[alerter]bugfix: preserve group alert recovery events

[hutiefang76]

What's changed

Close #4160.

This fixes two group alert lifecycle cases:

• do not let the firing repeat interval suppress pending resolved alerts in a mixed firing group
• recompute the persisted group status from all known member alerts, so one recovered alert does not mark the whole group resolved while another member is still firing

Regression tests cover both the in-memory group reducer path and the database store path.

Verification

• JAVA_HOME=$(/usr/libexec/java_home -v 25 2>/dev/null || /usr/libexec/java_home) ./mvnw -pl hertzbeat-alerter -am test
• git diff --check

[Copilot]

Pull request overview

This PR fixes two alert-group lifecycle edge cases in the alerter pipeline: ensuring recovery (resolved) events are not suppressed by the firing repeat-interval throttle, and ensuring persisted group status reflects the aggregate state of all known member alerts (not just the current push window).

Changes:

• Bypass the group repeat-interval throttle when the group payload includes any resolved member alerts.
• Recompute a group’s persisted status in the DB store layer from all member alert statuses (by fingerprint), and add regression tests for both reducer and store paths.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
hertzbeat-alerter/src/main/java/org/apache/hertzbeat/alert/reduce/AlarmGroupReduce.java	Adjusts repeat-throttle behavior so mixed firing groups with resolved members are still dispatched.
hertzbeat-alerter/src/main/java/org/apache/hertzbeat/alert/notice/impl/DbAlertStoreHandlerImpl.java	Recomputes persisted group status from stored member alerts before saving.
hertzbeat-alerter/src/test/java/org/apache/hertzbeat/alert/reduce/AlarmGroupReduceTest.java	Adds a regression test for “resolved bypasses repeat throttle”.
hertzbeat-alerter/src/test/java/org/apache/hertzbeat/alert/notice/impl/DbAlertStoreHandlerImplTest.java	Adds a regression test ensuring group status stays firing when other members still fire.

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[hutiefang76]

I rebased the branch onto the current master and rechecked the three earlier review points on the latest head: missing group rules now use the default repeat interval, resolved groups reload the full persisted member list, and firing groups skip the extra DB lookup. The focused AlarmGroupReduceTest and DbAlertStoreHandlerImplTest suites pass locally (11 tests, 0 failures/errors), with checkstyle passing across the reactor. The old threads are now outdated and resolved; this is ready for maintainer review.

[hutiefang76]

Thanks for the review. I rechecked the current head and confirmed the three points are covered:

• sendGroupAlert(...) now falls back to DEFAULT_REPEAT_INTERVAL when the cached group rule has been removed; cachedGroupUsesDefaultRepeatIntervalWhenGroupRuleWasRemoved covers that path.
• Historical group-alert lookup is only performed for an incoming resolved group, so firing updates do not add the extra database query; storeFiringGroupDoesNotQueryHistoricalAlerts covers it.
• When a resolved member arrives while another member is still firing, the persisted group is recalculated from the complete stored member set and the returned GroupAlert carries that complete alert list; storeResolvedAlertKeepsGroupFiringWhenOtherGroupAlertsStillFire covers it.

I reran AlarmGroupReduceTest and DbAlertStoreHandlerImplTest from the reactor with a Central-only Maven configuration: 11 tests passed, 0 failures/errors.

[hutiefang76]

Rebased this branch onto current master (8e9f8da), retaining only the follow-up behavior not already covered by #4316:

• For a resolved group update, reload the complete persisted member-alert set before deciding the group status, so another firing member keeps the group firing.
• Keep firing updates on the existing in-memory path without an extra database read.
• Preserve the no-rule default throttle behavior.

Validation completed:

• Targeted Maven reactor test: hertzbeat-alerter with its required modules
• AlarmGroupReduceTest: 8 tests, 0 failures
• DbAlertStoreHandlerImplTest: 6 tests, 0 failures
• git diff --check upstream/master...HEAD

The PR head now contains the rebase and is ready for CI review.