Bug: Redis layer fails the invocation instead of retrying when a record expires between SET NX and GET

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@coughlmao 已经在做这个了。

开始于 2026年11月1日。

  • #8736 来自 @coughlmao —— 未关闭

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Issue 类型
缺陷
描述清晰度
描述清楚
活跃度
活跃
技术栈
python, redis
领域
databases

调研方向

编辑 aws_lambda_powertools/utilities/idempotency/persistence/redis.py 中的 _put_record：在 SET NX 失败后捕获 IdempotencyItemNotFoundError 并抛出 IdempotencyInconsistentStateError。添加一个测试，使用在 GET 时返回 None 的假客户端，断言被装饰的函数执行。当该测试通过且 issue 中的代码片段返回 "ok" 时完成。

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描述

bug good first issue help wanted idempotency

[!WARNING]
For contributors, human or agent. Comment here to claim this issue and wait for the assignment before opening a PR; if two PRs show up, the assignee's stays. AI-assisted work is welcome, say so in the PR and tell us how you verified it: run the tests yourself and paste what you saw, do not describe runs you did not do. Read AGENTS.md first, it has the commands and the rules the CI enforces. This goes into 3.41.0.

Expected Behaviour

When a Redis record expires between the SET NX that fails and the GET that follows, the Redis layer behaves like the DynamoDB layer: it raises IdempotencyInconsistentStateError, which the handler's retry loop turns into a retry, and the invocation succeeds.

Current Behaviour

In CachePersistenceLayer._put_record, the GET after a failed SET NX goes through _get_record, which raises IdempotencyItemNotFoundError. That exception is not handled there, escapes _put_record and is wrapped as IdempotencyPersistenceLayerError, so the invocation fails for a race that is expected and recoverable.

Code snippet
# fake client: SET NX returns None (key existed), the following GET returns None (key expired in between)
layer = CachePersistenceLayer(client=racy_client)

@idempotent_function(data_keyword_argument="order", persistence_store=layer)
def process(order):
    return "ok"

process(order={"id": 1})  # IdempotencyPersistenceLayerError, expected: retried and "ok"

Compare with DynamoDBPersistenceLayer._put_record, where the equivalent race raises IdempotencyInconsistentStateError.

Possible Solution

In aws_lambda_powertools/utilities/idempotency/persistence/redis.py, _put_record: catch IdempotencyItemNotFoundError around the read that follows the failed SET NX and raise IdempotencyInconsistentStateError. Add a test with a fake client that returns None on that GET and assert the decorated function runs.

Item 10 of the Idempotency audit in #8603. No AWS resources needed.

Powertools for AWS Lambda (Python) version

latest

AWS Lambda function runtime

3.13

Packaging format used

PyPi

Debugging logs

No response

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