<fix>[kvm]: prevent metadata deletion when DVD returns empty

[zstack-robot-1]

ZSTAC-83682

Root Cause

When hypervisor metadata collection from DVD returns an empty list (e.g., DVD not mounted), saveHostOsCategoryList first deleted all existing metadata for the management node, then checked if the input was empty. This wiped all metadata, causing matchTargetVersion to become null and matchState to become Unknown, which suppressed hypervisor mismatch alarms.

Changes

Module	Change
kvm	Move empty-list check before metadata delete in KvmHypervisorInfoManagerImpl.saveHostOsCategoryList(), preserving existing metadata when DVD collection returns empty

Test

• Test cases in premium repo (HypervisorAlarmCase): testMultiClusterAlarmContinue, testUnknownStateTriggersAlarm

Related MRs

• premium: bugfix/ZSTAC-83682@@2 → 5.5.12

Related: ZSTAC-83682

sync from gitlab !9504

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 47efb85 and 8f78f0b.

📒 Files selected for processing (1)

• plugin/kvm/src/main/java/org/zstack/kvm/hypervisor/KvmHypervisorInfoManagerImpl.java

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总体描述

在 KvmHypervisorInfoManagerImpl 类中的 saveHostOsCategoryList 方法内，空输入检查逻辑被重新排序，从方法末尾移至顶部。现在当输入为空时将提前返回，避免不必要的数据库操作。

变更

内聚组 / 文件	变更摘要
KVM 虚拟机管理器元数据处理 plugin/kvm/src/main/java/org/zstack/kvm/hypervisor/KvmHypervisorInfoManagerImpl.java	将空数据验证逻辑提至方法开始。当未收集到超级监视器元数据时，现在立即记录警告并返回false，而无需执行数据库删除操作。

代码审查工作量评估

🎯 1 (简单) | ⏱️ ~5 分钟

庆祝诗

🐰 数据检查挪至前，
空值早返不浪费，
数据库无需做无用功，
逻辑更清晰，流程更顺畅！

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	标题完全符合指定格式 [scope]: ，且长度为60个字符，远低于72字符限制。标题清晰准确地概括了主要改动：防止在DVD返回空列表时删除元数据。
Description check	✅ Passed	描述与代码变更高度相关，详细说明了根本原因、具体变更和测试用例，与changeset内容完全吻合。

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch sync/yaohua.wu/bugfix/ZSTAC-83682@@2

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[ZStack-Robot]

Comment from yaohua.wu:

Review: MR !9504 — ZSTAC-83682 (zstack repo)

Scope: KvmHypervisorInfoManagerImpl.saveHostOsCategoryList() — 防御性 metadata 保护

业务背景

仅升级 MN 的 qemu 并重启后，物理机 matchState 变为 Unknown（因 metadata 被清空），且报警检查器只筛选 Unmatched 状态，导致 qemu 版本不一致报警缺失。本 MR 修复根因之一：DVD 采集返回空列表时先删后查导致 metadata 被清空。

变更分析

将 CollectionUtils.isEmpty(categoryVOS) 检查从 DELETE 操作之后移到之前，空列表时直接 return false 跳过刷新，保留已有 metadata。

验证链路：

• start() → refreshMetadata() → saveMetadataList() → saveHostOsCategoryList()
• 该方法标注 @Transactional，空列表提前返回时无 DB 操作，事务无副作用 ✅
• saveHostOsCategoryList 为 protected，仅 saveMetadataList 调用，调用链唯一 ✅
• 后续 refreshHostMatchState() 依赖 metadata 表数据（通过 collectExpectedHypervisorInfoForHosts 实时查询），metadata 保留后 matchTargetVersion 不会变为 null ✅

Upstream Freshness

分支基于 upstream/5.5.12 最新提交 (47efb851)，无冲突风险。✅

Verdict: APPROVED ✅

修复精准，改动最小化（仅移动代码顺序 + 增加 warn 日志），无副作用风险。日志信息 "no hypervisor metadata collected from DVD, skip refresh to preserve existing metadata" 清晰描述了行为和原因。

Suggestion

1. [KvmHypervisorInfoManagerImpl.java] 测试覆盖 — 当前 premium 仓库的测试覆盖了 Unknown 状态触发报警的场景，但未直接测试"空列表不删除 metadata"这一防御逻辑。建议补充一个测试：模拟 saveHostOsCategoryList([]) 后验证已有 metadata 记录未被删除，防止未来重构回归。

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🤖 Robot Reviewer