fix: add graceful termination of futures in vmaas_sync

[RostyslavKachan]

RHINENG-22131

Secure Coding Practices Checklist GitHub Link

• https://github.com/RedHatInsights/secure-coding-checklist

Secure Coding Checklist

• Input Validation
• Output Encoding
• Authentication and Password Management
• Session Management
• Access Control
• Cryptographic Practices
• Error Handling and Logging
• Data Protection
• Communication Security
• System Configuration
• Database Security
• File Management
• Memory Management
• General Coding Practices

Summary by Sourcery

Bug Fixes:

• Prevent premature completion of the re_evaluation process by awaiting all Kafka send operations before finalizing.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Ensures that all asynchronous Kafka send operations in vmaas_sync.re_evaluate_systems complete gracefully before logging completion and committing, by tracking created futures and awaiting them at the end of processing.

Sequence diagram for graceful completion of Kafka send futures in re_evaluate_systems

sequenceDiagram
    participant re_evaluate_systems
    participant EVENT_LOOP as EVENT_LOOP
    participant BATCH_SEMAPHORE as BATCH_SEMAPHORE
    participant cur as cur
    participant EVALUATOR_QUEUE as EVALUATOR_QUEUE
    participant LOGGER as LOGGER

    re_evaluate_systems->>EVENT_LOOP: loop = EVENT_LOOP
    re_evaluate_systems->>re_evaluate_systems: total_scheduled = 0
    re_evaluate_systems->>re_evaluate_systems: futures = []

    loop while More database rows
        re_evaluate_systems->>EVENT_LOOP: run_until_complete(BATCH_SEMAPHORE.acquire())
        re_evaluate_systems->>cur: fetchmany(size = CFG.re_evaluation_kafka_batch_size)
        cur-->>re_evaluate_systems: rows
        re_evaluate_systems->>re_evaluate_systems: msgs = lists of system ids
        re_evaluate_systems->>re_evaluate_systems: total_scheduled += len(msgs)
        re_evaluate_systems->>EVALUATOR_QUEUE: send_list(msgs, loop = loop)
        EVALUATOR_QUEUE-->>re_evaluate_systems: future
        re_evaluate_systems->>future: add_done_callback(lambda x: BATCH_SEMAPHORE.release())
        re_evaluate_systems->>re_evaluate_systems: futures.append(future)
    end

    alt futures not empty
        re_evaluate_systems->>LOGGER: info(Waiting for N Kafka send operations to complete)
        re_evaluate_systems->>EVENT_LOOP: run_until_complete(asyncio.gather(*futures))
    end

    re_evaluate_systems->>LOGGER: info(N systems scheduled for re-evaluation)
    re_evaluate_systems->>DB as DB: conn.commit()

Loading

File-Level Changes

Change	Details	Files
Track and gracefully await all Kafka send futures before finishing re_evaluate_systems.	Introduce a list to collect futures returned by EVALUATOR_QUEUE.send_list during batch scheduling. Append each newly created future to the tracking list after attaching the semaphore-release callback. After the batching loop exits, if any futures were created, log how many pending Kafka send operations exist. Use asyncio.gather within the existing event loop to await completion of all collected futures before logging total systems scheduled and committing the transaction.	vmaas_sync/vmaas_sync.py

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[sourcery-ai]

Hey there - I've reviewed your changes - here's some feedback:

• Accumulating all future objects in a single futures list for the entire while True loop can lead to unnecessary memory growth for large re-evaluation runs; consider periodically awaiting and clearing a batch-local list of futures (e.g., per DB fetch) instead of storing all of them until the very end.
• When using asyncio.gather(*futures) without return_exceptions=True, a single exception in one send operation will raise and skip awaiting the rest; if partial completion is acceptable or you need to ensure all callbacks fire, consider return_exceptions=True and explicit error handling/logging.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- Accumulating all `future` objects in a single `futures` list for the entire `while True` loop can lead to unnecessary memory growth for large re-evaluation runs; consider periodically awaiting and clearing a batch-local list of futures (e.g., per DB fetch) instead of storing all of them until the very end.
- When using `asyncio.gather(*futures)` without `return_exceptions=True`, a single exception in one send operation will raise and skip awaiting the rest; if partial completion is acceptable or you need to ensure all callbacks fire, consider `return_exceptions=True` and explicit error handling/logging.

## Individual Comments

### Comment 1
<location> `vmaas_sync/vmaas_sync.py:387` </location>
<code_context>
+
+            if futures:
+                LOGGER.info("Waiting for %s Kafka send operations to complete", len(futures))
+                loop.run_until_complete(asyncio.gather(*futures))
+
             LOGGER.info("%s systems scheduled for re-evaluation", total_scheduled)
</code_context>

<issue_to_address>
**question (bug_risk):** Async gather error handling might need to distinguish partial failures

Calling `asyncio.gather(*futures)` without `return_exceptions=True` means one failing Kafka send will raise and cancel the rest, changing behavior from “fire-and-forget” to “fail-fast and cancel peers.” If you want all sends to run and then handle/log failures individually, use `asyncio.gather(*futures, return_exceptions=True)` and handle exceptions explicitly so one bad send doesn’t prevent others from completing.
</issue_to_address>

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[sourcery-ai]

question (bug_risk): Async gather error handling might need to distinguish partial failures

Calling asyncio.gather(*futures) without return_exceptions=True means one failing Kafka send will raise and cancel the rest, changing behavior from “fire-and-forget” to “fail-fast and cancel peers.” If you want all sends to run and then handle/log failures individually, use asyncio.gather(*futures, return_exceptions=True) and handle exceptions explicitly so one bad send doesn’t prevent others from completing.

[RostyslavKachan]

/retest

[RostyslavKachan]

/retest

[RostyslavKachan]

/retest