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CacheFSAdapter

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CacheFSAdapter

What it is

  • A filesystem-backed cache adapter implementing ICacheAdapter.
  • Stores each cache entry as a JSON file under a configured directory.
  • Uses SHA-256 of the cache key as the filename.

Public API

  • class CacheFSAdapter(ICacheAdapter)
    • __init__(cache_dir: str)
      • Ensures cache_dir exists (creates it if missing).
    • get(key: str) -> CachedData
      • Loads and returns cached data from the corresponding JSON file.
      • Raises CacheNotFoundError if the cache file does not exist.
    • set(key: str, value: CachedData) -> None
      • Writes value as JSON to the file derived from key.
    • delete(key: str) -> None
      • Deletes the cache file derived from key.
      • Raises CacheNotFoundError if the cache file does not exist.
    • exists(key: str) -> bool
      • Returns True if the cache file for key exists, else False.

Configuration/Dependencies

  • Inputs:
    • cache_dir: directory path used to store cache files.
  • Depends on:
    • naas_abi_core.services.cache.CachePort:
      • CachedData (data model; must support CachedData(**dict) and model_dump()),
      • CacheNotFoundError,
      • ICacheAdapter.

Usage

from naas_abi_core.services.cache.adapters.secondary.CacheFSAdapter import CacheFSAdapter
from naas_abi_core.services.cache.CachePort import CachedData, CacheNotFoundError
 
cache = CacheFSAdapter(cache_dir=".cache")
 
key = "my-cache-key"
value = CachedData()  # populate fields as required by your CachedData model
 
cache.set(key, value)
 
if cache.exists(key):
    loaded = cache.get(key)
    print(loaded)
 
try:
    cache.delete(key)
except CacheNotFoundError:
    pass

Caveats

  • Cache filenames are SHA-256 hashes of keys; original keys are not used as filenames.
  • get()/delete() raise CacheNotFoundError when the corresponding file is missing.
  • Stored format is JSON generated from CachedData.model_dump(); loading expects JSON to match CachedData(**data).

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