feat(storage): BlobRedundancyManager — implement RocksDB EventListener for SST deletion

[Copilot]

createRocksDBListener() unconditionally returned "RocksDB listener not implemented" and OnTableFileDeleted() was a no-op, leaving the redundancy manager blind to compaction-driven SST deletions and unable to trigger replication for blobs that lost their backing file.

Changes

Core implementation

• createRocksDBListener(): returns a real RocksDBBlobListener instead of an error
• notifySSTFileDeleted(file_path) (new public method): write-locks blobs_, marks every BlobLocation whose path matches as is_healthy = false, collects affected blob IDs, and drains them into repair_queue_ with repair_cv_.notify_all()
• RocksDBBlobListener::OnTableFileDeleted(): delegates to notifySSTFileDeleted(info.file_path) — was previously a logging stub

Listener registration

• RocksDBWrapper::addEventListener(shared_ptr<EventListener>) (new): pushes into options_->listeners before open() so callers can wire the blob listener at DB-open time
• Added #include <rocksdb/listener.h> and class EventListener forward-declaration to rocksdb_wrapper

Tests (tests/test_raid_redundancy.cpp)

• CreateRocksDBListenerSucceeds — factory returns non-null
• NotifySSTFileDeletedMarksLocationUnhealthy — primary location transitions to unhealthy
• NotifySSTFileDeletedUnknownPathIsNoOp — unknown path does not crash or mutate state
• NotifySSTFileDeletedOnlyAffectsMatchingBlobs — sibling blob stays healthy
• RocksDBListenerOnTableFileDeletedTriggersReplication — end-to-end: OnTableFileDeleted via factory listener marks location unhealthy

Build / CI

• tests/CMakeLists.txt: test_blob_redundancy_event_listener_focused target running BlobRedundancyManagerTest.*
• .github/workflows/blob-redundancy-event-listener-ci.yml: matrix (gcc-12, clang-15, gcc-13) scoped to the touched files

Type of Change

• Bug fix
• New feature
• Refactoring
• Documentation
• Other:

Testing

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed

📚 Research & Knowledge (wenn applicable)

• Diese PR basiert auf wissenschaftlichen Paper(s) oder Best Practices?
  • Falls JA: Research-Dateien in /docs/research/ angelegt?
  • Falls JA: Im Modul-README unter "Wissenschaftliche Grundlagen" verlinkt?
  • Falls JA: In /docs/research/implementation_influence/ eingetragen?

Relevante Quellen:

• Paper:
• Best Practice:
• Architecture Decision:

Checklist

• Code follows project style guidelines
• Self-review completed
• Documentation updated (if needed)
• No new warnings introduced

Original prompt

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This section details on the original issue you should resolve

<issue_title>BlobRedundancyManager: Implement RocksDB Event Listener</issue_title>
<issue_description>### Context

This issue implements the roadmap item 'BlobRedundancyManager: Implement RocksDB Event Listener' for the storage domain. It is sourced from the consolidated roadmap under 🟢 Low Priority — Future (v1.9.0+) and targets milestone v1.8.0.

Primary detail section: BlobRedundancyManager: Implement RocksDB Event Listener

Goal

Deliver the scoped changes for BlobRedundancyManager: Implement RocksDB Event Listener in src/storage/ and complete the linked detail section in a release-ready state for v1.8.0.

Detailed Scope

BlobRedundancyManager: Implement RocksDB Event Listener

Priority: Low
Target Version: v1.8.0

blob_redundancy_manager.cpp line 768: "RocksDB listener not implemented" — the redundancy manager cannot react to RocksDB compaction events (SST file deletions) to trigger re-replication of blobs that lose their storage backing.

Implementation Notes:

• [ ] Implement a BlobRedundancyEventListener subclassing rocksdb::EventListener; override OnTableFileDeleted to trigger re-replication of any blobs whose backing SST was deleted.
• [ ] Register the listener via rocksdb::Options::listeners at database open time.

---

Priority: High
Target Version: v1.7.0

Raft-based distributed transactions across multiple nodes.

Features:

• Two-phase commit (2PC) protocol
• Raft consensus for transaction coordination
• Cross-shard atomic operations
• Automatic deadlock detection

API:

DistributedTransactionManager dtx_manager(nodes);
auto tx = dtx_manager.beginDistributedTransaction();

// Write to multiple shards
tx->put("shard1:key1", "value1");
tx->put("shard2:key2", "value2");

// Commit atomically across shards
tx->commit();  // 2PC protocol

Use Cases:

• Multi-tenant data isolation
• Geographic data distribution
• Horizontal scaling

---

Acceptance Criteria

• Implement a BlobRedundancyEventListener subclassing rocksdb::EventListener; override OnTableFileDeleted to trigger re-replication of any blobs whose backing SST was deleted.
• Register the listener via rocksdb::Options::listeners at database open time.
• Two-phase commit (2PC) protocol
• Raft consensus for transaction coordination
• Cross-shard atomic operations
• Automatic deadlock detection
• Multi-tenant data isolation
• Geographic data distribution
• Horizontal scaling

Relationships

• Roadmap row: Add comprehensive attack vector analysis for ThemisDB v1.4.0-alpha #259 (🟢 Low Priority — Future (v1.9.0+))
• Depends on: none identified during generation.
• Part of: consolidated roadmap delivery tracking.

References

• src/ROADMAP.md
• src/storage/FUTURE_ENHANCEMENTS.md#blobredundancymanager-implement-rocksdb-event-listener
• Source key: roadmap:259:storage:v1.8.0:blobredundancymanager-implement-rocksdb-event-listener

Generated from the consolidated source roadmap. Keep the roadmap and issue in sync when scope changes.

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes BlobRedundancyManager: Implement RocksDB Event Listener #4089

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