feat(replication): Multi-Tier Replication Manager (v1.8.0) by Copilot · Pull Request #4203 · makr-code/ThemisDB

Copilot · 2026-03-13T19:40:55Z

Implements hierarchical replication with three configurable durability/consistency tiers and automatic tier promotion/demotion based on per-collection access patterns.

Description

Three-tier model:

TIER_1_CRITICAL — 3+ replicas, SYNC, <10 ms SLA (financial transactions, auth)
TIER_2_STANDARD — 2 replicas, SEMI_SYNC, <50 ms SLA (profiles, catalogs)
TIER_3_ARCHIVAL — 1 replica, ASYNC, no latency guarantee (audit logs, metrics)

New files:

include/replication/multi_tier_replication.h — MultiTierReplicationManager, ReplicationTier, TierConfig, MultiTierConfig, CollectionAccessStats, MultiTierStats
src/replication/multi_tier_replication.cpp — Full implementation; thread-safe via independent shared_mutex for assignments and stats (lock-order enforced to prevent deadlock); per-tier config overrides; built-in defaults

Updated files:

tests/test_replication_ha.cpp — 19 new tests (MultiTierReplicationTest) covering all 5 ACs
tests/CMakeLists.txt — MultiTierReplicationFocusedTests focused target
cmake/ModularBuild.cmake — multi_tier_replication.cpp added to THEMIS_TRANSACTION_SOURCES
.github/workflows/multi-tier-replication-ci.yml — CI on Ubuntu 22.04/gcc-12 and Ubuntu 24.04/gcc-14
src/replication/ROADMAP.md — Phase 8 marked complete ✅

Usage example:

MultiTierConfig cfg;
cfg.auto_tiering_enabled  = true;
cfg.hot_access_threshold  = 100;  // accesses/min → Tier 1
cfg.cold_access_threshold = 5;    // accesses/min → Tier 3

MultiTierReplicationManager mgr(cfg);
mgr.assignTier("financial_transactions", ReplicationTier::TIER_1_CRITICAL);
mgr.assignTier("user_profiles",          ReplicationTier::TIER_2_STANDARD);
mgr.assignTier("audit_logs",             ReplicationTier::TIER_3_ARCHIVAL);

// Auto-tiering: hot data promoted, cold data demoted
mgr.recordAccess("audit_logs");
ReplicationTier t = mgr.evaluateTierPromotion("audit_logs"); // → TIER_3_ARCHIVAL if cold

Type of Change

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

This section details on the original issue you should resolve

<issue_title>Multi-Tier Replication</issue_title>
<issue_description>### Context

This issue implements the roadmap item 'Multi-Tier Replication' for the replication domain. It is sourced from the consolidated roadmap under 🟢 Low Priority — Future (v1.9.0+) and targets milestone v1.8.0.

Primary detail section: Multi-Tier Replication

Goal

Deliver the scoped changes for Multi-Tier Replication in src/replication/ and complete the linked detail section in a release-ready state for v1.8.0.

Detailed Scope

Multi-Tier Replication

Priority: Low
Target Version: v1.8.0

Hierarchical replication with different consistency and durability tiers.

Features:

Tier 1: Strong consistency, high durability (3+ replicas)

Tier 2: Eventual consistency, moderate durability (2 replicas)

Tier 3: Best-effort, low durability (1 replica, async)

Per-collection tier assignment

Automatic tier promotion/demotion based on access patterns

Architecture:
class MultiTierReplicationManager {
public:
    enum ReplicationTier {
        TIER_1_CRITICAL,    // 3+ replicas, sync, <10ms
        TIER_2_STANDARD,    // 2 replicas, semi-sync, <50ms
        TIER_3_ARCHIVAL     // 1 replica, async, no guarantee
    };
    
    struct TierConfig {
        ReplicationTier tier;
        uint32_t replica_count;
        ReplicationMode mode;
        uint32_t max_latency_ms;
        uint32_t min_availability_percent;
    };
    
