architecture

Transaction Module

Stand: 6. April 2026
Version: v1.3.0
Kategorie: 🧩 Architecture

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📑 Inhaltsverzeichnis

• Übersicht
• Source-Code Referenz
• Implementierte Klassen
• Beispiel
• ACID-Garantien
• Write-Write Conflict Detection
• Verwandte Dokumentation

Übersicht

Das Transaction-Modul implementiert vollständige ACID-Transaktionen mit MVCC (Multi-Version Concurrency Control) für ThemisDB.

Source-Code Referenz

Komponente	Header	Source	Beschreibung
TransactionManager	transaction_manager.h	transaction_manager.cpp	MVCC Manager
Transaction	transaction_manager.h	transaction_manager.cpp	Transaktions-Handle
Saga	saga.h	saga.cpp	Distributed Transactions

Gesamt: 2 Header, 2 Source-Dateien, ~900 LOC

Implementierte Klassen

TransactionManager

class TransactionManager {
    using TransactionId = uint64_t;
    
    struct Status {
        bool ok;
        std::string message;
        static Status OK();
        static Status Error(std::string msg);
    };
    
    // Begin Transaction
    Transaction begin(IsolationLevel level = IsolationLevel::ReadCommitted);
    
    // Statistics
    size_t activeTransactionCount() const;
};

Transaction

class Transaction {
    // Metadata
    TransactionId getId() const;
    IsolationLevel getIsolationLevel() const;
    std::chrono::system_clock::time_point getStartTime() const;
    uint64_t getDurationMs() const;
    bool isFinished() const;
    
    // Relational Operations
    Status putEntity(std::string_view table, const BaseEntity& entity);
    Status eraseEntity(std::string_view table, std::string_view pk);
    
    // Graph Operations
    Status addEdge(const BaseEntity& edgeEntity);
    Status deleteEdge(std::string_view edgeId);
    
    // Vector Operations
    Status addVector(const BaseEntity& entity, vectorField = "embedding");
    Status updateVector(const BaseEntity& entity, vectorField = "embedding");
    Status removeVector(std::string_view pk);
    
    // Commit/Rollback
    Status commit();
    Status rollback();
};

Isolation Levels

enum class IsolationLevel {
    ReadCommitted,  // Default: nur committed data sichtbar
    Snapshot        // Snapshot Isolation (point-in-time consistency)
};

Beispiel

TransactionManager tm(db, secIdx, graphIdx, vecIdx);

// Begin Transaction
auto txn = tm.begin(IsolationLevel::Snapshot);

// Multi-Model Operations
txn.putEntity("users", userEntity);
txn.addEdge(followsEdge);
txn.addVector(embeddingEntity);

// Commit
auto status = txn.commit();
if (!status.ok) {
    // Automatic rollback on error
    std::cerr << status.message << std::endl;
}

ACID-Garantien

Property	Implementation
Atomicity	RocksDB WriteBatch (alle oder keine)
Consistency	Index-Updates in gleicher Batch
Isolation	MVCC mit Snapshot Isolation
Durability	WAL (Write-Ahead Log)

Write-Write Conflict Detection

// Bei Konflikt:
// - Transaction A: UPDATE users SET name='Alice' WHERE id=1
// - Transaction B: UPDATE users SET name='Bob' WHERE id=1
// → Transaction B wird mit CONFLICT abgebrochen wenn A zuerst committed

Verwandte Dokumentation

• Features: Transactions - Feature-Details
• Architecture: MVCC - MVCC-Architektur
• Research: Git/GitHub/GitOps Vergleich - Vergleich zur Versionskontrolle