PythonAdapter

What it is

• An in-memory, thread-safe key/value adapter implementing IKeyValueAdapter.
• Stores values as bytes and supports optional TTL-based expiration using time.monotonic().

Public API

Class: PythonAdapter(IKeyValueAdapter)

• __init__() -> None

  • Initializes an empty in-memory store and a lock.

• get(key: str) -> bytes

  • Returns the stored value.
  • Raises KVNotFoundError if the key is missing or expired.

• set(key: str, value: bytes | str | memoryview, ttl: int | None = None) -> None

  • Stores value (normalized to bytes) under key.
  • ttl (seconds) sets an expiration time; None means no expiration.

• set_if_not_exists(key: str, value: bytes | str | memoryview, ttl: int | None = None) -> bool

  • Stores only if the key does not exist (or has expired).
  • Returns True if inserted, False if the key already exists.

• delete(key: str) -> None

  • Deletes the key.
  • Raises KVNotFoundError if the key is missing or expired.

• delete_if_value_matches(key: str, value: bytes | str | memoryview) -> bool

  • Deletes the key only if it exists and its stored value equals the provided value (after normalization).
  • Returns True if deleted, otherwise False.

• exists(key: str) -> bool

  • Returns True if the key exists and is not expired; otherwise False.

Configuration/Dependencies

• Depends on:
  • naas_abi_core.services.keyvalue.KeyValuePorts.IKeyValueAdapter
  • naas_abi_core.services.keyvalue.KeyValuePorts.KVNotFoundError
• Uses standard library:
  • threading.Lock for synchronization
  • time.monotonic() for TTL expiration

Usage

import time
from naas_abi_core.services.keyvalue.adapters.secondary.PythonAdapter import PythonAdapter
from naas_abi_core.services.keyvalue.KeyValuePorts import KVNotFoundError
 
kv = PythonAdapter()
 
kv.set("a", "hello", ttl=1)
print(kv.get("a"))  # b'hello'
 
time.sleep(1.1)
print(kv.exists("a"))  # False
 
try:
    kv.get("a")
except KVNotFoundError:
    print("expired")

Caveats

• Storage is in-memory only; data is lost when the process stops.
• Expired keys are purged lazily (on access via get, set_if_not_exists, delete, delete_if_value_matches, exists), not by a background cleanup thread.
• TTL is interpreted as seconds and is based on time.monotonic() (not wall-clock time).