation of related keys.

ct_cache.delete_by_patterns(
    "user:123:*",
    "session:*:active",
    is_global=False,  # or True if the patterns are global
    batch_size=500    # optional, number of keys to delete in each batch
)

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Committing and Resetting Cache

Commit cache writes after each request:

@app.after_request
def after_request(response):
    ct_cache.commit(response)
    return response

Reset cache if you need to roll back changes:

ct_cache.reset()

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Cache Key Specification Examples

You can use dynamic cache keys by referencing function arguments or nested data using $.

Basic Example

@ct_cache.cache(template_cache_key="idle_time_value:$idle_time", field="$idle_time")
def get_idle_time_value(idle_time: str):
    return {"idle_time": idle_time}

• If idle_time = 123, the cache key will be idle_time_value:123.

Keyword Argument Example

The decorator also supports keyword arguments, making it flexible for various function signatures.

@ct_cache.cache(template_cache_key="user_cache:$user_id", field="$user_id")
def get_user_by_id(user_id: int):
    # Function logic to fetch user
    return {"user_id": user_id}

• If you call get_user_by_id(user_id=42), the cache key will be user_cache:42.

Nested Dictionary Example

@ct_cache.cache(template_cache_key="user_cache:$user.id", field="$user.id")
def get_user(user: dict):
    return user

• If user = {"id": 01, "name": "User1"}, the cache key will be user_cache:01.

Nested Object Example

class User:
    def __init__(self, id, name):
        self.id = id
        self.name = name

@ct_cache.cache(template_cache_key="user_cache:$user.id", field="$user.id")
def get_user_obj(user: User):
    return {"id": user.id, "name": user.name}

• If user.id = 01, the cache key will be user_cache:01.

Deeply Nested Example

@ct_cache.cache(template_cache_key="deep_cache:$data.profile.info.id", field="$data.profile.info.id")
def get_deep(data: dict):
    return data

• If data = {"profile": {"info": {"id": 01}}}, the cache key will be deep_cache:01.

Static Key Example

@ct_cache.cache(template_cache_key="static_key")
def get_static():
    return {"result": 1}

• The cache key will always be static_key.

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