    // Assign collection to tier
    void assignTier(const std::string& collection, ReplicationTier tier);
    
    // Automatic tier adjustment based on access patterns
    void enableAutoTiering(bool enabled);
    
    // Get current tier for collection
    ReplicationTier getTier(const std::string& collection) const;
};

// Example: Multi-tier replication
MultiTierReplicationManager multi_tier;

// Tier assignments
multi_tier.assignTier("financial_transactions", ReplicationTier::TIER_1_CRITICAL);
multi_tier.assignTier("user_profiles", ReplicationTier::TIER_2_STANDARD);
multi_tier.assignTier("audit_logs", ReplicationTier::TIER_3_ARCHIVAL);

// Auto-tiering based on access
multi_tier.enableAutoTiering(true);  // Hot data → Tier 1, Cold data → Tier 3
Acceptance Criteria

Tier 1: Strong consistency, high durability (3+ replicas)

Tier 2: Eventual consistency, moderate durability (2 replicas)

Tier 3: Best-effort, low durability (1 replica, async)

Per-collection tier assignment

Automatic tier promotion/demotion based on access patterns

Relationships

Roadmap row: Security analysis and detection framework for LLM and LoRa adapter attack vectors #258 (🟢 Low Priority — Future (v1.9.0+))

Depends on: none identified during generation.

Part of: consolidated roadmap delivery tracking.

References

src/ROADMAP.md

src/replication/FUTURE_ENHANCEMENTS.md#multi-tier-replication

Source key: roadmap:258:replication:v1.8.0:multi-tier-replication

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 Multi-Tier Replication #4088

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

Co-authored-by: makr-code <150588092+makr-code@users.noreply.github.com>

Copilot

Pull request overview

Adds a new replication-domain component (MultiTierReplicationManager) implementing a configurable three-tier durability/consistency model with optional auto-tiering driven by per-collection access rates, along with focused CI and unit test coverage.

Changes:

Introduces MultiTierReplicationManager API + implementation with tier assignment, per-tier config defaults/overrides, auto-tiering, and stats.
Extends replication HA tests with a new MultiTierReplicationTest suite and adds a focused CTest target.
Wires the module into modular builds, adds a dedicated GitHub Actions workflow, and updates the replication roadmap.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
`include/replication/multi_tier_replication.h`	Declares tiers/configs/stats and the `MultiTierReplicationManager` public API.
`src/replication/multi_tier_replication.cpp`	Implements tier assignment, auto-tiering, and stats tracking with shared-mutex-based synchronization.
`tests/test_replication_ha.cpp`	Adds `MultiTierReplicationTest` validating tier defaults, assignment, auto-tiering decisions, and stats.
`tests/CMakeLists.txt`	Adds `MultiTierReplicationFocusedTests` target and ctest registration.
`cmake/ModularBuild.cmake`	Adds `multi_tier_replication.cpp` to the transaction module source list for modular builds.
`.github/workflows/multi-tier-replication-ci.yml`	Adds a focused CI workflow to build/run the multi-tier replication focused suite on Ubuntu.
`src/replication/ROADMAP.md`	Marks the module complete and documents delivered scope/tests/CI.

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src/replication/multi_tier_replication.cpp

+    // Simple rate: recent_accesses / window_seconds * 60
+    const double window = static_cast<double>(
+        config_.auto_tier_window_seconds > 0 ? config_.auto_tier_window_seconds : 60);
+    stats.access_rate_per_min = (stats.recent_accesses / window) * 60.0;


src/replication/multi_tier_replication.cpp

+ReplicationTier MultiTierReplicationManager::evaluateTierPromotion(
+    const std::string& collection)
+{
+    if (!auto_tiering_.load()) {
+        return getTier(collection);
+    }
+
+    ReplicationTier current = getTier(collection);
+    double rate = 0.0;
+
+    {
+        std::unique_lock<std::shared_mutex> lk(stats_mutex_);
+        auto& stats = access_stats_[collection];
+        if (stats.collection.empty()) {
+            stats.collection   = collection;
+            stats.current_tier = current;
+        }


