Modules Overview

Simba is organized as a multi-module Gradle project. Each module has a focused responsibility, from core abstractions to backend-specific implementations and Spring Boot auto-configuration.

Module Dependency Graph

graph TB
    subgraph sg_24 ["Build & Analysis"]

        BOM["simba-bom"]
        DEPS["simba-dependencies"]
        CR["code-coverage-report"]
    end
    subgraph sg_25 ["Application"]

        EX["simba-example"]
    end
    subgraph sg_26 ["Spring Boot"]

        STARTER["simba-spring-boot-starter"]
    end
    subgraph sg_27 ["Backend Implementations"]

        JDBC["simba-jdbc"]
        REDIS["simba-spring-redis"]
        ZK["simba-zookeeper"]
    end
    subgraph sg_28 ["Core"]

        CORE["simba-core"]
        TEST["simba-test"]
    end

    CORE --> DEPS
    JDBC --> CORE
    REDIS --> CORE
    ZK --> CORE
    STARTER --> CORE
    STARTER -.->|"springRedisSupport"| REDIS
    STARTER -.->|"jdbcSupport"| JDBC
    STARTER -.->|"zookeeperSupport"| ZK
    TEST --> CORE
    EX --> STARTER
    CR --> JDBC
    CR --> REDIS
    CR --> ZK
    CR --> STARTER
    CR --> CORE
    CR --> TEST

    style BOM fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style DEPS fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style CR fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style EX fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style STARTER fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style JDBC fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style REDIS fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style ZK fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style CORE fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style TEST fill:#2d333b,stroke:#6d5dfc,color:#e6edf3

Module Catalogue

Module	Role	Key Types	Dependencies
simba-core	Core interfaces, abstract classes, value objects	MutexContender, MutexContendService, SimbaLocker, AbstractScheduler	kotlin-logging, cosid-core, guava
simba-jdbc	JDBC/MySQL backend with optimistic locking	JdbcMutexContendService, JdbcMutexOwnerRepository	simba-core, JDBC driver
simba-spring-redis	Redis backend with Lua scripts and pub/sub	SpringRedisMutexContendService, Lua scripts	simba-core, spring-data-redis
simba-zookeeper	Zookeeper backend using Curator LeaderLatch	ZookeeperMutexContendService	simba-core, curator-recipes
simba-spring-boot-starter	Auto-configuration for all backends	SimbaJdbcAutoConfiguration, SimbaSpringRedisAutoConfiguration, SimbaZookeeperAutoConfiguration	simba-core + conditional backend deps
simba-test	TCK (Technology Compatibility Kit)	MutexContendServiceSpec, LockSpec	simba-core, JUnit 5
simba-bom	BOM (Bill of Materials) for version management	--	--
simba-dependencies	Dependency version constraints	--	--
simba-example	Example application	ExampleApp	simba-spring-boot-starter
code-coverage-report	JaCoCo aggregated report	--	all modules

Backend Comparison

graph LR
    subgraph sg_29 ["JDBC Backend"]

        J_REPO["MutexOwnerRepository"]
        J_SCHED["ScheduledThreadPoolExecutor<br>(polling)"]
        J_DDL["simba_mutex table<br>optimistic locking"]
    end
    subgraph sg_30 ["Redis Backend"]

        R_LUA["Lua Scripts<br>acquire/guard/release"]
        R_PS["Pub/Sub<br>RedisMessageListenerContainer"]
        R_ZSET["Sorted Set<br>contender queue"]
    end
    subgraph sg_31 ["Zookeeper Backend"]

        Z_LATCH["LeaderLatch<br>/simba/{mutex}"]
        Z_CUR["CuratorFramework"]
    end

    style J_REPO fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style J_SCHED fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style J_DDL fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style R_LUA fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style R_PS fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style R_ZSET fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style Z_LATCH fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style Z_CUR fill:#2d333b,stroke:#6d5dfc,color:#e6edf3

Feature	JDBC	Redis	Zookeeper
Coordination mechanism	Poll with ScheduledThreadPoolExecutor	Lua scripts + pub/sub	Curator LeaderLatch
Lock storage	simba_mutex table	Redis key (simba:{mutex})	ZNode (/simba/{mutex})
Ownership transfer	Optimistic locking via version column	Sorted set wait queue + pub/sub notification	ZK watcher on latch participants
Time source	MySQL current_timestamp(3)	System clock (client-side)	ZK server time
External dependency	MySQL instance	Redis instance	ZooKeeper ensemble
Best for	Existing relational DB infrastructure	High-throughput, low-latency	Strong consistency guarantees

Gradle Feature Variants

The simba-spring-boot-starter uses Gradle feature variants so consumers only pull the backend dependency they need:

dependencies {
    // Pull only the Redis backend
    implementation("me.ahoo.simba:simba-spring-boot-starter") {
        capabilities {
            requireCapability("me.ahoo.simba:spring-redis-support")
        }
    }
}

Available feature variants:

Variant	Capability	Backend Module
springRedisSupport	me.ahoo.simba:spring-redis-support	simba-spring-redis
jdbcSupport	me.ahoo.simba:jdbc-support	simba-jdbc
zookeeperSupport	me.ahoo.simba:zookeeper-support	simba-zookeeper

See Also

• simba-core -- core abstractions and design patterns
• simba-jdbc -- JDBC/MySQL backend
• simba-spring-redis -- Redis backend
• simba-zookeeper -- Zookeeper backend
• simba-spring-boot-starter -- Spring Boot auto-configuration
• simba-test -- TCK test base classes