`BlobRedundancyManager`: Implement RocksDB Event Listener

[makr-code]

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.