src/replication/multi_tier_replication.cpp

+ *   TIER_1_CRITICAL  – 3 replicas, SYNC, 10 ms SLA, 99.9% availability
+ *   TIER_2_STANDARD  – 2 replicas, SEMI_SYNC, 50 ms SLA, 99% availability
+ *   TIER_3_ARCHIVAL  – 1 replica,  ASYNC,   no SLA,  90% availability
+ */
+TierConfig builtinTierConfig(ReplicationTier tier) {
+    switch (tier) {
+    case ReplicationTier::TIER_1_CRITICAL: {
+        TierConfig cfg;
+        cfg.tier                 = ReplicationTier::TIER_1_CRITICAL;
+        cfg.replica_count        = 3;
+        cfg.mode                 = ReplicationMode::SYNC;
+        cfg.max_latency_ms       = 10;
+        cfg.min_availability_pct = 99; // 99.9% rounded to uint
+        return cfg;


include/replication/multi_tier_replication.h

+    // ── Internal helpers ──────────────────────────────────────────────────────
+
+    /**
+     * Recompute access_rate_per_min and recent_accesses for a collection.


include/replication/multi_tier_replication.h

+    /**
+     * Apply a tier change and update promotion/demotion counters.
+     * Must be called while holding the assignment write lock.
+     */
+    void applyTierChange(const std::string& collection,
+                         ReplicationTier    old_tier,
+                         ReplicationTier    new_tier);


tests/CMakeLists.txt

+    add_executable(test_multi_tier_replication_focused
+        test_replication_ha.cpp
+        ${CMAKE_SOURCE_DIR}/src/replication/multi_tier_replication.cpp
+    )
+
+    target_include_directories(test_multi_tier_replication_focused PRIVATE
+        ${CMAKE_SOURCE_DIR}/include
+        ${CMAKE_SOURCE_DIR}/src
+    )
+
+    target_link_libraries(test_multi_tier_replication_focused PRIVATE
+        ${TEST_LIBS}
+        themis_core
+        Threads::Threads


cmake/ModularBuild.cmake

    ../src/replication/replication_slot.cpp
    ../src/replication/raft_v2.cpp
    ../src/replication/schema_cdc.cpp
+    ../src/replication/multi_tier_replication.cpp


src/replication/multi_tier_replication.cpp

+void MultiTierReplicationManager::enableAutoTiering(bool enabled)
+{
+    auto_tiering_.store(enabled);
+    config_.auto_tiering_enabled = enabled;


Initial plan

5e922e4

Copilot AI assigned Copilot and makr-code Mar 13, 2026

Copilot started work on behalf of makr-code March 13, 2026 19:59 View session

feat(replication): implement MultiTierReplicationManager (v1.8.0)

387fde9

Co-authored-by: makr-code <150588092+makr-code@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Implement multi-tier replication for the replication domain~~ feat(replication): Multi-Tier Replication Manager (v1.8.0) Mar 13, 2026

Copilot AI requested a review from makr-code March 13, 2026 20:14

Copilot finished work on behalf of makr-code March 13, 2026 20:14

makr-code approved these changes Mar 14, 2026

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makr-code marked this pull request as ready for review March 14, 2026 06:13

makr-code requested a review from Copilot March 14, 2026 06:13

Copilot started reviewing on behalf of makr-code March 14, 2026 06:14 View session

Copilot AI reviewed Mar 14, 2026

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feat(replication): Multi-Tier Replication Manager (v1.8.0)#4203

feat(replication): Multi-Tier Replication Manager (v1.8.0)#4203
Copilot wants to merge 2 commits intodevelopfrom
copilot/implement-multi-tier-replication

Copilot AI commented Mar 13, 2026 •

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Description

Type of Change

Testing

📚 Research & Knowledge (wenn applicable)

Checklist

Goal

Detailed Scope

Multi-Tier Replication

Acceptance Criteria

Relationships

References

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Copilot AI commented Mar 13, 2026 •

edited

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