pssecret_server/utils.py

@@ -1,7 +1,10 @@
+from functools import lru_cache
 from uuid import uuid4
 
 from cryptography.fernet import Fernet
 from redis.asyncio import Redis
+from redis.exceptions import ResponseError
+from redis.typing import ResponseT
 
 from pssecret_server.models import Secret
 
@@ -30,3 +33,35 @@ async def save_secret(data: Secret, redis: Redis) -> str:
     await redis.setex(new_key, 60 * 60 * 24, data.data)
 
     return new_key
+
+
+@lru_cache
+async def _is_getdel_available(redis: Redis) -> bool:
+    """Checks the availability of GETDEL command on the Redis server instance
+
+    GETDEL is not available in Redis prior to version 6.2
+    """
+    try:
+        await redis.getdel("test:getdel:availability")
+    except ResponseError:
+        return False
+
+    return True
+
+
+async def getdel(redis: Redis, key: str) -> ResponseT:
+    """Gets the value of key and deletes the key
+
+    Depending on the capabilities of Redis server this function
+    will either call GETDEL command, either first call GETSET with empty string
+    and DEL right after that.
+    """
+    result: ResponseT
+
+    if await _is_getdel_available(redis):
+        result = await redis.getdel(key)
+    else:
+        result = await redis.getset(key, "")
+        await redis.delete(key)
+
+    return result

pyproject.toml

@@ -53,3 +53,6 @@ reportUnusedCallResult = "none"
 
 [tool.pytest.ini_options]
 asyncio_mode = "auto"
+
+[tool.isort]
+profile = "black"

tests/integration/test_utils.py

@@ -1,8 +1,9 @@
-from unittest.mock import patch
+from unittest.mock import AsyncMock, patch
 
+import pytest
 from redis.asyncio import Redis
 
-from pssecret_server.utils import get_new_key, save_secret
+from pssecret_server.utils import get_new_key, getdel, save_secret
 
 from ..factories import SecretFactory
 
@@ -33,3 +34,22 @@ async def test_save_secret_data(redis_server: Redis) -> None:
 
     assert redis_data is not None
     assert redis_data.decode() == secret.data
+
+
+@pytest.mark.parametrize("getdel_available", [True, False])
+@patch("pssecret_server.utils._is_getdel_available", new_callable=AsyncMock)
+async def test_getdel(
+    mock_is_getdel_available: AsyncMock,
+    getdel_available: bool,
+    redis_server: Redis,
+) -> None:
+    mock_is_getdel_available.return_value = getdel_available
+
+    test_value = "test_data"
+    test_key = "test_key"
+    await redis_server.set(test_key, test_value)
+
+    result = await getdel(redis_server, test_key)
+
+    assert result.decode() == test_value  # pyright: ignore[reportAttributeAccessIssue]
+    assert not await redis_server.exists(test_key)

tests/unit/test_utils.py

@@ -1,7 +1,10 @@
+from unittest.mock import AsyncMock
+
 import pytest
 from cryptography.fernet import Fernet, InvalidToken
+from redis.exceptions import ResponseError
 
-from pssecret_server.utils import decrypt_secret, encrypt_secret
+from pssecret_server.utils import _is_getdel_available, decrypt_secret, encrypt_secret
 
 from ..factories import SecretFactory
 
@@ -29,3 +32,17 @@ def test_secret_is_not_decryptable_by_random_key(fernet: Fernet):
 
     with pytest.raises(InvalidToken):
         decrypt_secret(encrypted_secret.data.encode(), random_fernet)
+
+
+@pytest.mark.parametrize(
+    ("getdel_effect", "expected_result"), [(None, True), (ResponseError, False)]
+)
+async def test_is_getdel_available(
+    getdel_effect: ResponseError | None, expected_result: bool
+):
+    redis = AsyncMock()
+    redis.getdel.side_effect = getdel_effect  # pyright: ignore[reportAny]
+
+    result = await _is_getdel_available(redis)
+
+    assert result is expected_result